mike77

For a while now my S4 auto makes a chirping/screeching noise when I shift from drive into reverse. It only makes the noise at the point of gear change. I think it only happens when the car is warm as I tend to notice it when I park up in the garage after a drive. I serviced the gearbox and diff last summer and there was no change.

It doesn't seem to be getting any worse but would be interested to get an idea what sort of repair I may be looking at in the future. Any ideas? It has about 80k miles on it.

Cheers
Mike

ammonman

First thing is to check the fluid level in the trans (hot in "N" after running through all the gears.) Is there any delay engaging reverse or slipping in reverse? The 4 speed boxes are known for short life of the reverse gear clutch plate set.

Mike

mike77

I'll check the level when hot.

I would say yes there is a small delay from going from D to reverse of about a second. I'll have a search around and read up on the reverse clutch and see what it involves.

Cheers

mike77

Looks full on

https://rennlist.com/forums/928-forum/853730-gts-reverse-gear-b3-clutch-replacement-diy.html

ammonman

Doing the reverse clutch pack is a bit involved. I guess I should have been more clear. Does reverse slip at all? Do you have to rev the engine to get reverse to actually engage and start moving the car? Early warning sign is the car struggling to back up a slight incline.

Mike

safulop

Yes from what I've seen there is always some delay shifting into R, even with a good transmission. The slight (1 second or less) delay is not a problem, I don't think.

Schocki

My GTS does the same when warm. Even after rebuilding reverse it did not change. I own the car for 13 years and it always did this noise when shifting into reverse. No further action required.

You should be concerned when you hear a rattling noise while driving backwards. That's reverse clutch piston B3 at it's limit and rubbing against the housing.