[Huzz]

I purchased a 1990 S3 Spider Veloce ( White ) Real nice shape( body, interior and mechanical) but I get a knocking against the floor boards when acceling in reverse and when accelerating hard in first. Everything looks phisically tight, but I'm thinking possibly the trans mount.
My question is: Are there any common things I should be looking at?
The previous owner had the driveshaft redone.

 

[Gubi]

Transmission mount or driveshaft center support bearing, I'd think.

Though even with new parts on both of those, I still sometimes get a single *thump* from the driveshaft when vigorously taking off in first. I just turn up the radio.

 

[Alfastruns]

Check the U-joints ! and check if they are in phase if the shaft has been taken apart before

 

[Tifosi]

Might not hurt to see if the exhaust is thumping the floorpan or bottom of the car too while poking around under there.

Could be hung funny, could be worn engine mounts letting things move too far under the torque load of the two lowest gears you have available.

 

[Huzz]

Thanks for all the input. I,ll have to take a 2nd look at everything including the new exhaust.

 

[rooony]

I have the same issue... Managed to get the car on some ramps at the weekend and it seems the exhaust is just hanging a little off centre and causing it to bang against the rear spare wheel well!

All sorted now!

Thanks for all the input. I,ll have to take a 2nd look at everything including the new exhaust.

 

[aralfa8589]

One other thing-
I had this issue right after rebuilding the driveline and replacing motor mounts.
Make sure there isn't a panic stricken pedestrian lodged under the car.