some questions

Taz's Master · 08-19-2002, 09:25 AM

These questions relate to my 1986 NA

First, I have a noise (constant low volume roar/whine/howl, difinately not a click/thump kind of noise) that seems to come from the right rear, only while coasting, usually in a high gear. Basically it is most noticable when I get up to the speed I want and back off, like I get up to 70 and coast down to 65 in 5th. I'm guessing wheel bearing? The passenger side rear (where the noise seems to be coming from) is missing the parking brake assembly, so I'm guessing a PO messed with that side.

Next is something I'm hoping isn't related, but might be. If I don't match revs, I get a significant vibration through the shifter, and the whole car seems to shudder. Does it also when shifting from third to fifth, basically when making big jumps in rpm's. Doesn't seem to be the typical indication the rubber center in the clutch is shot, but could that cause this? I pumped my tranny mount full of window weld (it actually looked fine when I pulled it out), could bad engine mounts cause this symptom?

I get a pretty good steering wheel shimmy at 50+, and a whole car shimmy that comes and goes, and I suspect bent wheels. They are on the to-do list. But I also get a squeek (from outside the car) and a pulse in the brake pedal. I had my front rotors turned and it didn't make much of a difference. The pulse/squeek are definately related to wheel speed, should I be checking my rear rotors, or should I be focusing on other areas of the brake system?

AFJuvat · 08-19-2002, 11:43 AM

Start with the brakes first.

Pulse in the brake pedal could either be a worn rotor or a hanging caliper - does the wheel want to turn when you hit the brakes hard?

Wheel shimmy - balance the wheels, check for wear and damage. Inspect ball joints, tie rods and steering universal for excessive wear/damage

Transmission - almost sounds like your clutch is slipping - could be clutch disk related or hydraulics. - you need to investigate this one further. Engine mounts will make you think the fillings in your teeth are going to fall out at idle.

Roar/whine - probably a wheel bearing - could also be a CV, they can also howl, especailly when they are excessively worn, albeit evenly.

AFJuvat

Taz's Master · 08-19-2002, 12:05 PM

She tracks pretty straight on or off the breaks.

The suspension parts actually look ok. No real noticable wear or damage. I recently replaced my sway bar bushings (rotted from a power steering leak), and the other parts looked ok. 2 of the wheels (16in phone dials) have visible damage, and one has been stripped of finish. I'll be sending them off to be repaired and refinished. Any reccomendations where they should go?

Hadn't really considered the hydraulics in the clutch. I get a decent launch (I have a limited slip) without the pronounced shudder I can induce at speeds. I don't really want to do the clutch, but would rather buy a clutch than a tranny.

I'll be checking the rear wheel bearings soon.

AF Juvat, that was a very quick response, thanks. Go ahead and buy that 911, but please oh please don't drift away from this board.

AFJuvat · 12:25 PM

In that case, your pulseing pedal is probably one or more warped rotors. Wear limit on the rotors is 18mm if memory serves. if the rotors are too badly worn, you will probably wind up replacing the brake pads too.

You can get some chatter/slip on the clutch if your hydraulics are shot - check behind your clutch pedal for drips. Also check the pedal itself, there should be no more than 2 - 3mm of free play in the pedal. There are a lot of variables on this one - ranging from hydraulics to bad (worn) disk to flywheel in need of resurfacing and beyond (read more $$$) This one you really need to take the car to a empty area and "play with" and see when/where the problem pops up

Wheels - I honestly couldn't tell you where to get them done, you will have to check around your local area. Be aware however, that you may have a cheaper alternative just buying a couple of wheels in good condition from a junk yard - 20th street Auto in Phoenix has about the best deals on used porsche wheels.

Do double check your control arms and ball joints - from 85.5- Porsche switched to an aluminum control arm. These parts are notoriously under-engineered and prone to failure. Check them for cracks/bends or excessive play in the balljoint. Balljoint failure will cause all sorts of expensive secondary damage (ask me how I know this one) when the ball joints are going, you can get a little shimmy and a popping noise as you go over bumps.

AFJuvat