already did wheel bearings, but getting vibration from front... struts?

Obin Robinson · 07-05-2007, 02:08 PM

we did the wheel bearings on my 944 only 2 weeks ago. everything has been fine and 99% of the rumbling has gone away. the only thing i'm noticing now is that under heavy braking i'm getting that familiar "rrrrrr" rumbling from the front. it's almost like a bad bearing sound, but that's impossible because we just did the bearings.

could it be a bad strut bearing? i actually had to tighten the top nut onto the strut earlier today. when strut bearings go bad don't they rumble all the time? why would this noise only pop up under braking?

for information sake the front suspension/braking of my car is comprised of:

Bilstein shocks (1 year old)
220# Weltmeister springs
951 sway bar (bushings are only 4 years old)
ATE slotted rotors
Pagid brake pads

everything else is stock and original to 1984. i don't want to get strut bearings if it's something else causing this problem.

thanks!

obin

KY944S · 07-05-2007, 02:20 PM

Could it be your pads and rotors?

flash968 · 07-05-2007, 02:23 PM

more than likely it is deposits on the brakes

however, it could be suspension bushings that only get stressed under a load - control arm bushings are notorious for this on many cars

is there any jiggle or vibration in the steering wheel?

Obin Robinson · 07-05-2007, 02:39 PM

jiggle in steering wheel? hmm, well it's more of a sound rather than a feeling right now. mind you in order to get it i have to get heavy on the brakes going from 55 to 0 in a short distance. i almost feel it more through the pedals than through the steering wheel. the vibration in the wheel was pretty much gone when i replaced the bearings.

could it be pads and rotors? not sure. does anyone else ever get any vibration or noise when they get heavy on the slotted rotors?

how could i tell FOR SURE that it's suspension bushings, strut bearings, or control arm bushings?

thanks!

obin

Obin Robinson · 07-05-2007, 02:55 PM

Quote:

Originally posted by flash968
mcontrol arm bushings are notorious for this on many cars

fwiw would i have to do ALL the control arm bushings, or is a specific one the culprit? i only pay $2-$3 an hour for labor on the 944 so i don't mind going back to pinpoint a problem.

obin

nynor · 07-05-2007, 02:56 PM

sounds like warped rotors to me.

924RACR · 07-05-2007, 03:05 PM

Hey Obin! Long time, all that!

I'd definitely be looking at crud on the rotors first. While bushings, strut mounts, etc., can allow vibration at speed like unbalanced whees (60mph characteristic), they don't cause actual audible noise in my experience...

Icey1174 · 07-05-2007, 03:25 PM

Braking noise or vibration is almost always a rotor/pad problem.

Although... I just replaced the rotors and pads on my Taurus. The vibration came back and it was getting worse over the past month or so. Then a slight squeek in the front end. It was a bad ball joint. I replaced the ball joint and it tightened up the front end. Everyone and their brother said rotors and pads. They also said it was the strut when they heard the squeek. I put it on a lift and the ball joint was so bad you could move the control arm with your hand.

These 944s have a bad geometric design for the ball joints. Check them out to make sure they are not the problem. I rebuilt my control arms about 2 months ago with the track performance ball joint kit from Rennbay. It was $200 for both ball joints. They also came with brass bushings.

KY944S · 07-05-2007, 03:55 PM

I would have to agree also with Icey. It could be any number of things listed.
Although I am not a Doctor, I play one on the NET...

Icey1174 · 07-05-2007, 04:01 PM

I play one at my house sometimes! The 944 is a good lurer!

The ball joint is always something good to keep an eye on with these older cars. The Porsche made it 20 years, the FORD only made it 4 years! Who would have thought?!?!?!

Obin Robinson · 07-05-2007, 04:17 PM

hmmm, ball joint eh? any way to tell FOR SURE that it's a ball joint? i wouldn't doubt it because the ball joints are original from 1984.

thanks!

obin

KY944S · 07-05-2007, 04:18 PM

YEEHAAWWW 200 posts baby

I get to do a set of HMMV ball joints tomarrow (They dont like those big a$$ tires).

Icey1174 · 07-05-2007, 04:26 PM

Put it on a lift or jack stands. Get a pry bar in there somewhere and try prying up and then down on the steering knuckle and or control arm. Look for any play in the ball joint. Look for dried out, cracked, or missing rubber dust boots on the ball joint too.

I did not have any play in my ball joints on the Porsche when I checked this way but I changed them anyway. When I got them apart the nylon cups were broken in many pieces in both sides. One ball was also pitted real bad. It was just a matter of time for mine to go. The track performance kit is the most expensive kit they have at $200. I think the cheapest kit is around $60. The track kit is the only kit wth brass bushings. For the time involved I would get that kit.

http://www.rennbay.com/ball-joint-rebuild-kits-porsche-944-ball-joint-kits-c-30_48.html

I did have a lot of play in the Taurus. When I replaced the Taurus it was tight again.

Obin Robinson · 07-05-2007, 04:29 PM

hmm. i'll put the car up on the lift and check it out probably this weekend. i am beginning to wonder about the ball joints because the last time i looked they did look a bit worn.

thanks for that link. those are all later model ball joints though. no kits like that for the early ones?

obin

Icey1174 · 07-05-2007, 04:37 PM

What's the difference? I only did a quick look around and I don't see anything saying they are different for that rebuild kit.

Obin Robinson · 07-05-2007, 04:41 PM

all the kits say "For use with all Porsche 944 cars from MY 1985.5 to 1992."

i am thinking though that i might just be able to get away with the basic ball joints for my car. they're not expensive. i WOULD love to have that nice racing-grade kit though. i like doing stuff right the first time.

obin

Icey1174 · 07-05-2007, 04:43 PM

http://www.pelicanparts.com/cgi-bin/ksearch/pel_search.cgi?please_wait=N&forumid=&threadid=&command=DWsearch&description=ball+joint&FILTER_944M=ON&FILTER_TECH=ON&FILTER_SUPP=ON&FILTER_ACCE=ON&FILTER_CARE=ON&FILTER_STUF=ON&FILTER_PERF=ON&FILTER_MISC=ON&FILTER_GADG=ON&FILTER_TOOL=ON

Looks like you can replace yours. 85.5 and newer we have to go the other route. Yours are still a lot cheaper. I think it listed them at $18 a ball joint! Please correct me if I am wrong!

Obin Robinson · 07-05-2007, 04:51 PM

yes it looks like all i really need is the ball joint and not the whole kit. fwiw the entire control arm assembly isn't that expensive either. hmmm.

for the price, i might just do new control arms (mine are a little rusty), ball joints, and bushings. i bet that will tighten up the car a lot!

however though i still have to establish that this problem is indeed the ball joints. i'll put it on the lift on saturday and spend a few hours doing some other small stuff as well.

any other input would be greatly appreciated. remember i don't have ANY of my 944 manuals anymore, not even the ones on CD

. all those nooks and crannies of my brain that were full of 944 tech advice are now stuffed with F/A-18 support procedures. you guys are all i have when it comes to Porsche opinions and expertise.

for that i thank you.

obin

flash968 · 07-05-2007, 05:01 PM

rotors almost NEVER warp, though a lot of shops will like to tell you they do - they do develop uneven deposits though, especially with aftermarket pads if you didn't carefully follow the break in procedure - they disguise themselves and are often misdiagnosed as warped rotors - in 30 years of doing this, i have only seen ONE set of warped rotors, and those were due to a frozen caliper

you could skip the rotors and sand the pads and see if it changes

if no change, i would look at control arm bushings, though both they and ball joints usually show up in wheel judder

Icey1174 · 05:13 PM

Manuals are on here. Do a search and grab them!