Checking intermediate servor pin clearance while in the car?

[PaulRV6]

How can I check the pin to band clearance to see if it is within spec with the trans in the car? With the trans out of the car I could push the servo in until the output shaft would not turn and note the movement. I would like to recheck it if its possible to see if there is any significant where on the band.
What are your thoughts?

Where can I buy a new 1-2 accumulator plate and bolts for the accumulator housing?

paul

 

[A2000RICH]

How can I check the pin to band clearance to see if it is within spec with the trans in the car? With the trans out of the car I could push the servo in until the output shaft would not turn and note the movement. I would like to recheck it if its possible to see if there is any significant where on the band.
What are your thoughts?

Where can I buy a new 1-2 accumulator plate and bolts for the accumulator housing?

paul

 

[A2000RICH]

if you are using a stock servo there is a really nice GM tool that lets you get a very precise measurement without removing anything but the servo cover-----------even if you are not using the stock servo you can use the same tool to make the adjustment with the pan removed by using the tool to depress the pin while you use a long screwdriver blade to "lift" the band off the drum to gauge how tight it is------------the tool is costly from Kent Moore but can usually be bought cheaply off Ebay for 10 to 30 dollars--------can't remember the number but it is pictured in the GM and ATSG manuals

 

[chris718]

There is alot more involved with checking band clearance and recording travel.The large cushion spring will collapse a certain amount before the servo piston starts to apply force onto the pin to move the band towards the center of the trans to lock the band.This travel will add to your recorded number.When pushing in on the cover the piston will push the spring into the bell of the pin and will stop when the band has clamped on the drum,then additional pressure on the cover will collapse the spring further untill it has allowed the 3rd acc piston tocontact the pin.The trick is to feel when this happens and adjust the numbers.Not doing this results in extra travel.The drum is a diameter and when measuring clearance if the stroke of the pin is .060" the clearance between the band and the radius of the drum is .030"This is what I shoot for.Typically the lining will compress after the band breaks in and this will increase the pin travel by a few thousandths.However the band becomes a sponge and retains oil so the compression is offset by the retention of oil.Using a .030"piece of shim slipped between the band and drum is how I set them now.I add the necessary shim or shims to get where I want to be.Does the clearance affect 2/3 or 3/2 quality?I believe it does somewhat and have settled on what I know works.Too tight and the band will polish the drum and the shifts will get long.Too loose and there can be a flair with certain size holes or combinations of 2nd knock oil paths.I do not use the factory accumulator housing at all.I have a block off plate that was advertised here a a while back.With our servo there is no bang w/out the accumulator .There may be with others but I havent tried it.The accumulator delete actually improves 3/2 backshift quality which is quite different mechanically from 1/2 shift because the circuit is void of any air and has already been charged.Also the drum is turning in the opposite direction than it is on a 1/2 shift.Because the servo is on the passenger side it now makes it more laborous for it to stop the drum on the 3/2.This is true regardless of the mechanical leverage the drum sees in anti rotation in 1st gear before the 1/2 shift.

 

[SSedan64]

Kent Moore Tool # is J-25014
A few listed.
http://motors.desc.shop.ebay.com/i....kBtn=&LH_TitleDesc=1&_trksid=p4506.m270.l1313

 

[PaulRV6]

Chris or anyone else, so are you saying that I should shoot for .060" stroke on the pin and that will really mean .030" band clearance? Can this be checked with the Kentmoore tool as shown above?
If it isn't that where do you add shims to get the proper clearance?
How tight/loose should the inner servor piston be to the outer servo, mine seems to be alittle on the loose side?
Thanks

paul

 

[lost2a6]

I've always removed all of the seals and then reassemble with the snap ring in place. Push on the cover with your hand only and note the clearance between the cover and the snap ring. Set the pin up for around .050-.060 and then reassemble with all seals in place and you should be good to go.

 

[PaulRV6]

Steve, and if you don't have .050-.060 on the pin, what do you do? How do you change or readjust this clearance? new pin, shims, etc?

Would the Kentmoore tool make this any easier? Thanks

paul

 

[Steve V]

You grind the pin down in small bits or add and extender tip an grind that down.

 

[PaulRV6]

Steve, I understand that now. How hard do I have to push on it, I guess once it hits the drum it wont move any more? So you go from the cover seated position to full travel against the band? I did notice that once I pushed in all the way on the cover I could not turn the drive shaft in one direction (the opposite direction though it still turned). Why I was asking is the ASTG book says to apply 100 in-lbs to the "tool" but I don't know how that relates to the force in on the pin.
Just trying to verify this is ok so I can rule out any possibilities of this being a problem and before going back on with the valve body.

Thanks, paul

 

[PaulRV6]

Steve or anyone else, I checked the clearance using your method and I got between .045-.055. At the point when I pushed in on it with my fingers I could not move the driveshaft in one direction, so I figured it must be clamped down on it. Does this sound good to go or should I do something different?

One thing to notice is the cover has a little bit of slop in it without the seals so that is why the reading has a .010 variance. Y ou can cock the cover slightly if you push in on it alittle off center or in a different position.

Also, how tight/loose should the inner servor piston be to the outer servo, mine seems to be alittle on the loose side with the black ring installed?

 

[Steve V]

Sounds good to me.

If using the CK plate don't be concerned bout the piston as he deletes the 3rd accum.

 

[PaulRV6]

Steve, I wasn't asking about the 3rd accumulator but the inner servo piston clearance to the outer servo ID?

Since you brought up the 3rd accumulator and I am using CK spacer plate, if it deletes the 3rd accum then why the new springs at all in his kit if it is not used? Maybe I am confused. Thanks for all the help.

paul

 

[Steve V]

3rd accumulator is in the servo,I never seen new springs for 3rd accum in his kit,but last time I used one was 2009.

 

[chris718]

The third accumulator is not deleted If "3rd accumulator"oil isnt sent to the servo piston to knock off the band the transmission would lock on a 2/3 ratio change.The routing has been changed.Third accumulator in function is the energy absorbed during he band being pushed off and the direct clutch coming on.The stiffer the return spring are on the servo the firmer the 1.2 will be as it will delay servo apply until maximum pressure has been reached in the circuit .This occurs when air has been purged and circuit is full.If you dont purge the servo will stroke at a lower pressure.Accumulator pressure modulated at the accumulator has nothing the do with the 2/3 at full throttle as maximum trim has been reached.

 

[Steve V]

I stand corrected on the 3rd accum :0)

Now Chris how bout answering his question about the piston fitment in the servo?

 

[chris718]

A loose fitting piston is fine,you can leave off the seal and it will make no difference.