wheel bearing replacement

[my911sc]

Hi,
How to replace the wheel bearings on 1980 911 sc? My car is kinda making rattled noise when I driving. How to determine it has a bad wheel bearing? Is that has bad wheel bearing. If so how many part involve for this job.
Thanks,
KSP

[Rot 911]

Front or rear? Fronts are easy, rears are hard. Rattle is not usually a wheel bearing going bad. They then to make a grinding noise. To check the fronts jack up a side, grab the top and bottom of the wheel and see if there is any play in the wheel.

[Gunter]

How to replace the wheel bearings on 1980 911 sc?
The Bentley SC Repair Manual explains it very nicely or, you can do a search here, lot's of info under "Wheel bearing replacement"
Like Kurt says: "The front is easier than the rear"

[my911sc]

Originally Posted by Kurt V

Front or rear? Fronts are easy, rears are hard. Rattle is not usually a wheel bearing going bad. They then to make a grinding noise. To check the fronts jack up a side, grab the top and bottom of the wheel and see if there is any play in the wheel.

Thanks Kurt,
I think both front and rear on left side.
KSP

[aston@ultrasw.c]

Originally Posted by Kurt V

jack up a side, grab the top and bottom of the wheel and see if there is any play in the wheel.

This will tell you if something bad is happening at that corner.

To better isolate the wheel bearing have an assistant stand on the brake pedal. This will clamp the rotor and prevent the bearing from moving.

If the play remains it is most likely something else.

If the play is eliminated it is most likely the bearing (or something related to the bearing, like the spindle)

[rusnak]

KSP,

I agree with Kurt, it's not likely a wheel bearing. If the rear wheel bearing is going bad it will make a (grinding) or even a howl like your car has a supercharger.

If the front are bad then it can make lots of noises. The wheel play issue is a bearing adjustment issue, not necessarily a bearing without grease or a bad bearing. If you can make it to a deserted road, try to coast with the engine off going about 25 mph or so. If you hear a whining, grinding, scraping or oscillating type of noise then you may have a bearing going bad, especially if the sound goes away or is altered when you apply the brakes.

My guess is that you have something loose though, such as a metal brake line hitting against the front strut, or a loose skid plate over the steering rack.

[my911sc]

Originally Posted by rusnak

KSP,

I agree with Kurt, it's not likely a wheel bearing. If the rear wheel bearing is going bad it will make a (grinding) or even a howl like your car has a supercharger.

If the front are bad then it can make lots of noises. The wheel play issue is a bearing adjustment issue, not necessarily a bearing without grease or a bad bearing. If you can make it to a deserted road, try to coast with the engine off going about 25 mph or so. If you hear a whining, grinding, scraping or oscillating type of noise then you may have a bearing going bad, especially if the sound goes away or is altered when you apply the brakes.

My guess is that you have something loose though, such as a metal brake line hitting against the front strut, or a loose skid plate over the steering rack.

This happened after replaced the CV's boot. It 90% I suspected on left rear wheel. Because I found down one of the bolt tie from axle's CV boot loosing thread. I tried to tie the bolt real hard but still hear the noise. Something else loosing??
Thanks a lot guys,

[rusnak]

KSP

I'm having a hard time understanding you, but if you have a 911SC and you have recently changed the CV boots, then you would have bought the new boots with a thinner flange. The older ones had thicker flange plates, and the new ones from Porsche have thin pressed metal flange plates.

The result is that you have to switch to shorter bolts on the CV boots. All 24 need to be changed. If you re-use your old bolts then they will hit the transmission and/or the trailing arm. This will either prevent you from being able to fully tighten the bolts, or it will lock the driveline against the trailing arm.

Looking up at the inner CV joint where it bolts to the transmission, you should be able to see 1-2 threads sticking out of the drive plate on the transmission. Any less, and your bolts are too short. Any longer, and they will hit.

I don't know if this is your problem, as I said I can't really understand what you're trying to say, sorry.

[my911sc]

Originally Posted by rusnak

KSP

I'm having a hard time understanding you, but if you have a 911SC and you have recently changed the CV boots, then you would have bought the new boots with a thinner flange. The older ones had thicker flange plates, and the new ones from Porsche have thin pressed metal flange plates.

The result is that you have to switch to shorter bolts on the CV boots. All 24 need to be changed. If you re-use your old bolts then they will hit the transmission and/or the trailing arm. This will either prevent you from being able to fully tighten the bolts, or it will lock the driveline against the trailing arm.

Looking up at the inner CV joint where it bolts to the transmission, you should be able to see 1-2 threads sticking out of the drive plate on the transmission. Any less, and your bolts are too short. Any longer, and they will hit.

I don't know if this is your problem, as I said I can't really understand what you're trying to say, sorry.

Rusnak,
Yes, I have recently replaced the CV boots by local guy at my house and we used the old bolts. My is 1980 911 targa and I in San Jose.
Thanks,
KSP

[shbop]

Originally Posted by rusnak

KSP

I'm having a hard time understanding you, but if you have a 911SC and you have recently changed the CV boots, then you would have bought the new boots with a thinner flange. The older ones had thicker flange plates, and the new ones from Porsche have thin pressed metal flange plates.

The result is that you have to switch to shorter bolts on the CV boots. All 24 need to be changed. If you re-use your old bolts then they will hit the transmission and/or the trailing arm. This will either prevent you from being able to fully tighten the bolts, or it will lock the driveline against the trailing arm.

Looking up at the inner CV joint where it bolts to the transmission, you should be able to see 1-2 threads sticking out of the drive plate on the transmission. Any less, and your bolts are too short. Any longer, and they will hit.

I don't know if this is your problem, as I said I can't really understand what you're trying to say, sorry.

Nice catch!

[Gunter]

rusnak hit on something.
The old Allen bolts will be too long, especially if you leave out the shim-plates.
KSP: Did you re-use the halfmoon shaped shim plates?
And, did you use new gaskets, or no gaskets?

Lift the car securely, climb under and check.
If the bolts are too long, you'll be able to feel the clonking when turning the rear wheel by hand.
That means the ends of the bolts are hitting something.

New Allen bolts are M8 x 1.25 x 50 mm (Quality 12.9) If they are too long, grind off a few threads.
Always use new Schnorr lock-washers.
Torque is 30 ft-lbs using a 6 mm Allen.
Not everybody uses the moon-plates.
As for gaskets, some use them and some don't.

[my911sc]

Originally Posted by Gunter

rusnak hit on something.
The old Allen bolts will be too long, especially if you leave out the shim-plates.
KSP: Did you re-use the halfmoon shaped shim plates?
And, did you use new gaskets, or no gaskets?

Lift the car securely, climb under and check.
If the bolts are too long, you'll be able to feel the clonking when turning the rear wheel by hand.
That means the ends of the bolts are hitting something.

New Allen bolts are M8 x 1.25 x 50 mm (Quality 12.9) If they are too long, grind off a few threads.
Always use new Schnorr lock-washers.
Torque is 30 ft-lbs using a 6 mm Allen.
Not everybody uses the moon-plates.
As for gaskets, some use them and some don't.

I used everything came with the packages which I purchased from Pelican parts except the old bolts. I'll check sometime this weekend... Thanks a lot Gunter,

[Brad394]

Originally Posted by my911sc

Hi,
How to replace the wheel bearings on 1980 911 sc? My car is kinda making rattled noise when I driving. How to determine it has a bad wheel bearing? Is that has bad wheel bearing. If so how many part involve for this job.
Thanks,
KSP

I don't mean any disrespect but if you don't know how to check for the problem then this might be one of those things you should have done for you. It is great to be a do it yourselfer but some things require a basic knowledge base of auto mechanics and if you don't have it then you should be 1) shown how its done by a knowledgeable person or 2) avoided doing it. There is a reason that an auto mechanic has such a long apprenticeship.

[ZOA NOM]

I disagree, this is precisely the kind of thing that creates valuable experience for the DIY-er. He's come to the right place, and has received great advice. Taking it to a "professional" will introduce another set of variables, and lighten his wallet unnecessarily. This forum has taken me from "how much torque on my lugs" to a full race motor rebuild, without a "professional" in sight.

[rnln]

then this board shouldn't be there or we shouldn't be calling it a "technical" board. Honestly, I have done so many things I had no idea how and what is in there before I took things aparts. This board has been providing great help, yes, he came to the right place as Zoanas said. Some knowledgeable one will sit down and write him something when he has the time.

[rnln]

rusnak,
does this apply to SC only or also carrera. I did the same thing he did, old bolts, and didn't pay attention on noise or not.
Thanks.

Originally Posted by rusnak

KSP

I'm having a hard time understanding you, but if you have a 911SC and you have recently changed the CV boots, then you would have bought the new boots with a thinner flange. The older ones had thicker flange plates, and the new ones from Porsche have thin pressed metal flange plates.

The result is that you have to switch to shorter bolts on the CV boots. All 24 need to be changed. If you re-use your old bolts then they will hit the transmission and/or the trailing arm. This will either prevent you from being able to fully tighten the bolts, or it will lock the driveline against the trailing arm.

Looking up at the inner CV joint where it bolts to the transmission, you should be able to see 1-2 threads sticking out of the drive plate on the transmission. Any less, and your bolts are too short. Any longer, and they will hit.

I don't know if this is your problem, as I said I can't really understand what you're trying to say, sorry.

[rusnak]

Hi rnln,

I think the problem is the switch from the thicker flange boots to the thinner pressed steel ones. The difference is probably about 5mm or less, so I can see that some people may not have a problem, but some people will. Some Carreras and 911SC would have had their boots replaced already, and so they would have been switched over to shorter boots.

I only mention 911SCs because I know that when these cars were made Porsche was still using the thicker flange on the boots. They almost made the half moon plates overkill because the flange was so thick.

I forgot to mention that I think the gaskets are totally necessary. You don't want your grease to leak out of the joint when it heats up and liquifies. Also, use new or new looking cv bolts. Be sure they are grade 12.9 strength rated, and you should use either Shnorr lock washers or red locktite, or both. Be sure to tighten up to spec, which is like 40-50 lbs or so, I can't recall right now.

[rnln]

I replace my boots and byt that time, I didn't pay attention to the thickness of the boot/gasket/flange. I got the kit from PP.
Thanks.

Originally Posted by rusnak

Hi rnln,

I think the problem is the switch from the thicker flange boots to the thinner pressed steel ones. The difference is probably about 5mm or less, so I can see that some people may not have a problem, but some people will. Some Carreras and 911SC would have had their boots replaced already, and so they would have been switched over to shorter boots.

I only mention 911SCs because I know that when these cars were made Porsche was still using the thicker flange on the boots. They almost made the half moon plates overkill because the flange was so thick.

I forgot to mention that I think the gaskets are totally necessary. You don't want your grease to leak out of the joint when it heats up and liquifies. Also, use new or new looking cv bolts. Be sure they are grade 12.9 strength rated, and you should use either Shnorr lock washers or red locktite, or both. Be sure to tighten up to spec, which is like 40-50 lbs or so, I can't recall right now.

[Brad394]

OK, before you flame me into oblivion, I expressed my concern as a former person of the trade. I feel if you can't diagnose a problem and are not sure how to fix it, you need to 1) find someone who can help you diagnose and 2) get someone with experience to help with the fix. Certain jobs, like this one for example, do not just requires good advise and the ability to read a manual but it requires "feel". The last thing you want is to find is you have over tightened or undertightened the wheel bearings while working the twisties.

I meant no disrespect to anyone and their abilities, I was just expressing my concern.

BG

PS...and yes I have used great PORSCHE advise from this very forum even with much experiance under my belt.

[rusnak]

Brad's point is valid of course. It's always better to have an experienced hand help you out, but what do you do if you're on your own? You struggle through it, which is why so many of us are willing to help out others - they are struggling through it by necessity.

One of the things that continues to elude me is the correct adjustment of the front wheel bearings, which is what attracted me to this thread in the first place. I don't have the "feel" for the correct amount of "clunk" in the wheel when you shake it. I have evolved to where I grease the hell out of the bearing, and then adjust it to a faint "clunk", tighten the pinch bolt as tight as it will go, and then obsess over whether the adjustment is correct, or am I burning the rollers or wearing out my expensive RSR spindles.......

ok sorry to wander off topic, KSP let us know if the noise goes away or not.