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Old 04-27-2012, 08:34 PM   #1
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Default Axle weight capacity (GAWR)

I hope this will become a discussion thread, where we can gather info, and post up solutions and improvements related to the rear axle of our Class B RVs.

I will come back to this first post, and add data, as it becomes available.

Gross Axle Weight Rating (GAWR).
Different axles have different GAWR's. From light duty cars up to huge military vehicles and earth movers.
Our Class B RVs typically have an axle for a 3/4 Ton or 1 Ton application.

First data point is:

From WikipediA:

Dana 60
Manufactured in both full float and semi float variations. The semi float axles have GAWR up to 5,500 lbs and the full float axles were rated up to 6,500 lbs.


Info from Booster:
The Dana 60 in the Chevy Roadtreks is actually a Dana Super 60 semi-floater. As near as I have been able to find out, the main differences are two extra bolts in a beefier rear cover (12 bolts compared to 10) to make it more structural, and bigger tubes and wheel bearings. Maybe some other internals, but hard to say.

The information on actual axle maximum load is very hard to find and sketchy, but it looks like most are saying right around 6K pounds, so the 6082# on the Chevy rating plate is pretty close and is equal to the tire maximum rating.
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Old 04-27-2012, 08:35 PM   #2
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Default Re: Axle weight capacity (GAWR)

Gross Axle Weight Rating (GAWR).
Different axles have different GAWR's. From light duty cars up to huge military vehicles and earth movers.
Our Class B RVs typically have an axle for a 3/4 Ton or 1 Ton application.

In this group, there are Semi-Floating and Full-Floating axles.
Visually, the semi floating axle, is almost flush, across the wheel mounting surface.



The full-floating axle, has a large hub protruding from the middle of the wheel mounting surface.


The full-floating axles almost always have a higher GAWR than the semi-floaters.

Ours R/T 190, Chevy Express 3500, has a semi-floating axle, that I believe is a Dana 60 (need to confirm).


From WikipediA:

Dana 60
Manufactured in both full float and semi float variations. The semi float axles have GAWR up to 5,500 lbs and the full float axles were rated up to 6,500 lbs.


5500 pounds!!! Is that all???

At 5400# on the rear axle, our R/T is nearly at full axle capacity of 5500#. It is over the spring capacity of 4970#.

Does anyone have any other info on the rear GAWR for these Class B RV's? There is a tag in the driver's door jam, that may say what the front & rear GAWR is for your rig.
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Old 04-27-2012, 09:25 PM   #3
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Default Re: Axle weight capacity (GAWR)

I think that if you got the optional transmission cooler/limited slip option it was a beefier rear end, but not certain. Ours is just like yours.
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Old 04-28-2012, 11:25 PM   #4
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Default Re: Axle weight capacity (GAWR)

I looked at the door stickers on our van today, and both the Roadtrek sticker and the Chevy sticker list the rear axle capacity at 6084#, and we have a semi-floater. The 6084 is the max tire capacity, so the actual rear end maximum could be more.
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Old 04-30-2012, 07:43 PM   #5
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Default Re: Axle weight capacity (GAWR)

I took a couple photos of the markings on the differential housing. The axle in our fan is definitely a Dana 60. Most of the info I can find out about the Dana axles show the 60 will have a casting number of "60" or "248".

This is where to look on a Dana axle, for the various markings.


This is not an easy spot to see, under a Roadtrek. The generator gets in the way. The photo below shows the view from under the generator, looking forward, at the rear axle. You can see the casting number on the casting. The tube in the upper left is the generator exhaust. The tube at the bottom is the sway bar we added.


A closer view of this casting number shows it to be "248"


As posted earlier, the Dana 60, with a Semi-Floating axle, has a GAWR of 5500 pounds. If it were a Full-Floating axle, the GAWR would be 6500 pounds.

Now I need to check my door sticker, and see what it says.
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Old 03-21-2015, 08:17 PM   #6
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Default Re: Axle weight capacity (GAWR)

I ran across this thread when I was looking for information as to what axle Roadtrek uses when you get the trailer towing package. I still don't know what they use, however, but can shed a little light on some of the questions in this discussion, as we have been looking at an axle swap.

The Dana 60 in the Chevy Roadtreks is actually a Dana Super 60 semi-floater. As near as I have been able to find out, the main differences are two extra bolts in a beefier rear cover (12 bolts compared to 10) to make it more structural, and bigger tubes and wheel bearings. Maybe some other internals, but hard to say.

The information on actual axle maximum load is very hard to find and sketchy, but it looks like most are saying right around 6K pounds, so the 6082# on the Chevy rating plate is pretty close and is equal to the tire maximum rating.

We hear of failures, but not all that many, I think, so they are getting by with the axle, although it was originally beefed up to take it from a 1/2 ton axle to a 3/4 ton axle, and is now on fully loaded 1 tons. The wrong offset wheels, if you have them, also put more load on the wheel and carrier bearings. Again, though, less failures than I would expect----except for us and some other 2007 vintage folks I have read about. There was likely a bad run of the big cast housings in that time frame, which caused early failures. Ours was rebuilt by GM at 5600 miles with all new guts, including gearset. We are now at 27K miles and it is getting a little noisy when the power is on. I wasn't all that concerned right away because all rear drives whine a little here and there, but when I had it in to be aligned, the tech drove it and said he thought the pinion bearings were going, or were loose, because it whined at all speeds when accelerating. I took it to a couple driveline guys and they said the same (as does the factory manual). They said if it were only at particular speeds, it would not be bad, but at all speeds probably is. Didn't know that. The oil is staying clean, so it is not at immanent death mode, but not pristine either. We have been kind of paranoid after the first failure so early, and that other 2007s that I have heard about got rebuilt twice under warranty, failed again and were replaced with a complete axle, housing and all, that finally fixed them permanently.

As near as I have been able to find out, GM used three axles in the one tons. The Dana Super 60 semi-floater 9.75" ring gear, the Dana Super 70 full floater 10.5" ring gear, and probably an American Axle (often called GM corporate) full floater, 11.25" ring gear (I have not been able to actually find one, though, and it may only be on cutaways). It may also be a Dana 80 in the 11.25".

Our fear is that we will have a failure on the road, and have to put $1500+ in the one we have, and it will probably still fail again besides. Since we have higher capacity tires and suspension, it made sense to look at getting the axle capacity up also, rather than just getting another Super 60 to put in complete. Most sources I found put the capacity of the Dana Super 70 at about 7500#, so that looked pretty good to me. The driveline guys I talked to all said that at 6000# load, you should not be on a sem-floater, and didn't really have much bad to say about the Super 70. The did prefer the 10.5" GM corporate that was used in previous models, for some nice features and aftermarket parts availability, but said both were extremely durable in a one ton.

When I started looking for a used, complete Super 70 with 4.10 gears, it became obvious they are a bit rare, and at least 50% more cost than the 3.73 versions in most cases. There is a carrier gear split at 4.10, so if you get a 3.73 and try to change gears, you can just put in a rear gear and pinion set. That wouldn't be bad, if you were going to add a posi unit you would need to change the carrier also, but it turns out there are no real "streetable" posi units for the Dana's in the aftermarket. All that you can get are the old plate clutch, always engaged, units that are so wicked scary on the slippery roads, or a very expensive air, electric, or cable locker. What is very interesting is that GM put auto lockup differentials into the Dana differentials. That lockup differential is made for them by Spicer, but you can't buy them outright. If you have one, you can get service parts from GM for them. Long story short, searched for a Dana Super 70, 4.10 gears, with the GM posi, which is really an auto locker called Gov-lock and only engages when you need it, and never about 20mph, so it very safe for the street.

It is interesting the most of the Dana 70s I found were cheaper than the Dana 60s, so they must sell few 70s and lots of 60s, which makes sense.

We now have one on the way that will get here in about a week. 84K miles on it out of a 2004. I don't have the setting tools and bearing and seal drivers for this style, so will take it in to have new seals, bearing inspection, and setup check. At 84K everyone said the bearings and gearset should be fine and good for 200K more minimum, so we will see, but it 10 year old, so seals are for sure.

Indications are that it is close to a drop in, although a very heavy one. It will need different rotors to clear the big floater hubs, but the driveshaft is listed as the same on the interchange charts, so we will see. Might need different u-joints, but couldn't find that out. All the other brake parts look to move right over.

Hopefully, this will put our insecurities to rest about recurring issues, and maybe the locker will make us a bit more mobile around the beaches and forests.
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Old 03-21-2015, 10:19 PM   #7
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Default Re: Axle weight capacity (GAWR)

Way beyond my skill set

So you have a Dana Super 70, 4.10 gears, with GM posi-traction on the way? I think you've wanted to do this upgrade for a while.

The '04 RT we owned had the 4.10 ratio, locking differential & external transmission cooler. I have no idea what axle was used. Maybe someone with the tow package option will see this topic and post the info for future reference.
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Old 03-21-2015, 10:27 PM   #8
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Default Re: Axle weight capacity (GAWR)

Quote:
Originally Posted by markopolo
Way beyond my skill set

So you have a Dana Super 70, 4.10 gears, with GM posi-traction on the way? I think you've wanted to do this upgrade for a while.

The '04 RT we owned had the 4.10 ratio, locking differential & external transmission cooler. I have no idea what axle was used. Maybe someone with the tow package option will see this topic and post the info for future reference.
It sounds like the 04 you had was a towing package Roadtrek, as the posi and cooler were what made it so. Do you recall if it was a full floater?
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Old 03-21-2015, 10:41 PM   #9
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Default Re: Axle weight capacity (GAWR)

Sorry, don't know. I didn't know the difference between full & semi floater back then.
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Old 03-22-2015, 02:51 AM   #10
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Default Re: Axle weight capacity (GAWR)

These guys make parts for the dana 60/S 60 that are darn near bulletproof. The S 60 is a Dana 60 manufactured by Strange Engineering.

http://www.strangeengineering.net/high- ... nents.html

Many of them are limited slip, and they also sell gears too. Or if you want to spend, you can buy a complete unit.

http://www.quadratec.com/ also sells differential parts too. Yes they are designed for Jeeps, but many parts will work in the Dana 60.

One thing that you haven't touched on yet though. You could upgrade your suspension, but the data plate still retains the old info. If you got pulled over and ordered to go to a scale they would fail you because they use the data plate info. It is possible to get a new data plate, but you'd have to pay to have the vehicle certified for that new weight. From what I understand this is different in the US and maybe other parts of Canada, I can only speak about Manitoba.

You should also upgrade brakes and tires if you were going to increase your GAWR/GVWR.
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Old 03-22-2015, 03:23 PM   #11
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Default Re: Axle weight capacity (GAWR)

Quote:
Originally Posted by Bruceper
These guys make parts for the dana 60/S 60 that are darn near bulletproof. The S 60 is a Dana 60 manufactured by Strange Engineering.

http://www.strangeengineering.net/high- ... nents.html

Many of them are limited slip, and they also sell gears too. Or if you want to spend, you can buy a complete unit.

http://www.quadratec.com/ also sells differential parts too. Yes they are designed for Jeeps, but many parts will work in the Dana 60.

One thing that you haven't touched on yet though. You could upgrade your suspension, but the data plate still retains the old info. If you got pulled over and ordered to go to a scale they would fail you because they use the data plate info. It is possible to get a new data plate, but you'd have to pay to have the vehicle certified for that new weight. From what I understand this is different in the US and maybe other parts of Canada, I can only speak about Manitoba.

You should also upgrade brakes and tires if you were going to increase your GAWR/GVWR.
All very true, and I had looked at the Strange site, as many people I know have their axles in the Mopar Dana 60 rears in their muscle cars. What they can't do anything about is all the weight that is on the axle in a semi-floater. They also have access only to the limited slip, clutch type, full time setups and don't use the GM setup that I know of.

As I mentioned, there aren't wholesale failures if the Super 60s in the Roadtreks, except in the build range of ours (2007). Rebuilds also seem to hold up better in the other years also, so it appears that there is something up with the 2007s. When I was making the rounds of dealers and driveline shops two different places (the GM dealer and a pickup truck hotrod shop) both said that in 2007 both Jeep and Ford had similar trouble with Dana axles that required complete replacements including housing.

For us, going to the bigger axle was kind of icing on the cake more than necessity, as others show that the Suprer 60s mostly do survive. But as long as we need to replace the complete axle there really isn't an good reason I can think of not to go the heftier setup, especially since (in used axles) the price is the same or less for the Super 70.

I got the van weighed last week. All tanks full, which never happens in real life, but only the camping things that stay in the van inside, no clothes or food. It came in at 4220# front and 5120# rear, with a rating plate of 4300/6082#, so we have some room, especially in back. Total is not quite a nice, as we only have 260# to the 9600# gross. Less in the tanks will help the front a lot, and there is a lot of room in the rear. I think we will easily stay within on axle weights, and close on gross. The new axle will be some heavier, don't know exactly how much, so that will go to our rear axle and gross weight, even though the only item that sees the extra weight is the tires and wheels.

We do have higher capacity tires with the correct wheels, so we have 6830# of tire capacity per axle. The rear axle rating of the 3500 Express is the same as the tire rating at 6082, so that is the limiting factor in the stock rear. We have 700# of increased front spring capacity, 5000# of airbag capacity in the rear. The brakes haven't been made larger in size, but have been upgraded to (IMO) some of the best high performance truck brakes around, from Hawk Performance.

I don't know about rerating in the States, I have actually never heard of anyone doing it in this low of a load range, but it certainly might be something to look into. We have never been force weighed, or heard of anyone who has, so I would be more concerned about liability issues in an accident. My guess is that we would pass pretty easily, if the rules aren't nuts, but you never know on that one.

I was looking the factory repair manual yesterday to see if I need to get any special tools for the wheel bearing adjustment on the Super 70, and also looked at the Super 60 to see how they did it on them. No wheel bearing adjustment on the 60s, not surprising as our axles move in and out a fair amount. No lubrication instructions either, so I assumed the standard pressed on the axle sealed bearing. Nope, when I looked up the bearing, it is a no inner race roller bearing, non sealed. It actually uses the axle shaft for the inner race and is lubricated by the differential oil that runs down the axle shaft. I you eat a bearing, you also have to buy an axle, unless the carnage is light enough to use some of the offset "repair bearings". I have never run across that kind of setup before, but most of what I have seen are much light duty stuff.

Time to look at rerating rules and see what is up with that. It would be kind of fun to have a one of a kind load rating plate!
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Old 03-22-2015, 10:22 PM   #12
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Default Re: Axle weight capacity (GAWR)

I should have been a bit more clear on the forced weighing.

It probably won't happen ever if you're just driving your B around. But if you're towing a trailer or boat it could happen, especially if there's any sag in the back end.
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Old 03-22-2015, 10:52 PM   #13
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Default Re: Axle weight capacity (GAWR)

Quote:
Originally Posted by Bruceper
I should have been a bit more clear on the forced weighing.

It probably won't happen ever if you're just driving your B around. But if you're towing a trailer or boat it could happen, especially if there's any sag in the back end.
Oh yeah, we have seen some very "interesting" towing situations pulled over by the authorities!

thanks for the clarification.

I did take a look at the rules in the states for getting re-rated, and it doesn't look doable for an individual. The sticker ratings are considered recommendations here, however, so probably no legal mess that way unless it was so bad they put it under dangerous vehicle or some sort of rule. The exception would be having the tires overloaded, from what I was able to find, and they will pull you off the road for that. That is an individual wheel weight measurement, which is hard for us to do, but we should be way under on that.
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Old 04-02-2015, 12:26 AM   #14
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Default Re: Axle weight capacity (GAWR)

A Dana 70 has a monster size differential housing. Any idea how much the ground clearance will change under that particular point?

There is a factory axle that can be purchased from GM that bolts straight in. It has everything already installed, including brakes. Last time I looked, I think it was about $3,500.

I have been considering a GM 14-Bolt, full floater. It is a standard axle on many GM 3500 and some 2500 pickup trucks. There are a ton of aftermarket lockers and LSDs for the 14-bolt axle. I just don't know if any of the models are wide enough for the van application.

@Booster: Do you have a thread documenting the axle work and install?
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Old 04-02-2015, 01:30 AM   #15
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Quote:
Originally Posted by Photog
A Dana 70 has a monster size differential housing. Any idea how much the ground clearance will change under that particular point?

My guess is that it will lose about 3/8", which is the same as the rear cover moved to the rear. It is 1/2 of the ring gear diameter size (10.5 instead of 9.75) so that makes sense. The location of the pinion u-joint looks to be the same, so that is good. The Super 70 is big, but not huge, and I read that it is made of nodular cast iron instead of grey cast, so the casting can be thinner and lighter. It doesn't really seem heavier than the 60.

There is a factory axle that can be purchased from GM that bolts straight in. It has everything already installed, including brakes. Last time I looked, I think it was about $3,500.

That is interesting, because I checked at the Chevy dealer before I ordered the used one. They said the only complete axles they can get are for current model year and only if warranty. Was the one you saw through GM Performance, maybe?

I have been considering a GM 14-Bolt, full floater. It is a standard axle on many GM 3500 and some 2500 pickup trucks. There are a ton of aftermarket lockers and LSDs for the 14-bolt axle. I just don't know if any of the models are wide enough for the van application.

As I mentioned in a previous post, my first choice would have been the 14 bolt, 10.5", corporate full floater. What I ran into is that they did not use them after 2002 when they went to disc brakes in the rear. Before that they were common in the vans (Marko has one). That gets you down to the Dana 70 or 80 if you want a full floater and more capacity in the age of our vans. I think they may have gone back to the 14 bolt for the full floater (I think the current semi-floater is probably the 9.5" 14 bolt) in 2009 and up when they went with the 6 speed trans and 3.42 gears, but not sure and didn't pursue it. The vans are a different width than all the other trucks, it appears. The driveline shop did a full crossover check, and couldn't find anything that would fit.

On edit-One thing that I forgot to mention that caused me all kinds of grief and confusion, and probably cost money at the same time. When I tried to use the "part finder" features on junk yard sites, that check the whole country network of yards, none of them would come up with the 10.5" axle with the 4.10 gears for a single wheel full floater, only 3.73. I called a few, and got the same information from them, that if it did exist, they couldn't find it. A huge light to heavy truck yard and rebuilder in Iowa said he didn't know how he would even find one, and questioned if they really existed. When I mentioned they were on ebay, he said that might be the only option other than calling all the individual yards. Most of the units on ebay were in the north, so condition is an issue. Ours was very rusty, with ebrake parts totally rusted solid. The rest is rusty, but OK, once I get all the rust off of the rotor/wheel mounting surface so I can get good runout. The bad finder information makes the whole search a lot more difficult.

@Booster: Do you have a thread documenting the axle work and install?

I have taken a few pics along the way, but not a lot. It is all pretty straightforward and bolt in. I have spent more time cleaning up and checking out the used (very rusty) replacement than in the swap itself. I did yield to my paranoia and took the housing with the gears in to the driveline guys for an opinion of anything needed (just a pinion seal) and then let them set the preloads and pattern. I wasn't confident as to how to handle setting up the used bearings, and what preloads to use. They were also so very helpful in getting all the information for me, so I felt I really owed them some business. Great guys. As of right now, the axle is totally in place, and the only change I had to make was to put 3/8" of spacer in my swaybar mounts. Used our parking brake parts, which bolted right on without issue. Used our pinion flange to maintain balance. Everything else has bolted right up. I would be completely done, but the full floater uses different rotors, and that allowed us to get the nice Hawk rotors for it. Unfortunately, Hawk is changing their design to foo-foo drilled and slotted appearance rotors, so it has been a bit hard to find the original style. I have some on the way now that should show up early next week
I don't know what type of limited slip/locker you are looking for, but with the Dana, it can get a little weird. The standard Dana plate and clutch type is available readily in the aftermarket, but not on the OEM installation, it appears. In the OEM install, you get a Gov-Lock locker. The only way to add a Gov-Lock to an open setup is to find a used or rebuilt one to put in. Neither Dana or GM will sell a new one into the aftermarket for a Dana Super 70. If you have the VIN that a used one (like ours) came out of, GM supplies repair parts for them. I didn't want a standard limited slip or locker, as they can be so wicked on ice or other slippery surfaces, especially at highway speeds. The Gov-Lock acts like an open diffy until you get 100 rpm difference in wheel speed, and then it locks them together. That makes it better is you are stuck and one wheel has almost no traction, and since it won't lock over 20 mph, you are much safer. We did have to pay substantially more to find a 4.10 geared unit with a Gov-Lock, though.

I will probably just put the pix up on this thread when it is all done, hopefully next week.
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Old 04-04-2015, 10:28 PM   #16
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Default Re: Axle weight capacity (GAWR)

The Super 70 Dana full floater is in place and ready to go as soon as the rotors get here. It really doesn't look out of place once it is in the van. The center housing is a bit wider and different shape, and wheel hubs are about all that give it away as being different. The bigger ring gear moves the cover back 3/8", so there is a spacer needed in the swaybar mountings. From the front side, there is a big bulge in the top of the case for the ring gear also, that the Super 60 doesn't have.









I would guess the actual swapping of the axle assemblies was only about 10 hours. I had substantially more time than that in checking out the junk yard axle and dealing with the rust on it. Getting the rotor locating surfaces, and wheel mounting area clean took many hours and lots of rust remover and sanding. It would have gone a lot faster if I hard pressed out the studs, but I really hate to do that as they often get messed up for straight going back in. Here is a hub after getting it cleaned up in the important areas. The flat face and the diameter right next to it are for the rotor, the wheel locates on the next step, smaller diameter and sets against the rotor, just like on the old axle. The discoloration is staining from the rust remover and baking soda neutralizer and doesn't affect the locations. You can also see the 1/8" NPT pipe plug I put in the hub so I could drain and fill the hubs without removing them at future oil changes.



The parking brake assembly that was on the Super 70 when it showed up.



Luckily the ones on the Super 60 in the van were identical, so they went right on perfectly



Wheel bearing pictures on next post.
Attached Images
File Type: jpg super70 rear.jpg (54.5 KB, 418 views)
File Type: jpg S70 dside front.jpg (56.2 KB, 416 views)
File Type: jpg S70 pside front.jpg (49.4 KB, 412 views)
File Type: jpg S70 pside end and pbrake.jpg (56.5 KB, 416 views)
File Type: jpg hub cleaned with drain.jpg (44.1 KB, 414 views)
File Type: jpg S60 pbrake.jpg (48.9 KB, 413 views)
File Type: jpg Pbrake S70.jpg (55.9 KB, 414 views)
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Old 04-04-2015, 11:02 PM   #17
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The wheel bearing area is where the difference of the semi floater vs full floater is the big deal, especially in load capacity and durability.

In the Super 60 semi floater, it appears they ran out of room for big enough bearings to support the weight they wanted. They use a single bearing that is lubed by the differential oil, which is the first time I have run across that. The smaller ones I have worked on all had pressed on axle sealed bearings. The bearings appear to be a cageless, full compliment roller bearing, with no inner race. They use the axle for the inner race. Not what I had expected to be sure. The wheel centerline is about 1" outboard of the bearing, so the bearing sees increased load and the axle bending forces. Because it is a straight roller bearing, it takes up no cornering loads at all, and all those forces are transferred to the carrier bearings in the differential, through C clips that hold the axles in. The carrier bearings see extra load from both the wheel being outside the wheel bearing and from the corning forces (or wind, or road crown). The C clips are very thick and locate inside the carrier axle gears to hold them in place in a groove in the axle. There is some clearance in all those parts, so the axles are free to move in and out about 3/32" which is a bit weird the first time you notice it.



The full floater uses a hub similar to a front hub, with two big tapered roller bearings in each hub. The hub is much larger than the axle tubes (which are the same size on both the Super 60 and 70) so they have lots of room for bearings. The inner races of the wheel bearings run on the housing instead of the drive axle and then the axle is bolted to hub. All the wheel weight is transferred to the housing instead of the drive axle, as is the side force from cornering and such, so the drive axle sees nothing but torque and no bending loads. No force is transferred to the differential carrier bearings either. The wheel centerline is about 1" outboard of the inside wheel bearing which is the largest, and further from outboard smaller bearing. The weight is between the bearings so the don't see any overhung loads.





You lightly grease the wheel bearings when you put them in, but they run in differential oil once it gets out to them in use. With drain/fill plugs in the hubs, I was able to fill them with oil, so there will be no delay in getting oil to them. The truck guys and driveline shops will jack up one side of the vehicle at a time and let it sit a couple of hours each way to fill the hubs, and I really didn't want to get into that routine.
Attached Images
File Type: jpg S60 wheel brg.jpg (36.9 KB, 377 views)
File Type: jpg S70 wheel brg outer.jpg (45.6 KB, 377 views)
File Type: jpg S70 wheel brg inner.jpg (56.9 KB, 374 views)
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Old 04-05-2015, 12:41 AM   #18
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Default Re: Axle weight capacity (GAWR)

That looks like a big job to me - must be very heavy. It looks pretty good all cleaned up but must have been a mess when you got it judging by the parking brake assembly. It also looks like you're nearing the end of the job.
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Old 04-05-2015, 01:18 AM   #19
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Default Re: Axle weight capacity (GAWR)

Too heavy to lift in by hand, or to even move around, so you either need some extra hands or lifts. The shipping papers showed it at 300#, but I think it was probably close to 400#. I used the cherry picker to move it around and set it on two sawhorses with a sheet of 3/4" plywood on them, but still held a lot of the weight on the picker. The hubs were the only rusty part that made a difference, that I had to use, the rotors and parking brake stuff got pitched as I didn't need them anyway. I was really glad the original parking brake stuff was the same.

When I put it in, I used my old scissor type transmission jack that is rated at 450#. I left the drive axles and hubs off, so the weight was almost all in the middle and very stable. It lifted it fine, and it only took about 10 minutes to have it mounted once I rolled it under.

I think in the big scheme of things, this is a pretty easy job, but you absolutely have to have the right tools and equipment or you are out of luck. Everything could be rented pretty easy, though. Cherry picker, transmission jack (or adapter for the floor jack), impact wrench and enough air to run it full power (if you have to take off all the ubolt nuts, ebrake brackets, etc by hand, you would be hurting by the end.

If I had more time before summer, I probably would have done a bunch more searching for a non rusty one, but with the national part finder being messed up that would be an major effort. There were some ebay sellers that were from Oregon and Washington, so if they had the right one, it would probably be a lot cleaner.

The good news, I think, is that not a lot of folks will need to convert to a full floater, and only a few more than that will need to totally replace the stock unit (they could get it rebuilt pretty easily). We were in the spot of having our original axle questionable (based on others in 2007 having to get complete replacements), so to prevent an on the road failure a complete replacement seemed a good idea. Since we were doing it ourselves, and it since the cost was similar, why not go to one with more capacity.

As a sidelight (bonus?) I now have the generator sitting on the floor so we can test how things will go this year without a generator
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Old 04-07-2015, 09:34 PM   #20
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Default Re: Axle weight capacity (GAWR)

Rotors finally showed up yesterday afternoon, so I have been messing with them. The rusty hubs did cause some runout issues, but I managed to use runout shims to get both sides within about .003" total runout. I prefer to get under .002 in most cases, but with 13" rotors that can be tough compared to the little 8" on the cars. We now have Hawk rotors to match the pads on both ends, although the Chevy rotors came out looking very good, so I think the pads are the biggest part of it.

Just got back from about 10 miles to bed the rear pads and see how things worked out. I think we got lucky on the gearset itself, and the driveline guy did a really good job of setup. The thing is essentially silent, quieter even than the Buick Roadmaster, and way quieter than the old one was even right after GM rebuilt it. Tiny amount of backlash so nearly no on/off clunk or slop. Shot the hub temps front and rear, and for the first time ever the rears were cooler than the front. Very happy with the results so far.

While I had stuff apart, I also took off the overload leafs from the rear springpacks and took them in and got them de-arched to about 1/2 of what the were. The goal was to get further than the 1/8" we had off the overload leaf in normal height driving (airbag set). We now have 1/4" or more on both sides between the overload and main spring, and the rear does seem to be riding quite a bit smoother than before, although based on a very small test drive. It will be interesting to see what we think when we get fully loaded and on a real trip. The de-arching itself was so simple, I was amazed. I thought they would do them hot, and run them through a curve roller set. Nope-100 ton hydraulic press with multiple bumps on spaced out parallels to put in a bunch of small bends to make the curve. It turns out that is how they make all their custom leaf springs, including very big ones for big trucks. The only time they heat is for the spring eyes, or 90 degree bends.

Total cost for both overload springs was $27 and they did it while I waited, and watched right in the shop. Great service!

We found a grass fed Bison ranch within about 100 miles of home, so as soon as we get some nice weather again we will take a run over to it and get some good Bison meat, and spend the night someplace there, to get a better test of the new rear, but looks good so far.
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