mrr23

iTrader: (3)

now her car finally cooked 2nd gear today. this is the second time it's happened. first time in my car. both were stock trans at the time as well. grant 77k on her trans is pretty good. but damn it man. been having a 3/4 flare for about a week now. so, i blamed the 3/4 clutch pack. guess that's not it after all. oh well, i was going to be putting a Yank SS3200 in this month anyway.

mrr23

iTrader: (3)

no ideas huh? never had this problem with my 700R4 in my 86TA. basically, the same trans, with minor changes and electronics.

jxaxsxoxn

iTrader: (2)

I think if you developed a shift flare when it failed then it must have had quite a bit of shift overlap when it ran ok. Thats just a guess.
The shift timing is very important.

The stock band sucks mainly when you put in a real big servo, the band anchors are not strong enough and they will either rip off or the pin will punch a hole through.

mrr23

iTrader: (3)

both trans were completely stock when they lost the 2nd gear band. both had the shift firmness added via the Vinci tuner. just seems like GM made it worse when they improved from the 700R4 to the 4L60e. go figure. of course having 502 rwtq with the wife's car didn't help any.

jxaxsxoxn

iTrader: (2)

I've read that the old style 700R4 band is stronger than the new style, but with so many aftermarket brands, types, etc out there now there should be no problem finding one that will last.

jimmyblue

iTrader: (11)

Can you explain more about shift overlap timing,
and what this might imply for people screwing
down the shift adaptation time trying to make
some events happen faster, while maybe others
have no such "handle"? Like, making apply faster
and release slower (both effects of high line?)
might be a way to increase "overlap"?

mrr23

iTrader: (3)

i've burned up a kevlar in my 00 formula. looking into a different one now.

jxaxsxoxn

iTrader: (2)

Mainly refering to mechanical transmission set up. Things that effect it would be servo travel as determined by pin length or shim thickness, 3-4 clutch clearance, 3rd feed hole size and second release hole size, line pressure as determined by the boost valve/spring(s).
Tuning can play a part in it too but my opinion is to get the mechanical stuff set up properly, then tune it.

Now shift timing is what I'm talking about, shift overlap is what you don't want, that would be the 3-4 applying before the band was fully released. Or even a cut loose, that would be the band releasing before the 3-4 was applied. One thing that helps is the design of the third accumulator, it's behind the servo so when third oil moves to apply the 3-4 it also moves to push the band off.

I'm not even sure this is the problem the original poster has, just a guess. If I had my hands on one of their burnt up transmissions maybe the problem can be narrowed down.

But like I said you need to take care of the mechanical stuff first, tune it later.

mrr23

iTrader: (3)

both were completely stock trans when the it first happened in both of them. something that popped into my mind is a conversation i had with mike senia at yank. he doesn't like the 13 vane pump as, according to him, it cavates around 6k rpms. well, most of us turn our ls1 cars to around 6200 rpms. wonder if it has anything to do with it?

when i had the trans in the 00 formula rebuilt the first time, i bought all kinds of goodies. superior HD shift kit, z-pak 3-4 clutches, torque drive (hardened input drum, shaft) larger boost valve, and some other goodies. at 1500 miles, i lost 3-4. took it apart. the kevlar band was burned and the z-pak gone. replaced those parts. at 700 miles i lost the 2nd again. after opening it, the new kevlar band was toast and the z-pak had over .050" worn!!! so, out went the z-pak and in went the commercial pack. new 2nd gear kevlar band and put in the superior 2nd gear super servo.

now i've finally taken out the stock 2nd gear band in her car. only thing ever done was up the shift firmness. which was done for about a year now. in the last month i upped the shift point by 300 rpms. which makes it shift around 6200 rpms. which is where i think about what mike senia said about the 13 vane pump cavatating.

jxaxsxoxn

iTrader: (2)

You should look at the factory stock set up specs of these transmissions. The range is very wide. Factory 3-4 clutch clearance does not work even at the tightest end of the range.

Cody Brooks

iTrader: (2)

agreed with what he just said most guys really tighten up the 3-4 clutch to make them last. I think the spec. is around .070- .090 or so (I can't remember off hand) and I've heard some set it up in the .030-.040 range.

mrr23

iTrader: (3)

my original post is about the 2nd gear band.

to let you know, the z-pak was set up to raybestos tolerances of .050"-.070". they were at .055".now imagine 700 miles goes by only to find out they wore to .105"

jxaxsxoxn

iTrader: (2)

and it sat for four days working it's way off the page.
sometimes you have to look at the whole picture.

mrr23

iTrader: (3)

ok now i'm getting confused. my only concern is why 2nd gear band gave way in both of my cars. 3-4 didn't go away the first go around. now, i'm not transmission super smart and all, but from what i have understood is the band reapplies to engage 4th. i could be wrong.

my only point is we are kinda getting away from the whole 2nd gear issue by now talking about the 3-4 clutch pack. my fault as i described my issues with my 00 formula trans. i look at a lot of pictures.

jxaxsxoxn

iTrader: (2)

No one can say for sure unless they touch the trans and look at it.

What I'm getting at is....during transmission operation, when it shifts from second (band applied) to third (3-4 applying, band releasing) the timing has to be right. It sounds like maybe you had a problem with 3-4 applying before the band was let off 100%. Thats a guess.

I've been thinking about this post during the past days.

It also depends on how much power you give it while it's making the 3-4 shift (applying the band).

I'd get a wider band made for full power shifts, an oversized fourth gear servo, a modified transgo kit, and block the fourth accumulator feed hole. At least. maybe some of the sponsors could offer some advice Yeah right, advice on buying their product maybe.
ProBuilt has helped me out and others and I've never bought anything from him. We need more guys like him in the forum.
People helping people, not just people trying to make their pockets fatter.

mrr23

iTrader: (3)

from what i've read, going to a wider band necessitates getting a new drum. that's the only resaon why i haven't yet in my 00 formula.

question, what does blocking the fourth accumulator feed hole do?

jxaxsxoxn

iTrader: (2)

You only need to get a new drum if yours is worn from the old band. If you put a straight edge accross the drum where the band rides and it's shaped like an hourglass you need a new one. I've seen a lot of high mileage 700's with no wear on this surface. Wear but not hourglass shaped.

If you want to be cheap and have a transmission hardparts supplier nearby you could pick up a slightly used drum for dirt cheap. I got some parts for a 4L80E that came out of a 2004 wreck that broke the trans case, most internals are still new.

As for blocking the fourth accumulator feed hole, maybe thats just something I like to do. Transgo kits for the 4L60E don't have you do this, I use plugs out of transgo kits for 700R4's. It makes the fourth shift more firm. I've read from two big name transmission builders (responding to my post) that blocking accumulators is very bad for about every transmission EXCEPT for the fourth in 700's and 4L60E's.
I believe it too, it doesn't really make the shift that much more firm. Now block the second accumulator (I've done that)....talk about annoying, and brutal low throttle to wot.

mrr23

iTrader: (3)

i'll mention that to my trans builder. and thanks for your replies. it just seems odd that i never once burned up my band in the 700R4. but, i've done it in both of my 4L60E trans.