hey guys so I'm building a 4l60e and I was going for a 3-4 10 clutch stack up which consist of 10 .063 bw hi energy frictions, 9 .060 Kolene steels. but I can't seem to find the right bottom/top backing plates. also, for the bottom plate does it need the tangs that go on the 3-4 apply ring? or is that not a problem? and if there's a better 3-4 set up you guys recommend, I've been looking for any updated 3-4 stack ups but can't seem to find any all-old forums. thanks guys.

 

Well you are not going to find plate combos that will accomodate 10 frictions?
Now can it and has it been done ? Yes in my own car as an experiment and its working 32k miles thus far, Is it nessesary? Not really 8 frictions with thicker steels is IMO Preferable for a daily performance driver .

But here is how I did it ? I bought 2 of these kits https://www.sonnax.com/parts/4544-he...king-plate-kit and used the thin re-enforced apply plate at both ends. I had to modify the plate for use on the top by grinding the legs off. Then I used the thin frictions and steels like yours except I used regular steels and raybestos GPZ frictions. I then modified the friction which I do on some of my extreme builds by drilling small fluid trapping cooling holes in them
As you can see this is not my actual set up I didn't take photos at the time, But this shows the plate modification. Its a time consuming and requires a drill press with small hole in plate so as not to distort the plates when drilling and an extremely good drill bit and patience as its a three part process drill all holes then chamfer from each side The a polish level rolock disc fine to debur.
Like I said I did this as an experiment doing 10 in my own car just to see how it went and thus far great .
But Honestly 8 friction with .076 steels or even ..090 with the same sonnax plate set up I mentioned is plenty at 800 rwhp I have built even higher.
Whats more important that number or type of steels /frictions is fixing the leaks .
FWD BORE PLUG
4-3 END CAP
AFL VALVE
SHAFT TO DRUM
PUMP STATOR TO BODY
BAND PIN TO BORE (Often overlooked but the bore in the case of these is generally pretty worn by now so either use sonnax pin with teflon rings or i groove my own ad use nyril rings or better yet bore the hole and use oversized pin with teflon or nytrol rings. But this is a huge leak in the 3-4 circuit via 3-4 accumulator/band release oil)
ENCAPSULATED CHECK BALL IN CASE
RELEASE BALL IN DRUM
MOULDED 3-4 PISTON IN DRUM -(Suggest the blue ones for extreme high rpm as they are stiffer, Reason above 8000 rpm the inner lip of the fwd, overun and 3-4 can be pulled or better described pulled in (Supposedly) I say this because the test I saw the guy do was outside the drum with no pressure applied to piston when it folded in. I question if it would actually happen real world with 200 plus PSI pushing on it )
ORINGED BOOST VALVE
OVER BORED OR TRANSGO PR VALVE UPDATE
PINLESS FWD ACCUM (I mention FWD oil twice here as any leak in the FWD oil is a leak to everything)

Other option for a super strong 3-4 as far as clutch set up 4L75E DRUM which uses TH350 size frictions and steel (not actually 350 but that size and thickness special made frictons steels and modified drum.

Sonnax smart drum uses stock frictions with bolt on backing plate and when the thin apply plate in that kit is added will accommodate 8-9-10 frictions depending on thicknesses used . I do have a preference to this drum as I KNOW they use a NEW GM drum to make these.

Also another company I cant remember name off hand but have one coming to look at make a drum with 10 percent larger 3-4 piston new. (Note made in china) 10 percent may not sound huge but with the area multiplication is huge.

Ok probably far more info than you were looking for. I tend to do that lol.

 

I ended up finding a .056 bottom plate with a .078 pressure plate on top with a .128 top plate .062 snap ring and got clearance to .025 or so. I like that idea for the steels that's sweet! I vacuum test the pump and valve body make sure all the valves/bores are not worn out/leaking. I always run an Oring boost valve they almost never pass vacuum test without that. another question so now that I have my stack up 10 frictions 9 steels now the release springs are too short. if I leave them out will that be a problem due to drag? my clearance is .025 on the tight side... is there longer springs I can use, that I can't seem to find? sorry for the bother.

 

I ended up finding a .056 bottom plate with a .078 pressure plate on top with a .128 top plate .062 snap ring and got clearance to .025 or so. I like that idea for the steels that's sweet! I vacuum test the pump and valve body make sure all the valves/bores are not worn out/leaking. I always run an Oring boost valve they almost never pass vacuum test without that. another question so now that I have my stack up 10 frictions 9 steels now the release springs are too short. if I leave them out will that be a problem due to drag? my clearance is .025 on the tight side... is there longer springs I can use, that I can't seem to find? sorry for the bother.

 

Do not leave out. I can never remember the number but you can get suitable longer springs at ace hardware. If I go there today ill take photo of part number.

 

i went to ace are they these? still seem a bit low maybe i got the wrong ones?

 

IMHO, while an interesting experiment, it is unlikely to result in a strong 3/4 clutch due to the very thin apply and backing plates.
Since the 3/4 piston pushes on just 4 thin tabs, the apply plate must be very thick or you will have 4 waves in the friction/steel plates which will cause hot spots and fast wear.
Next, a thin backing plate will allow the frictions/steels to "cone", again causing extra wear.
Personally I have always used the thickest GM apply and backing plates; I now use the Sonnax "Smart Tech" input drum which allows 8 or 9 frictions.
It interesting to read up on the Sonnax " Heavy Duty 3-4 Clutch Backing Plate Kit Part No. 74140-01K" which even claims that the thin apply and packing plates are the "leading cause" of 3/4 failure. (Not sure about thought.)
Frank describes using this Plate Kit and then very thin frictions and steels; however I think it was more as an experiment and not as a final "solution".

But, hey I understand you fully and have experimented with such things myself. Therefore, my wife had a custom sweatshirt made for me which reads "If Some is Good, More is Stupider".

 

Yes I explained a 10 friction is probably not the best possible idea , Now that thin apply in that kits actually has a re-enforcement ring around the bottom and is hardened steels so a pretty tough little plate.
I did it in my own car purely as an experiment as its my car. Of course I am actually a pretty lame hotrodder as I mostly drive legally and rarely go to track but its 32k miles thus far still solid.

In more real world if i was to use the SONNAX thinner plate top and bottom I would likely use it to install thicker 3-4 steels like 0.90 with 8 frictions. In any case the top and bottom should be hardened steel. You also can IMO get away with a bit thinner top and bottom if you do use the .090 steels as besides better heat sinking they by very nature will add to the structural integrity of the hold pack as far as coning and hot spots.

OP THAT IS THE SPRING AND AS LONG AS IT IS ABOVE THE TOP FRICTION INSTALLED IT WILL DO THE JOB,

THE TOP AND BOTTOM PLATE SHOULD BE PERFECTLY FLAT AND HARDENDED.

WITH FRICTIONS AND STEELS THAT THIN THE SHIFTS EVEN LIGHER THROTTLE WILL NEED TO BE ON THE RATHER AGRESSIVE SIDE TO REDUCE HEAT, BECAUSE WHILE YES YOU ARE INCREASING HOLDING AREA YOU ARE REDUCING HEAT SINKING ABILITY OF THE PACK CONSIDERABLY.

The way I get more in is i MACHINE the apply just enough to make it flat (most new ones are not even flat) then i use a primative but proven to me way to harden it . proven by trying to cut again in the lathe) this helps avoid flex. The at top plate i do same but then cut around the top similar to the way ford does the fwd top plate just over far enough to allow installation of the snap ring with some effort and deep enough to achieve my goal which for most builds is 7 to 8 frictions with as many .090 steels and maybe 1 .076 steel in middle of pack with the 8 friction.

But do want to make note , I am telling you how I have achieved the 10 friction and how, I am in no way suggesting or promoting you doing such . Several good reasons exist that it is really probably not the best idea overall.

Or the old saying "Just cause you can -Does not mean you should "