TF 727 rebuild & Upgrades

[dvw]

Not necessarily, that's what the threaded adjuster is for, to keep the servo travel the same with different levers.

Nope, 5.0 means the lever moves 5 times the distance from the set point. The set point clearance varys very little. Roughly 5/16" clearance from the servo plunger to the lever. A full turn of the adjuster is only .042".
Doug

 

[Wietse]

Transgo website actually mentions with the TF-2 kit that for best results a 3.8 - 5.0 lever is required on the front band.
If i already have a 3.8 or so i will reuse it, if not i will get one.

Edit: What about the roller bearing and bearing sleeve in the tail housing? They are not included in the rebuild kits as far as i can see.
Think it is smart to change them regardless of their condition while i am at it or not?

 

[dvw]

No need for the roller bearing change. The tail shaft bushing is easily changed if you have the proper driver. If it's not worn and you don't have the tool leave it alone.
Doug

 

[Wietse]

Still have not heard anything from A&A, send them an email on the 16th.
Are they still in business or maybe due to the pandemic are running on low/no employee #'s?

 

[dvw]

Still have not heard anything from A&A, send them an email on the 16th.
Are they still in business or maybe due to the pandemic are running on low/no employee #'s?

A&A normally answers the phone. I've ordered from them 2 times in the last month. Shipping was less than a week.
Doug

 

[Dipstick]

Nope, 5.0 means the lever moves 5 times the distance from the set point. The set point clearance varys very little. Roughly 5/16" clearance from the servo plunger to the lever. A full turn of the adjuster is only .042".
Doug

And how is the "set point" clearance set? With the threaded adjuster.

If the band is adjusted the same number of turns out from a certain torque with different ratio levers, the servo plunger travel will vary with the lever ratio.

As an example, 1 1/2 turns with a 5.0 lever will result in the same plunger travel as 2 1/2 turns on a 2.9 lever.

 

[dvw]

if you haven't had your transmission apart chances are you don't know what the lever ratio is. Many valve bodys/kits come with a generic set point 2 turns, 2 1/2 turns etc. When I mentioned the servo travel was greater it was based on a given set point. The greater travel is really not a big deal. The servo has plenty of travel range. The servo travel apply speed is very fast. So timing is affected very little. The biggest issue is making sure the band is not to tight and dragging. So when I'm wrong I admit it. And in this case I did not take into account the geometry of the pin/anchor, trans shaft centerline. So tonight I tested what 1 turn on the adjuster was worth. This was using a common 3.8 lever. Servo pin to lever clearance was set at .500". Then the adjuster was tightened. It took 2 3/4 turns to set the lever directly in contact with the servo pin. This works out to .180" per turn. So lets see how this works out. we will be using the 2 turns on the 3.8 lever recommended in the TF2 kit. That gives us .360" clearance. The 2.9 lever is roughly 75% of 3.8. .360" x 75% =.270". .270" is 1 1/2 turns (.180/4= .045" per 1/4 turn). What does this all mean? The band never stops the high gear drum and attached sun shell immediately. There is always slippage. Drum material, drum and sun shell weight, band material, band design, clutch friction material, clutch clearance, clutch piston size, clutch return spring pressure, fluid pressure, fluid type, and finally lever ratio (and adjustment distance) all play a part in this. What are we looking for? A quick 2/3 shift that doesn't kill the high clutch or band? A smooth shift with no overlap? Each will be a slightly different set-up. Learning what works over time is the key. If was cheap and easy anyone could do it. My 2 cents
Doug

 

[Dipstick]

The greater travel is really not a big deal. The servo has plenty of travel range. The servo travel apply speed is very fast. So timing is affected very little.

I have read varying opinions on that mostly based on the release cycle, the fluid volume needed to release the band affects the front clutch apply time so a loose band can cause rpm flare up on the 2-3 shift.

 

[dvw]

I have read varying opinions on that mostly based on the release cycle, the fluid volume needed to release the band affects the front clutch apply time so a loose band can cause rpm flare up on the 2-3 shift.

The fluid fill circuit of the high clutch is routed to the front side of the servo piston aiding release. In theory if the amount of fluid to fill the servo exceeded the fill capacity of the front clutch could this happen? The band would have to be pretty loose. I've never experienced it. On the other side of the coin if the band releases slower than the high clutch applies there will be overlap. Technically 2nd and 3rd applied at the same time. In a race application we actually use some overlap. The clutch slips slightly when its starting to apply. Slight overlap ensures no flare on the 2/3 shift under heavy acceleration.
Doug

 

[Dipstick]

Out of curiosity, I got out my tape measure and pocket calculator. 727 servo diameter is 2.75", front clutch piston is 5.50".

Using a clutch clearance of .060", it takes 24 CC's of fluid to apply the clutch and a servo travel of .300" requires 29 CC's of fluid to release. Springs assist the servo release and slow the clutch apply. Flow restrictions unknown, with a constant clutch clearance, it's easy to see how variations in the servo travel will affect the shift timing.

 

[66Satellite47]

Wietse, just re-read this thread. I've built many 727's over the years, mostly for drag racing. I agree with dvw on almost every thing. The Transgo kit worked well on one of my HD street builds. Use a 3.8 lever( I'd prefer for your application, or 4.2 if you can find or buy one0, red solid front band, 10 or 12 springs in the front clutch with 4 red clutch frictions, if your stock steels aren't burned/scored use them, rear band should be OK, look for any burning or flaking, the stock sprag should be OK but look at the tangs so they are not bent, wavy springs are not broken, & rollers are not worn out of round. Set the clutch clearances on the tight side of service manual recommendations, especially the front clutch, you may need to get the snap ring selection(dealer or aftermarket) to get the desired front clutch clearance.

I didn't like part throttle kickdown on most of street vehicles because it sometimes kick down unexpectedly or not when I wanted it to. My preference is kick down only when I decide I want it. Good luck.
These are just my opinions.

 

[Wietse]

Are the stock steels better quality than what you can buy after market from A&A? (Or any other good vendor)
Because if i would buy an overhaul kit from A&A it comes with new steels, so i wonder if there is any reason not to use them?
This kit: http://www.aandatrans.com/Products/...s-and-Regular-Steels-(1962-70)__MK22000A.aspx

Regarding springs, i remember reading somewhere the "from factory" amount of springs for the clutch, i believe the 440 had 10 springs and the 440 HP had 12 springs.
Mine is the HP so i should have 12 springs if the tranny is really original. (once i get it removed i need to check if the VIN is stamped in the housing)

Set the clutch clearances on the tight side of service manual recommendations, especially the front clutch, you may need to get the snap ring selection(dealer or aftermarket) to get the desired front clutch clearance.

What do you mean by snap ring selection, set of different thickness or something?
I had not looked into the details that far, but i was thinking it would be done with shims/washers.

 

[66Satellite47]

Yes, got mine from the dealer parts dept. Various thickness snap rings that hold the clutches & steels in the drum. The snap ring is how the clutch pack clearance is adjusted. The end play of the trans is adjusted with different thickness fiber thrust washers which are available in different thicknesses.