Adjusting SPF wheel bearings.

[Kelly]

I still haven't driven my car much but I've noticed a clunking at low speed after driving the car for more than say 45min. It can come from either side. It does seem to be coming from the rear axles or hub. So what is it that causes it?

Richard, I've been following the thread with interest and we have several things in common.

I have a similar problem and I too borrowed Kirby's pulling tool. The clunk has confounded me and unfortunately, this driving season for a variety of work and family related reasons, I've only had the car out twice, so the condition persists.

I actually have a recording of the sound because it is quite attention getting and I simply cannot get myself comfortable with driving a car at speed that has a potential drive train or brake issue. It used to be that the noise was faint to non-existent when the car was cold but now appears very early to almost immediately in the drive now. Symptoms seem temperature related.

I’ve had the car for several years. The first season no issue. The noise showed up shortly after a tire change and 4-wheel alignment. Not sure it was related. As I mentioned in my earlier post, I began trying to systematically isolate various causes. So firstly I inspected all of the suspension mounting points then suspended the car and checked bearing clearance on all four corners by feel on each wheel. My theory at that point was possibly brake pad printing on the (or slightly warped) rotors and I thought excessive bearing clearance might aggravate the condition since the thump is at definitely at wheel frequency.

I put a dial on the rotors but the bearing clearance was such that I could not get what I thought were reliable readings with the rotors on the car so off the rotors came. Well sort of. The Allen-headed flat head screws that hold the rotors on the hub when the wheel is removed were stuck on two of the four corners and they were soft as could be like many of the other SPF fasteners I’ve concluded. After liquid wrench and heat failed, I simply had to take a sharp chisel and work the outer diameter of each bolt until I got them loose followed by order #1 to McMaster Carr for some higher grade 400 series stainless replacement hardware.

So after measuring the run-out of the rotors off the car and concluding that was not it, I also removed the e-brakes as they had been mentioned a possible source.

Neither of these was the cure so I moved onto the wheel bearings as Kirby had told me he had to adjust his several times and others have mentioned that often the wheel bearing races are not seated properly at the factory. Kirby was also generous enough to lend his pulling tool to me. Again, I had several of the very small Allen/button head screws on the wheel bearing retainers/locks seized and had to resort to extreme measures to remove them (McMaster order #2 for replacements; if anybody needs some, I have 100 pieces now).

The axle on one side pulled very easily as Kirby described. The other was very tight. The anti-sieze on the threads of Kirby’s tool was applied by me. I had a lot of tension on the rear passenger side assembly and thought it should come so I did give it a whack with a hammer as mentioned above and got it loose but it pulled fairly hard.

Anyway, inspect and re-pack all wheel bearings, reassemble, and still no joy. The noise is still there; perhaps worse. So now my theory is a CV joint going South. Since the noise seems to be coming from rear passenger upright, I switch the half shafts from one side to the other thinking if it’s one of the 4 CVs, maybe the noise will jump sides. The grease in all 4 CVs looked good, no obvious issues with them upon visual inspection. Back together, out on the road, and still persists the thumping as prominent as ever!!!

So to re-cap, as noising initially appears at wheel rotation frequency, it only occurs when I apply brake, actually somewhat light brake because if I lean on it a little it does not clunk/thump upon more aggressive braking. After I get things good and heated up, it’s more pronounced upon braking but I can also make the sound occur more faintly buy weaving back and forth hard within the lane, and I can hear the sound in the rear passenger corner during one direction of the weave. Also, when it’s good and hot, it can make some noise as I pull off of stop and turn at low speed. It almost sounds like a rubbing chattering noise. As an owner of many LSD cars, I recognize this as the limited slip packs not slipping (it has a contemporary RBT-2). I don’t know if this is a related or separate issue. If that was the only problem, I would not be too concerned about it. If the root cause of the noise was the LSD, I also don’t understand why it only shows up under (light) braking and not otherwise under acceleration. Somewhere along the line I switched the lube in the transaxle to a Valvoline synthetic blend. I did add LSD additive. On a similar note, I did the same thing in my Pantera, and as the zf heats up after driving it, it seems to shift more poorly. I may go back to dino-lube in my transaxles.

Sorry for the ramble guys but I’m stumped and it seems on-topic with the thread. I’m open to any suggestions.

I have several mpegs of the noise but can’t get them to upload.

Best,
Kelly

 

[Seymour Snerd]

....inspect and re-pack all wheel bearings,

Kelly -- this is interesting. Were you able to inspect the wheel bearings well enough to be confident there were no pits in any of the bearing races and no chipped or deformed balls?

 

[Steve C]

Kelly,

When P2125 was new I had something like you describe.

Turned out I needed friction modifier; once added the noise went away.

I have since changed the gear oil (didn't add any additional modifier) and no noise.

Steve P2125

 

[Kelly]

Kelly -- this is interesting. Were you able to inspect the wheel bearings well enough to be confident there were no pits in any of the bearing races and no chipped or deformed balls?

I wiped away all the grease on each tapered roller assy, looked them over visually and rolled most all the individual tapered rollers betweeen my thumb and fore finger. I definitely didnt see any chips. I also didnt see any debris in the grease, at least the stuff that's deep in the bearing. As we know, the SPF cars arent really sealed units.

The races themselves looked great, no apparent flaws or signs of heat. I've heard wheel bearing noise before and not sure why it would only occur under braking if it was wheel bearing. Is that what you would expect?

I've also had several folks suggest that I go out and aggressively bed in the brakes. Other than buying new CVs and changing transaxle lube, I'm sort of running out of bullets.

I had a nasty thought about a ring gear bolt backing out and reasoned that maybe when you load the ring and pinion in deceleration it was just enough load the carrier the other direction and start hearing bolt head interference. However Lloyd Butfoy told me that all the newer RBTs leave with the ring gear bolts safety wired, so I sort of doubt it; plus, the noise is the same whether I brake in gear or in neutral, which seems to point to it being in the upright as opposed to the transaxle. ???

K

 

[Kelly]

Kelly, When P2125 was new I had something like you describe.

Turned out I needed friction modifier; once added the noise went away.

I have since changed the gear oil (didn't add any additional modifier) and no noise. Steve P2125

At this point, changing the lube and limited slip addditive couldnt hurt, but I'm not too optimistic about that being the source. Sort of thinking bad CV. I didn't mention it above but I did have a good look at them when I swapped sides with the half shafts and didn't see anything obviously wrong. The c-clips were present on both ends of each assembly.

I have two MPEG files of the sound but for some reason I can't access my web space hosetd by my ISP to post them and this site and the photo sites won't let me upload an mpeg. If you heard it, it sounds so intrusive you wouldn't think it would be hard to track down. Like I said, it's annerving enough that it really motivates you to go looking. Anyone want to take a shot at hosting the files for me and posting a link?

Best,
K

 

[Steve C]

Are you sure it isn't in the emergency brake assy?

Steve P2125

 

[Seymour Snerd]

I've heard wheel bearing noise before and not sure why it would only occur under braking if it was wheel bearing. Is that what you would expect?

My thought was based on these observations:

1. It occurs per/rotation
2. It occurs on one side and not the other
3. You've run without the e-brake (eliminates e-brake)
4. You've swapped axles and the noise didnt move (I think that eliminates CV joints)

Discounting the transaxle for the moment, that leaves only pad-to-disk and bearing-internal interfaces as places where some kind of interference or change in force could occur. So I was thinking maybe the application of light brakes with non-preloaded bearings causes a shift in relationship between cage/ball/cage, allowing a pit or deformation to come into play. IOW, it's a stab in the dark. :blank:

So, if that's not it, and it's not the transaxle (which I say only because I have no suggestions there whatsoever) then I think we're down to some form of free-play or slack that is allowed or taken up only when you use the brakes lightly or go around a corner. Makes me wonder if (for example) in the stack of things clamped by the knockoff nut there is something "rocking" under high enough force. As if, just to make something up, one of the drive pins were too long and bottoming in the wheel but not enough for you to sense when tightening it up.

 

[Kelly]

Are you sure it isn't in the emergency brake assy? Steve P2125

e-brake shoes and related hardware removed early on so not them.

K

 

[Kelly]

My thought was based on these observations........Discounting the transaxle for the moment, that leaves only pad-to-disk and bearing-internal interfaces as places where some kind of interference or change in force could occur. So I was thinking maybe the application of light brakes with non-preloaded bearings causes a shift in relationship between cage/ball/cage, allowing a pit or deformation to come into play. IOW, it's a stab in the dark.

Maybe I need to revisit proper bearing preload. What is recommeded/generally accepted procedure? It does happen to be the rear corner that pulled and reassembled hard, but dont think that would have prevented me from adjusting it properly once installed. It may however prevent it from staying properly adjusted.

K

 

[Richard]

Kelly thanks for your post, considering all the time, effort and money we’ve all put in, it’s disappointing to hear that what I’m doing may not fix the problem. Like you at first the noise didn’t show up until I had driven the car for more than an hour but now it’s all the time.

I was able to get the driver’s side apart without breaking the other tool knowing I had to give it a good whack or two while getting axle movement started. The passenger’s side was so tight that while putting the axle back in I had to use an air hammer to get the axle far enough in to allow the re-insertion tool access to any of the threads so I could pull it back into place.

On both sides the small alan screws were very lose. For those of you that haven't gone through this after removing the stub axle you'll need to remove the two small alan's and the keyed ring they hold in place. Under that you'll find a ring that when rotated add or loosen pre-load on the wheel bearings. All this just to get to those two little bolts.

A little late but while I was ordering a replacement set of tools for Kirby, Dennis told me he is having new stub axles made that just slide into place. I couldn’t bring myself to ask how much $.

I’m using a ZFQ with all the prescribed transaxle lube so I don’t think it’s our transaxles.

At this point if the problem persists my plan would be to remove the rear clip and mount one of the Hero cameras with a good view of the suspension. Between the recorded video and audio I should be able to pinpoint the source of the noise. If the problem isn’t the bearings I suspect a binding somewhere or maybe even the tub flexing at one of the suspension pickup points under load. That would be in the “Book of Bad” on page one. Has anyone tried disconnected the coilovers and manually lifting the suspension through its travel? I may try that before I button things up today.

The pictures are for those of use who haven't had the pleasure of taking all this apart yet.

 

[Seymour Snerd]

Richard -- thank you extremely much for posting the pictures. I have a couple questions:

1. Once the bearings and various collars and retainers are out of the upright, are the bearing outer races right there to see on both sides? If so, and given the suspicion that we are doing multiple cycles of pre-load setting in order to fully seat them, should we consider taking some more direct action to seat them, such as tapping-->pounding on them with a properly sized drift, or squeezing them with a threaded rod throught the upright, or taking the upright to a press and pressing them?
2. Regarding your difficulty getting the axle started back into the upright: I notice the small threaded hole in the end of the axle. Could that be used to pull the axle into place? Or (in an ideal world) does the insertion tool simply need more range? Regardless, do you have any idea why the small hole is there?
3. In the picture of the bearings, shields, adjuster, adjustment retainer, etc., what is the object on the far left? Seal? Spacer?

 

[Kelly]

.....If the problem isn’t the bearings I suspect a binding somewhere or maybe even the tub flexing at one of the suspension pickup points under load. .....The pictures are for those of use who haven't had the pleasure of taking all this apart yet.

One of my friends mentioned "oil-canning" of the chassis as a possible source of the noise. That's a hard one to confirm. And yes, those are some very familiar photos you posted. I have a similar collection of my own!

I really wish I could post those audio mpegs. I'll need to see what's up with my ISP/hosting site.

Best,
K

 

[Steve C]

Kelly,

Check 2 more things:

coil spring touching the tub?

heim joint wear or control arm to tub loose(check by rocking the wheel @ 11 and 5 not 12 and 6 like checking wheel bearings). I think it could be this.

Steve P2125

 

[Jac Mac]

This might be a 'twerp' question from me, but do these cars not run oil/grease seals in the rear hubs as in post#50 above, pic two I only see dust slingers/shields, no seals, plus on pic 5 there appears to be fretting where the outer bearing inner race would butt up against the flange area, have you ever chucked the axles up in a lathe to see if they are even straight, machined correctly

 

[Richard]

The left most ring is a spacer with a bevel on the backside that fits against radius in the hub, hope that made sense. I was very surprised that there are no seals anywhere but then again this is a race car and seals cause drag. The pictures show where the bearing races are. If the races weren’t seated from the factory driving as many miles as I have should have taken care of that. Spinning the assembly without the caliper does not show any run out.

I did think of using the threads on the inside nose of the stub axle but didn’t have a long enough bolt on hand and the air hammer worked well enough.

SPF quality control has been an issue for me today. The first side I took apart the bearing were a slip fit. The other side however was a different story. I was only able to remove the hub with a little help with my dead blow hammer. The second bearing took some work to remove which required the removal of the rotor required drilling one of the two bolts to get it apart. I just made a tool to turn the adjustment ring the help push the backside bearing back into place. I hope it works.

This is the fun part, right?

 

[Jac Mac]

You know, its not often I get lost for words....but , honestly, race car heritage maybe, but given that you have an e-brake & they expect to be able register & or warrant [WOF- a 6 monthly check all cars here in NZ have to pass ] these cars for use on public roads, the grease that obviously can be expelled from the outer bearing & find its way on to the e-brake shoes.... that setup .... look Im not going to type what Im thinking... its got too many four letter words in it... the day you have to worry about seal drag in a situation like that on an item that only spins @~2000rpm tops, yet you guys go on for pages about the rear main seal leaking one drop of oil in your garage overnight........FFS

Sorry, forgot to attach picture of areas that might have brg movement & be source of 'noise'

 

[Jack Houpe]

This might be a 'twerp' question from me, but do these cars not run oil/grease seals in the rear hubs as in post#50 above, pic two I only see dust slingers/shields, no seals, plus on pic 5 there appears to be fretting where the outer bearing inner race would butt up against the flange area, have you ever chucked the axles up in a lathe to see if they are even straight, machined correctly

This is a very valid question, it was rolling around in my head too. I have never had an issue with the wheel bearing problem and they are checked before each open road race I have done, which all together is over 350 miles and 300 corners at 100 MPH + so if they were going to loosen up or were loose I would know it by now and I drive it every chance I get. Mike Trusty also has never had an issue with his bearings. My serial number is 2164 and Mikes is 2165 so I wonder if there is a sequence of serial numbers that have this problem or if its random.

 

[Steve C]

Agree about seals but, Im was much more concerned with the fronts and that's why Grady and I came up with a sealing solution.

See "upgrades to P2125" in the SPF section

Steve P2125

 

[DaveM]

Sorry, forgot to attach picture of areas that might have brg movement & be source of 'noise'[/QUOTE]

Good observation JacMac. I've had problems with 2 of my stub axles. Basically SPF doesn't always seem to machine the clearances for bearing races tight enough. Check to see how loose the bearings fit on the stub axles. The outer bearing race should be a press fit and the inner bearing race a slip fit, but not too loose. SPF replaced one of my stub axles (LF) under warranty because I could not get bearing adjustment to last. The outer bearing was a slip fit and the inner a VERY loose slip fit. Another of my axles (LR) had a slip fit for the outer bearing, but I was able to remedy by green loctiting it to the axle. Adjustment has been OK for over a year now. The original design of these parts has its limitations in that the threaded adjustment collar's threads pound out with use and it gets a little sloppy. Also as Richard noted the locking set screws can back out. Blue loctite them or replace with hex head bolts (on front only, they won't clear on rear).

 

[DaveM]

Rereading my post I realize I probably should be referring to 'hub shafts' instead of 'stub axles'.