Rear diff mount options
 

You know the story of these cars, front diif mount bolts sheered off. My buddy Nick is getting the bolts off the casing, I want this bolt sheering bull to stop so I am upgrading, by getting both mounts.

Here is my dilemma. I cant find a replacement front diff mount. And SURE don't count. Turbine Tech has one, but their website doesn't work. And guess the only ones that I have found that sells them. You Guessed it..... SURE. I don't want to buy it used, nothing against used parts, but I rather buy used locally, and new thru the internet.

I checked edge and rpm, no luck. Any suggestions would be nice.

Call turbine tech directly and place an order. You don't HAVE to order from their website if it is down.
And cp-e has the other rear diff mount if you wanted to stay away from SURE.

yeah cpe or cs on the other one. I'll call them tomorrow, I just hope it comes this week since its coming from Canada.

You could always just ask them about shipping options when you buy it. You will obviously have to pay more for express, but if you need it by a certain time, then you might have to go that route.

But they will be better to answer that question for you.

or if you are looking for the front CorkSport; has it.

Corksport makes a front rear diff mount?

They do???? Link plz.

Corksport makes a rear diff mount, not the front. The turbine tech mount is nice, its what I have. If you cut off the bottom one or two bolt holes on the drivers side of the bracket, the diff can be dropped without removing the big pita bolt that holds the mount to the frame. That makes it ALOT easier to work on if you ever need to.

for issues that I wont mention (cough cough rust) we had to take out the diff. so the mounts are holding nothing. I am just wondering how long it would take them to deliver it. I ordered the cp-e rear diff mount mainly because I havent seen any complaint about it.

+1 on the cpe, its solid

took 2 months to get my cpe mount lol. Very solid compared to stock, the welds weren't pretty though but maybe I expected better after waiting 2 months.

Really the rear one is the main problem. It should hold just fine unless you're throw a crap ton of power at it.

I seen some ppl being fine with just the rear one, but having a stock rear one causes the front one to fail?

yes, it places tons of extra stress on the front mount.

Well changed my mind from cpe and went with corksport. Called turbine tech and they told me to send info over mail now I am waiting to see if they have it. If it doesnt make I'll just use the cs mount and hope they make a front diff mount pending the results of this one.

just run the rear for now, should take around an hour to change the front.

What'd you find out about the tt mount when you sent them the paper work. I'm in the same shape about wanting a front rear diff mount to go with the cpe mount I'll have

The front mount is the weakest of the two. When the MS6 came out, almost all of the failures were of the front mount, some occuring on cars less than 2 months old. Contrary to popular belief, the bolts do NOT fail in SHEAR, but low cycle bending fatigue, due to the offset vertical load and poor bolt locations on the side .... needed at least 3 or 4 to avoid the prying load.

If you add just the rear mount, you do nothing to resist the moment put on the diff due to axle torque, which moves the pinion shaft end upward (loading the front mount) and the rear down (loading the rear mount). The drive shaft torque reaction also pushes the left side (short wing) of the rear mount down, but does not load the front mount.

So there is no logic to saying the stock rear one causes the front one to fail, to answer your question.

In industry, rubber mounts/bumpers are used to avoid shock loading, which at a minimum doubles the peak reaction forces. The bushings should give to reduce shock loading, like dumping the clutch. For that reason, I like the CPE rear mounts that have 60 duometer bushings, vs the stiffer 80-90 durometers the others use, which is more appropriate for suspension bushings.

Both the Sure and the TT front mounts have those extra bolt holes to better react to the moment loading.


.

Removing two of those 3 bolts would put too much load on the one remaining bolt on that side of the diff. TT made a big effort to add stiff structure on that side to make sure all 3 bolts were sharing forces. I had actually posted about this design before TT came out with a mount. I could only find another idea I had to stop busting side bolts:

Differential issue - Page 3 - Mazda 6 Forums : Mazda 6 Forum / Mazda Atenza Forum


.

From what I have come to understand through reading various posts here, is that the rear mount is the more important one to replace because it allows the diff to twist, which leads to the bolts are shearing on the front mount. The rear mount is prone to breaking, and I'm not sure I have ever seen the front mount actually broken... Only bolts and the diff casting broken...

Correct, the rear mount breaks along a rib on the bottom side, on the driver's side. The front mount does not brake It fails the bolts in bending fatigue, NOT shear.

The failure process starts because the central bushing load is offset a few inches from where the mount bolts to the side of the diff. Because it is just 2 bolts that are side by side, thats a POOR design, vs having 3-4 bolts spread out to take the bending load. So the mount rocks against the side of the casing ( just a few ten-thoundths ) when heavily loaded, causing high bending stress in the bolt. This cyclic loading initiates cracks which propagate from the top and bottom, under the bolt head, at the first thread.

Looking at a failed bolt, especially if it's loctited in, you see smooth surfaces at the top and bottom fracture surfaces, and a narrow band of rough surface where a brittle fracture finally occured.

The new front mounts support the bushing on both sides, so no rocking.

The very soft "spoked rubber" bushing at the front can see full diff rotation due to axle torque, with out developing any load since it is so flexible in twisting.

Pics of the diff mounts and some broken stuff:

https://www.google.com/search?q=mazd...GaHJsQSvrYL4BQ


.

Cutting off the bottom two bolts on the TT mount isnt going to cause it to fail, its still overkill even without those bolts. That mount doesnt control twisting anyway.

In my prior post, I had explained the "twisting" moment that fatigues the 2 bolts on the oem bracket. The bolt busting moment is a reation to the torque applied to the rear wheels. I would not trust just 1 casing bolt to "balance" the pinion load support on both sides of the diff.

.

I don't know why you are even getting defensive about it. tts been shown here that the front diff mount is only really needed unless the bushing is shot in the stock one, or the car is going to see some serious abuse...

Sorry if I came across defensive about this. If you were an owner around 2006, you would recall that the front mount bolt fatigue failures was by far the most frequent failure, vs the rear. In some cases, the bolts were loose on a showroom MS6. Hopefully one of those original owners will make a comment.

Yes, I was thinking about the many owners that are going to the drag strip, some with a bigger turbo, vs normal driving.

And, it's possible Mazda upgraded the front mount at the contact ears, and was more careful about preloading the bolts in the end.

Thanks for your helpful comment.

.

Anyone have the rear diff mount bushing dimensions or alternate manufacturer part no. to perhaps just swap them on the oem bracket? TT used to sell but no longer

reviving a 7 years old thread may not get you much answers but the support itself may break apart if you stiffen the bushings...some broke it on oem bushings....

Holy necro, and what a coincidence. I sheared my diff bolts for the first time the other day. My MS6 has been sitting, for the most part, for almost 7 years. I've been getting it ready for daily duty. Replaced PTO, super smokey K04 is gone (CTS4 installed) and some other nags.

Wtf happened to turbine tech? I guess I'm in for a corksport/sure jugg combo.

Don’t call it a comeback!
Save us both the money and measure those bushings if you have a micrometer and access to the bracket. I am trying to order a set from Russia with love.

Oh I am not getting under there again.. pain in the ass. I'll ask my mechanic if he can take a few measurements. no promises

Why people seem to dislike the SURE diff mounts?