00pooterSS

iTrader: (40)

EDIT: It did in fact break the plate off the band, but not the anchor plate, the apply plate came off. Picture is attached.



I have a fresh built 4L60E with 900 miles on it. Has all the goodies, transgo shift kit, Sonnax 2nd and 4th gear servos, BW clutches, Sonnax smart shell, 4L70E input shaft/pump/drum, billet overrun piston, dual cage 29 element sprag, deep pan, all new solenoids and wiring etc etc... Basically it has every single thing you do to the highest level of trans builds except 5 pinions and billet shafts.

Transmission has been flawless for those 900 miles then all the sudden last night completely lost 2nd and 4th.

It set a fault code P0751 1-2 shift solenoid performance, which it will set if selected gear is not engaged, so it could be the band or the solenoid from what I gathered. I had read where another member had that code, no 2nd or 4th, and the solenoid fixed it. I tried the solenoid hoping to get lucky but it did not work.




I want to know how do I keep it from happening again, what would cause that?

This is with 400ish fly wheel HP. All bolt ons but stock long block. SS3800 stall.



Thanks in advance for any help.

Jarod

00pooterSS

iTrader: (40)

Bump for Monday.

Greaseymec

iTrader: (9)

I had a customer break one. Band ripped in half where the band anchor pad is welded to the band. Use a different band other than Transgo.

Mec

00pooterSS

iTrader: (40)

Cool, thanks for the feedback.

What did you go back with that held up? And mine was an Alto, so it was already not a Transgo.

Revmax

We see quite a few broken 2nd gear bands on our Diesel transmissions we do here.. As stated above they rip the spot welds off..

00pooterSS

iTrader: (40)

Thanks.

What's the fix? It has an Alto reinforced band. I assumed the Alto is as good as it gets.

CRAZYCUTER4.8

iTrader: (2)

I have used maybe 50 of them with larger servos and oversized boost valves, never seen a broken one.

00pooterSS

iTrader: (40)

Thanks man.

By the symptoms that's the only thing I can see it being. I suppose it could be some other failure but this makes the most sense. I will update once the trans is apart.

I wanted to see if anyone had this issue and how they fixed it so that I could get the parts ahead of time and have the trans repaired while I wait. The builder is an hour and a half from my house so I would like to have it fixed in one trip and not have to go back and pick it up at another time.

mrvedit

You said "I tried the solenoid...". I assume that means you dropped the pan and replaced the solenoid. If the have the pan off, you can apply air pressure (blow gun with rubber tip) to the hole underneath the 2/4 servo to test activating the band. You can also see/reach the band through an access hole. Therefore you should be able to confirm that the band is tight when you apply air pressure. Alternatively, put the trans in neutral and confirm that when the air pressure is applied that you can no longer turn the drive shaft.
If the band seems OK, you might have a malfunctioning 2/4 servo or other problem that does not require removing the trans.
Hey, I'm no expert, just my thoughts. And good luck.

00pooterSS

iTrader: (40)

I did drop the pan and replace the solenoid. But I don't have an air compressor. I looked around a little when I had the pan down and didn't see the band. Although I don't really know if I was looking in the right place either.

At this point I don't even want to mess with it anymore I would just rather pull the entire assembly and let the builder deal with it. I just want to learn and solve a potential repeat issue.

Those are great idea's and if the pan was still off and empty I would look into it, but to test the solenoid I had to refill it and try it out.

00pooterSS

iTrader: (40)

Bumping the thread to show that it was the apply plate that broke and not the anchor plate.

Curious if anyone else has had this happen and found a cause?

Or do you guys just think it was a parts failure?

The band that broke was an Alto Carbon band, there is now a Alto red band in the trans.

Vince B

iTrader: (1)

Funny I saw the title of the thread and then the picture and was thinking that's not a Kevlar band. I have seen these bands break but its kind of rear. I would look at the band clearance, 1-2 feed hole size, 1-2 accumulator sleeve for correct installation, line pressure, and a loose screw behind the wheel! OK the last comment might be a little harsh but its what I got for you. Another thing to think about is if you are having a 2-3 bind and the 3-4 clutch is applying before the band releases. This tie up might cause some premature stress on the band. Maybe you just got a bad band. I guess time will tell! HTH Vince

00pooterSS

iTrader: (40)

Thanks Vince. The builder did a complete tear down when this happened. He did mention he did not drill the 1-2 hole as big as it could have been drilled he used the "smaller recommended size by the Transgo kit" (my wording on that could be wrong I was dog tired when he was rattling off specs) I think it was .093??

He said he double checked the band clearance because he was a bit concerned with that since he had to grind the apply pin.

There is DEFINATELY a loose screw behind the wheel!! Haha. I told him that I am not easy on transmissions so make sure to build it to all hell, it broke the band after 900 miles lol.

He was also concerned with the line pressure. I contacted my tuner and he said there is not much additional line pressure added into the tune, he said "it's no more than any of the other cars that he has tuned that have used the same transmission builder" both of these guys have a hell of a reputation around here so I trust them.

The builder said he had only used a handful of the Kevlar bands and did not trust them after this so he went back to the trusty Alto Red Eagle band.

So hopefully it was a faulty band, as you said, we shall see....

sjsingle1

iTrader: (1)

the smaller drill size for 1-2 hole is .082..........bigger is .093

chris718

This is where the problems usually start.......too big of a feed hole.The most efficient set up I have found is to put the accumulator piston in and then the spring,like a 700r4,then drill the hole no bigger than .095"

00pooterSS

iTrader: (40)

Cool thanks for the info. I don't recall 100% if he said that he did or could have drilled it to .093. I do however remember him saying he always stays on the smaller side of the recommended sizes.

He has many many other 4L60E's running around in the area that have not had an issue but he did say mine was one of the only ones that he used the Kevlar band in. He said he also normally uses the Fairbanks second gear servo that applys the band harder than the Sonnax he used in mine.. So who knows.. Now it will be a test of time..

Gilbert@Ace Racing

I have seen that band fail similarly. Especially when used with the Fairbands servo. Yes it does stroke harder than the Sonnax piece. Because of that I got away from using them years ago and do not have band/drum failures.

Good luck with it!

g

mrvedit

What is your recommended servo and band?
00pooterSS said he had the Sonnax serve (not the Fairbands you mentioned.)
I have read that the Kevlar bands have less friction and therefore require more servo force. Is that true? Is that bad?
Thank you. (We all appreciate your very experienced input.)

00pooterSS

iTrader: (40)

Gilbert thanks for that response. Odd thing is, the builder has always used the Fairbanks and didn't have band failure's and mine did fail with a Sonnax that is not supposed to apply as hard, so that is completely backwards!!... So you think line pressure is the culprit?

And yes I am curious of this too ^^^^

Gilbert@Ace Racing

Quite frankly, a stock corvette servo and an Alto red band will handle anything the rest of the tranny will. There no reason to for the heavy duty servos unless you do not know how to properly manipulate the accumulators and the rest of the hydraulics.

To me they are expensive bling in this application. I would rather spend my clients money on something that will make it live, not beat itself to death.

g