Duster346
Chris Andrews
No, it will not cause your car to creep in neutral. It's hard to say without having your transmission on my bench, but like I stated before, it sounds like you have a hydraulic problem.
Clearance with dry vs wet clutches
- Thread starter Uncle Bob
- Start date
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mopowers
Well-Known Member
Yes, is was a measured 0.002" - so essentially zero (minimal).
Uncle Bob
Shiny paint causes stress.
Back to the drawing board then
CudaFactHackJob
Well-Known Member
I don't see how you can have .020 play in the clutch retainer but no clearance between the piston and spring. I just measured three used late springs and found less than .010 difference. The early spring stands about .055 taller. I suppose you could run the late piston with the early spring and mill the piston to fit, but $100 for a piston is nuts. I think the worry about worn out older springs because of their design is just confusion. Any older group will usually have more wear. When the forward clutch wears down and then that clutch is engaged many many times, then that spring is going to wear out and shatter. I don't think any spring is going to ever wear out if the clutch clearance is correct. Duster 346 what do you mean by, "everything to do with total unit end play." Was that a misspeak? Cuz it sounds like you're saying that spring to piston clearance affects overall trans end play.
CudaFactHackJob
Well-Known Member
.002 preload will probably increase the life of the spring cuz there's no shock to it like when the piston flies out and speeds up thru the clearance; slamming against the spring. Chrysler probably should have had a groove in front of the clutch retainer; near the bottom of the direct clutch engagement splines; to hold that drum solid. Also, I wonder if a lot of piston to spring clearance will increase the harshness of the drive engagement. It could very well be a hydraulic problem like Duster 346 said. I hardly ever recommend trying a different valve body, but if the manual valve measures the correct distance out of the casting for the drive position, about 1.82", then there could be an internal crossleak. Some transs, like the th350, are very critical in the manual valve placement, as any variance over 1/16" in either direction, could result in low forward clutch apply pressure. I'm thinking that if the manual valve arm is bent, then the manual valve itself could be in the wrong position in "D"; resulting in a crossbleed past the valve from neutral to the forward clutch channel.
Uncle Bob
Shiny paint causes stress.
FWIW I'm still piddling with this thing. I air tested the system from the pump/stator support and the rear clutch activates and retracts as it should. I air tested the case to see if there was any cross flow and there was not.
When air tested at 100psi the rear clutch piston retains the seal, but it does look like it's close to popping out. Of course it's got 100 psi behind it too so that' s probably expected.
There's about .035 play between the piston and the spring of the rear (forward) drum. It is an early style piston and spring.
I didn't take the VB apart because I think it's pretty danged unlikely there is a problem in it. All the forward and reverse functions worked just fine when last used. I haven't looked in the FSM for a way to test it but it's a Cheetah anyway so is likely a lot different from what the FSM would describe anyway.
I'm planning to lift this engine/trans in on the k-frame. I don't want to have to undo that, ever. So I want to get this right the first time.
When air tested at 100psi the rear clutch piston retains the seal, but it does look like it's close to popping out. Of course it's got 100 psi behind it too so that' s probably expected.
There's about .035 play between the piston and the spring of the rear (forward) drum. It is an early style piston and spring.
I didn't take the VB apart because I think it's pretty danged unlikely there is a problem in it. All the forward and reverse functions worked just fine when last used. I haven't looked in the FSM for a way to test it but it's a Cheetah anyway so is likely a lot different from what the FSM would describe anyway.
I'm planning to lift this engine/trans in on the k-frame. I don't want to have to undo that, ever. So I want to get this right the first time.
CudaFactHackJob
Well-Known Member
What is the height of the spring? remove it and place it on a flat surface to measure. What is the clutch pack clearance? How much endplay did the trans have? How thick are the thrust washers between the pump and front drum, and the front drum and the forward drum?
Uncle Bob
Shiny paint causes stress.
I do not know the height of the spring. There is .035 between the piston and the spring. The rear clutch pack clearance is .047. Endplay was <.020. The thrust washer between the pump and the front drum is missing. The thrust washer between the drums is .085.
CudaFactHackJob
Well-Known Member
I could compare that spring dimension to ones that I have. Endplay less than .020....depends on the case temp at the time the measurement was taken. A hot case with .020 will be all bound up tight when it's cold. What do you mean the thrust washer is "MISSING"?? Holy crap; remember I mentioned the drum moving around? Was that front washer around .140?
Uncle Bob
Shiny paint causes stress.
The front washer is just not there so I don't know how thick it was. I did look yesterday and it seems like there wouldn't be room for the available sizes even with a thinner #2 thrust. So I need to put it back together and check the endplay *again* but have bigger fish to fry with a plumbing problem.
CudaFactHackJob
Well-Known Member
Are you saying that the front washer wasn't in the trans when it was together and there was this forward creeping problem, and that there isn't room between the pump and front drum for an .084 washer? Are you sure that the ball bearing outer race is clipped into the tailshaft housing?
Uncle Bob
Shiny paint causes stress.
That's exactly what I had said, but it's not correct. There is an .085 fiber washer there. Once I got the plumbing fixed I was able to see that I had missed it.
It's the same as the fiber one between the drums (.085) and the brass/copper one between the input and output shaft is .061.
I measured endplay at .015 the factory way (push it back pull it out). I did not stand it on the tailshaft to do that.
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CudaFactHackJob
Well-Known Member
.015 end play is unusual with only those two thin washers in there; possible, but unlikely. I'm looking for a placement that would cause the forward drum to receive pressure while in neutral. I think it's in the valve body; like a misadjusted manual valve.
Uncle Bob
Shiny paint causes stress.
I reassembled it with all three thrust washers in place and am seeing about .017 endplay, so I'm planning to swap one of the brown fiber .085 washers out for a .065 to end up with .037 end play.
I'm still trying to figure out if changing the end play that much could have moved the relationship between the sealing rings and the fluid passages on the input shaft and caused some bleed into the circuit but TBH I haven't given it a lot of thought. It's sort of a no-brainer to get the end play back to factory spec because it won't hurt, and it might help.
I'm also thinking about getting one of the CRT H-D belleville springs for the same reason - won't hurt, might help.
I'm still trying to figure out if changing the end play that much could have moved the relationship between the sealing rings and the fluid passages on the input shaft and caused some bleed into the circuit but TBH I haven't given it a lot of thought. It's sort of a no-brainer to get the end play back to factory spec because it won't hurt, and it might help.
I'm also thinking about getting one of the CRT H-D belleville springs for the same reason - won't hurt, might help.
CudaFactHackJob
Well-Known Member
Did you check on how far the manual valve sticks out of the valve body when it's in "D"? Did you replace all the thrust washers with new? Not saying you should, just that that's a pretty tight trans with such thin washers... Did you check to make sure the rear bearing is seated?
Uncle Bob
Shiny paint causes stress.
Yes the manual valve measures correctly and the rear bearing is seated. I have not replaced any washers yet. I did not take the planetary train out but measured end play on that the last time I had it apart and wrote it in my Munro book. It was in spec. It seems like it's only out of spec tight because of the extra .020 of the #2 thrust.
CudaFactHackJob
Well-Known Member
I hardly ever recommend this; but I would put it back together, and if the problem persists, I would actually try a different valve body; just to eliminate that as the culprit.
Uncle Bob
Shiny paint causes stress.
I plan to change the VB to a LBA model anyway.
CudaFactHackJob
Well-Known Member
End play is tighter cold. The case heats up and expands. Did it creep forward in neutral more cold than hot?
Uncle Bob
Shiny paint causes stress.
I do not remember, and probably didn't pay any attention at the time.
CudaFactHackJob
Well-Known Member
If the input shaft and output shaft are binding up where they meet, because of no endplay, then it will creep forward as if in third gear when cold.
Uncle Bob
Shiny paint causes stress.
Good to know. I'm ordering parts soon.
Uncle Bob
Shiny paint causes stress.
I've got parts coming to correct the excess front clutch pack clearance, to allow .020 more end play, and to replace the Belleville spring with a HD version. It will be spring to summer before I know if the creeping in neutral is fixed or not.
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