vorteciroc

So does Kfxguy:

Kfxguy

iTrader: (1)

stop that!

btw, I cannot use my osha flip flops when building turbo manifolds anymore. I use a plasma cutter to make the holes. I tried it once, and it didn’t work out well.

pulido22

Hello, I have a 2001 Tahoe with a 5.3L 4L60E 4.56gears on 35" tires.

Having an issues with the over drive slipping and then grabbing. 1st , 2nd , and 3rd grab good. I think its a pressure issue, if I keep my foot in it and accelerate it never lets go, but as soon as reach cruising speed it starts to act up . Trans has been re-built twice. 1st time I had done at our local shop and it only lasted 1yr. I did it myself the second time with a kit from transmission bench, this time it lasted 3yr. I looking for trouble shooting help, really don't want to drop it a 3rd time.

FranksCustomTrans

Are you sure its overdrive 4th that's dropping or is it possibly lockup dropping in and out

pulido22

How would you troubleshoot the lockup, or what part would you suggest replacing. I had installed the kit this kit when I rebuilt it .

FranksCustomTrans

Well I would not go replacing parts just yet. First get a data logger on it and see if lockup is being commanded off and on when this happens . This you need to now before proceeding else you are flailing in the dark.

pulido22

Thank you for the info.

FranksCustomTrans

MODS needed to run the superior second servo with the sonnax 4th servo


With final assembly both the second and 4th servo should be in contact with band. pin with little or no gap between the center part and 4th servo . This would also be true of any servo set up. No the transgo spacer is not a fix imo, and longer pins do not assure this either I have found. It must IMO be worked out for each servo assembly individually.



I use the superior servo on the stage 3 and max series 4l60e and 700r4 max holding area and least 3rd accumulation possible. Hole sizes are .083 apply and .093 release accum side. stock accumulation set up for second.

vorteciroc

My Father says Nice Machine Work!

-Marcello III

FranksCustomTrans

Was just a quick cut , So didn't clean up as only purpose was to remove the area that would interfere with the Sonnax 4th and then to clear its washer.

Otherwise while it can still be done requires extreme tight band set up due to very very limited travel allowed with the sonnax servo. I do not suggest using any pancake style servo with the Sonnax 4th unless this machining is done else premature band failure or loss of 4th is very likely in semi short order.

vorteciroc

Dad asked to clarify with you if this is only done with the Superior Fairbanks Servo?

Thank you.

FranksCustomTrans

Only the superior servo , But some knockoff are out there as they are a super simple design and fool proof so would imagine with those you would need to do the same. Any servo that would limit the travel of the 4th servo before it reaches full travel due to colliding with the second servo assembly,
I see many do not account for even with a min clearance situation the band aftera few applies at max line will stretch and little as it forms better to the drum and will compress friction material. So whatever clearance you set for the band will be more once that is done.
If you ever noticed when you tear down OEM units even working well ones the band will be very sloppy , Yet it still worked , That is because GM figured this all in for longevity and made sure that servo had plenty of travel room.
The sonnax 2nd servo has the same physical dimensions as the factory servo so not needed here , But the 4th servo has the advantage or disadvantage of the rear center servo being able to travel beyond the stop of the forward outer servo. Advantage - If the outer does get to stop the inner will still apply the band though with much less apply area the down side.
As a general rule I set up all my bands to min clearance dry and still be able to turn the rev drum with no notable drag. Then use a 400 int band release spring to quicken release.

I have noted over the years many never mention checking the band clearance with the spring in or the load springs installed in the 3-4 but they do in fact make a considerable change to the clearance when installed.
The 3-4 load springs particularly as they compress the seal on the 3-4 apply piston and the servo cover gets pressed tight against the clip. I have noted a number if times I was setting up clearance and forgot to install these , THOUGHT WAS TOO TIGHT, Then noted I had not , Added them to find i had a perfect clearance.
To me and some disagree but a close clearance is a must on my builds as figuring for pressure and distance , The greater the distance the faster the servo and or 3-4 clutch slams the band or the snap ring at end of drum , Increasing risk of damaging the band lug or popping the top off the 3-4 drum.
So ideally I like close as possible with no drag with 3-4 drum horizontal and band same Turning the output shaft in a non park position each way with the banned and 3-4 set install should be close to the same as the drum and servo assembly missing with only a slight increase in effort turning one way than the other. Of course with trans in natural horizontal position.

sjsingle1

iTrader: (1)

did i miss why you prefer the fairbanks over the sonnax 2nd Frank?

FranksCustomTrans

Actually its the only one above the vet I consider enough of a change to justify cost.
That's why all but the stage 3 and max have vet servos.
It has the absolute max area for hold and the release side limits accumulation for the 3-4 set , Both desirable with MAX EFFORT builds.

sjsingle1

iTrader: (1)

i know the 2nd is all about servo area.....what are the servo area of the fairbanks vs sonnax...and the vette ? what is the side effect of to much servo area?

FranksCustomTrans

The sonnax is about 11 percent larger 2nd apply area over the corvette. The superior uses 100 percent of available area , So the absolute max hold possible.
The only side effect is depending on the hole sizes the superior can be a bit clunky I use smaller sizes to accommodate this .083 and a slightly larger .093 for the 3rd accum release side as the only return on these is actually the release spring. Always use the one that comes with the servo or better yet one from a th400/4l80e . it is just a rough guess from looking but I would say about another 10 percent over the sonnax. But also reduces the accumulation for 3rd to really whatever the release spring provides . Superior says it is 35 percent greater holding over the corvette.
It does not have a cushion spring, Some say good others bad, I do like that the band clearance setting with it is more exact.
The downside is I WOULD NEVER SUGGEST IT with a stock band, the extra push would probably tear through the band pin area or break the apply side off band. But as with all getting to carried away with shift firmness is always a problem for many building these. Bigger holes not always the best idea. It is a balancing act regardless of the servo type.

FranksCustomTrans

One thing I have learned since machine pumps. Replacing one side not good idea. Machining one side not good idea. Mixing matching pump sides not good idea.
The sides warp with each other and if you need to replace or machine a side it must me both sides. Else while it may work you will have a very leaky pump.

Nate21

Every time it shift from first to second it act likes it’s in neutral when I hit the gas and will just roll I need help!

FranksCustomTrans

I would suggest posting in the general trans forum for that, But will need a better description than that also .

FranksCustomTrans

Some notes about pumps
1-Pump halves should not be mismatched and kept together unless both sides of the pump have been freshly machined (reason these pieces warp together over time)

2- Again you should not replace one half of the pump to a used unit unless you have some method to assure the used sides plain is flat.

3- You can machine a pump pocket in a lathe, You will end up cutting a bit into the slide stops at bottom but since the are just stops and not seals no issues, Though make horrible sound doing it.

4- If you machine pump face you must cut the pocket the same amount or find an appropriately sized slide and rotor (easier said than done on the rotor slide assembly)

5-Before assembly be sure the slide and rotor are at least a few 1000s lower before the face with straight edge without oring installed in slide.
6-Rotor and slide should measure same height

7- Do not block the slide on a properly machined pump, This will cause uncontrollable high line pressure as the slide is part of the PR circuit. People do this regularly and normally it causes no issue because pumps are so leaky with age the slide plays little part in the regulation.

8-Regulator bores for the boost valve pretty much always leak due to erosion and should use o rings leaks can be very bad. This can cause lower than expected line at low throttle cruising speeds resulting in premature failure of 3-4 friction for example. (its not always just leaks)

9- NEVER enlarge the orifice for the TCC in pump will result in uncontrollable lockup at high line. If you have a leak issue there either use a sonnax with teflon seal or as I do a oringed version, But with either make sure the ring does not travel past the bore on apply and damage the tef ring or rubber ring or worse stick the valve, I have noted this is possible with some pumps. Solution is a spacer under spring at rear of bore to limit travel.

10- Pump alignment to case is critical to avoid leaks, particularly with the press in seals but should always be right, If correct with no rev input rings or pump seal you should be able to easily install and remove pump by hand .

11- Idle line should be no less than 60psi but I prefer 80 psi ideally .