Gray Area 934 Midboard Bearing Preload Setup

[fabr]

Breaking this out from the cv bolt thread. Original post:

Just an FYI update. I have recently had to replace the wheel bearings in my Gray Area 934 mids. They have now gone to a Koyo bearing and spec 65lbft for the 1/2" cv bolts with red loctite. You will need to either send the bearing plate or the complete hub in to GA for modification and maintenance. If you have a lathe you can do the easy mod yourself.

I had to replace the wheel bearings due to the fact that the hub was originally assembled ,direct from GA ,without the inner seal and the results was washed out wheel bearing grease killing the wheel bearings. One of the few times I haven't disassembled/inspected something before running. GA was good to deal with but they also basically ignored the fact they were the cause of my needing to spend $$$$ for their mistake. They gave me a small discount but would not even consider providing the missing seal(I didn't even ask for anything on the bearings at that point even though it was their fault for the failure).. I'm not very happy to say the least. It is what it is in the aftermarket though.

New update and questions:

OK,it has come time for both hubs to be serviced . I am totally confused on what the hell the reason was for a mod to the hub and a bearing spacer. As posted above, I had to replace hub bearings (driver side)due to the hub missing the inner seal from the factory. I was told the replacement Koyo bearing would assemble slightly thinner and would need the spacer ,supplied by GA,to get preload right. Fine,I was good with that.

Now I have both hubs apart and I find that the Koyo bearings in the drivers hub and the original(whatever brand) are the same exact width as would be correct for Timken and Koyo. Since there are no markings on the original (passenger side) bearings I would have to assume they are the ones GA had made in India . Bottom line is why did I have to do a mod to the hub and use a spacer with the Koyo bearings since apparently all 3 bearings are of the same spec width? Were the China bearings wider?

I do not recall what the mod was now. Regardless, all the hub components dimensions are the same side to side and the bearing widths are the same yet I have a approx. .050" spacer on one side. Something is not right. I either have one side with way too much preload or one side too loose. When new both hubs took about a 4 foot bar to be able to turn them with a lot of effort. In all honesty that seemed way the hell too much but was told they would loosen up. Well they did apparently as the passenger (no spacer behind the bearing)side bearing has worn a groove maybe .025 deep in the hub. That side did develop a barely noticeable bit of camber.

I am a bit mystified how the hubs can be identical now that I did whatever mod was done. I honestly do not remember what mod was or if the spacer was all there was to it now. Damn it sucks to get old and forgetful.......... LOL! Either way,something is not right.

Bottom line now is how much preload should there be? I would think something along the line of wheel bearing would be much more appropriate. Why would they need/want to be so tight? Am I wrong? I need to do some machine work and make some appropriate spacers to bring these hubs back to new condition. Any opinions on what sort of torque should be needed to indicate proper preload? I know new bearings would be a bit tighter than reused bearings.

Thanks for any insight.

 

[J Alper]

It hard to explain how much preload, but these are big bearing i run a decent amount of preload, These bearings are for a excavator pivot arm bearings, so it can take a chit load, i have a fixture we put the hub in, and if it turns easy with your hands, then it needs more preload, it should be hard to turn with your hands,

On the bearings spacing or different bearings, the big issues is the Race, if you do not change the race when changing the bearings the angle of the bearings to race can be different, different companies have slightly different machines and specs to the cone angle of the race and bearings,

I have just changed the bearings but when i do this, it is from the same source and same manufacture.

THE HUBS SHOULD BE SERVICED EVERY OTHER YEAR TO KEEP THE BEARINGS FROM BEING DESTROYED,
THE ONLY HUBS WITH INNER SEALS ARE,
These use the same large seal inside and out,

1. kartek PME
2. Proamm
3. Fortin
4. Jamar

Gray Area, Tatum, Gear One have a Dust Guard, it is not a true seal, so the bearings should be greased more often.
I have had hubs come apart on me, so depends on the manufacture, on the Tatum's i torque them to 110lbs then back them off and go to 70lbs with Loctite,
Main reason I back them off is that the Tatums do not have a thrust ring where the head of the bolts are like the Gray Area, just small washers that imbed into the aluminum
Gray Area i torque to 100lbs with Red Loctite the metal ring that the bolts go against work very well on holding the hub together,

Couple of things we do when we service a set of brakes, one if they are tatums we add the ring like gray area, I can put this on our website if anyone wants some i just have to cut some out,

Another trick that will make life easier on the Tatum brakes is, when you go to reassemble drill out the aluminum hub for the CV bolts go, they get compressed from the bolts and make the bolts hard to go in,

I also change the hardware from an capscrew allan bolt to a true CV bolt from Kartek, like a PME or ProAm and same as a Fortin.

 

[fabr]

Jason,I bought these hubs from you originally. When I had the original issue with the missing seal and ruined bearings in the one hub you (or GA,I do not now remember if it was you or GA) sold me the replacement koyo bearings. I do not now remember if it was you or GA that advised me of the mod and spacer that was needed to use the Koyo bearings. What was the mod and why was it and/or spacer needed? It appears that all the bearings used are same size spec. Yes,the bearings and races need to be same brand,not mixed brands as there are differences between brands and will not match up but they all assemble to the same installed width/thickness. My question is how can a approx .050 spacer behind the bearing be needed when all the components of both hubs are dimensionally the same. Something is/was not right. Oh well,I'll dummy up the hubs without seals and set bearing preload to "very snug" for the used bearings in one hub and "very,very snug" for the new ones. LOL!! At this point it does not matter the why , I was just curious what the deal was/is.

 

[KLC]

Sorry if this derails the thread , it was not my intention.
Fwiw, I bought a set of brand new Tatum midboards a number of years back, right out of the box you could not rotate the hub there was so much preload. Once clamped in a big vice we had to use a 4' pry bar in the studs to rotate them, the CV would not move freely either. My fabricator, being a former John Deere technician cautioned against using them as is. We ended up taking them apart and measuring the clearances and it ended up being the CV body itself that was the culprit. We chucked it up in his lathe, indicated it and took about .0015" from the outer diameter. We found that not only was it not round, it was being distorted so much from an excessive press fit that it actually closed up all of the clearance between the balls and star, so much for a race prepped CV huh! So when it was all said and done we had a set of new midboards that would actually rotate stiffly by hand, and a CV joint that worked well. There was little grease in the bearings as shipped by Tatum too, we corrected that upon reassembly. I am now about 3 seasons on them and when jacked off the ground, the wheels are still stiff to turn by hand and zero movement in the bearings. It's probably time to tear them down for a rebuild.

 

[fabr]

Not a derail at all. Interesting .

 

[fabr]

I'm fabbing a hub holding fixture so I can measure the required torque to rotate the hub. I wish there was an actual spec for that both for new and reused bearings. From what evidence I see in the bearing races indicates too much preload for sure especially with the 4 foot lever being needed to turn them when new. Maybe I'm wrong about that. I have my doubts about that however.

 

[fabr]

I assembled the hub today ,with the holding fixture, that has never been apart before. I used new Timken bearings and cups. I left the seals out for this mock up to not skew the results. After torquing the cv bolts in 3 steps,50/75/100lb.ft., and rotating the hub after each successive torque step, I used a torque indication load cell to measure rotating torque. I found it to take 28lb.ft. to rotate hub. To put that in perspective it was able to turn the hub by grabbing onto the rotor and it took quite a bit of effort to turn. It damn sure did not need a 4 foot bar to turn it though. It does not turn easilyby any means but I think it is right. When I get the bearings for the other side sometime next week I will assemble the other hub and do the same test to compare. I predict the result will be the same.

Sooooooo,again,why the approx .050" shim supplied to me to be used???????? To satisfy my curiousity I will reassemble the second hub with the koyo bearings as it was for the last year or so and see the resulting turning torque both with and without the spacer. It would be nice if the dealer or GA actually measured the rotating torque of a new hub assembly and replied here.

Anyone ever tried turning a new tatum hub? Are they as tight new? For all intents and purposes tatum and GA are the same design hub.

 

[Bobalos]

Sorry if i missed it, is this a midboard hub like the gear-one midboard? Does that take this kind of bearing?

 

[fabr]

Yes,taper roller. ll225749 and ll225710

 

[Bobalos]

It is surprising how much preload they put into these. It seems with all of the hubs made from aluminum they must grow a bunch with heat.

 

[fabr]

The bearing carrier is steel just as the cv and bearings. Any expansion pretty much cancels out any other expansion. The aluminum hub is pretty much irrelevant .

 

[J Alper]

Jason,I bought these hubs from you originally. When I had the original issue with the missing seal and ruined bearings in the one hub you (or GA,I do not now remember if it was you or GA) sold me the replacement koyo bearings. I do not now remember if it was you or GA that advised me of the mod and spacer that was needed to use the Koyo bearings. What was the mod and why was it and/or spacer needed? It appears that all the bearings used are same size spec. Yes,the bearings and races need to be same brand,not mixed brands as there are differences between brands and will not match up but they all assemble to the same installed width/thickness. My question is how can a approx .050 spacer behind the bearing be needed when all the components of both hubs are dimensionally the same. Something is/was not right. Oh well,I'll dummy up the hubs without seals and set bearing preload to "very snug" for the used bearings in one hub and "very,very snug" for the new ones. LOL!! At this point it does not matter the why , I was just curious what the deal was/is.

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,

 

[J Alper]

The bearing carrier is steel just as the cv and bearings. Any expansion pretty much cancels out any other expansion. The aluminum hub is pretty much irrelevant .

That is not true, actually the hub plate that the wheel bolt to is what the bearing race sits against, the bearings ride on a steel inner hub, but pushed together from a steel boot flange and 6061-t6 hub on the other side, Then the CV bolts ride against aluminum housing on the older hubs, if it does not have a steel ring that the bolts ride against, i would call GA and get that .125 plate, it will help hold tolerance on these brakes,

 

[parker@gearone]

So much going on, ill try to make it as short as I can.

First, I want to mention that Gray Area was recently sold to a new owner. New owners name is Geoff and he is a great guy, yes he is my direct competitor but I would consider him a friend and we talk on a regular basis. He is committed at doing things right and improving his products & expanding his product line. I still think Gear one hubs are the best but I may be biased.

Second, Centerboard hubs (or mid boards) are unlike any other automotive hub, that tends to scare people. But they are actually very simple, strong, and great design. Yes outboards are better, but Mid boards are a lot more cost affective for sand car applications.

Third, I dont understand all the debate of torque on the CV bolts! Mid board hubs are very simple there are 5 components that set the preload in the hub,
1. The step in the aluminum hub (aluminum hat with studs pressed in)
2. The step in the boot flange ( the piece the cv bolts thread into that the boot usually clamps on to.)
3. the spread in the bearing carrier (the large steel piece that bolts to the trailing arm that the races get pressed into)
4. The width of the CV joint
5. The "T stack" of the bearing
If the hub is correctly designed and all the tolerances are held during manufacturing the Cv itself should act as a "crush sleeve" and your preload should not change if you torque your bolts from 80ft lbs. to 500 ft lbs. (don't try and torque them to 500ft lbs.!)

That being said there should be no changing the "preload", All the preload should be figured out and manufactured into the hub and held to size in the 4 parts listed above! It is crucial you use a quality bearing, Chinese and other third world country bearings never hold there tolerance! It doesn't matter how well Gear one, Gray are, Tatum, Kartek, pro am, Jamar etc... hold size if you put Chinese bearings in it that have a different T stack than what the hubs were intended for you're going to have issues. (I will attach a photo showing the "T stack" of a taper roller bearing)

We torque centerboard hubs to 110-120 ft lbs with RED LOCTITE! That is the correct torque value for a 1/2-20bolt. These bolts NEED to be torqued to at least 110 ft lbs! question anybody who tells you otherwise!

Proper torque insures proper clamping force and evenly distributes the load across the threads!

To little torque and it can eventually loosen up and lead to catastrophic failures.
To much torque can lead to failure of the bolt and also lead to catastrophic failures.

Lastly, Once greased & torqued with seals installed. You should be able to turn the hubs by hand. I'm not going to put a number on it since they are gray area hubs, but you should be able to grab the wheel studs and muscle it back and forth.

Sorry for going off the rails, reach out to Geoff I am sure he will make things right.


Also I am working on new hubs with the hopes one day Alper will say Gear one makes the best

 

[parker@gearone]

The LL225749 is a great bearing it can take a ton of preload.
the reason we preload Mid board bearings so much...

Imagine a car that weighs 3500lbs drifting through the sand at 60+ mph on a 35"+ tall tire... That's a lot of load on the bearings... a lot more than your average daily driver.
Now if you go to Funcos Instagram you don't have to imagine it there are plenty of videos of it...

 

[L.R.S.]

I've prepped hubs from every manufacturer except Summers Bros (need special tools to set preload with shims) and can say that @parker@gearone makes the best hubs and has the absolute BEST customer service in the off-road industry. I've placed several orders with Gear One in the past two weeks and all were delivered the next day. My client in Ramona, CA called me to say he got the parts and couldn't believe it was next day shipped.

Parker's explanation of hub assembly is not only true for his hubs, but also Tatum and Gray Area (most common hubs I prep). I'm glad an actual manufacturer has said it out loud- the preload is built into the hub design. Assemble it correctly, with quality parts, and torque them. Simple.

The wheel ain't getting any rounder.

 

[fabr]

I've prepped hubs from every manufacturer except Summers Bros (need special tools to set preload with shims) and can say that @parker@gearone makes the best hubs and has the absolute BEST customer service in the off-road industry. I've placed several orders with Gear One in the past two weeks and all were delivered the next day. My client in Ramona, CA called me to say he got the parts and couldn't believe it was next day shipped.

Parker's explanation of hub assembly is not only true for his hubs, but also Tatum and Gray Area (most common hubs I prep). I agree. I'm glad an actual manufacturer has said it out loud- the preload is built into the hub design. I agree,IF tolerances are met. Assemble it correctly, with quality parts, and torque them. Simple.It SHOULD be that simple but is not if there is any damage to the bearing carrier,hat or boot flange or if the cv thickness varies as can happen. .If there is wear on the faces that the bearings or races bear on then repair or replacement prts are in order is necessary. I am a fully equipped machine shop and will do any repair needed in house.

The wheel ain't getting any rounder. Sure it can. LOL!

I'm going to reply to this post first as it is the simplest. I will make my comments in bold above. I will try my best to not disparage any parties. That is NOT my intention here.

 

[fabr]

The LL225749 is a great bearing it can take a ton of preload.
the reason we preload Mid board bearings so much...Yes it is a very good bearing whether it is a timken,koyo,and likely whatever brand wherever it is made. I still have no real answer to how much preload there is intended to be . It's a really simple question. A rotating torque spec or a few simple dimensions is all it takes to bring this to a conclusion. I know you cannot speak for others but how about your 934 mids? .ine a car that weighs 3500lbs drifting through the sand at 60+ mph on a 35"+ tall tire... That's a lot of load on the bearings... a lot more than your average daily driver.
Now if you go to Funcos Instagram you don't have to imagine it there are plenty of videos of it...

 

[fabr]

So much going on, ill try to make it as short as I can.

First, I want to mention that Gray Area was recently sold to a new owner. New owners name is Geoff and he is a great guy, yes he is my direct competitor but I would consider him a friend and we talk on a regular basis. He is committed at doing things right and improving his products & expanding his product line. I still think Gear one hubs are the best but I may be biased.

Second, Centerboard hubs (or mid boards) are unlike any other automotive hub, that tends to scare people. But they are actually very simple, strong, and great design. Yes outboards are better, but Mid boards are a lot more cost affective for sand car applications.

Third, I dont understand all the debate of torque on the CV bolts! My question has absolutely nothing to do with the cv bolt torque in the least.Mid board hubs are very simple there are 5 components that set the preload in the hub,
1. The step in the aluminum hub (aluminum hat with studs pressed in)
2. The step in the boot flange ( the piece the cv bolts thread into that the boot usually clamps on to.)
3. the spread in the bearing carrier (the large steel piece that bolts to the trailing arm that the races get pressed into)
4. The width of the CV joint
5. The "T stack" of the bearing
If the hub is correctly designed and all the tolerances are held during manufacturing the Cv itself should act as a "crush sleeve" and your preload should not change if you torque your bolts from 80ft lbs. to 500 ft lbs. (don't try and torque them to 500ft lbs.!) Totally agree .

That being said there should be no changing the "preload", All the preload should be figured out and manufactured into the hub and held to size in the 4 parts listed above! Again this is a given since there is no provision to do anything other than assemble as is or machine one surface or another to modify any preload,done at your own risk of course. It is crucial you use a quality bearing, Chinese and other third world country bearings never hold there tolerance! It doesn't matter how well Gear one, Gray are, Tatum, Kartek, pro am, Jamar etc... hold size if you put Chinese bearings in it that have a different T stack than what the hubs were intended for you're going to have issues. (I will attach a photo showing the "T stack" of a taper roller bearing) Completely agree.

We torque centerboard hubs to 110-120 ft lbs with RED LOCTITE! That is the correct torque value for a 1/2-20bolt. These bolts NEED to be torqued to at least 110 ft lbs! question anybody who tells you otherwise! Again complete agreement.

Proper torque insures proper clamping force and evenly distributes the load across the threads!Ditto.

To little torque and it can eventually loosen up and lead to catastrophic failures.
To much torque can lead to failure of the bolt and also lead to catastrophic failures. Double ditto.

Lastly, Once greased & torqued with seals installed. You should be able to turn the hubs by hand. AND therein lies the rub. I would absolutely agree with this description of how the hub should feel fully assembled. As I have posted earlier I questioned GA about the massive torque it was taking to rotate the hubs when new. I was informed they had to be that way and would loosen up after a short run in time.Without any exaggeration I had a 4 foot bar between the lugs and it took probably 1/2 my weight to get them to turn. Probably 80 pounds at even 3 foot would be around 250 lb.ft. needed torque to turn them. Maybe I'm crazy but that is not right,IMO. I'm not going to put a number on it since they are gray area hubs, but you should be able to grab the wheel studs and muscle it back and forth.Would you be willing to put a number on yours?

Sorry for going off the rails, reach out to Geoff I am sure he will make things right.


Also I am working on new hubs with the hopes one day Alper will say Gear one makes the best

 

[fabr]

That is not true, actually the hub plate that the wheel bolt to is what the bearing race sits against, the bearings ride on a steel inner hub, but pushed together from a steel boot flange and 6061-t6 hub on the other side, Then the CV bolts ride against aluminum housing on the older hubs, if it does not have a steel ring that the bolts ride against, i would call GA and get that .125 plate, it will help hold tolerance on these brakes,

What I posted is true. Your description is also correct. Any expansion of the alum hat will not affect the preload. As for the .125 plate it will make for an inadequate cv bolt thread engagement. At least it would with the cv bolts the hubs came assembled with. I will counter bore for hardened washers instead.