Trans Question.

Hi All.
When I shift from 2nd to 3rd the car almost stops. Don't notice it at speed but when cruising at light throttle, back to the pit it almost throws me into the dash pad
I rebuilt the trans at the begining of the season, been doing it all the time but i had other stuff to sort out.
What have I done wrong?
TIA

You're experiencing severe overlap wherein the front clutch applies before the kickdown band releases...in essence in two gears at the same time.

Two ways to reduce the overlap are to delay the clutch engagement by using more return springs in the clutch drum or restrict the fluid flow to the clutch with an orifice restrictor in the case.

I heard if the band adjustment was to tight it would cause something like this. Am I off base?

TransGo claims their valve body mods greatly reduce this.

I have fine tuned this by adjusting the spring load on the servo. Getting thrown into the dash is pretty severe though and may need more than fine tuning.

Previous discussion on this topic.

https://board.moparts.org/ubbthreads/ubbt...tml#Post1906918

I install TF-2 and

Who, brand and part number, valve body is it? I've seen shifter cable adjustments make bad things happen on more than one Mopar with both reverse manual shift valve bodys and some standard valve body with shift kits in them . Most of those where bad on the 1st to 2nd gear shifts though I like to have my cables adjusted so the male pin on the cable end drops into the hole on the shifter arm hooked to the valve body in all three forward gears as well drops in in nuetral also, no forcing it

Hi All.
Thanks for the replies so far. Here's a little more info. Problem seems worse when the trans is hot.
The front drum is a CRT steel that fits 6 thins. I recall checking the clutch pack and the clearence being on the tight side of the limit with 6 plates. Billet servo with all the springs. Lever is a 4.2, we've tried backing off the band but it was still the same. The valve body is a Griner RMVB LBA.

I am going to stick with this topic because I have a TCS billet front drum that I was planning on having installed in the race 727 that was built by local guru Pat Blais. He told me earlier that there can be clearance issues in the front clutch pack when you use the billet front drum. Aside from that, why are you going through the gears on the way back from a run? Why not just leave it in high or 2nd and motor gently back, you race on the track, not the return road.

From the description of your car, I thought it was a race only ride and then I realized you were street driving it and seeing the problem under part throttle on the street, not surprised at that now. Good luck taming it down.

It didn't do this before I rebuilt the box for this season. I'll be pulling it apart over winter just need some pointers on what to look for.

I let a local trans shop set a bracket 727 trans up for me one time, they added additional plates to both drums thinking that was the hot set up for a "race" motor, it isn't That rascal would try and creep in nuetral when revved up The shop used a Trans Go shift kit also, it was like your deal on jackstands, I could see the rear wheels almost stop on the 2 to 3 shift with someone in the car revving it up and shifting it on jack stands

Yep, it will also creep in neutral too.

You will need more clearance in the front drum 6 clutches will crab before the band is released open up the clearance and maybe put a stiffer spring on the band.

That's got me thinking, I've rebuilt it the way it was before, same clutch pack clearance and we never had that overlap issue. I'm wondering if the servo is sticking or not releasing correctly for some reason.
So for 3rd gear we have front band released and front clutch pack engaged?

So for 3rd gear we have front band released and front clutch pack engaged? Yes

I'm wondering if the servo is sticking or not releasing correctly for some reason.

You haven't mentioned 1-2 shift quality. Reason I do is - if the springs in the front servo are too soft, they create an excessively firm 1-2 shift and an overlap on the 2-3. Slightly stiffer front servo springs can slightly soften the 1-2 and get the band released a little faster, which cleans up the 2-3 shift.

1st to 2nd shift is barely noticeable at light load. Guessing this puts the blame on the clutch pack.

No clutch pack involved in the 1-2 upshift but a faulty front servo could cause both the soft 1-2 shift and the balky 2-3 shift.

RPM trace shows the same RPM drop for both shifts (aprox 1000rpm), and roughly the same time (drop and recovery) of 0.3 - 0.4 seconds. But this is obviously under full throttle. The shift is more triangular than sawtooth. Is the shift time normal?
Can you air check the servo in question?
Thanks

It's easy to air check the front servo apply because the port in the case is round but the servo release port in the case is odd-shaped so it take a little creativity to introduce air into it.

Just took the box apart today, front band and front clutch pack burnt up. Also found that I'd installed the rear servo seal upside down.
We've put new front and rear servos in, renewed the clutch pack, band and air checked everything. Everything else seems good to go. Also have the front clutch pack clearance set at .090" (6 thin reds and kolenes)

How many springs in the front clutch ?

you light 1-2 was because you burnt the band , hopefully you aren't using a Kevlar band in the front.

All of them, cant remember how many, 14? it's a billet steel front drum with a blue aluminium anodised piston. Normal red band for the front drum.