Pinion Snubber & Diff Mount Replacement (Convertible)
 

My front diff mount finally gave out last week, so I got to take on the task of replacing it. I picked up the competition mount sold by Mazdatrix for $84, and while I was at it, I also bought a $10 pair of energy suspension bump stops (http://www.summitracing.com/parts/ENS-4-6104G). One of the bump stops would be used as a pinion snubber, as suggested by others in some of the threads I sifted through. This is the run down on taking care of both at the same time.

EDIT: It looks like the PN on Summit's site has changed to this: http://www.summitracing.com/parts/ENS-9-9101G/

1) Remove Y-pipe or entire cat-back system
2) Remove bolt/nut from rear link
3) Remove 21mm nuts (2) from subframe mounts & pry subframe down for clearance
4) Remove all five 17mm nuts from the front diff mount (these can be VERY tight)
5) Place jack under subframe for support
6) Remove one 17mm nut from rear diff mount & loosen nut on the other one (this allows the front of the diff to be rotated to the passenger-side, which will make taking the mount out very easy)

https://www.rx7club.com/attachment.p...1&d=1260159532

7) Replace front mount & tighten down the 5 nuts
8) Drill 3/8" hole at dimpled location (Yes, it is in the same spot as found on coupes)

https://www.rx7club.com/attachment.p...1&d=1260159532

9) Place pinion snubber in position, shim with washers & tighten nut (A helper is needed to do this)

https://www.rx7club.com/attachment.p...1&d=1260159532

10) Guide subframe back up onto studs & jack it and the diff back up into position
11) Thread subframe & diff nuts back on
12) Bolt exhaust system back up

Something to note would be the fact that I left the driveshaft and heat shields in place, but I also had to be careful not to lower the subframe/diff too far. If I went too far, the driveshaft would have popped out of the transmission. I spent about 5 hours on this project, but a lot of that was devoted to trying to get the nuts off of the front diff mount. I think Mazda put loctite on them from the factory, and I was wishing I could use an impact gun down there. In the end, long ratchets and wrenches did the job. Anyone doing this project needs to give themselves a whole day to spend on it.

And the end result? No more clunk between shifts and on harsh throttle input!

Nice writeup! How were the rear diff bushings? I had not replaced mine when I did the comp mount and snubber install a year ago, and eventually the mount sheared off the subframe. The bushings have since been replaced by MMR Delrins, and with a reinforced subframe bracket, I haven't had any problems since!

so you didnt take the subframe down completely, you just pry it from the front?

The rear bushings actually looked to be in pretty good shape. Hopefully that means I won't run into any problems with them down the road.

Yeah, I pried/lowered the subframe off of the front studs & loosened the rear diff mounts. The whole subframe/diff assembly was allowed to droop, and I kept it where I wanted it with a jack. It worked pretty well actually. The toughest part was working the subframe back onto the studs when I was done. The last picture I posted shows the gap between the snubber & diff before raising the subframe back up all the way.

How did you decide how many washers were needed to shim the snubber and is it preloaded when the subframe is tightened up?

Jack the subframe back up all the way and check for clearance between the diff and the snubber. Lower it down, then add washers as necessary. I actually have a small gap between the end of my snubber and the diff itself, so it's not preloaded. I was worried about excessive road noise and vibration if it was directly on it. Anyone with preloaded snubbers experience this? It would be fairly easy for me to go back and add washers to it.

I tried changing mines last month.
I did it the exact way you did. Though it was just me by myself doing it, and I am pretty big, fitting under the rear of the car was a tight squeeze lol. I tried Prying it out but damn thing wont drop far enough, even with both rear diff bolts out. So i just installed a pinion snubber where its just touching the diff by a hair. After I finished installing everything back, I remembered I forgot to take out the vertical rear link......I got mad real quick, and cooled back down just as quick and said fuck it lol
I will probably try again later next month or during spring, but it has to be before autox starts up new again. I might just bring it to my brothers workplace and use his lift to do it.

Forgetting to unhook the rear link will do that, hah. If you do it on a lift, be careful once all of the nuts are off or loosened. The whole thing will want to fall on your head, and you won't have the luxury of a hydraulic jack to hold it up. Of course it won't fall all the way since the rear shocks will still be bolted in.

My snubber is preloaded and there are no vibrations caused from this. Moderate vibrations are from the Delrin diff bushings and only occur at low engine speeds.

^ Good to know. I'll have to see if I can shim it closer once this week of rain ends.

sexy ill be doing this on the gf's sisters car

just followed your directions and installed my mazdatrix comp mount.
What sucks is that i didnt even need a front diff mount.....and the one that was in there was a mazdatrix comp mount....though now i know i need the rear diff mounts now lol

worked t 11am finished everything at 2. just me alone in the street, in 30f degree weather....
What ever you do, get help! Would be much easier.

Were you getting a clunk in the rear end that lead you to believe you needed a new front mount? Doing it on the street in 30 degree whether doesn't sound fun, and yes, having a second person really helps. Especially when it comes to handing you tools so you don't have to get out from under the car 50 times.

Hmm. I am putting a turbo diff in for my LS1 swap. I am going to put the delrin rear mounts in and a new front mount with the snubber. My cousin has his clunking all the time and looks broken at the subframe. I put the bump stop in but need to shim it down much further.

^ That seems to be the standard practice with V8 cars: stronger mounts all around + a preloaded snubber.

I am going to remove the entire subframe. I think that will make it easier. The front mount is such a pain in the ass.

yea, if I let the clutch out a little too fast or even sometimes too slow, the rear end will start clucking.
Or if I suddenly step on the clutch

I was installing my RB Rev TII exhaust and was thinking might as well install the front mount also since I failed last time. Took me 6 hours to complete everything....I didnt even eat yet, soooo hungry


Its not that hard, but its pretty time consuming. If you take your time, its a piece of cake.
Took the two bolts and link off the subframe and dropped it 2 inches below the studs where the subframe bolts to the body. Elevate with jack or jack stand.
I took the driver side nut off the rear mount, and the passenger side is only threaded on atleast 3-4 turns. Took a pry bar and start prying the subframe and diff to a point where you can pull out the mount or let it drop by itself.

I was prying and moving the mount at the same time.
Took me only 3 hours but I already knew what to do after my first failed attempt lol.

if you are doing it on the lift, then taking out the subframe is so much easier.

So how to tell which mount is needed. I have a vibration all the time between 40-60 and it gets worse while slowing down with the car in gear. Sorry about the newb question, but what is a pinion snubber? I just want to have everything ready when I go under the car.

Very good write up im looking forward to doing this later this week

I bought my "truck bump stops" a month ago. Have yet to install. Good write up though. I'll be preloading mine. Better for my clutch-kicking so terrible it's awesome dorifto machine.

Delrin rear mounts + competition front mount + snubber = bulletproof.

If you want you can add delrin subframe mounts as well

The whole ass is going to get delrin'd out when i can afford it.

I want the parts back there to do their job, not be all lazy and quit on me. :D

It's definately NOT a bad investment for those of us wanting kickass suspension. Very easy on the wallet. Easier than replacing diff mounts OVER and OVER and OVER again and risking breaking where the mount bolts into the subframe.....

The snubber alone is worth every penny because it prevents just that.

For those who installed snubbers: did they come mounted to a bolt? I ordered the energy suspension bump stops that everyone keeps talking about but its literally just the stopper w/ no bolt included or attached.

What size should I get and how did you secure it to the bump stop?

http://www.energysuspensionparts.com...Shock-Eyes.asp

They make ALOT of bump stops. You should be using one that has a bolt attached to it.

hmmmm.....so I'm guessing its part number 99101 from that page?

I ordered mine from summit based on the part# posted in a similar thread to this one :-/ . Oh well, w/ derilin rear mounts and comp fronts, I'll do this when I get around to it.

I posted the link to the exact bump stops in the writeup: http://www.summitracing.com/parts/ENS-4-6104G.

where does the hole come up to on the inside of the car?

I'll be doing this soon :)

I just bought solid rear end mounts and solid sub frame mounts and I am getting ready to put my rear end back in my car. And I am getting ready to put A bump stop in my car. Will these work http://shop.advanceautoparts.com/web...P|GRP60035____ I check summit racing with the link that was on here but I need one this weekend and They are out of them right now.

sounds like a plan

good write up, i'm gonna be doing this here in the near future, just snapped a n/a lsd stub shaft in the diff. i hpe this will reduce wheel hop a bunch. also gonna do the subframe bushings

For the first timers, here is the pinion snubber installed.

Attachment 721516

how many washers is everyone installing to get it preloaded?

so far I've seen 2 and 3...

9 ended up being the magic number for myself and jjcobm, which works out to about 9/16". It will probably vary depending on the condition of the bushings, etc...

I think i only needed one, maybe two.

But thea mount depends on the thickness of your washer of course...

...and how much preload you think is appropriate, lol

I have an extra one if anybody needs it. $5 + shipping

Adding a pinion snubber shouldn't have any negative affects to my auto x set up, right?

Just did this mod after inspecting my front diff mount and saw that is it ripping. Didn't need to drop the subframe to do so since i can fit my hands in there lol.

Did it get rid of any wheel hop?

Most of it yes, but most of the "hopping" i get now is the worn out trans/engine mounts that i will replace with poly ones. I clutch kicked it at 8 grand rolling about 20mph and just spun and felt firm with just the trans/engine mounts wiggling

Nice ..

Just to add my recent trouble with this mod :

The image summit has on their website there is not correct for that part
number.

Our image should be correct:
http://www.energysuspensionparts.com...sp?prod=4.6104

The part number that matches the image you're seeing on Summit is this one:
http://www.energysuspensionparts.com...sp?prod=9.9101

And the Prothane equivalent:
http://www.energysuspensionparts.com...sp?prod=191318

The picture matches what you get (or at least what I got). The PN seems to be wrong though. Summit calls is 4-6104G, but that PN matches the rounded version on energy suspension's site. I still have the other one in the package somewhere; I'll take a look at the PN on it. I wouldn't be surprised if it's 9.9101.

Well, i used your part number 4.6104 and got the wrong ones (without bolt) :(

Every fc should pack this mod in. Im running nitto cheaters and would and was getting so much wheel hop now just as smooth. I wish mazda did this from the factory
I have a extra one if anybody needs it..

So I'm about to swap my diff in my 88 vert to this lsd I got from another member, and I'm going to be putting one of these snubbers in. Couple questions...

Did you find the correct p/n for the snubber that has the bolt?

What diameter hole do I need to drill?

Is it okay that I keep my factory mount?

Correct me if I'm wrong here, but it will be easier to install the snubber at the time of diff change, yes?

I'm going to be clutch-kicking and what-not so I'll run it preloaded. Probably not too much, just snug I guess...

http://www.energysuspensionparts.com...sp?prod=9.9101

3/8" i believe did it for me

Yes you can keep the factory mount on

Yes, it is MUCH easier to install at the time of the diff swap.

Awesome X4 thanks!!

yeah guys part number 4.6104 @ summit racing shows the pic of the snubber that rotaryrocket has and the one everyone is talking about but the actual thing is a non bolted one... :(

so the actual PN is 9.9101

i seen the pic and the part number matched but i got some weak ass "2000 FORD FOCUS BUMP" things!

Added a link in the 1st post to what looks to be the new PN: http://www.summitracing.com/parts/ENS-9-9101G/. The original link is exactly what I ordered back in '09.