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#1
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clutch wont release
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. |
#2
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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.
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64 Lemans hardtop 4spd, buckets |
#3
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#4
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disc springs hitting flywheel bolt heads ???
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#5
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Sorry read post wrong. Disc in backwards? Most have the spring stepped portion to the trans.
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64 Lemans hardtop 4spd, buckets |
#6
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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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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#7
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EDIT: Ok, my turn to read post wrong! .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#8
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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.
Definitely in correctly. If it was backwards it wouldn't sit flat and flush I tried it. |
The Following User Says Thank You to abefromen For This Useful Post: | ||
#9
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#10
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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.
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64 Lemans hardtop 4spd, buckets |
#11
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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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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#12
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#13
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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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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be Last edited by HWYSTR455; 09-27-2023 at 02:35 PM. |
#14
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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 |
#15
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First pic is clutch pedal at rest all the way up. Fork is at about mid window. According to the RAM instructions it should be more towards the front of the window opening.
Second pic if fully depressed. Impossible to see inside the window without a bore scope to see how far fingers are down. But without a bottom inspection hole to see what the disc is doing looking in with a bore scope may not say much. Old clutch with the flatter diaphragm fingers with same short TO bearing worked fine.......new PP with more raised fingers same short TO won't release disc. Makes no sense. |
#16
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Ok, have to admit, not too familiar with the chebbie stuff, I can see the angle of the bell, and the bend on the fork, so maybe it needs to be at rest further forward, not sure.
It kinda looks like theres a witness mark on the bell fork opening, maybe it's reaching max travel? It does look like you have more room to maybe go to the next height TO though, that might do it. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#17
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I take that back, think the pivot ball needs to be longer, or an adjustable one so you can move it taller. That would make the fork go forward without it going at an angle, which would be the case if you went to the next height TO.
Is that bell cast aluminum? If it's steel or else, you can cut into it and not worry about it failing. Think you're on the right track. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#18
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That pic of the fork I posted has less of an arch to it, maybe because it's a Pontiac one.
.
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#19
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Yeah, more I look at that pic at-rest, more I think the next size up TO isn't going to help, it will probably put the fork at more of an angle and create an 'arch' path of travel, making it hard to initially push the pedal in.
Difference between the 2 TOs that the RAM website lists is a touch over a 1/4", that may make the end of the fork too close to the bell. It's a toss up, you could try the next taller TO, but I think if you ever have to replace it again, the adjustable ball would be a better option. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#20
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