4L60bliss

I know all about clutch pack clearance, but its good to get some non-OEM biased points of views once in a while

I'm trying to find out what the reccomended clearances are for the Foward Clutches and the 3-4 clutches.

Stock Specs are:
OEM Foward: .030"-.063"
OEM 3-4: .060"-.094

At work, I'm obligated to run the clearances specified in the service manual (see above), however, "other" transmissions, I can do what I want, and I usually run about .035" on the 3-4's and about .045" on the Fowards.

Most of these transmissions have the TransGo HiRev springs, and usually have a 9-clutch 3-4 setup. I have seen recommended 3-4 clearance (right out of the Hi-Rev springs instructions) state .015"-.035". That seems kinda tight (.015")

With that in mind, what are some non-OEM ranges for these two clutch packs to shoot for?

4L60bliss

^bump


Nobody wants to throw there 2¢ in?

transfixleo

A lot of people run a tighter 3-4 setup than stock but the TransGo Hi Rev kit is a whole 'nother animal. Follow there specs ONLY if you have that kit.

On a stock unit, Forward clearances will not affect performance other than perhaps a slightly quicker apply, since they stay ON in all gears. Tigher 3-4 can help somewhat with 2-3 flair concerns.

Jay 727

I'm not a transmission tech but I build them for myself and friends. My personal preference on non shifting clutches is to keep the reverse stock, forward doesn't bother me if it's a little on the tight side. Again I'm not a builder and I don't have access to a million different thickness steel plates and pressure plates so this makes things difficult.
I never seem to have problems with th350's and 400's but 700R4's are a little more sensitive.
I have a stock 700 in my v-8 s-10, it has a few holes drilled in the spacer plate and the fourth accumulator blocked, a .472 boost valve, nothing special. It was rebuilt with raybestos clutches set to stock specs. It was fine with a near stock 350 but when I went with a different cam and heads it developed a bad 2-3 flare. I changed nothing but the 3-4 clearance, went from .06? to .025.
Of course being a light truck helps the trans out some I have hauled some heavy loads in it and it still shifts firm loaded down with weight.

transfixleo

Ray's? Hmmm. Also how high does it rev? Over 5500?

Jay 727

I try not to rev past 5500 but with limited traction showing off on the street it has seen six. When I run it at the track I shift around 5800.
How would I know if the 3-4 was centrifugally applying?

4L60bliss

If you tear it down, and see "hot spots" or "leopard spots" on the steels, then you probably have a centrifical apply situation. If you have them, you'll know what I mean when you see them. Stock 3/4 "booster" springs are "supposedly" good up to 5500 RPM. TransGo Hi-Rev springs are good up to 7800 RPM.

Jay 727

Well that sucks, it would probably slow my 1/4 mile times down wouldn't it.
I have a set of trans go 3-4 springs out of a 2&3 kit (from another build up), they send three different types and I have two sets left over, maybe I shoud have put them in during the build up... too late now.

mdricken

I'm so confused on this issue. Haynes and ATSG quote OEM specs like .06-0.09 for the 3-4s and 0.04-0.06 for the Forwards. But then Paul Zank in his Technical Video says "your 3-4 plates must be at least 20 thousands LESS than the Forward clutch clearances" - totally backwards!!!

Right now I've got just about equal clearances, maybe a little more on the 3-4, at 0.035".

The more and more I read it starts to seem like one big crap-shoot anyway. Is there going to be any harm done in just going with the 0.035? I don't have the hi-rev springs and was planning on throwing out the stock ones and drilling that #44 hole in the seperator plate. Also, I have a 9-clutch setup on the 3-4. Thanks!