IcemanG17

sounds like a dying wheel bearing to me......both my 928's ate passenger side wheel bearings (front and rear) pretty steady since I drove thunderhill so much

dr bob

Mark --

Remove the half-shaft and rotate the drive hub by hand. Wiggle it too. For a bearing to make that much racket to the point you can hear/feel it over the race exhaust, it's going to be pretty bad. Pull the disk off and see if there are parking brake bits rattling around in there; You'll need it and the axle out to swap the bearing regardless.

The rear offset you run has a much greater angular loading on the rear bearings than us mere mortals normally apply. Add the high cornering forces especially with those new tires, and you know that the bearings aren't going to be too happy.

For those playing along at home, the rear bearing is an angular double-row ball bearing, with the two inner races facing each other. It's a great application for that style of bearing so long as the bearing ends up somewhere near the middle of the wheel and the load is mostly radial. Cornering forces and offset move the load angle, multiplying the load on one of the bearings and fractioning it on the other. Usually it's the bearing section with the heavier load that gives up first, especially if/when there is impact loading thrown into the mix.

The Good News is that the bearings are relatively inexpensive last time I looked, somewhere just north of $100/ea. I think Bill Ball near you has the Sir Tools B90 toolset that makes replacement on the car pretty simple and quick.

Jim Devine

Here's some clecos - surplus- they work just as good as new ones- pick the size for the size rivets you are using

http://www.yardstore.com/clecos-clec...ecos-used.html

and the pliers: http://www.yardstore.com/cleco-pliers-used.html

mark kibort

the video is being uploaded now. got the race and the clip of the bearing alone on the cool downl lap

the only thing that puzzles me, is the vibration.. usually, well, the one time I blew one at sears MUCH harder than t-hill by the way on bearings. that's where racks,and bearings give up their lives. the one time It did blow, it made a racket, on the right turns, not left... that was the indication. this one makes noise and vibration going straight.
that's a good idea since its coming off anyway, or is it? I forgot. do you have to remove the half shaft at the diff?

anyway, the offsets I run are not that deep, but with the spacer and the rim half, much more of a leverage point than stock .. however, cornering might have some muting factors. bottom line.... I replaced the holbert rear bearing 10 years ago..... (It was 15 year old) and this bearing is 30 years old, so I don't think the bearing is seeing anything it cant handle, especialy since the car has run faster in the past many times. the brand new tires, are only very slightly better than tires I was getting from Darrel anderson and others. since 2008, ive been getting pretty nice gifts of used tires that work well. and the offsets have never changed.. I just call It "its time".

however, on the jack stands, I run the tires up to 120, turn off the engine, neutral, and jump out and listen. the pasengerside is very noisy, even when I support the a-arms so the CV angles are near parallel. it coasts down very fast. lots of friction with the driveshaft and fluids I bet.. ill try and get a video and maybe a way to keep constant throttle to keep it at 3000RPM in 5th on stands . either way, its coming apart. thanks for the advice . Ive forgotten the first step in removing the hubs etc. don't know if I can bother Bill to help. he has helped me way too much over the years!

found the pic of the 2008 replacement of the driver side wheel bearing , soooo, its time for the passenger side now, right?

mark kibort

Here is the race footage... go to the end, near 10:15 and 12:10 for wheel bearing noise

the lap with the the 991 RSR behind me is interesting too. at about 4:40

better on the rear view cam... ill have that up next.

rjtw

Wow -- only 1 other car in the top 10 was NOT sponsored... and the next oldest car in the top 10 was from 2001. Incredible!!

dr bob

Interesting way to try and at least hear the noise better. Does that tell you definitively that it's a wheel bearing? Not really. So pull things apart as I suggested and turn the drive hub by hand. If it's anything but buttah-smooth put a new bearing in.

Use your mechanic's stethoscope to listen to the bearing in the carrier as you spin the wheel as part of your 100mph vibration test on the stands. Bearing noise transmits nicely through the carrier. Be Sure to do those tests with the suspension loaded, so that the half-shaft and CV joint angles are consistent with what they experience on the car while driving; letting the wheels and suspension dangle while you do spin-up tests is, um, not a good idea on several levels

Yes. Take the opportunity to inspect the half-shaft for radial play at both of the CV joints while it's still in the car. If there are torn boots or wear/radial play noticed, get some rebuilt half-shafts to put in. A worn CV joint will cause a lot of vibration, and in the process will trash the wheel bearing. Whatever you end up doing to one side, do it to the other side too all at once.

Cool thing about bearings. Each time you drive, they wear. But every time you stop, all the wear disappears and the next time you drive, you start out with new bearings again. It's a miracle!

Just because a bearing has seen service and hasn't worn out to the point of you noticing it yet doesn't mean it isn't wearing. Where is the tire relative to bearing? What G forces and impacts have the bearings endured? The bearing is designed to take a certain amount of loading both radially and axially. Moving the load relative to the bearing changes how the load is applied to the ***** and races. The bigger the effective offset load angle, the more uneven will be that loading. Can a bearing run that way for a while? Yes, obviously. Will the wear and heat load on the smaller area of the outer races eventually cause lubrication breakdown, galling and spalling of the races and the *****? um... Yes!



The hub comes off using the B90 toolkit. It has a frame that fits around the hub and puts pressure on the cast upright/carrier. Grease the threads on the jackscrew before you start so you don't damage it, and also don't damage the nut inside. The jackscrew then extracts the hub from the bearing. The inner race of the outer half of the bearing will come off with the hub, and will need to be removed before it's all put back together. Then the snap ring holding the bearing in the carrier comes out. The tool kit has an assortment of round drive plates. Find the one that barely fits through that inside hole so it can contact the outer bearing race. Then put the jackscrew back in and tighten on it to get the bearing out. If you choose not to enlist the aid of the toolkit owner, your options move to removing the carrier/pright and taking it to a machine show where you can get the old bearing pressed out and the new one pressed back in. Removing the carrier means you'll be realigning the rear wheels when you are done. Consider that you could -pay- Bill Ball to bring the B90 tool and help, and still come out many dollars ahead net.


Do both of them. Seriously.

And the info for services like this needs to live in your notebook Much easier to keep track of what you did and when you did it that way, vs fishing around for the pics you might have taken way back when you did it. Write stuff down!

mark kibort

I didnt update my further testing. YES, great idea, i did the same test again with a friend and then used the stethoscope to listen to each carrier. WOW, a friggen percussion band in the passenger side! , driver side, smooth as silk. diff sounds good. i think its pretty clear its the bearing.
no radial movement at all with the tire being pushed and pulled . but LOTS of bearing noise and clanking around, like springs are floating around in there too.

now the vibration worries me, but the half shafts feel nice. well lubricated (in and out that standard .5" of movement and absolutely no radial play. could they be slightly out of round due to bearing wear and internal destruction?


now the B90. ill see if bill wants to yet again, come out and help. or maybe i drive it to his house ...... i seem to get the picture. use the tool to pull out the bearing guts and then again to pull out the outer race? now, how do you get it back in?
if i pull the hub as i did before, why an alignment? nothing adjusted comes off the car, i dont remember anyway

thanks again. the process starts soon. i have the bearing! so all set to replace now. just the method is the next step to decide.

btw........i have detailed note of all changes to the car.... just didnt look in my book yet.. i was just refreshing my mind on that replacement and remembered that cute picture. (and side we were working on)

EDIT: just checked my records. driver wheel bearing changed sept of 2005! bill ball was there at sears that day.. the day i was racing the ferrari challenge car . he did a bunch of video that day. and, the passenger side wheel was hit pretty hard in 2007 by the mazda 3rd gen, at sears a year later. probably damaged the bearing took 10 years to fail!

mark kibort

cup car pic
rear cam video

mark kibort

Here is is a great little video of that GT3R

mark kibort

just found my old rear wheel bearing socket. its 1 1/4 " not 33mm. I think i remember the correct metric socket being 32mm. anyway, i only have a 1/2" drive so i dont think that can break the nut loose, right? ill have to stop by the shop to have them crack it and then drive it home to start disassembly.

FredR

Mark,

That things needs a 3/4" drive or greater to crack it assuming you are talking about the stub axle nut.

The pic you showed earlier with the rather large torque wrench held by the little one would do the trick nicely- presumably you do not have that in the tool locker.

Rgds

Fred

mark kibort

yep , that was a loaner... illl have to crack it at the shop, drive it home and take it apart .. reverse if i can get it back together.. otherwise, the carrier will have to be pulled.

dr bob

You'll need to pull the half-shaft out to get the carrier out.

Some parts stores have tool-loan and free-rent programs for stuff like this. Worth a phone call or two to locate one near you. Bill Ball -may- have one in his arsenal, as it's the same setup needed to tighten the crank nose bolt for a timing belt change. Different-size socket, same 3/4"-size drive.

mark kibort

I dont remember having to pull the half shaft out. doesnt it just slide out with the carrier being removed? its been 10 years! good call on the torque wrench rental. however, ive always done the crank nose bolt with a half inch drive breaker bar.... but ball parked the torque. i know what 300lbft is, and i know what 100lbft is... its on the high side of in between.
Ill have to see if Bill is a wrench for hire on this project!

is this the right one? its a big bearing!!