FC3S Differential Pinion Brace (By Ray Platek)

[bikedad]

If you look at the pictures of what I did in the first post you will see that I boxed the pinion mount so there is no movement.

If pinion angle adjustability was wanted a heim joint configuration could be used instead of the bar stock I used. But, I'm thinking you're going to need a pretty beefy heim joint to withstand the forces put on it.

[Rx5.0]

This is all it says
5/16" flat stock cut 7" each
Whats the thickness and what's the length and width ?  If you can help me I would really appreciate it.

[digitalsolo]

Looks like 1" wide to me.

5/16" would be the thickness, and 7" would be the length, just like it says (and you quoted)

[DDv8]

Blake beat me to it.   I was going to say 1 1/2 wide since a 1/2 bolt head is 3/4" wide

DD

[Rx5.0]

Thanks a lot. I will post some results of this mod once I do it

[atli126]

 


 

 

this seems to be holding up fine. Have did a few autox's on it, a few road trips and now my t56 is in. So I can really bang on it now.

Thanks,
Bret

[gc3]

just posting up how mine ended up.

used a lower profile bar than atli126, but reached it further back on the subframe.




i paint everything white so i can find cracks easier.

one thing i thought about is the direction of the bolt in the upper hole.
if for whatever reason the bolt backs off, my bolt wont interfere with the dshaft/pinion.

[atli126]

So I wanted to come back and update that my front diff mount ripped on me. I never did the pinion snubber bushing up top, so do you think that is why the front mount ripped. I also didn't box weld the competition mount. I still have the sway bar dog bone in place so I'm kinda confused as to why it ripped

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[atli126]

But I also pulled out the delrin wing bushings last year or 2 years ago for the mazdaspeed 30% stiffer bushings and less nvh over 40 mph but immediately after I did that I had pretty aggressive wheel hop issues. I know wheel hop tends to break stuff. But this time I'm going to definitely put the pinion snubber in there and get a new competition front mount prob from racing beat

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[bikedad]

So I wanted to come back and update that my front diff mount ripped on me. I never did the pinion snubber bushing up top, so do you think that is why the front mount ripped. I also didn't box weld the competition mount. I still have the sway bar dog bone in place so I'm kinda confused as to why it ripped

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If you didn't box the pinion mount then yes that's why it ripped. It stretches like a rubber band under load and can only take so many hits. Those tabs on the mount washer don't offer any protection. (If they're still even on there any longer)
A snubber might have helped a little but that also has a tendency to compress under extreme load. Again, the pinion mount rubber can only take so many hits before it fatigues.

What GC3 did with the bushings on the mount would help with NVH but that link could also break under load after a few hard hits. (You have to understand how much load is applied at that point) His saving grace is ease of replacement when it breaks.

[atli126]

 


 

 

this seems to be holding up fine. Have did a few autox's on it, a few road trips and now my t56 is in. So I can really bang on it now.

Thanks,
Bret

This is my setup. I used the sway bar link (dog bone) first and now everything but the front diff mount is still good. I have the mazdacomp rear diff bushings (may, 2015) and the front mazdacomp diff mount (2011, when we boxed it)

I'm now trying to figure out if I want to replace the stock rubber subframe bushings with delrin.

I pulled the delrin wing diff bushings bc of terrible nvh and road noise on Highway trips for shows and autox over 20 minutes away. I'm really trying to keep my car a street car (ac, ps, poly bushings, tein flex with edfc, "street" 200 tw re11a ;-) etc)

Also could I run a solid diff mount from pbm

https://store.partsshopmax.com/shop/FC/SolidBushing/FCSDB.html

with the delrin subframe bushings? Or is that going to be too extreme?

http://pages.ebay.com/motors/link/?nav=item.view&id=111814656780&alt=web

Or should I stick with the mazdascomp front mount from racing beat and do the pinion snubber and keep the rubber subframe bushings?

Can the Mazdacomp front mount be reinforced at all with welding on it? Is that what some have did? If so does that push back to the full Metal front mount for less and no rubber (but with full Metal it Could rip the subframe right?)

Ugh I'm stuck and need to order new parts and stuff today

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[bikedad]

Unfortunately I can't offer too much more advise on what you should use.
I've since converted to a Ronin 8.8 conversion.
I will say that I am using the Mazda Comp diff bushings over the Delrin and have not noticed any wheel hop and NVH is very minimal to almost none existent except for a slight whine at about 70mph. (Not obtrusive at all)
The Ronin setup uses a pretty solid pinion mount but I'm using the Ford Explorer stock rubber bushing.

[gc3]

with my setup (poly bushings in the dogbone, mazdacomp rubber front mount, solid uhmw rear mounts) running 275 NT01s I never got wheel hop. With the stock lm7 I was running I doubt I could break the endlink.
As for NVH, I had lots of it, but no idea how much was due to the way the diff was mounted. everything was loud and noisy and obnoxious.
 I never ran a snubber bushing above

[largeorangefont]

You CANNOT run a solid front diff mount with rubber subframe bushings. You will rip the mounting tabs off the subframe.if you want to keep it a street car, replace your mazdacomp front mount.

[atli126]

with my setup (poly bushings in the dogbone, mazdacomp rubber front mount, solid uhmw rear mounts) running 275 NT01s I never got wheel hop. With the stock lm7 I was running I doubt I could break the endlink.
As for NVH, I had lots of it, but no idea how much was due to the way the diff was mounted. everything was loud and noisy and obnoxious.
 I never ran a snubber bushing above

Thanks for the reply the nvh is mainly attributed to the delrin rear diff bushings. Once I swapped them out with the mazdaspeed rear diff bushings. The nvh over 40 mph went away and overall the whole car is way better.

But that was last year and that's when the wheel hop came on like crazy and prob broke the front mount.

With my setup could I run the delrin subframe bushings and the solid front mount?

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