Front Diff Mount Keeps breaking! HELP
 

I have just spent 2 hours replacing the front differential mount in my 87 RX7 Turbo II and took it for a ride and fixed it for the moment. After about 3 hard 1-2 gear shifts the mount broke again. I know theres a mazda competition mount that I can get but looking at the design it looks like its the same fail design as the stocker just harder bushings. I saw the old owner welded a bracket from the mount to the diff with 1/4 inch angle iron and that had broken too. Does anyone have a way to fix this problem?

Buy a pinion stubber, use the search funtion if you don't know what I'm talking about, it is a $20 part you might as well do that when you replace the front diff mount again. You don't want a solid front diff mount... also are you sure your diff bushings are fine?

Okay ill look for that, Thanks! The diff bushings looked good but only glanced at them. They looked stock so they could use replacements. Are you talking about these two bushings?
http://www.racingbeat.com/RX7-1986-1...ial/12054.html
http://www.racingbeat.com/RX7-1986-1...ial/12053.html

Or these?
http://www.dropengineering.com/mazda...hmw-86-92.html

Take a look at these also, if you don't mind the wait.
https://www.rx7club.com/group-buy-product-dev-fc-rx-7-268/fc-semi-solid-diff-mount-938333/

Otherwise, upgrade the diff bushings as they normally share some of the diff's load. Once they get worn, all of the load goes to the front diff mount. I have the solid looking ones in your 2nd link on my car. It's a little noisier but I haven't had a problem since. Pinion snubber is also a good idea :)

I'd would use Derlin for the diff bushings, and replace the crown caps as well.

all you need is a rubber pinion snubber you get at autozone for $6

drill hole in driver side bin the diff is below it just position it in the right place
then when you shift hard there is just a little play so the the mount dont play
learnt that trick at actco raceway
no more broken mounts

theres a write up somewhere

https://www.rx7club.com/showthread.p...pinion+snubber

I installed mines when I changed to a S4 turbo diff. Wheel hops on hard launches (mostly because of the rear diff mounts needing replacing), but not as much as before without it.

i get a clunk sometime when very sudden changes are made such as flooring and letting go of the pedal completly.
im thinking new driveshaft and look into tranny mounts and front dif mounts.
what do you guys think?

It's your front diff mount canonize

and these arnt the ones that bolt vertically to the chassis?
if not are they up by where the drive shaft connects to the rear end?
and will changing shafts help at all or should i do that when i change the mounts?

The front diff is at the front of the diff where the driveshaft bolts on.
Changing drive shaft will not solve the clunking problem. You will have to change the front diff mount and install a pinion subber to not make it snap later on in life.

Its a tough job to change the diff, but its doable when you take your time.

^He's right that's a front diff mount all the way, i know exactly the clunk your talking about.


How many people had this problem (broken front diff mount) while running factory suspension (coilovers)?

Thanks for all the great information guys!!!

Also great writeup on the pinion snubber, Thanks for the links Black Knight and MacZPayne!

yea got under my car to look into my front mount and it shot 100 percent tore.
i can push my differential up maybe a whole inch where it connect to the shaft. doesnt look like any of my mount is connected to the rear end anymore.
and i will be doing to pinion snubber but anyone got a front mount for sale?