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.

 

Forward Clutch Clearance should be 030" - .063".

For the 3-4 clutch, you need to assemble the clutch and measure the clearance between the plates.

What is the stack sequence that you're using for the 3-4 clutch?

It looks like you have a 5 friction 3-4 clutch? I think it stacks:

1. Retainer (has the turned down tabs)
2. Stepped Apply Plate
3. Steel
4. Steel
5. Friction
6. Steel
7. Friction
8. Steel
9. Steel
10. Friction
11. Steel
12. Friction
13. Steel
14. Friction
15. Selective Backing Plate
16. Snap Ring

You might want to wait for a more informed answer but I hope this helps a little bit.

 

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.

 

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?
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.

 

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