[abefromen]

Have an '81 Firebird that was a factory sbc 305 car with 4 speed BW ST10 trans. Bought it with a '76 350 sbc swapped in at some point.
Engine was wiped out so I put in an '87 350 sbc......... One piece RMS engine.

So the issue is the clutch will not release. Pedal feels perfect and everything is adjusted properly. The first clutch I used was from LUK but it had a grinding noise coming from it when depressing the clutch pedal with the engine not even running. It wouldn't go into gear when I had it running so I thought the pressure plate was bad. Swapped in the new RAM clutch, same problem.


I used a new ATP 168 tooth flywheel for the '87 350 engine that accepts the bigger 11" clutch. (RAM 88764 with short TO bearing.) Same size flywheel that was on the '76 engine I pulled out.
I transferred everything else from the old engine to the new one, all OEM stock parts..........bell housing with the short pivot ball (PN 3729000). Also used a new NOS fork PN 14066235. It's a replacement for the original fork. It's beefier but the geometry is the same looks to me. TO bearing is installed on the fork correctly with the clips inside the collar.
Correct short head flywheel bolts from ARP also used.

I double and triple checked everything before I installed the new RAM clutch and everything seemed in order. All linkage good, no binding or hanging up. Pedal is smooth as butter and I can feel it depressing the PP properly..........but it wont' release the disc.

I wouldn't think so but does the newer sbc 350 engine with the one piece RMS need the longer pivot ball for the fork? Is the bigger flywheel an issue? I measured the height of the flywheel from the back of the block to the face of the flywheel on the old '76 engine I took out and it was 2 5/8", same measurement on the new 350 with the new 168 tooth ATP flywheel.

I am open to any suggestions as what to do next because this doesn't make sense unless I am missing something obvious. I have done many clutch jobs before but I am a bit stumped. The Chevy bell housing is all enclosed, no inspection hole/opening in the bottom to at least see the disc and try to turn it. Makes this prob tougher to figure out.

[Lemans64]

Not sure that flywheel will work on that engine? 1 piece rear main seal engine uses different flywheel. Info from another site.
In 1986 a crankshaft and flywheel change was made to the improved, once-piece seal design. 1986 and newer Chevy engines will not accept older flywheels due to the different crank flange and bolt pattern. Older bellhousings, however, will work on 1986 and newer engines.

[abefromen]

Originally Posted by Lemans64

Not sure that flywheel will work on that engine? 1 piece rear main seal engine uses different flywheel. Info from another site.
In 1986 a crankshaft and flywheel change was made to the improved, once-piece seal design. 1986 and newer Chevy engines will not accept older flywheels due to the different crank flange and bolt pattern. Older bellhousings, however, will work on 1986 and newer engines.

It's a correct flywheel for the one piece RMS engine. The older sbc flywheel won't even fit the hub of the crankshaft of the '87-up engine.

[Scott Thelander]

disc springs hitting flywheel bolt heads ???

[HWYSTR455]

Did you test fit the clutch disc on the input shaft? Maybe it's getting hung on the shaft. Was it difficult to mate the trans to the bell?

You mentioned 11" setup, did you hold the disc up to the plate to make sure it fit? Possible stuff got mixed up from another box.

And just to ask, the 'flat' side of the disc is towards the flywheel?

You can drill an inspection hole in the bell too, if you need to.

If there's too much pedal throw, fingers/To might be able to hit the disc.

It's rare, but possible, the TO isn't centered on the fingers, or one side of the TO is under the fingers. You can try to peek in the hole the arm passes thru and make sure it's flat on the fingers.

Can't always trust the TO part listings either.

Just throwing stuff out there...


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[abefromen]

Originally Posted by HWYSTR455

Did you test fit the clutch disc on the input shaft? Maybe it's getting hung on the shaft. Was it difficult to mate the trans to the bell?

Test fit to the input shaft before install. Smooth as silk. Trans went in no issue at all, practically by hand I could push it in

You mentioned 11" setup, did you hold the disc up to the plate to make sure it fit? Possible stuff got mixed up from another box.

Yes. Compared old disc to new, both identical. Only thing that was different was the fingers of the new RAM stock replacment PP were a little higher than the old plate that came out. (see pic) No idea if it's original or not but it does have corporate blue over spray on it. Could be OEM original idk. Has balance weights on it like I have never seen on replacements

And just to ask, the 'flat' side of the disc is towards the flywheel?

Yes

You can drill an inspection hole in the bell too, if you need to.

Could but would hate to do that. Why the hell does Chevy have a completely enclosed bell on this engine? No inspection plate like on a Pontiac. Stupid design.

If there's too much pedal throw, fingers/To might be able to hit the disc.

Something to check if I could actually see the PP in action.

It's rare, but possible, the TO isn't centered on the fingers, or one side of the TO is under the fingers. You can try to peek in the hole the arm passes thru and make sure it's flat on the fingers.

I'll look

Can't always trust the TO part listings either.

New TO exact same height as old one that came out.

Just throwing stuff out there...

Thanx for all suggestions, Getting more help here than other Chevy dedicated forums I belong to!


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[Lemans64]

Sorry read post wrong. Disc in backwards? Most have the spring stepped portion to the trans.

[HWYSTR455]

Originally Posted by Lemans64

Sorry read post wrong. Disc in backwards? Most have the spring stepped portion to the trans.

Pretty sure the flat side of the disc usually goes towards the engine/flywheel.

EDIT: Ok, my turn to read post wrong!


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[abefromen]

Originally Posted by Scott Thelander

disc springs hitting flywheel bolt heads ???

Short head ARP bolts were used. No witness marks on anything. I test fit the disc to the flywheel beforehand and it fit flat no touching.

Originally Posted by Lemans64

Sorry read post wrong. Disc in backwards? Most have the spring stepped portion to the trans.

Definitely in correctly. If it was backwards it wouldn't sit flat and flush I tried it.

[Lemans64]

Just another thought, are you putting throw out bearing on fork correctly, the spring on fork goes on the groove with fork, not behind bearing?
Sorry not trying to say you did it wrong, just throwing out idea's.

[HWYSTR455]

Well, guess it could be a defective plate, but not sure that would give the same results.

So when the fork is in the 'relaxed' position, with the fork free play slack taken up (just resting the TO on PP fingers), is the rod pad 90 degrees to the centerline of the drivetrain?

If it's not, and the pad is more towards the rear of the car, that could mean you're not getting enough pedal/linkage throw. To correct, it would require a different or adjustable pivot ball in the bell.


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[abefromen]

Originally Posted by HWYSTR455

Well, guess it could be a defective plate, but not sure that would give the same results.

Thia RAM clutch is the second i have tried. First was a LUK brand and it had a grinding noise when depressing the clutch pedal and I was unable to go in gear. Thought pressure plate was defective. Replaced with the RAM same result but it's smooth & quiet with a normal feeling pedal adjusted with the proper free play so the TO is not touching the fingers

So when the fork is in the 'relaxed' position, with the fork free play slack taken up (just resting the TO on PP fingers), is the rod pad 90 degrees to the centerline of the drivetrain?

If it's not, and the pad is more towards the rear of the car, that could mean you're not getting enough pedal/linkage throw. To correct, it would require a different or adjustable pivot ball in the bell.

what do you mean by rod pad? The round pocket end of the fork where the push rod sits in?
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Originally Posted by Lemans64

Just another thought, are you putting throw out bearing on fork correctly, the spring on fork goes on the groove with fork, not behind bearing?
Sorry not trying to say you did it wrong, just throwing out idea's.

yes i made sure it was. All suggestions appreciated. Since this is a stock set up it's really got me puzzled

[HWYSTR455]

Rod pad, correct, the pocket where the push rod meets the fork. It's 'flat' there where the divot is, and that flat spot angle should be 90 degrees to the centerline of the driveline.



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[abefromen]

Originally Posted by HWYSTR455

Rod pad, correct, the pocket where the push rod meets the fork. It's 'flat' there where the divot is, and that flat spot angle should be 90 degrees to the centerline of the driveline.



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I will check that out.
Also found this at the RAM website:

CHECKING CLUTCH FORK ANGLE AND MAKING APPROPRIATE ADJUSTMENTS
1960’s-70’s GM applications used several different fork pivot ball lengths and release
bearing lengths. Understanding fork angle will help you achieve the best release position for
the fork to minimize pedal effort and maximize bearing travel. For optimum operation, the
fork should have an angle to the front of the bellhousing exit window when the bearing is
just touching the fingers. If the fork is positioned in the middle or to the rear of the window,
travel and leverage is lost. To compensate for this, RAM offers two longer release bearings -
pn 488L is 1.560” overall and pn 495 is 1.810” overall.
You can pre-check the need for a longer bearing by sliding the transmission in and, before
proceeding with completion of the install, pulling the fork up manually to check and make
sure the fork is angled to the front of the exit window in the bellhousing when the bearing is
just touching the clutch finger

[abefromen]

So after pulling the trans for the third time I was able to take a look at the PP in action.

Had someone push down on the clutch pedal and the disc dropped. It is releasing as it should be. But with the trans installed and engine running it will not go into gear. As soon as I shut the engine down I can shift into any gear.

When I had the trans out on the bench a while back I took the shift cover off to change the gasket. Reinstalled the shift cover and bench shifted it thru all gears. Also had the tail shaft housing off too to change the rear bushing. Nothing in the main case was taken apart.

I'm ruling out a trans issue because it shifts fine when engine is off and when I had it on the bench.

Trans was not hard to install either. Went right in practically by hand. Didn't draw it into the bell with bolts.

Still searching for an answer.

["QUICK-SILVER"]

Any chance the splines on the pilot shaft are bottoming out against the pilot bushing?

Clay

[HWYSTR455]

Originally Posted by "QUICK-SILVER"

Any chance the splines on the pilot shaft are bottoming out against the pilot bushing?

Clay

That's a good thought! I was focused on the clutch setup!


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[Singleton]

You stated that the flywheel was brand new. Don't assume that it was surfaced correctly from the factory.

Several years ago I had a similar issue, difficult to place the trans into first gear, grinding going to reverse. Everything was Brand New, Autogear M22, Hurst shifter, fork, throw-out bearing, clutch disc/PP, and Hays flywheel, all new.

Tried everything I could think of to the fix the issue, adjustable throw-out bearing, adjustable pivot, different clutch linkage, nothing worked.

Finally, after a couple thousand miles of putting up with the gear grinding, I decided to change the clutch and pp to a different manufacturer. I doing so I also figured that I would take the NEW Hays flywheel to the local machinist and have it resurfaced, for the hell of it. Turns out the flywheel surface was WAY off, not close to being true. That was my issue the whole time, even with the clutch depressed, the high point of the flywheel was touching the clutch disc at every revolution, just enough to keep the input shaft slowly spinning causing the gear grinding in reverse and the difficulty going into 1st gear.

So don't assume the new flywheel is true.

[HWYSTR455]

Very true on the surface, and to add to that, balance too.

I've never seen one so far out on surface runout to cause dis/engagement issues, but it could happen.



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[400 Lemans]

Originally Posted by abefromen

So after pulling the trans for the third time I was able to take a look at the PP in action.

Had someone push down on the clutch pedal and the disc dropped. It is releasing as it should be. But with the trans installed and engine running it will not go into gear. As soon as I shut the engine down I can shift into any gear.

When I had the trans out on the bench a while back I took the shift cover off to change the gasket. Reinstalled the shift cover and bench shifted it thru all gears. Also had the tail shaft housing off too to change the rear bushing. Nothing in the main case was taken apart.

I'm ruling out a trans issue because it shifts fine when engine is off and when I had it on the bench.

Trans was not hard to install either. Went right in practically by hand. Didn't draw it into the bell with bolts.

Still searching for an answer.

Thats the same symptom's i had in a 69 c10. It was 3 speed in the floor and didn't want to go into first with the engine running. You could put pressure on the shifter and at the same time turn off the ignition off and it would drop right into first gear. Had ran the tranny a little low on lube at one time, but before that it always shifted fine. I always blamed it on synchronizers after that. Later i bought a Muncie m20 4 speed and swapped it out and left the same clutch, pressure plate and throwout bearing in place untouched. Solved the problem.