GregWS6&z28

iTrader: (8)

Ive had this happen to my built 4L60E before, but I had a Sonnax 4th gear servo go bad on me. My builder sent me a Superior Servo and it fixed it. 2 years later it happened again and I lost 4th gear. NOthing appears to be wrong with the servo or the seal. I bought a TCI 4th servo to try to fix my car to drive to the track and it did nothing.
other important info:
1. all gears (2nd) shifts fine)-- not a pin to band issue?
2. trans thinks its in 4th, commanding with HPT doesnt change anything.
3. at low rpm and low mph it feels like it goes into 4th, but will not at HIghway speeds.
4. at low speed I can get visual of going into 4th if I downshift to 3rd, RPM's will rise. At highway speeds going down to 3rd does nothing to change rpms.

-shouldnt be the pressure switch. that was new with the servo change the first time.

any builders chime in with any info? DO I need any extra washers or something to make up any clearance issues? Thanks guys

performabuilt

iTrader: (25)

I would imagine its possible the band clearance has opened up a bit and the 4TH servo could be colliding with the divider between it and the second servo. I am assuming a fairbanks second servo. If this is the case you will be able to tell when looking at the divider there will be markings where contact was made near the pin area.
Hope this helps

GregWS6&z28

iTrader: (8)

what is this divider per-se? DO I need to remove the second gear side to check it out? Anything can I do to remedy band clearance? Should I have gone back with a different servo?

Its weird that this happened. Ive rarely driven my car in the past year, maybe a few times 3 or 4 miles, working fine, then one day it wouldnt go to 4th.

Thanks Performabuilt

performabuilt

iTrader: (25)

Well the only other possibility would be the 3-4 shift valve suddenly stuck but with the history this iss likley your issue.
I would need to see what kinda washer set up you have in there having multiple servo changes.
You will need to remove at least the 4th gear part of the servo.
The "divder" its the silid billet peice between the fourth servo and second servo
Ussually you can indeed use a washer or two to fix this but they must be the same diameter as the black washer that is under the eclip on the band pin.

GregWS6&z28

iTrader: (8)

when I changed from the sonnax to the Superior I reused the gold washer I believe. It's been so long ago. (there is no spring and I did not use the spring with the TCI 4th either). DO the washers get stacked on the one on the E-clip on the pin? Or the washer to the 2nd gear side? can you point me?

performabuilt

iTrader: (25)

Ah the gold washer is the issue
its to large outside OD and will hit and cause a slipping or no 4th condition
Replace the gold washer with a washer identical to the black washer under the eclip on the pin.

GregWS6&z28

iTrader: (8)

i "think" i did the gold washer. If I had ,why would it have worked flawlessly for 2 years? Again I'm sorry, the E-clip on the pin is the one right under the 4th servo you're talking about? IF I do have the wrong washer in there do you know the outside diameter and thickness so I can go get another one?

performabuilt

iTrader: (25)

I will measure it today. Ussually I just use a spare one likes under the eclip.
I am not sure why you would have had it with a different servo for so long. However its the easiest thing to try first, After that its a trip into the valve body.
The gold washer is not actually wrong just it does present this issue with the fairbanks servo. I am aware of the issue because like your builder I see listed we use the fairbanks servo .
I will get that information for you today.

GregWS6&z28

iTrader: (8)

thanks so much!!!!

GregWS6&z28

iTrader: (8)

took the servo out a little while ago and this is what I saw.

1. servo cover is not leaking, outer cover seal looks good.
2. servo seal that is seen in the zoom view here appears to be opposite orientation. It angles opposite of the picture. I installed it the way it came from TCI. maybe it needs to be flipped? I cannot press it with my hands into the servo cover.
3. Washer and E-clip are installed in this order (pic) {2nd gear servo side} [washer] [e-clip] end of pin (4th servo) and (servo Cover).
4. There is about 1/16" of slack between the washer and the E-clip. It's not tight.
5. Washer is small enough to fit into the 2nd gear side hole (dont know what it's called)
6. Washer is a little smaller than a quarter. About 7/8" wide, 7/16" hole for pin, and 1/16" thick.



cant tell if thats a groove in the washer or not. the other side doesnt look like that.

could it be the servo seal being backwards? wrong washer? issue with the slack between the washer and E-clip?

Thanks for reading, sorry it was long.

performabuilt

iTrader: (25)

Zoom pictures of the servo oreintation dont work for me .

GregWS6&z28

iTrader: (8)

the link isnt working?

the black seal is facing the opposite direction for me, sent that way from TCI installed.

performabuilt

iTrader: (25)

The black lip seal should be oreinted exactly the way the picture from TCI shows ither wise it would seal poorly at best. If it is reversed in fact that may well be your problem.
Frank

GregWS6&z28

iTrader: (8)

does the servo need to be pressed into the cover before it's installed? I would think by pressing the servo in as the seal is orientated, it would flip the opposite direction....

what about the slack between the e-clip and washer. look like the right washer? it's not gold. right size?

performabuilt

iTrader: (25)

No you have to carfully slip the lip down into the servo . It will not just slide in.
The lip has to face to the outside since the 4th oil comes up through the band pin and fills the cap the lip facing toward the cap is how the seal is attained.

GregWS6&z28

iTrader: (8)

well, that may be it then. I guess I need alot of vaseline to get the servo to go in. also, is 1/4" travel too much when you push the cover in from the outside?

performabuilt

iTrader: (25)

As a general quick reference as long as the cover does not transvel in more than the thickness of the round retaining ring you are good.
That style servo should not experience any issue with contacting the inner servos.
And yes vasaline and a feeler guage or a long fingernail lol as a old builder I used to know would use lol.
Just hoping you have not allready fried the band

GregWS6&z28

iTrader: (8)

band fried? 2nd is still working perfectly. The cover does move in more than the retaining ring

performabuilt

iTrader: (25)

Well the band could still be burned time will tell. A burned band will actually hold a while. Not as well mind you but a while. But good luck with the servo and post back the results

GregWS6&z28

iTrader: (8)

thanks man! hopefully I'll be able to get back under there in the next few days to try it out. will keep posted here.