IIRC the front diff itself is not responsible for seal the trans fluid out of the diff fluid. The seal responsible for that is the one that seals the carrier, which the front diff just sits inside of. The front diff also spins independently of the carrier on bearings. So, any fluid leakage would be assembly or fitment issues when installing the front diff. Not the front diff itself..

 

in the case of a clutch type front diff they all come with replacement (non-stock) carriers. So a fluid leak would be the fault of the aftermarket diff.

 

or the installer forgetting a O ring for example...

 

Ah gotcha.

 

Makes me want to pull mine apart and check it.. Though I guess it would probably be quickly obvious if the Redline shock proof fluid came out not thick and red. Will be changing fluids soon again, so will check that.

 

thing is.. if you have a plate front diff.. you need to run the same LS oil in both the gearbox and transfer... this is of course not so good for shift quality... that is why I am trying to have the front diff and ACD -transfer box share the oil and have the box have separate oil..

 

You lost me. Why do you think they need to share the same oil? Front diff is fed from the port between trans and t-case (oring location) and drains back through the axle tube. T-case is free to use its own separate fluid.

 

because if you use plate front diff then it needs LS type oil. Synchro gearboxes dont particularly like LS type oil. So the ideal solution would be for the front diff to share the transfer box oil, as it is Ls type oil due to plates for the ACD, and leave the gearbox to run non LS type gear oil. As a matter of fact the Evo X has this type of solution... the front diff is not lubricated from the gearbox.. (ok, it is due to SST gearbox, but still)

 

Grice has been running a clutch type front for at least 10 years it seems (dont recall when he started, but its been a long time). No extra wear with the standard trans fluid. That was also the word I got from Mfactory on my diff as well. Just run standard fluid which for me is one of the Redline variants (MT-90 or 75w-140NS (TRE recommendations)).

Best I can tell you is it doesnt chatter like the rear diff without friction modifiers does. Which best I can surmise, the chatter is a sign of plates that might be seeing excessive wear.

 

Yeah, mt-90 works just fine with all of the clutch diffs I've run.

 

that is good to know. I have hear mixed experiences from the UK with even some guys modding the evo 6 transfer boxes to separate the oils... I am still investigating the option of separating the gearbox from the front diff oiling on my e9, if anything to keep possible metal shavings from the plate diff from getting into the box..

 

That was a concern I had to but hasn't seemed to make much effect on shifting. The best bet is probably a little more frequent oil changes though if we think of rear diff also having similar debris potential, it has significantly less fluid and doesn't seem to be functionally harmed with normal service intervals.

If you were super worried, you could do a cooler/filter pump for trans and modify case to spray 4th gear (I think thats the one that needs it) directly. Win on all front other than weight/complexity. For AX or TA though, I'll just stick with things as they are unless a sequential falls in my lap.

 

i would literally flush at 5 miles and then 10 miles and then 50 miles if i put a clutch diff in my trans. that's where the majority of that break in wear will be. after a couple thousand, that will completely stabilize and i imagine that's gonna be a non issue. use a strong drain plug magnet lol

 

That drain interval would be wayyyyy excessive. I would change in the first 500-1000, then again in 1000-1500. Then resume your normal interval.

Even with a brand new built trans, and tcase with a new front diff, TRE told me to leave the fluid in for at least 500 miles, and he actually prefers 1000 miles since he uses a moly assembly lube that he likes to see stay in the oil to ease the break in cycle on the gears with the extra lubricant.

 

you gotta compromise. that's where all the clutch plate wear is gonna be, not talking about a built trans here