Question about differential mounts
 

Is it possible to reinforce the current differential mounts or maybe a cheap way to replace them? I know racing beat and mazdatrix have them, but I rather not spend 200 bux replacing them. I just finished installing my torsen and when i gas it, i heard a loud thud noise in the back. Sounds like my bushings are done :(

It's most likely the front diff mount, not "bushings".
No, there is no cheap way around it.
You just need to bite the bullet and replace it.


-Ted

Get the comp mount from mazdatrix if you have to replace it, unless you like a lot of slop in your mounts, then get the stock replacement. Good thing about the stock replacement is least amount of vibration.

Sounds like the front diff mount like Ted said....

My car used to wheel hop like crazy...... to fix it i made an adjustable pinion snubber ($2 worth of ready rod and some thick belting) to keep the snout of the diff from snapping up.

also i flipped the two caps on the two rear diff mounts so that they now pinch the diff tight instead of having all that up and down play...... all stock bushings

I have absolutely no wheelhop in any scenario and can pull 1.5 60fts with out breaking a stock NA LSD...

The compartements are just removed so you can see, the other end sits right ontop of snout and have it adjusted with a 1/8" clearance between the two

http://i152.photobucket.com/albums/s...Picture668.jpg

^ Dude, a writeup on making that would be sick.

OR just search pinion snubber...

OR if you werent the noob you would realize most pinion snubbers are done with rubber stops, not like this where it is adjustable

I can preload the diff down if i want.... takes 2mins to adjust

Don't even start.
There is NO need to be able to be able to adjust your pinion snubber as quickly as your shocks. I adjusted mine when I installed it; job done.

Hahaha, I am still laughing, That was very clever :)

I just like to get people ruffled..... nothing serious

;)

a friend of mine makes solid polyeuthane mounts out of the stock mounting brackets. They are pretty slick. Lemme see if I can find pics of them.

I just got mine installed from him and it makes a HUGE difference.

i found this
http://theg2ginc.com/fcdm/fcdm2%20[320x200].jpg

FOUND HERE
http://theg2ginc.com/fcdm/

How the hell can you do that?

I just installed one, and there is no way you can adjust those damn things in 2 minutes! :P

I like the idea of the felt pad...
I had the diff hit my my snubber, and it went BANG!
I think I need to tighten it down a little bit more. :)

Oh, and that "solid" diff mount above...
I don't like the design.
There's something fundamentally bad about it.
Sure, it'll work very well when new, but once things start to loosen up, it's going to tear itself apart.
The pinion snubber is a much better design and cheaper too.


-Ted

I'll let you (and the forum) know how it performs for me.

i took my front diff mount and welded it together, no clunking and is not noisy or anything. worked perfect and was free. only bad thing is you have to drop the whole sub frame down to get it out.

I fibbed a little...:)

One guy below with a wrench on the bottom nut, and one guy inside with a wrench on the upper nut.... then its about 5 mins

Like you said, when i first put it on i left a gap of about 1/2"....... yeah BANG when you snap it up..... so just screwed it down so that it barely touchs the diff if not up just a hair.....

If anything it makes a very faint rattle when i am in the burnout box, and i dont hear anything during shifting, or during ON/OFF throttle transitions on the street......and just seems super tight compatred to before with nothing

Well i tightened all the subframe and diff mounts and the noise is gone during normal driving. But if i really gas it in 2nd, i hear a small thump. I think i'm going to get the mazdatrix competition one since it's only 100.

Thanks for the help guys.

While under load with a bad mount and a pinion snubbe,r the diff wont move up because the snubber stops it, but it is still going to try to twist around it, pulling on the mount, and eventually ripping it apart. Maybe if you started with a good mount and a pinion snubber, you wouldn't have an issue, but most 20 year old cars don't have one, and by the time you buy a new stocker plus the snubber you spend more than the poly mount costs.

I've sold almost 20 of them and still none broken. Polyurethane is much more durable than rubber, even when being stressed repeatedly. It is also more resistant to chemicals than rubber, which is a good thing because most ppl have a leaking pinion seal and that softens up the stock rubber quickly. I agree that the pinion snubber is cheaper, but certainly not a better design. It's like putting a band-aid on a broken arm; you aren't really fixing the problem.

Not trying to start an argument, but I've seen lots of setups and give you this information from experience.

My freaking diff mount sheard from the subframe. Probably because I didn't drop the entire subframe, just loosend it enought to get a wrench in there and tighten it. I just retapped the rear seatbelt holes and used two large bolts, one side lands on the diff, the other just off the mount, works good, but transfers some noise when accelerating. I hope it doesn't punch a hole in the nose of the diff case tho, I had a snubber/rubber cone on the end of the bolt, but that got torn off from the force of the diff against the bolt... This is a bandaid, i know. but works none the less... Where did you find that large snubber?

a few questions for zbrown and RETed...

first of all, in your cases, what causes the diff to have enough play to contact the snubber given a 1/2" gap?

i've got an energy poly (beehive style) snubber currently, whose intended purpose is just to relieve stress from the front mount. i'm not worried about wheelhop since i don't launch it, so would it be a mistake to preload it?

i'm going to be doing a full rearend refurb soon both to fix a clunking (not front diff mount, though- already had that one...i'm thinking cv joints or diff internals) and i want to solidify it to match the mazdacomp engine/trans mounts that just went in. i just want to make sure that i end up going with the right type of snubber setup.

also, zbrown, what are you referring to when you say that you flipped the read diff mount caps? is this something that i will find on the car when i take the diff assembly out? i'm looking at the two stock mounts i have right now, and i don't see this.

finally, i have a used front diff mount that is in great shape, the rubber is not cracked at all, etc. would it be a mistake to install this, or would the snubber prevent further weakening of it? (i can't even locate a part # for this, apparently FBO -> FBY doesn't translate for this?)


i know there's a good number of questions here, but this will be the third subframe drop since i've had the car, and i'd rather it be the last for a while...

If you take a look at all the individual components, you'll understand.

I was actually surprised my car went BANG!
I can't have more than 1/4" MAX if clearance when the car is resting.

You can blame the *rear* diff mounts for all the slop.
I was surprised I could push the snout of the diff and up and down at will when my front diff mount failed / sheared.
The rear diff mounts are basically USELESS.
They are rubber with LOTS of voids in them.
If you've ever seen the trans mount, you'd understand.
Most of the FC's that have seen hard driving will probably have "dead" rear diff mounts.
This is the trick zbrown has been talking about...

Getting back to the bang...
I think the driveshaft falls down when the car is driving.
No way to confirm this short of running a remote camera while driving, and I do not have the resources to do this. :(
I've running a BIG bump stop back there - it's almost as big as your fist!
At rest, the bump stop barely spins, so there's some contact there.
I'm going to try and tighten it up, since I needed a bolt and nut to keep it in place - it's not the typical threaded stud that almost everyone else uses.

I don't see a problem preloading it unless we're talking about a LOT of preload.
The problem is if you're actually screwing up the angle of the pinion versus the angle of the driveshaft.
In a perfect world, you want both to be zero.
Any deflection of angle puts stress on the u-joints!
So, as long as you're not preloading to the point of screwing this up, I'd say it's okay.
Then it becomes a matter of if you can take the added noise from the bump stop to diff contact...


_Ted

Ted sums it up well

Using a snubber with a like new OEM mount is a good idea....

Before i had the snubber i finally realized i had to do something when i was under the car once and saw that the "block of rubber that hangs off on a bracket on the front of the diff, whatever that is called" was moving up about 1-1.5" and had been contacting the body of the car....

either on launching or hard acceleration it would twist that snout up that far, by looking at it you would never think it is possible but it was i assure you

put that snubber (the main thing) and flipped the caps and have no wheelhop and acts totally different....... and i preload mine just a hair to get rid of the noise is all

zac

alright, thanks both of you. that's exactly what i needed to know. i'll be dismantling all that soon here...