Car shakes when backing up

[azzar0]

Hello,

I noticed that when I back up the car shakes a lot. I also have to give it plenty of gas. I think this is fairly new, I always back up into my garage and I noticed this behavior only recently. Does anyone know why it shakes and what the fix is or what does it mean? All other gears are fine. Could it be a sing of an aging clutch?

MY98 2.5L 5spd 69K mi

Thanks,

azzar0.

[timbo]

Sounds like it might be somthing to do with the clutch. Would have said maybe oil on it but not sure why it doesn't do it in the forward gears. Do you have an oil leak?

[azzar0]

Sounds like it might be somthing to do with the clutch. Would have said maybe oil on it but not sure why it doesn't do it in the forward gears. Do you have an oil leak?

No, no oil leak. I will have to run more tests and see how it behaves.

Thanks.

[aztecw]

Mine does the same thing, usually when the outside temp is hot and I've been stuck in traffic for a bit. I've had it turn off on me when I don't give it enough gas. It has been doing it since I bought the car, about 2-1/2 years ago with 77,000 miles. Now with 105,000 it doesn't seem as though it has gotten any worse.

[Glyn]

This is likely to be the clutch or the dual mass flywheel.

The gearing for reverse is very low therefore the torque at the wheels is much greater than any forward gear (You cant do the same speed for revs in reverse than you can in first gear) This will then mean slight fluctiations in revs produces a pronounced surge in torque at the wheels which in turn gives the effect of shaking.

Before completly blaming the clutch/flywheel ensure your tickover is stable, that with aircon engaged there is no hunting etc, the smoother the engine runs the less opportunity for surging.

You model has the idle speed control valve, this could be sticking, or the throttle body needs a good clean (Do you have fluctuating idle)

If you have not cleaned the throttle or the idle speed control valve then start here - always do the least expensive fix first - take it to a garage and they are likely to swap the clutch & flywheel just because it makes a few bucks

You will find instructions on the cleaning in the forum

Good luck

[azzar0]

This is likely to be the clutch or the dual mass flywheel.

The gearing for reverse is very low therefore the torque at the wheels is much greater than any forward gear (You cant do the same speed for revs in reverse than you can in first gear) This will then mean slight fluctiations in revs produces a pronounced surge in torque at the wheels which in turn gives the effect of shaking.

Before completly blaming the clutch/flywheel ensure your tickover is stable, that with aircon engaged there is no hunting etc, the smoother the engine runs the less opportunity for surging.

You model has the idle speed control valve, this could be sticking, or the throttle body needs a good clean (Do you have fluctuating idle)

If you have not cleaned the throttle or the idle speed control valve then start here - always do the least expensive fix first - take it to a garage and they are likely to swap the clutch & flywheel just because it makes a few bucks

You will find instructions on the cleaning in the forum

Good luck

Hi Glyn,

I cleaned the throttle body just last week. I used to have little fluctuating idling and hesitations when changing 1st to 2nd gear at low RPMs. After I cleaned the TB I noticed improvement.

The engine is running smoothly, I just have this issue with backing up. If I give it enough gas and go a little faster it doesn't shake, it's just when I back up using a 'normal' approach.

If it is the clutch or the dual mass flywheel, can I still drive around like that or should I have it replaced right away? I would hate to have to put that kind of money into it now.

Thanks,

azzar0

[rsfeller]

Any chance you are applying the e-brake and it's sticking until you get in forward motion? My rear calipers are getting in need of a rebuild and I think they tend to drag. Additionally, when the wife applies the hand brake I note that everything sticks if the car has not be driven in days.

[azzar0]

Any chance you are applying the e-brake and it's sticking until you get in forward motion? My rear calipers are getting in need of a rebuild and I think they tend to drag. Additionally, when the wife applies the hand brake I note that everything sticks if the car has not be driven in days.

That's why I don't let my wife drive the car! Just kidding, she gets to drive it once a month :D

I didn't notice any sticking. I changed all brakes a couple of weeks ago and the calipers looked good...

Shawn - how do you feel about assisting me in changing the clutch? :)

Thanks,

azzar0.

[Glyn]

You dont mention the idle speed control valve being cleaned, however if the idle is stable i guess you can rule that out.

Check the engine mountings just in case you have a broken or soggy one, if they are soft it will amplify any irregularity and create a shake.

You can continue to drive the car as it is without causing any damage so its safe to delay spending money at the moment.

The likely thing is the clutch plate, it may be at the end of its life and slightly distorted or indeed contaminated with oil, when you slip the clutch it tends to grab and release causing judder, what is it like if you lift off the clutch at tickover, no additional revs and slip the clutch in slowly to reverse?

I mentioned the dual mass flywheel simply because this type of flywheel has two parts with a spring that applies pressure between the two parts - as you engage drive the spring takes up the initial drive to ensure smooth gear changes (not quite as simple as this but it aids the explanation)

If you are handy with a spanner and know someone who can assist, then you will save big time, may as well change the RMS whilst your at it (will have to change it if the clutch plate is contaminated with oil)

Good luck

Edited May 25, 2008 by Glyn

[azzar0]

You dont mention the idle speed control valve being cleaned, however if the idle is stable i guess you can rule that out.

Check the engine mountings just in case you have a broken or soggy one, if they are soft it will amplify any irregularity and create a shake.

You can continue to drive the car as it is without causing any damage so its safe to delay spending money at the moment.

The likely thing is the clutch plate, it may be at the end of its life and slightly distorted or indeed contaminated with oil, when you slip the clutch it tends to grab and release causing judder, what is it like if you lift off the clutch at tickover, no additional revs and slip the clutch in slowly to reverse?

I mentioned the dual mass flywheel simply because this type of flywheel has two parts with a spring that applies pressure between the two parts - as you engage drive the spring takes up the initial drive to ensure smooth gear changes (not quite as simple as this but it aids the explanation)

If you are handy with a spanner and know someone who can assist, then you will save big time, may as well change the RMS whilst your at it (will have to change it if the clutch plate is contaminated with oil)

Good luck

Hi Glyn,

I wish I had a lift and a transmission jack, but I don't :( I don't think I can do any clutch work with the car lifted on regular jacks.

I think I still have some life left in the clutch - the RPM doesn't jump up when I switch gears (which would be a sign of an aging clutch) and when I put the car in reverse I don't have a hard time, it goes in easily.

I will have to exercise my reverse driving. I usually back up into my garage and the distance from the driveway to the garage is not that big - I don't usually fully release the clutch, which could also explain the shaking. I need to test on a flat surface with the clutch fully released and see how it behaves. Then I can try on a slope, again with the clutch fully released and see what happens then.

Thanks for your advice, I'll let you know how these tests perform.

[Glyn]

You can get away with removing the gearbox by having the car on stands, and two people will be able to lift the gearbox out without a jack.

Try reversing with no additional revs, just slip the clutch in slowly then foot completely off the clutch

[privateselling]

Hello AzarrO,

I do not want to mix up things but are you sure that the 02Sensors of your car are working correctly?

I had a same driving problem as you had, especially when back-up driving.

The clutch was changed at a Porsche Centre without any result. They could not find any other cause!

Then I bought the Durametric interface and I could immediately see that one 02sensor was dead, I still wonder why the Porsche mechanics did not notice this with their PST2...

After changing the 02sensor myself, the car drove smoothly.

See also my last post of February 4, 2007 in this Boxster Forum topic : "Boxster 2.5L -MY1999 - Fault codes P0152 / P1115 / P1119, 02 sensor problems".

http://www.renntech.org/forums/index.php?s...ost&p=61329

I hope this can be of any help to you.

Regards,

Alfred

Edited June 1, 2008 by privateselling

[Tool Pants]

I had clutch chatter when taking off in 1st. 67,000 miles. It was also hard to push down the clutch pedal.

Clutch was replaced yesterday. It was down to the rivets on the pressure plate side, and had started to score the pressure plate. Also typical heat checking on the flywheel.

No more chatter and I can push the pedal down with my thumb. Feels like when I bought it 9 years ago.