Car shakes itself apart when hot.
 

After being on the road for a while the car starts to shake wildly when I try to take off in 1st gear. It feels like the car has no mounts and the engine is just bouncing around.

I have a lightweight flywheel but don't know if it's counterweighted. Also the car had a full 5lug and LSD swap in it.

1987 S4

Please help?

Jason

I would make sure that your flywheel is counterweighted, and check your motormounts.

But would that only happen after the car has been running for a while? When it first starts up and for the first 10-15 minutes it runs fine.

I'll check them tomorrow.

Jason

I hate to sound like a dick, but how long have you driven a stick? Sometimes you can get a bad launch and release the clutch too early.... OR your clutch has worn and you car can shudder as it gets going.

what would that have to do with the car shaking when warm? if he were bad at driving stick, dont you think he would have this problem most of the time, not just when the car is at temp?

Does it continue to do it once you've let off the clutch/fully in gear? Or only when you're accelerating from a stop?

Is it possible a brake caliper could be sticking badly, and it's trying to break loose?

I have been driving a stick for over 15 years, including military vehicles and rigs :-)

Only when from a stop, I'll check the brakes when I get home. Because I do have a slight shudder when breaking... might be time for new rotors and to disassemble the 4pot calipers and rebuild them.

moreso the last part, about the clutch being worn, but even then it wouldnt matter warm or hot.

The clutch is new, as is the flywheel.

It is going up on the rack soon, I think the exhaust leak that I discovered is blowing right on the trans mounts as well.

Gonna have to see when I get it up.

Check for vac leaks, its possible for them to show up when thermal expansion sets in on the manifold and associated parts. Does the engine suffer from power loss when it vibrates this badly?

No power loss at all.


I am thinking its that things are overheating due to an exhaust leak. After a long interstate trek yesterday the shifter, ebrake and pretty much the whole tranny tunnel was too hot to touch. This seemed to increase the shaking.

I am hoping to have this wrapped up this weekend and I'll let you know

It may be that the exhaust leak has baked your transmission mounts, causing it to rumble when moving; but if the mounts were toasted then it should shake all the time. I had a bad exhaust leak once off of my RB header in my old N/A, since the leak was right next to the shifter it would shake everything around a bit. You won't find out till you get it up on stands and inspect everything. Hope you fix it.

Update:

Got the exhaust all fixed...

Then, 3 hours later, the clutch exploded... lol

No pedal and the car will not engage any gear... it will shift through all the gears, but the clutch will not bite.

Fun stuff.

Oh, and new Master, slave and SS Lines. I can see the slave pushing and nothing is happening.

Hindsight 20/20: Your clutch is about to kick rocks, the shaking is a good indication.

You mentioned it was a new clutch, what type clutch did you install that failed so quickly?

Did you change out your throw-out & pilot bearings while swapping out the clutch?

sad story bro, give us an update if its still messed after you reinstall a new clutch

Box,

I did not do the clutch... but apparently it was an autozone clutch. I have an Excedy Organic on the way.
And I was told that all the clutch parts were new... I think it was not properly broken in... but now I have an excuse to get all new clutch stuff. :-)

Lesson #1287: Never believe what you hear from someone trying to sell a car...

MMmmm... Sorry to hear that. Had I seen this, I could have forewarned you. I had the EXACT same problem. When I first bought the car I replaced the clutch with one from... you guessed it : Autozone. I even resurfaced the flywheel. About a month later, that exact same issue started up. I checked all the mounts, driveshaft was good, so the only thing it could have been was the clutch. Luckily I hadn't thrown away my old one, so I decided that since the disc itself was garbage I'd try only the pressure plate. Bingo. Their pressure plates apparently are made of crappy steel and get blue-spotted EASILY.

Moral: Don't buy PARTS from discount parts stores. Adhesives, spark plugs, bolts, oil, etc. is ok, but DON'T buy their replacement parts. Their belts squeal, timing belts snap prematurely, ps pumps, ac compressors, etc all crap out quickly.

yeah... I do not get replacement parts from there. I have been building cars for some time and usually get OEM from the dealership when I have to replace. (The discount helps)

But this is my first rotary and I am glad I found this place.

I'll give an update by the weekend when I get the new clutch in.

Thanks again everyone who helped.

I know this is an old thread but i'm glad i found it. My car is having the same EXACT issue now. Guy i bought it from said the clutch was just changed at Mazda. When it's cold it starts off fine, hell i've even autocrossed it, but as i drive it for extended periods of time with constant starting and stopping it shudders at even feather releases. Thanks for posting up your solution and sharing this info, i love this site!

Does no one properly break in clutches anymore? seriously? "oh yea, new clutch last week and then I took it to an event and now my shits acting funny". No shit? Please, tell me more...

Unfortunately I've no way of knowing how it was broken in but i feel ya. Said it was changed around 80k i bought it at 90k. Looks like I'll have my own opportunity though if i end up replacing this one.

No one mentioned the term for this - Clutch chatter - and it's a bitch.

Very common to get worse as the car is driven and the clutch heats up from use. After a rest period (i.e. a few hours), it is fine, until it warms up again.

As mentioned, engine and tranny mounts can cause these symptoms, but more commonly the cause is improper clutch break-in, failure to machine the flywheel smooth and to get rid of hot spots, or a defective (i.e. clutch disk springs) or warped clutch assembly.

Note that some performance clutches with little or no springs on the clutch disk can cause symptoms like chatter, especially if mounts are weak.

I get slight clutch chatter when my car is nice and warm. Good mounts all the way around, clutch disk is fine and the pressure plate is mostly fine. Before I replaced my mounts with mazdacomp mounts it would chatter like crazy when warm.

I can only suspect 2 things in my case...

1) When I first bought the car, it had a clutch with 2k miles on it. When the engine got taken out, further inspection revealed a new clutch but a factory pressure plate (it looked that way anyway) and the pressure plate fingers had slight grooves in them ( like the PO liked to ride the clutch)

2) When i first bought the car, I was always used to clutch engagement very high up on the peddle. It took me a few miles to get used to the engagement being lower on the pedal and I think I overheated it once or twice.