car judders when accelerate

[Stealth1]

1995 bmw 318ti e36 .
when i pull away from a stop the car seems to judder "like a pigeon head" it only happens when i accelerate hardish or if i'm pulling away in a rush.
the engine light is off and everything else seems to be fine.
what else could this be? could it be a leak in the vacume pipes or something? i've just had the clutch changed as last one started to slip.
any help would be great. it only does this in first gear.

[John_in_VA]

It could be drive shaft-related. If you feel the judder in the transmission tunnel between the seats, the center support bearing may be bad ("center mount" #12 in this diagram).

[Junk]

Was the old clutch pretty bad and did you re-surface the flywheel? Maybe it needs breaking in?

If you check the center bearing, you might want to make sure it is pre-loaded. The bracket is slotted and it is supposed to be pushed ~5mm towards the front of the car.

[Stealth1]

Hi, thanks for the pic, i'll have a look in a while, i don't feel anything thru the car itsself when driving etc. it only happens when pulling away in 1st. i have just found a rip in the air flow boot from the box to the carbs what i'm about to test it out, could that cause it? sounds silly but little things first before the big money things lol could that cause more air to enter the engine and less fuel to burn causing it to judder?

its more like when i pull away in first it seems to go but then something is stopping it causing it to jump and stop jump and stop etc.. its like the engine dies and starts again without cutting out. and it only happens in first gear from a stop..its all ok when changing up and down and even reverse gear is normal.

someone told me the clutch could have grease on it but if it had grease on it, it would start to slip and cause it in all gears?
i was also told to try and slip the clutch what could stop it?

[Stealth1]

Originally Posted by Junk

Was the old clutch pretty bad and did you re-surface the flywheel? Maybe it needs breaking in?

If you check the center bearing, you might want to make sure it is pre-loaded. The bracket is slotted and it is supposed to be pushed ~5mm towards the front of the car.

hi, the last clutch wasn't too bad as it was only slipping a tiny bit and when the person changed the clutch over he gave me the old one back and it don't seem to bad. i think he done the job all good as he has changed the clutch before and everything was good. he said the flywheel was in good condition so there was no point in a re-serface? i've had the new clutch in the car for around maybe 200 miles? it feels as if its already broken in but i might try and cause it to slip as someone told me that may fix the problem without taking it all out again.

[Mr.Squeelerz]

Check and see if it consistently hits on the same rpm when it happens.

If your boot is clearly ripped you might as well just go ahead and order new one right now. Having rips or cracks can cause your car to stall. Not saying this is your problem, but you should probably replace it as soon as you are able to.

[Stealth1]

Originally Posted by Mr.Squeelerz

Check and see if it consistently hits on the same rpm when it happens.

If your boot is clearly ripped you might as well just go ahead and order new one right now. Having rips or cracks can cause your car to stall. Not saying this is your problem, but you should probably replace it as soon as you are able to.

got my new boot from the trusty breakers. glad i found the rip.
anyhow, it don't matter what rpm its at unless its under 2000rpm.
if i rev it up say 3000rpm and let the clutch go it will jump and stop and jump and stop but if i hold the clutch down just after the biting point it will just go as normal, like it needs to slip before it takes off normal. maybe its not fully broke in yet, would that cause it?

[pdxmotorhead]

With a cracked boot the engine rocking under power can open and close the crack, messing with the air flow meter... Fix it first! It fixed the same problem on my car!

My opinion: I Never ever put a new clutch on a used flywheel unless the used flywheel is almost brand spanking new and still has the machine marks. They need to mate together and if the flywheel is not machined its still carrying the deposits of material and the surface hardening from the old clutch disk.

Dave

[Junk]

exellent point as always Dave, never thought about a ripped boot flapping, that sure could make things run funny.

if that's not it, and you check what John_in_VA said, center bearing, you might make sure the trans and engine mounts are tight while you're in the neighborhood..

I've had a couple cars judder/shake like you say pretty badly and neither of the clutches looked bad (not grinding on rivets yet anyway) so I was surprised how badly they could behave. On my ti, it got really bad when I would drive through a large puddle, bucked real bad and barely would accelerate from a stop for a few hundred yards or so until it all dried out I guess.

I'm with Dave on the resurface, I can really notice the difference in brakes (smoothness) when I change pads and rotors vs. changing pads only. Even braking power has been really bad last few cars I did changing pads only..until they got broken in, which I'm sure takes awhile longer with a worn rotor.. not to mention the squeeks from high smooth spots until you sand them down..

[cooljess76]

Exact same thing happened to my friends car. He swore up and down it was a clutch problem and I kept telling him to check his intake boot. Finally, he took my advice and found the split intake boot. Basically it was a combination of two things. The intake boot was leaking, causing the engine to misfire and the motor mounts were worn, allowing the engine to rock back and forth which in turn opened the split in the intake boot momentarily, just long enough for the engine to sputter and kick. In his defense though, it felt exactly like someone who was learning to drive a manual.

[pdxmotorhead]

Yea, I sprung for a new O2 before I found the boot leak,,, another 80 bucks I'll never get back...

Dave

[Stealth1]

Originally Posted by cooljess76

it felt exactly like someone who was learning to drive a manual.

lol thats how i feel when i was driving it, all the jumpy starts etc.. anyway, i fixed the intake boot and it seems to be a lot better, fingers crossed its only that, i'll keep ya'll updated, lets see if i jump up and down the road later lol