Looks like I have a transfer case problem :(!

[TrevorS]

I've been hearing clunks that I've traced to the transfer case, and so I've just finished removing it -- the very first time it's ever come off (fought me pretty hard). The fluid was changed just a few thousand miles ago (Pennzoil Synchromesh), but when I drained it this week, it looked dirty. I've never touched a transfer case before, but I think I may see at least part of the problem. Any helpful thoughts (experience appreciated ?

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The last two photos look like trouble to me . (The transaxle output shaft does have some on-axis play, but stops before coming out -- no apparent transaxle fluid leakage.)

 

[Gstclipse69]

What weight oil is Pennzoil Synchromesh? I thought it was common to use Synchromesh in the tranny for dsms, and a heavier weight gear oil ie Redline Heavy Shockproof in the transfer case and rear end.

 

[TrevorS]

What weight oil is Pennzoil Synchromesh? I thought it was common to use Synchromesh in the tranny for dsms, and a heavier weight gear oil ie Redline Heavy Shockproof in the transfer case and rear end.

The container doesn't specify the weight but it's definitely a huge improvement over the OE transaxle fluid, and the OE transfer case spec is the same as the tranny (SAE 75-85). In any case, the sounds have been present since well before my fluid change, me just now trying to address it. Unfortunately, it's not looking especially good ! (FWIW -- I'm aware Red-line Shockproof is often used in the AWD differential.)

Checked the '90 shop manual and it specifies GL-4. I currently have Royal Purple GL-4/5 SAE75-90 in the differential and so I guess I should put that in the transfer case as well.

It looks really ugly at the base of the splines in the photo. I just wouldn't have expected machining to leave it that way. Looks more to me like repeated impacts, complete with debris behind it. Is that really normal appearance?

==============================LATER============================

It looks really ugly at the base of the splines in the photo. I just wouldn't have expected machining to leave it that way. Looks more to me like repeated impacts, complete with debris behind it. Is that really normal appearance?

Well, well, well -- that which I took to be damaged metal at the base of the splines must actually have been old grease! I just cleaned the interior and there's actually nothing there except splines and smooth metal. There's no sign of fluid leaks around the seal, so perhaps the reason for the loud clunks is mostly the oil I've been using ? That's making me wonder about my transaxle oil which is also Syncromesh, feels great for shifting, but could it be a problem for the two differentials (front and center)?

 

[Gstclipse69]

I was going to say earlier those pics dont look that bad to me. Your splines look to be in good shape. Like you've stated, I think I would put that royal purple in the transfer case and see what happens. People have been using Synchromesh in dsm transmissions for awhile, I think it would be fine for the front and center differentials.
However, I just replaced my tranny fluid, and I was looking over all the threads about which fluid to use and it seems many lately are recommending to go with oem mitsubishi fluid. Jacks Transmissions LLC — Genuine OEM Mitsubishi Trans Fluid
All in all though, I dont think I would get too worked up about the synchromesh.

 

[DSMTyson]

In the X-case and use the Mitsu DiaQueen for the Evo VII-IX. STM: MITSUBISHI DIAQUEEN LSD GEAR OIL | 3775610 Redline heavy shockproof is great too.

for the trans: http://www.streettunedmotorsports.com/parts/diaqueen_mr_trans_fluid.htm

 

[pauleyman]

The transmission output shaft doesn't have any sort of positive retainer, just a ball. It's normal for it to have axial play. Quite a bit actually. It isn't like a shaft with taper bearings which may have no movement. I'm talking 20 to 50 thou or more.

 

[bryanwheat]

Syncromesh is way to thin for a transfer case. Why would you put that in there in the first place? Is is a light oil with a friction modifier for manual transmissions, not a transfer case. If the oil was not clean when drained after only a few weeks than you have some kind of internal wear going on. I'd pull it apart and inspect it before reinstalling it.

 

[TrevorS]

Syncromesh is way to thin for a transfer case. Why would you put that in there in the first place? Is is a light oil with a friction modifier for manual transmissions, not a transfer case. If the oil was not clean when drained after only a few weeks than you have some kind of internal wear going on. I'd pull it apart and inspect it before reinstalling it.

Why, because it seemed reasonable given my light duty and I wasn't strongly advised against! It's always easy to be fountains of knowledge after the fact ! You wish to proclaim me an idiot? Fine, what ever pleases you !

 

[bryanwheat]

Why, because it seemed reasonable given my light duty and I wasn't strongly advised against! It's always easy to be fountains of knowledge after the fact ! You wish to proclaim me an idiot? Fine, what ever pleases you !

I don't think you are an idiot, i was just wondering why.

 

[TrevorS]

I don't think you are an idiot, i was just wondering why.

Basically three reasons:
1. I thought that if Syncromesh was considered satisfactory in the transaxle, it would also be OK in the transfer case (factory spec is same for both).
2. I was guessing the two fluids were in close proximity to each other (probably not separated by more than a seal) and if I used the same fluid in both it wouldn't matter if there was any cross leakage.
3. Syncromesh is much cheaper than Royal Purple and I'm perennially cost sensitive.

I did go Royal Purple in the differential for extra protection (I'm reasonably familiar with differentials , but at $20 a quart, I considered it a splurge. Just had to buy another quart yesterday to refill the transfer case. As for Redline, I've no doubt it's the racers choice, but as an easy going driver, I don't think it should be necessary and I can't justify the further cost.

 

[bryanwheat]

I've been running the supertech gl5 in these for many years without any problems. There is no need for that expensive shit in the transfer and rear diff. I would use it in the transmission though.

 

[TrevorS]

I've been running the supertech gl5 in these for many years without any problems. There is no need for that expensive shit in the transfer and rear diff. I would use it in the transmission though.

OK, what do you think would be a reasonable choice for my transaxle oil given my description of how I drive? I'm open to considering superior alternatives, but as I said, I'm a pretty easy going driver and cost is always a serious factor. That MR oil looks great, but the cost gives me the shudders. As I don't have an EVO 6-spd, what's adequate for my '90 GSX?

 

[bryanwheat]

I use gl4 in the transmission and gl5 in the gear boxed. Pick your brand, most are pretty much the same thing.

 

[TrevorS]

I use gl4 in the transmission and gl5 in the gear boxed. Pick your brand, most are pretty much the same thing.

May I ask how you would evaluate your shift feel? I've rebuilt my cabin shift mechanism (tightened it up with nylon bushings -- better than new IMO) and installed a Delrin bushing at the transaxle "shift" lever. The action is very positive, but also mechanical and grainy in feel (to be expected IMO -- nothing to provide shift fluidity, such as transmission lever mass).

 

[JusMX141]

The fluid was changed just a few thousand miles ago (Pennzoil Synchromesh)

Why did you choose Synchromesh in a gearbox without synchronizers?

There are two gears and four bearings inside a transfer case- all steel, no brass. Use the heaviest synthetic GL5 gear oil that you can get your hands on or you'll accelerate gear and bearing wear on top of dealing with sealing issues. We sell a generic 75W140 at my workplace- I normally use that fluid and change it often along with the trans fluid (every other oil change).

 

[TSIturbo91]

Well lesson learned. It's ok to make mistakes. Just have to learn from them and your fine. It's when ya do the same thing over and over that makes it a problem.

Anyway, as said before synchromesh is a bad choice for a gear oil in the transfer case. A heavier weight oil is better. Fewer moving parts and a lot more contact area requires a thicker oil. Seepage from a seal shouldn't be enough of an issues to use 1 single oil and if it is there are bigger problems. So if it's just a daily driver and your not hard on it a standard recommended gear oil and weight should be fine.

 

[TrevorS]

Well lesson learned. It's ok to make mistakes. Just have to learn from them and your fine. It's when ya do the same thing over and over that makes it a problem.

Anyway, as said before synchromesh is a bad choice for a gear oil in the transfer case. A heavier weight oil is better. Fewer moving parts and a lot more contact area requires a thicker oil. Seepage from a seal shouldn't be enough of an issues to use 1 single oil and if it is there are bigger problems. So if it's just a daily driver and your not hard on it a standard recommended gear oil and weight should be fine.

Thanks for the input !

There are two gears and four bearings inside a transfer case- all steel, no brass. Use the heaviest synthetic GL5 gear oil that you can get your hands on or you'll accelerate gear and bearing wear on top of dealing with sealing issues. We sell a generic 75W140 at my workplace- I normally use that fluid and change it often along with the trans fluid (every other oil change).

So you're saying for the transfer case and differential, forget the factory specified GL-4 75-90W and go GL-5 75-140W? Any qualifiers?

 

[JusMX141]

Differential is different- especially if it's an LSD where specific friction-modified fluids are required to maintain LSD operation....but in a transfer case, use whatever heavyweight gear oil you'd like, GL4 or GL5. No clutches, no synchros in a transfer case.

 

[TrevorS]

The transfer case is re-installed and filled with Royal Purple GL-4/5 SAE 75-90W. Just took the car out for a brief run and the clunk sound is definitely attenuated with the heavier transfer case oil. That leaves me with the question of whether I should continue using Syncromesh in the transaxle (I believe the primary source of the rest of the clunk), or switch to Redline MT-90 (thinking specifically of the front and center differentials, not the synchronizers). It costs roughly $60 to make that change and from reading, I'm liable to lose a little ground on shifting quality -- the Syncromesh shifts very easily.

 

[TrevorS]

Ordered three quarts of Redline MT-90 from Amazon -- interested to see how it compares to Syncromesh. I'm hoping for further clunk reduction, but preferably without loss in shift quality. Will probably find out later this week!

 

[TrevorS]

Put two quarts MT-90 into the transaxle (just a very little dribbled over into the pan). Put the corner back together, lowered the car, and took it for a short run. Shifter feels smoother -- less grainy and a little more resistance. Transaxle still clunks, though maybe not as loud or often, not sure -- need time with it I guess. Didn't notice any loss in shift behavior, and the smoother more resistive feel works for me. So, is Redline MT-90 a better choice for me than Pennzoil Syncromesh? Maybe, but it does cost some 50% plus more. If it does a better job of protecting the transmission from wear and tear, then I'd say it's worth it. Should be noted, of course, I'm not a hard driver.

Moving on, the braking feels absolutely dynamite, and at about 20mph (third gear) I gently rolled on the throttle and the car attitude closely followed the pedal position, a very satisfying uptilt and driver pressback ! I love this car !

 

[TrevorS]

Put two quarts MT-90 into the transaxle (just a very little dribbled over into the pan). Put the corner back together, lowered the car, and took it for a short run. Shifter feels smoother -- less grainy and a little more resistance. Transaxle still clunks, though maybe not as loud or often, not sure -- need time with it I guess. Didn't notice any loss in shift behavior, and the smoother more resistive feel works for me. So, is Redline MT-90 a better choice for me than Pennzoil Syncromesh?

An update on the MT-90 Vs Syncromesh in my transaxle. Guess the oil has had time now to work throughout the transaxle and I'm noticing two things, the clunk seems to be near enough eliminated -- at worst, much quieter than before. However, the gear shifting has definitely become worse. It's now reliably balky getting into reverse and just fought the third to fourth transition as well. I'll try adjusting the cabin "select" cable adjuster to see if I can better tune-in fourth.

==========================NEXT DAY=========================

I'll try adjusting the cabin "select" cable adjuster to see if I can better tune-in fourth.

Whew! It's now shifting just fine, including reverse -- seems Syncromesh is much more forgiving than MT-90. Also, the clunk has been attenuated so much that it's no longer identifiable as a "clunk" ! So, I guess Redline MT-90 is a winner, though I had to re-adjust the "Select" cable length for optimal shifting. Lucky I learned that trick !

Thanks for the help guys !