2-3 shift after transgo hd2 install
2-3 shift after transgo hd2 install I just installed a transgo hd2 kit in my 99 ws6 4l60e. The car was tuned in the spring and the tuner did change some shift points and shift firmness. I got the shift kit installed and test drove the car. The 1-2 shift is exactly what I was hoping for. The 2-3 shift is almost like a double shift into 3rd. At WOT the car is banging off the rev limiter before it shifts into 3rd. I know this problem can be fixed with tuning but the shift when it does shift makes me think I may have done something wrong. The instructions were not the greatest and there were a few steps that had me second guessing myself. I’ve done a lot of the old 350 turbo B&M shift kits but this is my first 4l60.
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
Ah, the joys of synchronous clutch/ band changes... the 2-3 shift requires sensitive timing of a band and clutch pack to feel right.
Sounds like you may have a 2-3 shift tie-up... The 2-4 band may be releasing too slowly.
Is the transmission stock other than the TransGo HD2 modifications?
Has the valve-body been vacuum tested for circuit leaks? Almost all of these valve-bodies have some leaks...
Has the 3rd accumulator check ball capsule been tested for a leak?
Do you know the 2-4 servo end-play?
Do you know the 3-4 clutch pack end-play?
If not stock... What else has been modified?
Have you installed a Sonnax 3rd accumulator check valve?
Have you blocked either the 3-2 control valve or down-shift valve in place?
Some of the other guys here who still use HP Tuners will probably want to look at your tune file and give you feedback on it.
Sounds like you may have a 2-3 shift tie-up... The 2-4 band may be releasing too slowly.
Is the transmission stock other than the TransGo HD2 modifications?
Has the valve-body been vacuum tested for circuit leaks? Almost all of these valve-bodies have some leaks...
Has the 3rd accumulator check ball capsule been tested for a leak?
Do you know the 2-4 servo end-play?
Do you know the 3-4 clutch pack end-play?
If not stock... What else has been modified?
Have you installed a Sonnax 3rd accumulator check valve?
Have you blocked either the 3-2 control valve or down-shift valve in place?
Some of the other guys here who still use HP Tuners will probably want to look at your tune file and give you feedback on it.
I use hptuners and shift kits.
I would guess you have a higher than stock stall speed? Thats one thing that makes the 2-3 shift soft.
The most common is getting the feed hole sizes wrong, third apply and band release, those two will have a negative effect on a transmission that used to feel right on the 2-3 shift.
Of course, as mentioned, the 3-4 clutch clearance and 2nd servo travel has an effect on 2-3 shift feel.
If it felt normal before the kit it needs to be corrected by fine tuning or re-doing things done as instructed by the kit.
I would guess you have a higher than stock stall speed? Thats one thing that makes the 2-3 shift soft.
The most common is getting the feed hole sizes wrong, third apply and band release, those two will have a negative effect on a transmission that used to feel right on the 2-3 shift.
Of course, as mentioned, the 3-4 clutch clearance and 2nd servo travel has an effect on 2-3 shift feel.
If it felt normal before the kit it needs to be corrected by fine tuning or re-doing things done as instructed by the kit.
The transmission is stock but I am running a yank 3600 converter. When I installed the kit I put one gold shim in the servo. How do you check the band end play? I read to put shims in to tighten the band up but still having it loose enough to turn the driveshaft in both directions. Another method was to check the amount of servo travel. I’m pretty sure that you need an 1/8” of servo travel. If I’m wrong let me know. I’m pretty sure this may be where the problem is. Like I said the transmission shifted fine before the install I just wanted quicker shifts.
In an f-body it's easy to use a pry bar against the floorboard and servo cover. Push the servo cover in and look at the gap between the retaining ring and cover. 1/8" is too much in my opinion, but again the relationship between the servo travel and 3-4 clutch clearance can determine 3rd shift feel. And too much travel means it can release faster than the 3-4 clutch applies.
I usually set the servo travel the thickness of one gold shim, '062 IIRC. Usually when I put both gold shims in the servo hardly has any travel so taking one out gives it the ideal travel. I've had to use both shims to get the travel right but not often at all.
This is only one very small potential problem.
Do you know what size you drilled each hole in the seperator plate? This is one other area thats useful to adjust band release/ 3-4 apply.
From what you described you need to get 3rd to apply earlier/faster and/or the band to release later.
I usually set the servo travel the thickness of one gold shim, '062 IIRC. Usually when I put both gold shims in the servo hardly has any travel so taking one out gives it the ideal travel. I've had to use both shims to get the travel right but not often at all.
This is only one very small potential problem.
Do you know what size you drilled each hole in the seperator plate? This is one other area thats useful to adjust band release/ 3-4 apply.
From what you described you need to get 3rd to apply earlier/faster and/or the band to release later.
I drilled all the holes .093”. The 1-2 had either .082” short shift or .093” full race and hi stall. The 2-3 shift had .093 or .101” hi stall or full race. In hindsight I wished I wouldn’t have pissed with the transmission. Yes, if you can follow directions you can install one of these. My problem is I didn’t fully understand the shift events that take place and that as was previously said above the 2-3 is a combination of synchronous events. Live and learn I guess. Also, I really appreciate your help with this. Let me know if you see anything wrong with what I’ve told you so far. I’m going to get back under the car and check the servo travel and put the other shim in to shorten the travel to get it closer to .062 travel. I see where what I’m experiencing is referred to as a shift flare. It seems the band is releasing just before the clutch pack is engaging.
TECH Junkie
Joined: Nov 2013
Posts: 3,913
Likes: 366
From: White Bear, Mn
Edit: Re- read your first post and saw its hitting the limiter at wot. Combination of the band not releasing fast enough and 3-4 clutches not engaging fast enough
Last edited by 98CayenneT/A; Oct 13, 2019 at 10:41 AM.
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Verdad Gallardo TECH Junkie
Joined: Nov 2013
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From: White Bear, Mn
Hey guys I put the other shim in the servo and shortened the travel up. It is a lot better now. It shifts where it use to at about 6700 rpms. I think I didn’t do a very good job of describing what the car was doing. After reading your replies it was releasing the band before engaging the clutches causing the rpms to spike up and hit the rev limiter. I still would like it to shift a little faster into 3rd.
TECH Resident
Joined: May 2006
Posts: 969
Likes: 119
Yes, that is what I do too. Except that you want the band release at .099" - .101" and the 2-3 shift at .135" when using the Corvette servo. Keep the band clearance at a minimum. One thing not mentioned here, is that when you go over 6,000 rpm, the line pressure starts to drop (on all GM pumps) and if this shows up, it will always be on the WOT 2-3 shift as a "flare". The pump will need the TransGo Hi-rpm steel rings and priming spring to keep the pressure up and flat to 8,000 rpm.
Yes, that is what I do too. Except that you want the band release at .099" - .101" and the 2-3 shift at .135" when using the Corvette servo. Keep the band clearance at a minimum. One thing not mentioned here, is that when you go over 6,000 rpm, the line pressure starts to drop (on all GM pumps) and if this shows up, it will always be on the WOT 2-3 shift as a "flare". The pump will need the TransGo Hi-rpm steel rings and priming spring to keep the pressure up and flat to 8,000 rpm.
Yes, that is what I do too. Except that you want the band release at .099" - .101" and the 2-3 shift at .135" when using the Corvette servo. Keep the band clearance at a minimum. One thing not mentioned here, is that when you go over 6,000 rpm, the line pressure starts to drop (on all GM pumps) and if this shows up, it will always be on the WOT 2-3 shift as a "flare". The pump will need the TransGo Hi-rpm steel rings and priming spring to keep the pressure up and flat to 8,000 rpm.