Helpful automatic transmission information for GM
On The Tree
Joined: Apr 2021
Posts: 187
Likes: 23
From: Israel
My orifice sizes are as follows:
Band release - .104"
Rev input - .104"
3-4 clutch and 3-4 clutch signal - .110"
1-2 shift - .096"
2-3 shift - .140"
3-4 shift - .110"
Low/reverse - .093
Forward clutch - .086"
I do like the extra sealing rings with the Sonnax pistons as well as the rings on the servo pin.
Band release - .104"
Rev input - .104"
3-4 clutch and 3-4 clutch signal - .110"
1-2 shift - .096"
2-3 shift - .140"
3-4 shift - .110"
Low/reverse - .093
Forward clutch - .086"
I do like the extra sealing rings with the Sonnax pistons as well as the rings on the servo pin.
No idea then whats wrong.
Maybe Tune?
TECH Enthusiast
Joined: Jan 2019
Posts: 677
Likes: 490
From: Roxana, IL
My orifice sizes are as follows:
Band release - .104"
Rev input - .104"
3-4 clutch and 3-4 clutch signal - .110"
1-2 shift - .096"
2-3 shift - .140"
3-4 shift - .110"
Low/reverse - .093
Forward clutch - .086"
I do like the extra sealing rings with the Sonnax pistons as well as the rings on the servo pin.
Band release - .104"
Rev input - .104"
3-4 clutch and 3-4 clutch signal - .110"
1-2 shift - .096"
2-3 shift - .140"
3-4 shift - .110"
Low/reverse - .093
Forward clutch - .086"
I do like the extra sealing rings with the Sonnax pistons as well as the rings on the servo pin.
If you would be kind enough to name the 2 holes I can go from there
TECH Enthusiast
Joined: Jan 2019
Posts: 677
Likes: 490
From: Roxana, IL
Does B2Fast enjoy a firm to very firm shift and you prefer a slightly shorter shift than OE? I once had an old 76 Le sabre 350 (Buick engine) TH350 and 273 gears. I installed the sk350 box kit from transgo and it would bark the tires on a mid to full throttle shift. Just firm below that and I did not drill any holes out at all. Same kit in a 74 Nova 6-cyl 273 gears and it shifted ok-firm at all throttle settings. I even checked vacuum at the modulator and installed a small modulator. no changes..
TECH Junkie
Joined: Jun 2008
Posts: 3,203
Likes: 1,391
From: Nitro Alley
He is using a Recipe that I gave to Dana/ PBA many, many Moons ago.
Creates a very FAST 2-3 Up-Shift that can be firm with Throttle (CHUuuuuuuuuurRP!)
On The Tree
Joined: Apr 2021
Posts: 187
Likes: 23
From: Israel
Yes.
The world of the whole drivetrain planning is somewhat new and confusing for me. I dont even know where to start hahah.
My Specs :
Im 4700 LB weight
Rear end 3.73
Stock Stall
Wheel size 33" BFG AT 285/70/17
1-2 - .074
2-3 - .135
3-2 - .135
3-4 - .110
BR - .101
FwD Clutch -stock
Lo/Rev - .Stock
Rev - stock
Super servos harsh for my application.
After i lifted the truck and put on 33's, it became slooooow
The world of the whole drivetrain planning is somewhat new and confusing for me. I dont even know where to start hahah.
My Specs :
Im 4700 LB weight
Rear end 3.73
Stock Stall
Wheel size 33" BFG AT 285/70/17
1-2 - .074
2-3 - .135
3-2 - .135
3-4 - .110
BR - .101
FwD Clutch -stock
Lo/Rev - .Stock
Rev - stock
Super servos harsh for my application.
After i lifted the truck and put on 33's, it became slooooow
Possibly the tune but every one has their own personable idea of shift feel. The real question here is what stall is he using compared to you. That has a lot to do with it. Weight of vehicle, torque curves and gear ratio play in that to.
Does 2bast enjoy a firm to very firm shift and you prefer a slightly shorter shift than OE?
Does 2bast enjoy a firm to very firm shift and you prefer a slightly shorter shift than OE?
Its def not a hard shift at WOT but its fast and holds no doubt. Part throttle, its a nice little bump thats quick. Thats the best I can describe it but its far from harsh
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Joined: Mar 2023
Posts: 1,824
Likes: 1,162
From: BERWICK PA
Yes.
The world of the whole drivetrain planning is somewhat new and confusing for me. I dont even know where to start hahah.
My Specs :
Im 4700 LB weight
Rear end 3.73
Stock Stall
Wheel size 33" BFG AT 285/70/17
1-2 - .074
2-3 - .135
3-2 - .135
3-4 - .110
BR - .101
FwD Clutch -stock
Lo/Rev - .Stock
Rev - stock
Super servos harsh for my application.
After i lifted the truck and put on 33's, it became slooooow
The world of the whole drivetrain planning is somewhat new and confusing for me. I dont even know where to start hahah.
My Specs :
Im 4700 LB weight
Rear end 3.73
Stock Stall
Wheel size 33" BFG AT 285/70/17
1-2 - .074
2-3 - .135
3-2 - .135
3-4 - .110
BR - .101
FwD Clutch -stock
Lo/Rev - .Stock
Rev - stock
Super servos harsh for my application.
After i lifted the truck and put on 33's, it became slooooow
I am assuming you used wide band in the build and the sonnax servo which should only yield a firm but not overly aggressive 1-2 shift and have little effect on the 3 or 4 shifts.
I have ,092 on all mine in my own trans with the same servo and wide band for 2nd and .100 on the other gears, My shifts up and down are not overly agressive at all under part throttle and perfect at WOT. I do, however, have a 2800 stall. I think a lot of the difference is the stall as far as the 1-2 higher stalls act as basically a cushion to the shift shock.
But perhaps more, make sure the pressure tables in your tune at part throttle are stock, Trust me even a 10 percent change can have dramatic effect here.
Did you assemble the 1-2 accumulator in correct order and stock ? springs then servo? I have seen a few people put in backwards thinking or seeing a diagram of a 700r4 set up.
In anycase unless you are sure its stock, I would look at the tune first then if all normal there (if you are not sure what normal is I am sure someone here or in the tuning section can share some stock tables for your vehicle.)
Also I do not know your engine build but have noted persons with super chargers and turbos can have issues with part throttle and 0 throttle up and down shifts particularly downshifts due to MAP signal spikes than can happen with these combos . Had a customer a while back with that issue, we looked at the data log and saw where on the downshift in particular the pressure would spike and noted that the same happened with the MAP signal. He did solve it but not being a tuner, I am not exactly sure how he did it. Many think only the MAF,TPS,RPM and SPEED affect shift times and pressures but actually a bit more is involved. I would certainly datalog if you can and look to see if any spikes under the conditions of the harsh or clunky shift.
If all looks normal in tune and other things I mentioned I would consider changing to a Corvette servo and drop the 2-3 feed to .100 or even .092 which is what I use with towing trucks and 4x4 with large wheels.
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
On The Tree
Joined: Apr 2021
Posts: 187
Likes: 23
From: Israel
Your 1-2 feed is actually much smaller than I use .092 however your 3 and 4 feeds are rather much larger. I use .100 on those.
I am assuming you used wide band in the build and the sonnax servo which should only yield a firm but not overly aggressive 1-2 shift and have little effect on the 3 or 4 shifts.
I have ,092 on all mine in my own trans with the same servo and wide band for 2nd and .100 on the other gears, My shifts up and down are not overly agressive at all under part throttle and perfect at WOT. I do, however, have a 2800 stall. I think a lot of the difference is the stall as far as the 1-2 higher stalls act as basically a cushion to the shift shock.
But perhaps more, make sure the pressure tables in your tune at part throttle are stock, Trust me even a 10 percent change can have dramatic effect here.
Did you assemble the 1-2 accumulator in correct order and stock ? springs then servo? I have seen a few people put in backwards thinking or seeing a diagram of a 700r4 set up.
In anycase unless you are sure its stock, I would look at the tune first then if all normal there (if you are not sure what normal is I am sure someone here or in the tuning section can share some stock tables for your vehicle.)
Also I do not know your engine build but have noted persons with super chargers and turbos can have issues with part throttle and 0 throttle up and down shifts particularly downshifts due to MAP signal spikes than can happen with these combos . Had a customer a while back with that issue, we looked at the data log and saw where on the downshift in particular the pressure would spike and noted that the same happened with the MAP signal. He did solve it but not being a tuner, I am not exactly sure how he did it. Many think only the MAF,TPS,RPM and SPEED affect shift times and pressures but actually a bit more is involved. I would certainly datalog if you can and look to see if any spikes under the conditions of the harsh or clunky shift.
If all looks normal in tune and other things I mentioned I would consider changing to a Corvette servo and drop the 2-3 feed to .100 or even .092 which is what I use with towing trucks and 4x4 with large wheels.
I am assuming you used wide band in the build and the sonnax servo which should only yield a firm but not overly aggressive 1-2 shift and have little effect on the 3 or 4 shifts.
I have ,092 on all mine in my own trans with the same servo and wide band for 2nd and .100 on the other gears, My shifts up and down are not overly agressive at all under part throttle and perfect at WOT. I do, however, have a 2800 stall. I think a lot of the difference is the stall as far as the 1-2 higher stalls act as basically a cushion to the shift shock.
But perhaps more, make sure the pressure tables in your tune at part throttle are stock, Trust me even a 10 percent change can have dramatic effect here.
Did you assemble the 1-2 accumulator in correct order and stock ? springs then servo? I have seen a few people put in backwards thinking or seeing a diagram of a 700r4 set up.
In anycase unless you are sure its stock, I would look at the tune first then if all normal there (if you are not sure what normal is I am sure someone here or in the tuning section can share some stock tables for your vehicle.)
Also I do not know your engine build but have noted persons with super chargers and turbos can have issues with part throttle and 0 throttle up and down shifts particularly downshifts due to MAP signal spikes than can happen with these combos . Had a customer a while back with that issue, we looked at the data log and saw where on the downshift in particular the pressure would spike and noted that the same happened with the MAP signal. He did solve it but not being a tuner, I am not exactly sure how he did it. Many think only the MAF,TPS,RPM and SPEED affect shift times and pressures but actually a bit more is involved. I would certainly datalog if you can and look to see if any spikes under the conditions of the harsh or clunky shift.
If all looks normal in tune and other things I mentioned I would consider changing to a Corvette servo and drop the 2-3 feed to .100 or even .092 which is what I use with towing trucks and 4x4 with large wheels.
Forgot to mention, i use the 8TAD, 08 Tranny.
It already has only 1 short spring in the 1-2 acum and its already firm out of the box.
Yup, first spring and then piston (Replaced with a new aluminum one).
The clunk sound i get is when 3rd applies and when 3rd releases no matter what direction, upshift or downshift.
Its harsh when 2-3, 3-2, 3-4, 4-3. Its the servo banging for some reason.
Even the sonnax servo has to be 0.060" of travel right?
My shift pressures are stock
Last edited by Edward Stark; Nov 28, 2023 at 06:24 AM.
Teching In
Joined: Jun 2009
Posts: 6
Likes: 2
Great info here.... on my initial 4L60E build I used the pretty billet servo... I'm surprised I didn't break the ring gear it shifted so hard even a low throttle. I finally reprogrammed to really lower the pressure and extend the shift time enough to where it was acceptable. Then I broke the trans...:~(. In the process of fixing and replaced the pretty billet crap with the corvette servo like I should have to begin with.
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Joined: Mar 2023
Posts: 1,824
Likes: 1,162
From: BERWICK PA
Hi Frank,
Forgot to mention, i use the 8TAD, 08 Tranny.
It already has only 1 short spring in the 1-2 acum and its already firm out of the box.
Yup, first spring and then piston (Replaced with a new aluminum one).
The clunk sound i get is when 3rd applies and when 3rd releases no matter what direction, upshift or downshift.
Its harsh when 2-3, 3-2, 3-4, 4-3. Its the servo banging for some reason.
Even the sonnax servo has to be 0.060" of travel right?
My shift pressures are stock
Forgot to mention, i use the 8TAD, 08 Tranny.
It already has only 1 short spring in the 1-2 acum and its already firm out of the box.
Yup, first spring and then piston (Replaced with a new aluminum one).
The clunk sound i get is when 3rd applies and when 3rd releases no matter what direction, upshift or downshift.
Its harsh when 2-3, 3-2, 3-4, 4-3. Its the servo banging for some reason.
Even the sonnax servo has to be 0.060" of travel right?
My shift pressures are stock
Next replace the servo release spring with a spring (The one between the case and servo ) with a spring from a 400 intermediate band servo it's a good bit stiffer and will increase accumulation for 3rd while lessening impact of the band applying too
If you do these things I think you will end up right where you want to be.
Normally with a higher stall 2800 or more your present set up would probably feel fine but with the stock converter not so much,
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Joined: Mar 2023
Posts: 1,824
Likes: 1,162
From: BERWICK PA
I am not sure on part number I generally save them from TH400 and 4L80E As I actually use the stock 4l60e and 700r4 servo return springs in place of them.
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Thread Starter
Joined: Aug 2006
Posts: 10,854
Likes: 80
From: BLOOMSBURG PA
I want to clear the air for the general public trying to learn and keep misinformation out of this forum as much as possible. For those in this thread complaining billet servos including the well known sonnax saying they are harsh and too much.... they clearly don't understand fluid management or shift kit hole sizes. A big part of the information that is posted by "engineers and professionals" with their listed sizes are way too large for a larger billet servo in regards to area, volume, and pressure. The corvette servo is great but will require larger hole sizes than i would care for in a racing application - In the same scenario ... a larger billet would be require more conservative hole sizes to work optimally. Hopefully this puts a stop to the myth that billet is bad and the ton of misinformation that was just thrown out there.
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TECH Junkie
Joined: Dec 2012
Posts: 3,620
Likes: 1,332
From: Iowa
The issue with the corvette vs billet servos isn't just about harshness on the 1-2
It's the bias ratio of apply vs release
It's how the timing works on the shift.
Fairly condescending to say "clearly don't understand fluid management"
Especially considering you posted a whole youtube video that outlines the fact that you have no idea how the sonnax 4th gear servo works.
There's many ways to skin a cat. I can make something live with the smallest 4cyl servo and I can make it live with the largest superior servo.
I can make either shift firm enough to knock your fillings loose, and I can make either shift soft enough that grandma wouldn't mind driving it to church.
We don't all have to do things the same. But we should all have a decent level of mutual respect on here.
It's the bias ratio of apply vs release
It's how the timing works on the shift.
Fairly condescending to say "clearly don't understand fluid management"
Especially considering you posted a whole youtube video that outlines the fact that you have no idea how the sonnax 4th gear servo works.
There's many ways to skin a cat. I can make something live with the smallest 4cyl servo and I can make it live with the largest superior servo.
I can make either shift firm enough to knock your fillings loose, and I can make either shift soft enough that grandma wouldn't mind driving it to church.
We don't all have to do things the same. But we should all have a decent level of mutual respect on here.
Thread Starter
Joined: Aug 2006
Posts: 10,854
Likes: 80
From: BLOOMSBURG PA
Lol you dont know me at all or what i have done. The youtube video was for the general public not for a tech head.. It was a sales video for people that do not care to know what you guys do. Im aware sonnax has a dual piston servo and used it for many years.. we did do the math and between the 2 pistons, our equates to a very slight larger area but with way less drag than they have (which is the true benefit). Yes There are many ways to skin a cat, but blatantly saying billet is too harsh like many have on here is plain wrong which clearly indicates they do not understand. Nothing offensive was implied so lets not go down that road and be professionals. Truthfully this thread wasn't supposed to be about the servo. It was supposed to be about Helpful information i put out there throught the youtube until it was hijacked by a bunch of guys who tried to pick me apart on one video when they clearly do not understand the basics of fluid. Apply and release timing can be adjusted in more ways than parts combos FYI but you knew that already?
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Last edited by performabuilt; Dec 15, 2023 at 08:37 AM.