Bumping noise when I hit the gas
 

Okay everyone. I FINALLY got my first RX-7, and this problem is plaguing me. When I hit the gas from no throttle (only when the car is in gear...i.e.: under load) there is a noticeable bump coming from either behind and/or under the seats. I think that it's something to do with the transmission mount on the tailshaft...but I'm not sure. Does anyone have any idea what this might be?

Thanks very much, in advance,
Collin

Front diff mount. :D

+1

my car does that too. and i even have the mount in the car.... juuuuust not installed ;)

Heh...well I was gonna edit my post. Here's what I was going to change it to:

Okay everyone. I FINALLY got my first RX-7, and this problem is plaguing me. When I hit the gas from no throttle (only when the car is in gear...i.e.: under load) there is a noticeable bump coming from either behind and/or under the seats. I think that it's something to do with the transmission mount on the tailshaft...but I'm not sure.

The reason I think it's something to do with that rear tranny mount, is because the other day, I was driving down the road, and I hit it and the input neck of my resonator broke off. I took it to a muffler shop and they fixed it, but they told me that I needed to get the transmission mount fixed. They showed it to me and it seemed like there would be play if torque was applied. They said that was why my exhaust broke, because the loose mount was allowing the motor to pivot and flex the exhaust.

I got it up in the air and tried to tighten that bolt, but I couldn't crank it down any further...so it seems like there's supposed to be a bushing of some sort. If anyone could provide me with a picture of the rear transmission mount (a real picture...not one from a diagram) so that I can compare it to what mine looks like, I'd be very greatful.

Does this sound like it could be the problem?

Thanks very much, in advance,
Collin

DOnt have a picture no. But still sounds like the diff mount... 99%

Would it be asking too much for you to take one if you get a chance? I just need a picture of the rear transmission mount.

Thanks a million in advance,
Collin

Cant. My car is about 400 miles away. Im sure someone else can help you out!

Here are some pics for you. The two small ones are your tranny bushings, and the other is the front diff mount.
http://i78.photobucket.com/albums/j1...9/100_0442.jpg
http://i78.photobucket.com/albums/j1...9/100_0437.jpg

where'd you get them?
is there a "better" version that lasts longer than OEM?
mine just went bad.. err it was nice spirited driving til today when i started hearing a "clunk"

Thanks very much for the pictures, but none of them look like the rear trans mount that I need. There seemed to be the remnants of a "bushing"? I don't know the proper word. I went to Mazda's parts dept. and the diagram had something called a "washer" listed there. On my RX7, it almost looks like there was something there...but 20 years of time and shit tons of vibration disintegrated it.

...Does anyone have ANY idea what I'm talking about?

Thanks,
Collin

The pics are of Mazdaspeed tranny mounts. I got them from www.corksport.com

Do you know anywhere I can get a better front diff mount?

I believe that the bump is totally unrelated to the tranny issue. I stuck my hand on top of my compartments earlier and caused to happen again, and sure enough, it was stronger there than it was on the seats.

The tranny mount issue is that there's something that is supposed to go between the nut and the brace. I included an image from the FSM for a 90 model....I know they're different...but it give you guys an idea.

What I need is the piece between the washer above "A", and the brace that all the "B" bolts hold up. Like I said...that pictures from a 1990 model, so what I'm looking for is probably different. On mine, it looks like that "washer" curls up and it's just supposed to hold a bushing (which is MIA...so it's probably disintegrated by now). Please...does ANYONE have any clue what I'm talking about?

Thanks,
Collin

I ordered what I think is the part and it should be here tomorrow mid afternoon. I'll let you guys know if this fixes things. I'm almost positive that it won't fix the bumping though...

In the meantime, however, I'd appreciate any input.

- Collin

You need to replace the forward differential mount. This is a common problem, and drove me nuts when it happened in my car.

NMJ87T2 is pointing you in the right direction. The front mount is very hard to see, even when you're under the car with a droplight and a magnifying glass.

Lift the car on stands, climb under the car and push up on the nose of the diff where it mates to the driveshaft. If it moves a lot, or you hear a clunk you've found the problem.

Good luck with the washers. If it doesn't work, I have one of the competition-stiff mounts for sale: https://www.rx7club.com/showthread.php?p=6952728

I'm sure it won't fix the clunking...there's no doubt in my mind that you guys are right about that...I just hope to God that it makes my motor stop breaking my exhaust...