Technical Chrysler MoPar rear axle tools - anyone own or have access to a Miller pinion depth gauge??

I have an old Zoom pinion depth micrometer and it has worked perfectly for the Dana 60 and 8-3/4 work I have done so far. Well up till now that is. Recently a friend brought me a set of factory 3.91 gears to set up for his 489 case, and now I have a problem. The end of the pinion (opposite the yoke end) on the factory 8-3/4 ge****t is not a precision controlled (i.e. ground) surface like it is on the aftermarket ge****ts. These ge****ts need to be setup by locating off of the the pinion head bearing locating surface. The service manuals show this tooling and describe the setup procedure... but these tools are no longer available.

Does anyone here own or have access to one of these old Miller toolsets? I think the C-758-D6 set also contains the SP-5387 part that I need a couple measurements / dimensions from.

If so, please reply or shoot me a PM.

I am trying to help my friend get his rear end ready for the 2015 Meltdown Drags!

Thanks!

 

I'm sure you know better than me, but do you need to be that precise? I've put a couple of 8-3/4s together just playing it by ear and had no problems. I wrecked a couple bearings going on and off but you probably already know there are checking/setting bearings available that slip fit. Anyway, just my effort at trying to not let perfect get in the way of good enough, if it doesn't have to.

 

I sold a local dodge dealer a open rear end 8 3/4 for 2 bills and the old chunk someone set up. "poorly" somewhere along the line. They didnt have the miller tool set any more . So I have a limited slip unit that I'll put on some 2.94s or 3.55s for a 489 case. From what I can read of the post, the back heel of the pinion of stock gears is not finish machined. And that makes the job a little more tedious. If I remember right, my brother made me a tool for this ,if I can find it.
Does anyone have experience with 56 and earlier 8 3/4 mopar rearsd? I have a new old set which may do someone some good. Republic gears.

 

i will check to see if i have it. i will pm if i do, i wont be able to check until sat.

 

Question: Could you not machine the end of the pinion, so it would suffice as your "precision controlled" surface?

Just curious.

 

The only way that would help would be if I knew the exact checking distance for that particular ge****t. I only know the ± correction factor the factory wrote on the pinion end... and of course the pinion depth tolerance is ± 0.002"

Easiest thing would be to get that SP-5387 spacer (or its dimensions).

 

The tool is used to check the machining variation of the THIRD MEMBER. Think about this, because it is important. You can check that actual dimension with a depth mike and a straight edge after removing the large pinion bearing CUP and the diff bearing CAPS. Measure from the diff bearing saddles to the bottom of the pinion bearing counterbore, then subtract the thickness of the straightedge. Obviously, this won't tell you much until you compare the dimension to other third member's dimensions. If you were playing with several third members, as in racing, it would be worthwhile to measure this dimension and stamp it into the casting.

The relative depth of the PINION is often marked on it, also Ford 9", Dana etc.

If you have a correctly setup ge****t in a complete, ***embled third you don't need the tool, all you need is the relative depth variations of the old and the new ge****ts and adjust pinion depth shims accordingly.

I suspect that third member machining variations are less than ring and pinions for various cost related reasons, so in case of starting with diss***embled units, ***ume the third's dimensions are the same. Also, variations of 0.002" or less are not significant, a lot of mfrs shim setups do not allow for changes of less than 0.002".

Ignore all pattern info about backlash. That's what a dial indicator is for. Just focus on the pinion depth part. This simplifies things a lot.

Finally, if you set the ge****t up for absolute minimum backlash, with a dial indicator set across the diff bearing caps ["Ford " method], it and your hand turning a wrench on the pinion nut will tell you a whole bunch about the quality of the ge****t and it's cleanliness.

 

AJ

Do you know anyone with a 12" dial calipers?
You could machine the gear end square, measure o.a.l. with dial calipers, then do the math from yoke end to set up with your pinion depth mic. from yoke end specs.
Hope this helps

Norb

 

What's wrong with just putting it together, put some white marking compound on the gears, see how it looks...adjust shims and backlash as needed...???

Should only take an hour or two, not nearly as much trouble as tracking down 50 year old special tools

 

I always start with the shim that is on the pinion that I removed from the housing then check pattern and adjust from there. I have never used a pinion depth gauge I have only used the pattern on the ring gear.
It has taken years to really understand the pattern and what it should look like.

 

There are many ways to skin a cat. The above suggestions will get the job done, some faster than others. I appreciate the helpful advice, but let me explain a bit more.

That 3.91 ring & pinion, bearings, and case parts that were supplied to me are a bunch of loose parts scrounged up that were never ***embled together, so I have no shim thickness starting point.

That C-758 pinion depth setting tool is the fastest and most accurate method of setting correct pinion depth, and that is why I wanted the dimensions of that one spacer. I just knew that there would be more than one set of factory 8-3/4 gears on my bench sooner or later. Well it turned out to be much sooner than I expected. Three more ring & pinion sets arrived needing to be set up as well - and all are factory ge****ts that I can't use my Zoom depth mike on.

Fortunately a helpful HAMBr got me in touch with one of the MoPar drag racing legends who of course had that Miller tool set handy and got me the dimensions I needed. Thanks!

 

your welcome. can you post that dimension for us. it would be nice to record it for possible future use.

 

The critical dimension I needed is 0.219-0.220 inches. The other dims are 0.540 overall thickness, 1.371 ID x 2.495OD x 1.859 shoulder dia.