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Hello, I知 having trouble figuring out the correct clearance for the forward clutches. I知 measuring about 0.035 with the feeler gauge. The Atsg manual seems a little confusing first it says 0.030 to 0.063 then 0.040 to 0.063. Next when I stack up my 3-4 clutches if I leave out the last steel before the backing plate, then the backing plate sits really far below the snap ring groove. If I put the last steel in then the backing plate is on top of a steel, which I知 guessing is bad. The underside of the backing plate is shiny and looked like it was on top of a clutch. I attached some pics.
Re: 3-4 clutch stack up and forward clutch clearance
I went back and tried my 3-4 clutch pack stack up again. This time I eliminated the use of the flat apply plate, the one with the wide tabs, it sits on the raised portion of the stepped apply plate . In place of it I used a regular steel. I知 getting about 0.065 with the feeler gauge for a clearance. I attached a picture to show the comparison between the regular steel and flat apply plate. Also, does anybody think 0.035 for my forward clutch clearance is on the tight end on the specification.
Re: 3-4 clutch stack up and forward clutch clearance
You are way over thinking this.
The 3-4 clutches....
1. Stack the steels and the frictions per what ever the book says, install the snap ring.
2. Measure the clearance between the backing plate and the friction below.
3. Does this measurement fall in the range specified in the table in the book?
Yes? Line up the tabs of the frictions, drop it in the case and move on.
No? Remove the snap ring and measure the thickness of the backing plate. Do some math and determine how much (plus or minus) is needed to get within the specified clearance. Go to the table and select the appropriate thickness backing plate and purchase it.
4. Re-assemble with the new backing plate. Confirm the clearance is within specs, line up the tabs of the frictions, drop it in the case and move on.
Your Forward clutch clearance of 0.035" is within the specified range of 0.030" - 0.063". Yes, it's towards the low end of the range but it's still acceptable. If it wasn't, I would think that GM would tighten up the tolerance window to exclude 0.035". The Forward clutch is applied in every range except for Park, Neutral and Reverse. It's not like it's being applied off and on while you're driving down the road.
Re: 3-4 clutch stack up and forward clutch clearance
I went back and tried again
1) 3-4 retainer( thin with hooked legs)
2) stepped apply plate( really thick, like backing plate)
3) flat apply plate( 0.076)(looks like a regular steel wider surface area notches)
4) 6 clutches and 5 steels ( 0.082/clutch thickness) (0.077/ steel thickness)
5) backing plate
6) snap ring
I知 getting 0.070 with the use of a feeler gauge, here are some pics from the atsg manual and my completed drum, I知 having a gut feeling the atsg manual is sketchy.By looking at my old 3-4 clutch痴 the friction teeth are worn away.
I guess it痴 my own fault for not carefully taking apart everything and measuring my old clearances. I hear going tighter than 0.060-0.080 is better for the 3-4 clutches
04-04-2020, 08:18 PM
