Gray Area 934 Midboard Bearing Preload Setup

J Alper said:
Must Be Gray Area, I have not seen a .050 spacer, for me i would Machine the Boot Flange on the High or load side to do the Preload, Machine the boot flange i feel is the best option, if it has a spacer in it now, you can send it to us and we can machine the flange, but that is how i would do it,
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Maybe you missed it but the .050 spacer is what I was sent either by you or GA along with the koyo replacement bearings. I was advised to use it between the hat and bearing. Sorry but I will do my own work as usual and get it right. I think I got a correct description of how tight these things should be from parker. I hope he,and you will do a simple test of the rotation torque your assembled hubs require . That info would settle this . At this point I think the description parker gave would be in the 30ish lb.ft. range. A far cry from what I believe my new hubs would have been in the 250+ area. 30-250+ is quite the spread.

As to LRS's points ,I agree assuming no damage to any bearingor cup bearing points,it's a no brainer. Clean inspect replace any damage and assemble. It is what it is for most people.
 
Thanks everyone for the input. Greatly appreciated.
 
@fabr Torque rant was long overdue before this thread existed and I did not exclusively mean it towards you. More to get it posted on the forums.

We test preload with no grease or seals. Just a light bearing oil.

I can not speak for Gray area hubs, They are quite different than ours.

But 30ft lbs greased and with seals seems about right, its best you reach out to GA to see what they recommend. Note this number may change slightly from "hub to hub" that is completely normal due to seals and amount of grease. (I was shocked how much the seals and grease increased the drag...)

Never a bad idea to document the "drag torque" that way you can check in between seasons.
 
it has been my experience there is no real reliable repeatable way to measure something like this ("drag" on a rotating item). overcoming the static friction to get it moving is dependent on too many things. grease, no grease type of grease, how much grease, how tight is the seal, how well does it sit against the item, does it change very time its assembled, 6 mounting bolts torqued in exactly the same order with the same amount of TQ @ each stage, lots of lock tight, a little lock tite, orientation of the spacers & the bolts/hub/CV, etc, etc, etc. can something be measured +/- 300% maybe............
 
G
parker@gearone said:
@fabr Torque rant was long overdue before this thread existed and I did not exclusively mean it towards you. More to get it posted on the forums.

We test preload with no grease or seals. Just a light bearing oil.

I can not speak for Gray area hubs, They are quite different than ours.

But 30ft lbs greased and with seals seems about right, its best you reach out to GA to see what they recommend. Note this number may change slightly from "hub to hub" that is completely normal due to seals and amount of grease. (I was shocked how much the seals and grease increased the drag...)

Never a bad idea to document the "drag torque" that way you can check in between seasons.
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Good info parker Thank you.
.
 
Bobalos said:
it has been my experience there is no real reliable repeatable way to measure something like this ("drag" on a rotating item). overcoming the static friction to get it moving is dependent on too many things. grease, no grease type of grease, how much grease, how tight is the seal, how well does it sit against the item, does it change very time its assembled, 6 mounting bolts torqued in exactly the same order with the same amount of TQ @ each stage, lots of lock tight, a little lock tite, orientation of the spacers & the bolts/hub/CV, etc, etc, etc. can something be measured +/- 300% maybe............
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I agreed with a bit of that but for the sake of argument,take the 300 percent as fact,that would only be 90. A lot less than 250+
 
Parker freggin rocks!!!!! That’s all I know.
 
A day spent not learning something new is a day wasted. :)

I have always been under the impression that bearings were made to a spec that was a constant from brand to brand. In other words a ll225749 /ll225710 from Timken or Koyo or whoever would for all intents and purposes be the same dimensionally . Apparently Koyo doesn't subscribe to that theory. LOL!! What I found is that the printed T stack specs for koyo may or may not be correct depending on when made. When looking up the T stack dimension for timken and koyo the spec is identical currently. Unfortunately koyo did make some with a noticibly different t stack dimension. That is why I had to do a mod,as instructed, to the boot flange offset and use the spacer to use the koyos that GA provided as replacements for the india/chinese/whatever the hubs came with. Long story short ,I reassembled the hub with the koyos and spacer as it was running. Lo and behold the turning torque with the used bearings was only 12 lb.ft. I will do a bit of machining to return the boot flange to original spec so both hubs match and only use Timken bearings in the future to avoid this BS .

For those that have GA hubs,if the bearings are koyo , be very careful if needing to replace one or both bearings as they may be thicker/thinner than the ones being replaced even if using koyo to replace koyo. If timken you should be good to go but verify.

Bottom line is that the cv bolts NEED to be torqued to 100-110 lb.ft. and if it takes more than moderate effort to turn the hub then it is too tight and needs addressed.None of this needing a long bar to turn and letting them loosen up on their own. I guarantee the bearing and cup will suffer from that. With the timkens there is a dimension for both the hat offset and boot flange offset that will give the correct preload.

Now that GA is under new ownership I hope this will not continue to be an issue with new product.

For what it is worth , anyone that claims it is proper to use cv bolt torque of a lesser value to set preload,they are just wrong. Very wrong . The cv must be firmly sandwiched between the hat and boot flange with proper 1/2" bolt torque or the cv is just floating between and that is bad. Cv bolts coming loose or breaking will be the result and the root cause for even needing loctite or safety wire. As parker indicated above preload will not change with torque after all clearance is gone from between the cv and hat/boot flange to allow correct bolt stretch. Doesn't matter whether 100 or 1000 lb.ft.. Less than 100 will not give the bolt stretch needed to keep the cv bolt tight. Bolt stretch is just as important to a cv as a rod bolt is to a rod.

OK,rant over.:)
 
So,what are the consequences of way too much preload a person might ask. Here are a few pics that show the onner and outer race being bound up so bad the inner race and bearing were locked together for enough time to actually spin the inner race on the hat and the boot flange registers till enough wear occurred to allow the bearing to spin in the cup. This,of course,created wear that screws up tolerances badly. Blow up the pics and the evidence is obvious. I will need a new boot flange and hat to correct this issue now.

The pic on the left clearly shows the surface that the bearing inner race rides upon in the hat. It has eaten into the face approx. .025" and the vertical wall is also now undersize due to debris wearing it away apparently. I suppose I could machine a flanged "shim/washer/repair sleeve" that would restore the OD of the offset in the hat and save the hat but I'd rather just replace it unless GA wants $$$$$$$$ instead of $$$$. LOL!! The boot flange being steel shows the same was occurring but being steel it will be "OK".

The 2 pics to the right are of the bearings. Pics are just 2 different of the same bearings. Bearing to the left in each pic are of the bearing inner race that was eating away at the aluminum hat. The pics to the right in each pic is of the bearing that rides upon the steel boot flange. All 3 of the pics clearly indicate a bearing with way the hell too much preload(as in needing a 4 foot bar to rotate)and preventing the bearing from rotating in the inner race. The race was spinning until enough wear occurred to allow the bearing to finally rotate in the inner race properly.
I looked back and I bought these hubs about 8 years ago. I certainly do not expect GA to do anything being so long. Been running the car on and off for 4 years or so. It was a very long car build.Long story no one is interested in. LOL!! It would be nice to see a big fat discount though!;)

FWIW,this has been an expensive lesson to not just trust even a manufacturers word on how something should be when your gut says BS.

I just wanted to post the pics to hopefully save some others some $$$$. If anyone has some GA hubs ,at the very least , insist upon same brand bearings as come out of them to avoid this crap. If the same bearings are not available and you have to send the hubs in,I would be very,very disappointed if I was chatged for any machine work needed to get the preload right. THAT should be on them. IMO,of course that is worth less than $.02
:ROFLMAO:
 

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Bobalos said:
it has been my experience there is no real reliable repeatable way to measure something like this ("drag" on a rotating item). overcoming the static friction to get it moving is dependent on too many things. grease, no grease type of grease, how much grease, how tight is the seal, how well does it sit against the item, does it change very time its assembled, 6 mounting bolts torqued in exactly the same order with the same amount of TQ @ each stage, lots of lock tight, a little lock tite, orientation of the spacers & the bolts/hub/CV, etc, etc, etc. can something be measured +/- 300% maybe............
Click to expand...
One way to do it that I learned in high school diesel mechanics class is wrap a cord of some kind around the "hub" of whatever it is you want to measure and then pull it with a spring scale while watching it. Divide the measured force by the radius of the hub and you can get a pretty good estimate of the rolling torque. Obviously this won't work on anything that has excessive starting torque, and accuracy is dependent upon how good your scale is, but it works better than you might think if there is a physical way to do it on your assembly. I recall using it to set the cranshaft bearing preload of the air brake compressor on a diesel engine.
 
Good luck after Bruces Wife past away, Bruce lost interest, I tried to order some pulleys from gray area and they are out of them, not sure what the new owner is doing on brakes,
 
I am so glad we corrected the preload issue on the Tatum hubs I bought, they would have ground themselves to death in short order had we listened to Tatum and just "ran them until they loosen up". That is just a poor excuse from someone who just didn't care. Several years in now with the new correctly preloaded hubs and they are still firm to spin by hand.

Working for GM for 3 decades, I built A LOT of differentials, I would use a beam type inch-lb torque wrench to measure pinion rotating torque to determine what the bearing preload was. It was a very narrow specification, used bearings were 30-50 inch-lb and new bearings were 15-30. There was always a "breakaway" torque to get the bearing spinning that was not important, it was the rotating torque that mattered. Some techs just slapped them together and called it a day which typically meant the truck would return several thousand miles later with a noisy diff. and pitted pinion bearing races. I always set them up correctly, another 1/2 hour spent doing it right meant I'd never see the truck again. ;)

Someone needs to engineer a rear hub that is lubricated with oil rather than grease, bearings that rotate in an oil bath are much more protected thermally than those lubricated with just grease. Even the front wheel hubs on my Freightliner motorhome chassis are lubed with oil, but that is the topic of another discussion.
 
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I could not agree more KLC. You are spot on.

The aftermarket is filled with poorly designed parts with near zero actual QC other than aesthetics and it will not likely change. Why is that? I feel it is because there is less money made on well designed products and true QC. No endless maintenance and sale of replacement parts that are highly inflated price wise. It is not forced upon the makers of said parts since the vast majority of people using these inferior designed parts have no clue as to what is correct . They will always have bragging rights for the broken/damaged parts because their buggy has the "power to tear shit up" or the old"I really drive my shit hard and that is why I keep breaking whatever". No,the truth is that the damn $$$$ parts are shit to begin with and actually designed to need excessive maintenance and replacement $500 bearings and $80 and/or $45 seals. This topic is a perfect example of poorly designed crap from some well known ,even respected,builders. I'm not pointing any fingers ,they know who they are.

BTW,since I'm in the mood,those $500 Timken 934 mids bearings can be readily had (genuine Timken)for approx $175 depending on where bought and those $45 inner seals can be had for a whopping $9 ea.Yes,I just bought 10 for $9 apiece including shipping from the UK. Haven't looked for the $80 outer seal yet as I have 2 sets of the $80 ones on the shelf.Yes,we are getting hosed. I am sooooo tired of getting the hose. I am now on my 2nd set of mids,,and both are the same crap. No way to set preload without machining and the same old BS that they have to have way excessive preload or they will destroy themselves. What a joke,a very bad joke. I'm very fortunate to have lathes and mills to correct this shoddy crap. Most people are at the mercy of excuse makers/service providers for the manufacturers that profit from said crap designs and have no choice but to accept it.

All it would take to prevent most ,if not basically all,mid board bearing service would be a true inner seal instead of the nearly useless dust seal that is used and a simple shim set to set bearing preload. Those 2 very simple things would make hub bearing service almost a thing of the past. Yes,the cv would still need regular service and that could be done without any hub disassembly unless a cv needed replaced.. As to the oil bath for bearingssuggestion and also the cv in oil bath,that is doable. But since almost everyone running a conventional 930/934 midboard would never care it is not a viable option,IMO. From the price point now on mid hubs there really is no excuse for the improvements not being done. At the very least the preload should be set on each and every one going out the door whether new or freshly serviced. That obviously is not the case.
 
KLC said:
I am so glad we corrected the preload issue on the Tatum hubs I bought, they would have ground themselves to death in short order had we listened to Tatum and just "ran them until they loosen up". That is just a poor excuse from someone who just didn't care. Several years in now with the new correctly preloaded hubs and they are still firm to spin by hand.

Working for GM for 3 decades, I built A LOT of differentials, I would use a beam type inch-lb torque wrench to measure pinion rotating torque to determine what the bearing preload was. It was a very narrow specification, used bearings were 30-50 inch-lb and new bearings were 15-30. There was always a "breakaway" torque to get the bearing spinning that was not important, it was the rotating torque that mattered. Some techs just slapped them together and called it a day which typically meant the truck would return several thousand miles later with a noisy diff. and pitted pinion bearing races. I always set them up correctly, another 1/2 hour spent doing it right meant I'd never see the truck again. ;)

Someone needs to engineer a rear hub that is lubricated with oil rather than grease, bearings that rotate in an oil bath are much more protected thermally than those lubricated with just grease. Even the front wheel hubs on my Freightliner motorhome chassis are lubed with oil, but that is the topic of another discussion.
Click to expand...
Spot on!
 
fabr said:
I could not agree more KLC. You are spot on.

The aftermarket is filled with poorly designed parts with near zero actual QC other than aesthetics and it will not likely change. Why is that? I feel it is because there is less money made on well designed products and true QC. No endless maintenance and sale of replacement parts that are highly inflated price wise. It is not forced upon the makers of said parts since the vast majority of people using these inferior designed parts have no clue as to what is correct . They will always have bragging rights for the broken/damaged parts because their buggy has the "power to tear shit up" or the old"I really drive my shit hard and that is why I keep breaking whatever". No,the truth is that the damn $$$$ parts are shit to begin with and actually designed to need excessive maintenance and replacement $500 bearings and $80 and/or $45 seals. This topic is a perfect example of poorly designed crap from some well known ,even respected,builders. I'm not pointing any fingers ,they know who they are.

BTW,since I'm in the mood,those $500 Timken 934 mids bearings can be readily had (genuine Timken)for approx $175 depending on where bought and those $45 inner seals can be had for a whopping $9 ea.Yes,I just bought 10 for $9 apiece including shipping from the UK. Haven't looked for the $80 outer seal yet as I have 2 sets of the $80 ones on the shelf.Yes,we are getting hosed. I am sooooo tired of getting the hose. I am now on my 2nd set of mids,,and both are the same crap. No way to set preload without machining and the same old BS that they have to have way excessive preload or they will destroy themselves. What a joke,a very bad joke. I'm very fortunate to have lathes and mills to correct this shoddy crap. Most people are at the mercy of excuse makers/service providers for the manufacturers that profit from said crap designs and have no choice but to accept it.

All it would take to prevent most ,if not basically all,mid board bearing service would be a true inner seal instead of the nearly useless dust seal that is used and a simple shim set to set bearing preload. Those 2 very simple things would make hub bearing service almost a thing of the past. Yes,the cv would still need regular service and that could be done without any hub disassembly unless a cv needed replaced.. As to the oil bath for bearingssuggestion and also the cv in oil bath,that is doable. But since almost everyone running a conventional 930/934 midboard would never care it is not a viable option,IMO. From the price point now on mid hubs there really is no excuse for the improvements not being done. At the very least the preload should be set on each and every one going out the door whether new or freshly serviced. That obviously is not the case.
Click to expand...
If you found genuine timken LL225749/LL225710 for $175 a set, I will take 100 sets...

I have contract pricing on this part number with timken and pay more than twice as much as $175.

You wont be the first or last to think you have found the best source for these bearings.

www.ebay.com

TIMKEN NEW TAPERED ROLLER BEARING LL225749/10 | eBay

NEW TIMKEN TAPPERED ROLLER BEARINGS. Half price. Part numbers LL225749/10 AND LL420549/10 are Timken at half price. TIMKEN NEW HUB BEARINGS.
www.ebay.com

I hope these aren't the ones you found for $175.

Counterfeit bearings are a huge problem.. only buy from a reputable source and not ebay amazon etc....


As for $9 seals I pay roughly 3x that for quality seals...
Also when you have any questions you should reach out to the company that sold you the $9 seals for advise.


Oil bath, Yes this has been thought of. but a lot easier said then done... I do believe the CV would benefit greatly from being submerged in an oil bath. Figure out how to seal it properly and now were talking:D

We will see an oil bath CV in the future. But it wont be in a "midboard" application...
 
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