We are rebuilding a transmission on a 977L and there are a number of rings that go into the pistons that seal the fluid. The original rings taken out of the transmission have a gap of 0.013" and the new rings we bought (CTP) have a gap of 0.025" on the ID ring and 0.043" on the OD rings. Does anyone have a spec for these? There has to be something published somewhere... The rings in question are 5M6132, 5M6141 and 7M1177. To size the rings I ordered OEM CAT rings, one of each, standard size, and the gap was similar to the original rings. Thinking maybe the discrepancy could be in the CTP rings.
The ring gaps are in service manuel under power train specs. I would try calling your cat dealer and ask for technacal they should be able to tell you
I would have thought that also, but they are not. The only reference I can find to them is a Reuse & Salvage Guideline SEBF8006-01 entitled "Clutch Housings and Clutch Pistons For Transmissions And Torque Dividers". Unfortunately that document is not freely available. There is a SMAG SEBD1721 from 1977 with the following text (the bold is mine) - More oversize cast iron seal rings are now available for clutch housings and clutch pistons. With the use of oversize rings, clutch housings and clutch pistons can be salvaged (repaired) if their bores are machined larger. A revision to Guideline For Reusable Parts, "Clutch Housings and Clutch Pistons For Transmissions And Torque Dividers" gives a complete list of all the oversize rings. The form number for the revision is SEBF8006-01 and this is a replacement for the former SEBF8006. The important addition to the revision is part numbers and dimensions for .030" (0.76 mm) larger rings for clutch pistons. Formerly, only .015" (0.38 mm) larger rings were available for the clutch pistons.
All we have is this, no ring gaps here ☹️
basically the trans has end gaps everywhere with what was in it... 0.014" all the way up to 1/16". Not sure what would happen if we ran with a target gap of 0.035" and it was too much but I know what would happen if the gap was too small...
I know I've seen that witten is it possibly in the assembly instructions
Didn’t see anything there either. You saw it for a 977?
We are going to wing it and go 0.015”-0.035” on our gap spec. 12.5” diameter or so. How does that make everyone feel…?
Sounds about right
If it is too small or too large what do you think could go wrong
It’s been a long time since I did transmissions but those numbers sound right to me I think you will be fine
It doesn’t surprise me that the Ctp rings aren’t sized right. I’ve had ctp planetary shafts that were oversized and the planetary gears became hard to turn when new needle bearings were installed. Ended up ordering cat shafts. As long as the modulation valve can deal with the extra leakage it will work. Might be a slower shift.
I managed to dig up some information. Target end gap for those cast-iron piston rings is between 0.005" minimum and 0.020" maximum.
yeah I am not surprised either... it was just hard to point fingers when we didn't even know a spec. Now that we have the spec to work to he can mix and match rings and get it right... I think he's working to about 0.013"
How did you type that emoji???
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on my iphone lol
I see how it is @CM1995
My Droid can type them, but they don't show up.
ok besides the emoji talk... One more question, the parts book (pic attached) shows two different piston types. first, third, second and reverse are the same while forward is different and has the different ring, noted. In reality, both the forward AND reverse pistons are different on our trans. We have the rings for the forward piston but do not have a PN for the odd ring on the reverse piston. Does anyone have a different parts diagram or is there an update that was made? Machine SN is 11k07398
Pic
Are you certain that the transmission is the original for the machine.? Does it have a Serial or Test Number plate on the case.?
I am not, it could, it will take me a few days to get that info
I think this might be it......... An upgraded higher-capacity reverse clutch. See the attached. You're going to need a few more parts in addition to the clutch piston ring that you may not have planned for.
ok so now a curveball... I believe I need 0.015" oversize ring for 9P5364. do you see that PN anywhere?
Careful with over size rings we used to mark housing when they were cut over size good idea to check ring where it is not worn
very good point
I suggest that you measure the bore in the clutch housing first in order to determine if the housing has actually been bored oversize. Come back with your numbers. Meantime I will try to find a specification. EDIT: Specified (standard) clutch housing bore diameter - 14.883 ± 0.003 inch You had better cross your fingers now and hope that the bore is within tolerance, because there are no oversize rings listed for that piston Part Number.
yeah... its really, really hard to get an ACCURATE measurement on those bores. the bore is down inside kind of and a pair of calipers will not cut it for a diameter measurement like that. we have been treating it like an engine piston bore... measure end gap and adjust. That is ok, I guess I just need to get a ring and a housing, it is worn enough that the current ring has a end clearance of 0.045" maybe that is the way that we are supposed to do it anyways
Have the existing housing metal-sprayed and honed back to standard size.? What does the piston O/D measure.? Spec is 14.857 ± 0.003 inch. Quote from Cat - "Clutch housing bores that already have been machined 0.76 mm (0.030 inch) larger can be brought back to the original size using the metal spray technique."
Why not use a suitably-sized pair of these to get the bore size then measure over the prongs with outside calipers.?
Put the ring gaps in the top position of the housing's when you build the transmission up, it helps vent air as the oil fills making for a better job, I thought you could buy over size rings Non O.E. a run around with a flap wheel can soon ease things, I hardly get to work on Flat Drive D6 's these days although a customer of mine has just bought a D6D LGP, so I live in hope it needs a brush up.
good tip on the gap facing up