jbrill

ok, i knwo i shouldn't be dowbshiffting into second, without matching revs ( I always do except on this one occasion..) anyways when im in 3rd and oif i were to downshift to 2nd i get a HORRIBLE vibration throughout the car. I did a search but it appears that there is no direct answer to this...

I just rpelace my exhaust and right after is when i noticed the shudder, I read somewhere that it a person on here was having a very similiar problem and it was due to a exhaust hanger that wasnt fitted/ done up right.

I do have a spring centrered Sachs clutch but it was not doing this before i put the new exhauts on...

Thoughts anyone?

car is a 1990 s2 with just over 50,000kms

tifosiman

If you don't match the revs, that is normal with a spring centered clutch.

jbrill

really? im not talking just a little vibration... my car feels like it is bouncing off the ground lol

Z-man

If I may ask a stupid question -- if you know that you shouldn't be downshifting without rev-matching, then why do you still do it?

Use the brakes to slow down the car, not the tranny...

-Z

jeeper31

I would never use a tranny to stop the car. Only a real woman!

Clown Pedro

ZING!

Jay W

Most likely is the exhaust not hung sturdily enough allowing the vibration of the driveline to shake it. This then magnifies the shudder, the rather heavy exhaust system acts like a pendulum on a clock. I had a bad hanger and downshifts shook the whole car badly if I didnt match the revs.

jbrill

Jay W could u measure the distance between your exhaust and your rear sway bar? i have a feeling my clearance is to tight there and it is smacking causing the vibration

Dsalillas

My 90 S2 Cab does the same thing. Just like yours it only does it in second. If I blip the throttle all is well. I use the brakes when going in to a turn but if I don't match revs or blip the throttle when coming out the cars shakes very violently. I asked this same question a long time ago and got the same answers on using the tranny to slow down but that is not the case.

jbrill

have you ever removed/adjusted your exhaust? It for sure has to do with somethign in the exhaust system, from the catalytic converter back.... I have a feel my new exhaust is hung to tightly and it close to the body, and when the exhaust shakes form a down shift it hits my rear sway bar.

I have a feeling that this only happens when downshifting to second because the gear ratio is quite a large change form 3 to 2 and causing the motor and torque tube to flex more than the other gears... The reason it probably doesnt shake form 2-1 is because you are probably traveling at to low of a speed in second gear when u make the change from 1st.

Iknow you shoudl always rev match, but when somethign is wrong or not functioning properly on the car you should always diagnose the problem and fix it. my car never did this before and now its a **** off just to know its there.

JohanvdWalt

Why not down shift to second or brake with the tranny? I do all the time and have done so for many years on many cars. Specially on trackdays it help you slow down a hole lot quicker and not over cooking the brakes.

My cab started vibrating when down shifting a while back but since I knew the clutch was bad when I bought the car I knew where the problem was - car is still in the shop as I type this , when the Clutch came out it was clear that tis is where the problem was it was badly burned, the diaframe and release bearing was also shot. According to service history it has done service for 5years and 80 000km. I will report back after the first test drive tomorrow.

JohanvdWalt

Are we talking about a vibration or a rattle here?

Jay W

Mine is not a rattle so there is plenty of distance from the exhaust to the suspension on my car. What I get is a large but quiet shudder in the car, caused by the exhaust swinging around under the car when the smaller vibrations of downshifting push on the semi-loose exhaust system.

JohanvdWalt

While replacing my clutch we determined that the motor mounts were also long past there replace by date - this can also cause vibration.

jbrill

mines not a rattle either, its a heavy vibration throughout the whole car. i was just curious becaus ei thought having the exhaust to close to the body might be causing this... why is your exhaust swinging around under your car Jay? what do ou mean by this?