4L60-E 3/4 Clutch Pack Clearance Issue

[HotRodPC]

Below is a PM sent to me from Christian Nelson. Could be good info for several and other opinions can be helpful, so I'm posting his question in a thread.


I was putting together the 3-4 clutch pack last night, and ran into a problem.

The old clutch pack was 6 clutches, 5 steels.

The new alto is 8 clutches, 7 steels.

Now, when I watched the video, there were 2 types of lower and upper pressure plates. The older style had a 2 piece bottom, and beveled edge top. The newer style had a one piece bottom, and flat or square edge top. Mine had what seems to be a mixture of the two, a one piece bottom with the beveled edge top.

When I assembled the pack, there is absolutely NO clearance between the top pressure plate and the clutch where I am supposed to have ~.086 in.

Is it because I have the wrong top piece? Do I get a different sized pressure plate? SHould I take a clutch pack out? I don't think I should do that, since it would probably be too much play then..

What is your advice?

 

[HotRodPC]

I can think of 3 things it could be. Is this the Commercial Alto Pak? If so, it should have come with its own directions. Be sure you are following their instruction precisely.

For example, my 1st guess, are you supposed to delete using the bottom pressure plate and the first steel is used in its place instead?

#2, are you using the correct set of pressure plates? Is it possible this trans was rebuilt before and someone used differeent pressure plates and they won't work with the new clutch pack.

#3 What did this trans come out of originally. Is it possible this trans/Clutch drum is out of a lighter car or maybe a V6 auto that would require 1 less piston and steel? Not sure the 4L80-E does that, but I know or a fact Th350 did. If you were working on a lighter duty trans, you had 1 less clutch and 1 less steel in each clutch pack. The way to get around this is to use the thinner piston out of drums with heavier duty application.

Let us know what you figure out. Maybe Pops will also make a suggestion.

 

[Christian Nelson]

Delete the bottom pressure plate? There's a thicker steel that came with the kit, but I thought that was for the two piece bottom pressure plate. I have the 1 piece one. That thicker steel has no "feet" that stick down like the bottom pressure plate I have does. On the two piece one, the bottom most piece has feet that stick down, on the one I have, it's got the feet, and is thicker than the two piece. What I am wondering is, if the two piece bottom is thinner than the one piece bottom, necessitating a thinner top pressure plate, but that had not been done on this transmission.

Well, that is my question about the pressure plates I have, it seems they are mismatched. The bottom one is the one piece, but the top one is beveled like what is supposed to accompany the 2 piece bottom pressure plate. I don't know the history of this transmission, it may very well have been rebuilt before. That could explain why the bearings, etc look so nice.

It came out of my wife's Suburban. 3rd gear began slipping and she drove it home in 2nd gear. I checked the fluid level, it was low (like not on the dipstick low) and still slipped when I filled it back up. I tore it down, everything looked practically new except for the 3-4 clutch pack which is what I am currently replacing with the Alto Red clutch pack. No instructions came with this clutch pack. It came with 8 clutches, and 7 steels, with a thicker steel which I assumed was for the top of the two piece bottom pressure plate.

I cannot remove the bottom steel, or pressure plate, since the 1st clutch in the pack sits directly on top of the bottom pressure plate.

 

[Christian Nelson]

Well, I did some research, and found this post...

Here's the thread, for context.. http://www.camaroz28.com/forums/archive/index.php/t-406007.html

You will need to increase the clutch 3-4 clutch count to 8, use Borg Warner Hi-Energy clutches, along with kolene steels. Use the .062" snap ring here and the .128" pressure plates as this will allow the use of thicker steels. Add the Trans-Go Performance Main & intermediate/reverse boost valve or the Sonnax boost valve. Add the Trans-Go HD release springs to the overrun & 3-4 apply pistons in the input drum. This will keep the 3-4 clutches from trying to apply on the top end (above 5,000 rpm) of 1st or 2nd gear, and will release the 3-4 clutches much quicker on a 3-2 or 3-1 downshift. Enlarge 3rd gear feed apply to .155", reduce 3-4 clutch clearance to around .030", use the Corvette servo (if you do not already have one), and set the band clearance to a minimum (.060" - .075"). If the Kevlar band is in ok condition, then reuse, but the Borg Warner Hi-Energy 2-4 band is much better. I prefer the Trans-Go "modified" Perfromance Shift here, but this will do. I stopped using the Alto Reds back in 1996, as the BW Hi-E's were superior. These changes should work out very well. Oh, yes make sure you do the air, bushing, & piston check as Frank describes.

Now, I'm not gonna go out and toss my clutches, but he mentions a certain size pressure plates and snap ring size (along with a side note of adding the heavy duty release springs to keep the clutches from trying to apply due to centrifugal force above 5,000 rpm) so I may order these parts. What do you think?

Looks like 4l60e.com I can get the top, bottom and snap ring for this for $19, and they want $33 for rings that can stop centrifugal apply up to 7800rpm..

Don't know if I need THAT heavy of springs, but I'd like to hit up that ebay deal for $12. I wonder if I can get the springs, plates and snap ring from the same guy on Ebay..

 

[Christian Nelson]

Aha! I think I may have found the info from Alto's website.. Looks like the odd loking steel I got with the set is supposed to replace the top pressure plate.

TECHNICAL NOTE: Dimensional differences can exist in the various input housings and housing com- ponents. The recommended clutch pack stack-ups must be exact in each and every installation. In addi- tion, the original stepped apply plates (item “C”) require a steel plate against it which takes up needless space in the clutch pack. We recommend installing the furnished .125” flat backing plate in place of the stepped apply plate. First, assemble the clutch pack according to the application you have. Air check the 3-4 clutch several times to seat all components. If the clutch clearance is not .025” - .040” use our suggestions listed under Adjusting the Clutch Pack Clearance.
Early V-6 regular or heavy duty applications: Reinstall the original .125” apply plate. Install seven (7) frictions, six (6) steels and the furnished .125” backing plate. Reinstall the original .128” top snap ring.
Late V-6 regular or heavy duty applications with stepped apply plate: Discard the original stepped apply plate. Install the furnished .125” backing plate, seven (7) frictions and six (6) steels. Reinstall the #3 or #7 top backing plates and the original .093” top snap ring.
Early V-8 regular or heavy duty applications (option 1): Reinstall the original .125” apply plate. Install eight (8) frictions and seven (7) steels along with the #3 or #7 top backing plate. Reinstall the original .128” top snap ring.
Early V-8 regular or heavy duty applications (option 2): Reinstall the original .125” apply plate. Install eight (8) frictions, seven (7) steels and the .125” top backing plate furnished. Install the custom .062” snap ring.
Late V-8 regular or heavy duty applications with original stepped apply plate: Reinstall the original stepped apply plate. Install eight (8) frictions and eight (8) steel plates. Reinstall the original #3 or #7 top backing plate and the original .093” snap ring. IMPORTANT: FIRST install a steel plate on top of the stepped apply plate.
Early V-8 performance or race applications: Reinstall the original .125” apply plate. Install nine (9) frictions, eight (8) steels and the .125” top backing plate furnished. Install the original .128” top snap ring or the furnished .062” custom snap ring.
Late V-8 performance or race applications with stepped apply plate: Install nine (9) frictions and eight (8) steels. Reinstall the original #3 or #7 top backing plate and the original .093” top snap ring or the furnished .062” custom snap ring.

 

[HotRodPC]

OK, I was backwards on my #1 guess. Sorry bout that. I am getting confused with Th350 and Th450 since all but 1 700r4, that's all I've worked on in the last year. But as I figured, part of the pack actually deletes one of the OEM parts, and in this case it happens to be the top pressure plate. Good Info Find.

 

[HotRodPC]

I'm suprised Pops didn't poke his head in on this thread with some tips. So you're obviously in process of building a 4L60-E.

 

[HotRodPC]

Just wanted to say, we're doing a good job with tags guys.

I happened to be doing a search for Alto Commerical Clutch Pak, and low and behold, about the 5th result down, I see the address, www.gmsquarebody.com and it took me directly to this thread. Awesome **** !!! I know I've spent alot of time tagging threads, and noticed someone else has tagged a few too. Thread tagging is something all of us have access to do if you're willing. Lets keep it up and keep the site growing !!!