1G 2nd Clutch Failure - Anything to Check?

[VraspirA]

I have had two clutch failures that seem to me like mechanical failure of the clutch assemblies themselves, but I want to make sure this doesn't suggest some other problem before I put in another.

My 90 GST is basically stock, and I don't drive very aggressively.. maybe spiritedly once in a while, but not really pushing things that much.
A few years back, I pulled the tranny to replace the synchros - sent the clusters to Jacks, added some steel shims as needed to the bearings (pretty sure I did new bearings at the time too). The stock flywheel was just starting to touch off the tips of the rivets holding on the friction material, so it was great timing for that too.

The first was an ACT sprung street disc I used with a new OEM pressure plate and TOB on my stock flywheel (was going to get OEM disc too, but they were all out). I remember it feeling like we had to force the tranny on the first try, so we pulled it back off before bolting on and reseated which felt better. The clutch worked fine after fighting to get proper disengagement (there were plastic pieces that protruded a little which would touch off to the plate fingers if I set the travel too far) and ran for about 1 year and 15k miles before the hub splines basically sheared off. (after shown)

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The second was a Platinum Driveline 05071 stock replacement style from RockAuto because this was my daily at the time. Went in well and drove great for a the last two years and 15k miles until it gave up, this time the steel plate between the hub and disc busted completely apart. (see before and after) The TOB had started to squeak every tenth cold start or so, but otherwise I had actually been thinking to myself how this cheapo clutch was doing so well, slowed down from 60 to 40 mph for someone turning left and it basically let go when I went to speed back up.

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So far I can't think of some common issue with the trans or engine that would cause these two failures, so maybe I just have to stop buying cheap clutches

Any ideas?
- seems to me flywheel runout would have caused noticeable vibrations or weird engagement
- not sure how I could get 160k out of the original clutch if the input shaft were screwed up, and I don't imagine it could get bent just in shipping
- my current best guesses are the ACT hub was softer than it should've been (maybe slightly dinged up from installation - though we didn't see anything between attempts), and the PD steel was just too thin for highway bumps over time..

Or suggestions? I'm leaning towards a South Bend K05048-HD-O at this point, but only because SB seems to have a good reputation here.

-Aaron

 

[dustyboner]

i like clutch masters. i have never had any problems with their clutches and i have run multiple ones down to the rivets.
you might check out the fx200

Clutch Masters FX Series Clutch Kits for DSM / Evo 1-3 (05048)

Clutch Masters single disc FX Series clutch kits fit all AWD and FWD 1G/2G DSM, GVR4 and Evo 1/2/3 models. The discs are different for each kit and each is recommended for use with daily driving, high power street cars, drag racing or road racing.

stmtuned.com

 

[twicks69]

Well, the ACT failure looks to either be a material hardness issue or it had a bent hub from hanging a transmission on it while installing the trans. The second failure looks like a cheaply made clutch, along with having the potential of a bent hub from hanging a transmission on it while installing.

Please be sure to have all the load off the transmission when installing, either by using a floor jack and balancing pad (grab a piece of 14"x14" 3/4" MDF and carpet it. Use it to have more surface area on the transmission instead of just a jack holding the trans so it doesn't slip off. Or, simply use an engine cherry picker if you have one, and chain up from one or two of the passenger side mount holes and install the trans fully supported. This will help prevent premature clutch hub failures.

As for clutches, well, the South Bend Clutch K05048-HD-O is essentially a totally stock Exedy clutch, it uses around a 1800-1900# cover spring and is as soft as stock for pedal pressure. If I recall, it is just a 4 spring, 4 rivet hub on that disk. Still, I have been selling SBC clutches for almost 15 years and I have had the best luck with their brand overall, but there are a few other options available still from other manufacturers that are just as good as this clutch, if not a better value.

My preferred one for this would be a Competition Clutch 5048-2100 Stage 2 organic full face sprung hub clutch disk kit. Simple, durable, better hub design than the SBC HD-O disk.

Action Clutch also has a decent economical heavy duty sprung hub organic disk with 6 rivets and encapsulated springs, - ACR-1059 is the part number.

If you are wanting a Kevlar friction material clutch disk, then either the SBC K05048-HD-TZ would work, or the Clutch Masters FX200 mentioned above would work just fine. If you want the better clutch disk hub, then the Clutch Masters FX300 disk has the heavier duty hub with more springs and rivets. Or the Action ACR-1060 is their sprung hub Kevlar disk kit offering.

If you want a STOCK level clutch, well, the Exedy EXE 05048 is a basic organic disk 4 spring / 4 rivet hub disk kit and is hundreds of dollars cheaper than the options above.

 

[Kryndon]

One word about the Comp Clutch Stage 2, I have it on mine and the clutch pedal is BY FAR the stiffest/heaviest I have ever driven. It's uncomfortable in the city but then again I got chicken legs so that doesn't help... It's lasted me almost 19k miles and has started to grind bad against the flywheel, which I am certain are the rivets. Make of it what you want, I don't know how long a performance clutch is meant to last but it's also held up to quite a bit of launches and slips.

 

[bastarddsm]

Did you have all the bolts in, and the dowels as well? I would check the flywheel surface for runout as well. Are you sure your transmission shim job is good?

Either something is out of whack or you are far more abusive to it than you realize, but I doubt that. The second disc looks very nice for 15k on it. It's possible that you just got 2 junk clutches, but man idk. I've run some cheap parts store ones and beat the hell out of them and not had that kind of failure.

Are you lugging the shit out of it all the time?

 

[dwb]

Imo it looks like you got two bad discs. I've personally had a couple ACT discs fail in other ways with similar mileage.

 

[92AWDHX40]

I never had act fail , except one pp plate was very used and old, sbc here now waiting to break it in shortly, thanks tim.

 

[VraspirA]

Thanks for all the info on clutches, definitely helpful since I haven't seen much of them yet.
Obviously we all think of ourselves as great drivers, but I do think I'm pretty gentle given the car. Even when I have a little fun I'm usually not rushing through the shifts or anything, and goose it mostly after the clutch is fully engaged. I know for a fact my uncle (original owner) drove it way harder during it's first 120k and I was able to get 40k afterward no problem.

One of the complaints I had with the OEM plate | ACT disc combo was that the pedal/spring pressure felt way softer than the original - is it possible there were different pp versions for the early 1G's? The guy at Jacks made a comment about my cluster having the 'better\stronger' (I assumed that meant early 1G) gears..

Also glad to hear it's plausible these were just crap, but I'll definitely try to check things out.

No missing bolts and both dowels in place every time.

I know we tried to be very careful about getting the transmission lined up, but I also remember struggling to get it in on attempt 1 for the ACT. And as much as I remember the second clutch going together much better, that could be relative to botching it the first time..
In both cases we had the transmission on a floor jack with towels as padding, but having taken this apart a third time now I feel like I understand the orientation to sneak it past the frame better.

We also did our best (first time though) doing the preload shims per the service manual, measuring with crushed solder, etc...
That said, being a broke college kid at the time I bought one roll of shim stock (I think .005") and put as many layers as I needed per the cheap digital caliper I had. I'm pretty sure you can hear the race spin against them when lightly engine-breaking with the tranny warmed up. That's another thing that nags me but also never wanted to have to do again this soon.

Bastarddsm, are you thinking that an under-shimmed input shaft would get pushed off-center when gear forces push the shaft away from the engine?
Now that you mention it that makes sense I think - is there any way to know without pulling it apart first though?

 

[bastarddsm]

Yeah, that type of failure almost has to be from something out of line. Play with the trans and a dial indicator. Shouldn't have any endplay. might end up having to take the thing apart, put the indicator base on the crank and sweep the input bearing race, make sure nothing is out of wack there.

In my career, I've only had 1 clutch disc kinda get close to comming apart. It was a china xtd one, and i had the trans in and out a bunch. Forcing it on, letting it hang in the input shaft, missing dowel. it was close to falling apart.

Most of the time discs don't last long for me, but it's the friction material is worn, and not the hub comming apart.

 

[VraspirA]

I'm probably just thinking of this backwards, but how would I see the dial if I have to mount the bellhousing around it to see if the bearing race is concentric with the crank?

Edit: Oh, I suppose you stick the mounting rod through the input shaft hole and have the dial indicator outside.. right?

 

[VraspirA]

Few more questions here -

Does anyone know the part number for the drive shaft circlips? Or is there a trick to make sure they're gapped the right amount to be effective?
The service manual says non-reusable everywhere but I can't find a part number, and the best I can find on MitsubishiDirectParts is MB896916 (previously MB290118?), which is shown in the right place on the image, but it's a crude shape drawn in which looks more like a C-clip that reminds me of my brother's Mustang rear axle clips..

Is there a best known way to get the transmission in and out without stressing the hub? So far I've found that pulling the trans off past the dowels and rotating the diff side downward seems to be the ticket.

For the ClutchMasters, it sounds like Kevlar is a great option for long-term life. I see the fx200 says 2-3x life and equal torque holding to the fx100, and fx300 says it'll handle more torque but doesn't make claims about the life. Is it reasonable to think the 300 would be a long-lasting clutch even with higher torque capability?
Are there any actual numbers for these? The website only references 70% and 110% "increased" torque holding over OE but seems to be a general classification.

Given my history here I like the idea of a beefy hub assembly..
On the Competition Stage 2, I see some pics with 3, 4, and 6 rivets on the hub and the only site with more than a general photo (STMTuned) shows 4 rivets. These do actually have a reference number though (350 ft*lbs) - would the OE standard be rated for 300 ft*lbs, since that's roughly the stock output?
Kryndon mentioned these feeling pretty stiff - would you say significantly more than stock? I remember thinking something was wrong when I tried my buddies PT Cruiser in high school because the clutch was so soft compared to the GST (my only other manual experience at that point).

Is resurfacing the flywheel a need in a case like this where I have only had so many miles on the surface and it's in good shape (no uneven spots or signs of heat)? If so would just scuffing the surface a little be sufficient for good break-in, or would that be a bad call?

 

[bastarddsm]

I'm probably just thinking of this backwards, but how would I see the dial if I have to mount the bellhousing around it to see if the bearing race is concentric with the crank?

Edit: Oh, I suppose you stick the mounting rod through the input shaft hole and have the dial indicator outside.. right?

yep

 

[Mello]

My preference is the Southbend clutch over the Competition. They have a nice oem pedal feel. I got the 2100# SS pressure plate with the full face sprung Kevlar disc from Tim @twicks69 TMZ Performance. This is a daily & it's a fun driver. Yes Kevlar discs have good longevity, better than organic discs & handle a little abuse better too.

 

[dustyboner]

Does anyone know the part number for the drive shaft circlips? Or is there a trick to make sure they're gapped the right amount to be effective?
The service manual says non-reusable everywhere but I can't find a part number, and the best I can find on MitsubishiDirectParts is MB896916 (previously MB290118?),

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[VraspirA]

That's a pretty slick looking tool! Is that software something you have at home?

The images on https://www.mitsubishidirectparts.com/ seem backwards to me (17 and 18 look like the boot straps).. have you ordered this part before and could confirm? Or maybe there's a better source you all know of.

"Boot Kit C-Clip" - - - #4 is listed as MB896816
"Drive Shaft Snap Ring" - #18 is listed as MB160387

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[VraspirA]

After moving (threw in the OE clutch to drive across town) and having a kid, I'm finally getting to take a look at my transmission.
So far I've measured the gaps, which I'll post next, and hoping to check for any runout/misalignment to the bell housing in the next week.
Current goals are just to keep this as a reliable backup car with occasional joyrides, no big power upgrades planned at this point.

Hoping to confirm a few things though:
- Can I get shims from Tim (@twicks69)? Last time, I reused the OE shims, plus a layer or two of shimstock that I cut into rings, but that doesn't seem ideal.
- I'm hoping the bearings (~30k daily miles) should all be OK to keep using. There are some patterns in the light which appear much more intense in the pictures, but I can't feel anything with a fingernail.. is that an adequate test? (If I decide to build power someday I'd do different preloads anyway)
-> does having used bearings this affect the preloads I should set??
I know for tensioning industrial belts there are tech papers from Gates, etc. about setting different tensions under and over so many hours of use.

[...]
I would want to have preload/endplay of the shafts to be something along the lines below based upon the parameters of power levels and temperature conditions.

Stock/Street Transmissions with less than 400TQ at the crank:
Input Shaft --> 0.004" - 0.007" PRELOAD
Intermediate Shaft --> 0.005" - 0.007" PRELOAD
Center Differential --> 0.005" - 0.007" PRELOAD
Output Shaft --> 0.003" - 0.005" PRELOAD
Front Differential --> 0.002" - .0067" ENDPLAY

[...]
If you are trying to make a transmission to last 100,000 miles, use the factory specifications for everything EXCEPT the input shaft -- please-oh-please put around .004-.007" PRELOAD on it in stock form. If you are trying to make a transmission that can last 30,000 miles on a heavily modified car going to the race track and "spirited" driving, well, I would follow my recommendations listed above.

In this circumstance, you are reusing worn bearings, and that may be the issue; they may be out of spec causing your measurement variations that are significant. Otherwise, it is the process you are doing the solder method, or the physical solder itself.

I got myself a hoist now, so might have to "practice" pulling the engine to make extra sure I don't flex the clutch on install this time.

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[VraspirA]

This is what I've measured to be the gaps and existing preloads:

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[pauleyman]

That's gaps are teeny. What are you measuring and how?

 

[VraspirA]

I'm using the normal crushed solder method to measure the tapered bearing races to case gaps with bolts torqued to 29 ft-lbs..

Tighten your case fasteners evenly by hand, then torque to 29 ft/lbs evenly. Let sit for like 10 minutes if you like, then disassemble and measure your solder thicknesses. If you have one of the two pieces either damaged or severely different in thickness (i.e. like 0.010" variation, half-crushed, etc.), then do it over until you get accurate measurements that are repeatable. Your ranges should look around the numbers below based on NEW bearings used with undamaged case sections (AWD as an example below):
Input Shaft: 0.035"-0.045" (shim range available is 0.017"-0.057")
Intermediate Shaft: 0.035"-0.045" (shim range available is 0.031" -0.056")
Center Differential: 0.040"-0.060" (shim range available is 0.044" -0.070")
Front Differential: 0.030"-0.045" (shim range available is 0.017"-0.057")
Output Pinion Shaft: 0.045"-0.060" (shim range available is 0.042" -0.075")

From this listing (granted that's AWD not FWD) I'm within "normal" other than input being .002" bigger which makes sense given they're used bearings. The intermediate being .002 smaller I'm not sure though..

I did the crushed solder test twice, once basically as-is, and once after cleaning the RTV and chasing threads. Trans is in my basement at 68-70 F, using a (low/mid-range?) Fowler micrometer, averaging 2 measurements of each 1/2" solder piece (.062" rosin core). Both times I let it sit for a day after torqueing before removing to measure, and they came out within .0006" except the differential went down .003", but I cleaned up some grit on that locating pin before the second measurements and that makes it more in line with the existing shim as well.

Am I missing something?

 

[pauleyman]

Nevermind I misread your data.

 

[danl]

https://www.dsmtuners.com/attachments/pxl_20230203_154324993-mp-jpg.686269/

That race looks pitted. You said it feels fine?

Early 1990 FWD’s have a different clutch alignment tool from what I recall. The difference is, from memory, a small stub on the end. Though either alignment tool should be fine. The fwd trans slips on very easily. I usually put them on my chest, slide under the car on a creeper, and bench press them into place. It should slip on quite easily. As previously mentioned, don't let it hang on the disc.

 

[VraspirA]

In the picture I agree it looks just like pitting, but I can't feel it. Maybe it's just early stage pitting?
In person it's almost hard to see the pattern that's so obvious in the picture.
I'm no bearing or metallurgical expert, but based on rusty parts I would expect the metal coming apart to make noticeable pits by the time it's visible.

That's interesting, I've always just used whatever came with the disc. Are you talking about a stub beyond the single smaller diameter that locates into the flywheel?

 

[danl]

I am not positive there is a 1990 specific one but for some reason I have two, both blue, and the pilot hole is different between them. I may have gotten one in 2001 and picked up another later and they were changed slightly. I won't be around my junk for 2 weeks at which point I"ll try to track down what I have (if not lost) and report back.