Gruanching noise over speed bumps

[dean legg]

Hi All

On my 84 911 wide body every time i go over a speed bump there is a loud granching noise from the rear drivers side torsion bar area
Only doing 2- 10 mph

I can't replicate the sound when stationary, as reported on other posts

This noise doesn't happen at higher speeds

Chuck from Elephant replaced all the suspension only 4000 miles ago so I can't really see anything wearing out
I can't take it back to Chuck as i'm 4000 miles away

Any ideas would be greatly appreciated

Thanks Dean

[Rot 911]

Have you greased the polybronze bearing?

[dean legg]

Where would I find that?

[JP911]

Torn rear sway bar mount?

[Rot 911]

Pull off the torsion bar cover. Look for a grease zert on the bearings.

[notfarnow]

Originally Posted by JP911

Torn rear sway bar mount?

+1

If you look at the rear sway bar mount, you'll probably see that the bracket has pulled clear off with a chunk of the mount.

weld in the updated reinforced ones:
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=WVO-RARB&catalog_description=WEVO%20RARB%20Console%2C%20eac h%2C%20%39%31%31%2F%39%31%31%20Turbo%20%28%31%39%3 7%32%2D%38%39%29

[jorian]

I agree with Jake. I had the same issue on my 87. I replaced the factory units with Wevo ones. Bombproof.

[Chuck Moreland]

Dean's car doesn't have Polybronze. We opted for rubber bushings all around. But FYI for anyone who has them, they can be greased with the cover plate place.

I think the torn sway bar mount is a likely candidate. These fail regularly, and Dean your car is pretty high mileage on original mounts.

The bumpy roads you travel load the sway bar heavily. You've put 4k miles on those roads, good chance a mount has torn. This could certainly make the noise you describe and near the torsion bar too.

[notfarnow]

FWIW, when they first tore away, I was able to weld it back together and weld over a bit of metal to reinforce it. It pulled away again within a year or so. The WEVO unit is a permanent solution.

Grinding out the old ones isn't as bad a job as I expected. You have to move the oil lines over, and take out the sway bar. Once you clean the area you can see where the spot welds are holding the brackets on. Grind them off, then clean up the area to weld on the new ones. The whole job took me maybe 2-3 hours, and I'm not all that bright.

[dean legg]

Thanks for all your input guys

Just worked out a sway bar mount is an anti roll bar mount..... in my english manual

I'll check it out tomorrow.... but in my manual I still can't find out where it is

Can one of you helpful guys post some photos to give me a clue
I feel a complete numpti asking this, i'm an ok mechanic, but the terminology
just throws me

If this is the problem the wevo kit is the solution?
And these have to be welded on?

Thanks in advance Dean

[Flieger]

Here is a factory 911ST with reinforced anti-roll bar mounts.

[jorian]

The Wevo bits need to be welded on. The old mount needs to be cut off, mounting area cleaned up with an angle grinder. When you weld the new mounts on its a good idea to bolt the mounts to the bar and fit it as a unit to ensure proper alignment.

[dean legg]

Managed to get a look under the car and everything looks ok

Anti roll bar mounts all intact

Could it be the rubber bushings making the noise?
If so ,how and with what grease could you use?

Cheers Dean

[sjf911]

Originally Posted by dean legg

Managed to get a look under the car and everything looks ok

Anti roll bar mounts all intact

Could it be the rubber bushings making the noise?
If so ,how and with what grease could you use?

Cheers Dean

I have the same noise from both sides with the same rubber bushings. I suspect it is related to lack of bonding to the underlying metal allowing movement especially when cold and stiff, it seems to go away when the temperature is warm.

[dean legg]

Here its 30C every day! So I don't think its heat related

And mine only does it on one side. After an hour drive its still there

[dean legg]

any ideas any one?

[sjf911]

Originally Posted by dean legg

any ideas any one?

You are getting frictional movement between the spring plate and the rubber bushing, between the rubber bushing and the torsion tube surface, or the antiroll-bar and its bushing. You could disconnect the roll-bar and see if the noise continues.

[Nine, Frau!]

That torn metal associated with the sway bar pulling out can be hard to notice. Stick your face really close to the car, right in front of the rear wheels and look closely where the sway bar attaches. This just happened to me and it took a minute to notice what had happened. I also read that this happens right after you beef up the diameter of your torsion bars.

[dean legg]

Steve

I think you are right

Do you know of a fix for this?

Cheers Dean

[rfloz]

If your car is lowered and/or you are running tall tires, you may be getting some tire rub back there.

My T/L is and I get tire rub on the right rear when I take a passenger on an auto-cross run. Just pull the tire and check for shiny spots.

FWIW, my rear anti-roll mount was cracked pretty good on one side and emitted no noise. If it is an issue for you, the WEVO mounts (see above) are well worth the effort and cost.