ApexAnimal95

I'll be installing a new 3.3 r&p in a couple of weeks.
I need a good tutorial for setting contact patch. I've done and read about backlash. But I haven't seen anything for contact patch.
Also a good source for new seals and shims would help.

Thanks. Yes I've done some searching. Just haven't found what I'm looking for.

Zed.

Mazda?
seriously, thats where my oilseals came from

as to mesh 'contact patch' theres plenty of images on the internet (& workshop manuals?) but if you've not stripped the 'donor' diff you can check the mesh (with marking-compound) and try to replicate it?

the pinion intrusion / depth is set by a solid shim between the pinion gear & the inner bearing, I try to use the one that came with the donor pigshead as these are usually matched @ the factory (fingers crossed!) and unless theres a problem don't play with other shims.

if you can handle the waffling & wandering off on tangents, theres some diff stuff in this post & the next page

https://mighty5s.com/post/40218/thread
and continued a bit here
https://mighty5s.com/post/40346/thread

you can use 'the force' for mesh, preloads & backlash but that might come with experience

Rich.

WigglingWaffles

Ericthecarguy did a good video about setting up a ford 8.8
not a miata but a good reference

ApexAnimal95

Thanks. That helps a lot. I'm surprised I can't find anything on YouTube. Or anywhere else so far.
A question about the crush tube. Do I need to replace that? Or do I reuse what I have? Just tighten until I feel no play and the pinion turns freely?

technicalninja

The original shims work good with original Mazda parts, original bearings. Look at the bearings to find manufacture It will NOT say Mazda, it will say NTN, Koyo, NOK or some such brand.
Often times a "bearing supply" company can get the exact brand at 30 cents on the dollar versus the dealer.
In Ft.Worth I've used Purvis bearing supply for 3 decades to source bearings I needed. Sometimes you hit a home run, sometimes you don't and Mazda should be your source.
Inexpensive aftermarket bearings should be avoided at all cost. They WILL NOT be cheaper in the long run.
I detest Chinese crap...

The crush sleeve should be replaced any time you have the pinion out of the housing.
The only time I'll reuse one is if I'm trying to replace a pinion seal ONLY in an installed diff.
Even then I'm super careful on not over-torqueing the old crush sleeve.
I will mark the installed "clocking" of the pinion nut and try to be just a tiny bit tighter when I'm done.

Installing a brand new crush sleeve is usually much harder than you expect.
You are setting the pinion bearing pre-load and need to be perfect here. The turning torque measurement is the way I go.
You will need a spring scale and a bit of ingenuity to achieve proper readings.
Work up slowly to the required torque. If you go past this point you will have to rip it back apart and replace the crush sleeve again.
I have NEVER used a torque wrench to set sleeve crush. The initial torque needed to start rotation IS higher than the rotational torque reading during rotation and if you use a torque wrench you will most likely have too little preload on the pinion bearings.

I use engine oil as a build lubricant as gear oil can effect readings more than a thinner oil. A tiny amount of engine oil will not hurt a diff at all.

Patterns are super tricky especially when installing used parts into a different housing.
Best method is to check pattern on the gear set you will be installing when it's in its original housing and I'll try to re-create that pattern in the new housing (or new center section).
It doesn't sound like you have that option if you're getting a new ring and pinion set.

Pattern up the original gear set (as long as it was quiet in both accel and decel) and try to hit that with the new stuff.
Lots of vids available on gear pattern. Most are applicable to your install.
Gear pattern is gear pattern regardless of the manufacture.

Try to take installed depth reading off of the original pinion and install new pinion to to this depth FIRST.
Pinion depth is the start of everything...
Pinion depth, followed by pattern, followed by back lash is the normal progression for me.
All will effect pattern, pinion depth being the master (and the most difficult to change).

One note. I will get pinion rotational torque close but not final, set up the rest of the diff and then finalize rotational torque as leaving a bit of crush will allow you to take apart pinion multiple time (if needed) without having to replace the crush sleeve.
The crush setting should not change pinion depth. Pinion depth is controlled by pinion itself, the first bearing and its race, and the washer between that bearing and the pinion.
I will set everything up then take the diff back out of the housing to set final rotational torque on the pinion.

Good luck, very few professional technicians do internal diff work. They just send them off to a diff builder to get it done.
I do as well on appliance cars, the only time I do it myself is when it's something special like you are working on.
You're in the top 5% here...

technicalninja

Another little "trick"
The first pinion bearing is usually the hardest one to install or remove, The other bearings are not interference fit as the #1 pinion is.
Freeze the pinion and warm up the bearing. Makes initial install EASIER.
It will still be a PIA to remove later but sometimes you get lucky and don't have to take it back apart.
A really good bearing separator and a press are commonly needed to take it apart.
Get the pinion cold enough and the bearing hot enough and they can just slide together without a press the first time...

The single most common beginner mistake is to forget the washer that goes between this first bearing and the pinion.
Remember the shim! Put it in its proper place BEFORE you install the first pinion bearing.

SpartanSV

I use one of these to measure turning torque for the pinion and it's the right tool for the job IMO.
​​​​​​
​​​​​​I don't have a link but there's a mazda service manual procedure for this. Follow that and you'll be fine.
​​​​​​

technicalninja

That will work OK just make sure to take readings during rotation!
It will show a higher reading at the beginning of movement and often the rotational torque reading is so low as to make the beam torque wrench hard to read.
This is what I was talking about regarding "spring scale"
It still requires pinion to be rotating during measurement.

Now, that torque wrench will have MANY MANY other uses where the spring scale will not so torque wrench is BETTER tool to purchase.
Spring scale is more accurate IMO.

ApexAnimal95

@technicalninja Regarding the crush sleeve. While I do not at all doubt what you're telling me about replacing it, it's not the easiest part to find. I'll go through a dealer and find it I guess.
But what I find odd is that, 1, places like rockauto don't have it. That's where I found all the bearings and seals. And 2, supermiata sells a rebuild kit for the diff which "includes everything you need except shims". But no crush sleeve. And no mention of the crush sleeve. And you're telling me the factory shim/washer should be fine.

So far what you have shared has been extremely helpful. Thank you.

SpartanSV

I'll add that ninja is absolutely right about the crush sleeve. I've also reused them when only replacing the pinion seal, but I would never reuse one if I'm replacing anything in the diff. I also always order two if the assembly is at all time sensitive since it's easy to go to far and have to start all over.

technicalninja

I'd take apart the original diff for your car and try to buy the same brand bearing. I would bet they will be SKF but I might be wrong.
I'd use original brand or Timken as second choice. I doubt that you will find Timken stuff in a Miata diff.
You WILL be closer with original brand over any other regarding shim selection.
I'd also PREFER that the country of origin is Japan.

You will have to get some of this stuff from the dealer, crush sleeve, any needed shims, and I prefer OEM seals over ALL aftermarket.
The dealer will NOT have this stuff in stock. You will have to order and it may take a while to get it in because you will most likely be ordering stuff they have NEVER had before.
Pretty much no-one builds diffs anymore...

Please. please post your final results as I too will try to go 3.3 if I see enough folks get them to work QUIETLY.
Noise seems the biggest hurdle to clear here.

ApexAnimal95

@technicalninja what is the rotational torque supposed to be? Is it fully installed with axles attached? Or just the 3rd member?

​​​​Correct me if I'm wrong, part number 16 in the following link is the crush sleeve, correct? This place always has good prices and is only 1 day shipping away for me.
https://www.zoomzoomnationparts.com/...T/F693123.html

technicalninja

16 is correct.
Torque is checked with everything besides the pinion out of the carrier so "Pinion Bearing" drag alone.
I don't know what the factory service manual says regarding the actual number. I would verify this myself if I was doing it anyway.

technicalninja

I am assuming that you have seen this very recent thread on exactly what you need.

http://www.miataturbo.net/suspension...-setup-104433/

If you haven't you should have searched.
These guys have RECENTLY done this crap and may have suggestions...

ApexAnimal95

@technicalninja I did see that thread before I posted. But I didn't read it thoroughly enough at first. I wasn't seeing info on the pinion part. But after you shared I read it more thoroughly. Thanks.
I have a coworker with some pretty good experience with cars. He said he would help me.
This is the Walter Motorsports set BTW. Not m factory. This would be the first of the 2nd batch which went through a new process apparently. I hope to hell this works out. Got all my parts ordered.