Recently I’ve been getting a thumping from the floorboards in my 97 D1, it begins at around 20 mph and is loudest at 25-30, although I think it’s just quoted down by the sound of the engine after that. If I shift into neutral I can still hear it thumping much faster at higher speeds(it matches my speed). It happens only after I drive the car for a long time, for example I drove the car on short trips around town for a few days and it didn’t happen at all, but as soon as I took it on the highway for 15 minutes it’s back. The longer the car sits the longer it takes to come back. It also doesn’t seem to happen when I’m turning left at all. Both of my driveshafts are completely solid, visually and by trying to turn them. I’m not sure what to look at next as the only similar problem I’ve found has to do with t-case/ trans mounts, but this happens even when the car isn’t putting down any power.

 

CV joint(s)?

 

I had this issue for a bit. It was that rear step thing bouncing up and down after that support shock died.

 

how would I test this? I just did my right side brake caliper so I had the hub apart, everything looked fine to me on that side at least

 

I don’t have a rear step and I’m almost 100% sure it’s coming from the drive train just because of how rhythmic it is

 

I just lifted my front end and spun the wheels, obviously I can’t replicate 35 mph with my hand but there was absolutely no noise coming from any of the components.

 

Good that you checked the drive shafts! Make sure your lug nuts are good and tight. (Voice of experience).

Worn CV joints make more noise at full turn.

 

Does your ebrake work okay? I've seen those drums make some funky noises.

 

I’ll check the lug nuts first thing next time I look at at. Most of the time it’s just the simple things that get overlooked. It only makes the noise at full speed going straight, I don’t think it’s the cv’s. Thank you for the ideas

 

yes I use it every time I stop even though I have an auto, I can tell that it is working because 1) I’ve tested it on hills and 2) the car doesn’t roll if I put it on and then put it in park with my foot still on the brake(I park like this every time). I also know it deactivates when I release the handle because the car drifts at the same speed, rolls fine in neutral and requires the same amount of power to move.