Question : Mix/Matching HTOB and Getrag-282

[TGP37]

96 Grand Prix 3100 SFI
Getrag-282 from a 1989 McLaren Turbo
Bell housing is W-Body swapped during the rebuild. But came from another donor of another make/model. Getrag was built by Pontiac Jeff from Engineering Performance in Florida.

The Hydraulic throwout bearing fits a 1993 Cavalier 5-Speed (among others I'm sure).


Are there any dimensional differences requiring the HTOB to be shimmed? And if so, how much?

Because I am using a new clutch system, new master-lines-slave. But I can not get the clutch to disengage the trans. And I bleed the f**k out of those lines. Pushed fluid up from the bottom bleeder until no bubbles, then bleed back down using a check valve to prevent air going back up. I seriously doubt the issue is air in the system.

The clutch pedal has excellent travel length, starting 1" ahead of the brake pedal rested and goes to the steel frame. It has a pressure kick back so the pedal doesn't just rest.


This is crazy frustration. I think I might need to pull the engine-block again just to measure the distances.

[Superdave]

I didn't think the Turbo 3.1's ever had a HM282 trans.. They were all auto IIRC...


What year is the bellhousing?

What clutch?


Pics would help, i've had quite a few HM282's apart and changed bellhousings and clutch styles plenty of times.

[TGP37]

I didn't think the Turbo 3.1's ever had a HM282 trans.. They were all auto IIRC...


What year is the bellhousing?

What clutch?


Pics would help, i've had quite a few HM282's apart and changed bellhousings and clutch styles plenty of times.

The bellhousing is from a 93-94 w-body mount.
Not sure about the donor car for the trans itself. I thought it was an 89 GP McLaren but it may have been a Cavalier. Since the bell housing needed swapped for w-body mounts, it couldn't of come from a w-body.

PontiacJeff said it is a 93-94 trans now, after swapping bellhousings. He was the guy who built this trans for me.

Flywheel- 89 Grand Prix McLaren
Spec 3 clutch- 3100-3400 v6
Master- 89 Grand Prix McLaren
Slave- 93 Cavalier
-4AN clutch lines

Not many pics on this laptop. This is the inside of the bellhousing. I placed the htob w/o anything between the htob and bellhousing.


I'm just going to pull the darn block/trans and get the Speedway Hydraulic Release Bearing set-up tool. Too many different parts to know for sure what the clearance is now.

So I guess my REAL question is what is the best clearance I should aim for? I read 0.1"-0.125" is optimal but it was a Ricer forum found through google.

Also, shimming the htob....can I simply shim the htob with steel cut to size/thickness or must I use proper shims? Assuming I need to shim, I won't know for sure until I remove the trans and measure.

And what is best to shim to make up the difference? Flywheel or HTOB? It will be easier to shim the flywheel small amounts, but need to keep the starter aligned as well. To shim the HTOB I have various thickness steel sheets (0.012" - 0.032" - 0.064") so I can stack for a precise amount. Maybe I should shim both to prevent larger extensions on either side. Again, if I need to shim.

Funny, I always said I wanted to learn more about performance engine building. Well, looks like I got what I asked for, lol.

[Superdave]

i've swapped HM282 parts for years and never ever had to shim anything. as long as the TOB setup matches the bellhousing it should work fine. The masters are also different between the internal and external slave setups, If yours is an 89 then it's for the external and that may be causing a problem when used with an internal slave.


I'm assuming you have a stock 60v6 flywheel for a 5 speed 2.8 or 3.1 Gen 2 engine, and the clutch is made for the same setup. Part numbers would be helpful though. It has happened in the past that people get an incorrect pressure plate that causes all kinds of problems.


The flywheel, pressure plate and disk are all the same for all V6 HM282/NVGT550 trannies regardless of the slave setup.

[TGP37]

PontiacJeff from Engineered Performance sent the Spec 3 Clutch and assured it was a correct match. The flywheel (new) was matched to a 3.1 Gen2.

As far as the Master/Slave combination it should not prevent some form of pressure plate engagement. I read on another forum mixing those two should be fine. If the slave is smaller, pedal action is stiffer and visa versa. But when I pull the trans I'll definitely be testing the slave to see it work and measure how much travel when pedal is pushed.

When I removed the flexplate there was a shim roughly 1/8" thick between the flexplate and crank. That shim was not used installing the flywheel, and I am beginning to think that is the problem. Now I think having a shim for the flexplate would warrant the use of the same shim for the flywheel.

EDIT: Master Cylinder Bore, both 89 GP and 94 Cavalier have master bores of 7/8", among others. So the Master Cylinder should match.

[pocket-rocket]

I wouldn't install the shim, but that's me.

You have a hydraulic slave, it takes up the extra slack from clutch disc wear just like your brake system does for pads. That's why hydraulic clutches don't need to be adjusted like cable driven clutches as the disc wears.

[Superdave]

It could just be a bad slave too...

Pulling it out would be a good idea though, you could test it on the bench and see what it's doing. You might be able to pull the starter off and with some luck be able to see the slave through the hole and have a buddy push the pedal.


Flywheel shims are sometimes used after a flywheel has been shaved a few times, on the older HM282's with the shift fork this is sometimes needed. For yours you shouldn't have to worry about that. Especially if the flywheel is new.

[TGP37]

The slave is also new. At least I had the bright idea to build with the idea of removing the engine in the future. Maybe the slave needs a good bench bleeding before install.

I'll be sure to update this thread when I find out what was wrong.

Thanks Dave

I wouldn't install the shim, but that's me.

You have a hydraulic slave, it takes up the extra slack from clutch disc wear just like your brake system does for pads. That's why hydraulic clutches don't need to be adjusted like cable driven clutches as the disc wears.

I didn't install the shim either for the same reasons. I remember we discussed that a while back.

Correct me if I'm wrong but, the pressure plate fingers move closer to the slave as the clutch wears over time. So the slave will travel the furthest it needs to when the clutch is new, and the clearance decreases as the clutch wears. Any further clearance increases could render it unable to depress the fingers properly. Just an idea, the real answer lies in measurements and visual inspection.........EDIT: I just realized a surfaced flywheel would move the entire pressure plate away from the HTOB. Noting this is what you are probably referring to. It is the wear of the clutch plate that would move the fingers towards the HTOB.

I knew a 2-ton engine lift was a good investment...lol

[pocket-rocket]

Correct me if I'm wrong but, the pressure plate fingers move closer to the slave as the clutch wears over time. So the slave will travel the furthest it needs to when the clutch is new, and the clearance decreases as the clutch wears. Any further clearance increases could render it unable to depress the fingers properly. Just an idea, the real answer lies in measurements and visual inspection.........EDIT: I just realized a surfaced flywheel would move the entire pressure plate away from the HTOB. Noting this is what you are probably referring to. It is the wear of the clutch plate that would move the fingers towards the HTOB.

I knew a 2-ton engine lift was a good investment...lol

I didn't think it that far through last night after working all day, then tearing into an Aztec preparing for a head gasket job (previous mech did LIM gaskets, didn't use loctite, so I lucked out with a LIM gasket job and the car goes back to my friends car lot sooner ).

Yes, you would be correct on the wearing of it all. Like Dave mentioned, when a flywheel gets resurfaced, sometimes you do need the shims. The 2k Sonoma I rebuilt and put a new clutch in needed one. I didn't think it would, but my machine shop guy said it did so I didn't question it and bought one. Those suckers are expensive... $20 for the one I got. But yeah, yours being a push type, the fingers would go closer to the TB as the disc wore. Mine moves away being a pull style, but the concept of the hydraulics being self adjusting is still there.

Engine hoists FTW! I use mine for more than just pulling engines. It's also come in handy holding parts to spray paint

[TGP37]

Okay, this is what I found.......

My clearance is 0.1" (actually just shy of 1/8" which is 0.125") - PERFECT

The fingers had signs of engagement with the htob. - GOOD SIGN

The HTOB, however, had an issue with bubbles. Really small micro bubbles that looks like contamination in the fluid. I lowered the slave and positioned so air had a clean upwards path. Power bleed from the bottom up. But still had air in the slave, I could feel/hear it in the lines.

I then decided to pump the slave by hand. Drawing from the reserve and pumping back up. By pumping the slave I could really feel the air in the system, bubbles jetting is the best I can describe it. I noticed a reduction after several pumps, after a good 15-20 minutes pump/bleed/pump/prime... I finally got the slave free of air. Now the slave has force when the pedal is depressed.

I can only speculate why the air was so hard to get out of the slave.....? Maybe a design flaw....

Testament to bench bleeding!!! It can save time and money.