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727 question #246225
03/07/09 08:53 PM
03/07/09 08:53 PM
Joined: Jun 2004
Posts: 119
SE VA
hemibee69 Offline OP
member
hemibee69  Offline OP
member

Joined: Jun 2004
Posts: 119
SE VA
Well today the first day at the track for the year 2nd gear was not there. It did not flare up like it was slipping, it just seemed to still be in first and went on the limiter.I went through my trans over the winter. Put in a supersprag, new soild red front band. New clutches and thrust washers. Griner brake, releases OK, 1st, rev and High gear are all fine. I checked the band and the adj was still about 1 3/4 turns. Same case, and brake as last year. I thought if 2nd was broke the engine would rev like it was neutral. Does it sound like a servo sealing problem? When I drive in the pits and shift it seems to shift after 10-15 seconds. Any experience like this before? This is not my first 727, but my first to have a problem immediately after going through it. Sorry for the length of the post, but want to know the best place to look first.


1969 Orig Hemi Super Bee Post 4 spd Red on Red (Sold sadly)
1970 Cuda Drag car 500" B1/BS 8.63 @ 155 mph
1970 Challenger SE 383 4 bbl A/C PB PS Leather
1971 Orig 440+6 Cuda 4 spd Shaker In-Violet
Re: 727 question [Re: hemibee69] #246226
03/07/09 10:03 PM
03/07/09 10:03 PM
Joined: Jan 2003
Posts: 16,917
NC
440Jim Offline
I Live Here
440Jim  Offline
I Live Here

Joined: Jan 2003
Posts: 16,917
NC
Here is some thinking out loud to hopefully trigger the answer.

In a TF transmission, the only difference between 1st and 2nd is the front band stopping the front drum. Plus, if you have 1st gear band apply, it lets go so the rear drum can spin (say CW). The sprag stops it from turning the other way (say CCW). So either the band is not stopping the front drum, or the rear band is not releasing (if you have LBA).

But I am thinking the rear band is releasing since you say it is like it isn't shifting at all, ie front band is not stopping the front drum. That points to a front servo issue. I was thinking a band strut bent or the ears on the band broke, but you said the adjustment is still the same, so that rules that out.

The good news is that you can do a lot to check that without pulling the trans out of the car. But you will have to remove the valve body (it could be the problem too). After pulling the valve body, put air pressure with a rubber tipped gun on the hole that pressurizes the front servo and see if the action tightens the band and listen for excesses leakage.

I do this "dry" when I build the trans, just lube on the rings. But after circulating fluid, be ready for a shower of fluid. Some leakage is normal. I will look for a pic to show which hole to pressurize.

EDIT: This attachment has the port labelled, "Front Servo Apply"

Last edited by 440Jim; 03/07/09 10:07 PM.
Re: 727 question [Re: hemibee69] #246227
03/07/09 10:05 PM
03/07/09 10:05 PM
Joined: Dec 2007
Posts: 10,542
BROOK PARK, OH
WILD BILL Offline
Senior Member of the Junior Dragster Club
WILD BILL  Offline
Senior Member of the Junior Dragster Club

Joined: Dec 2007
Posts: 10,542
BROOK PARK, OH
Make sure the linkage is set right. If that's not the cause, check the KD band apply servo. Might also be the band going south.

Re: 727 question [Re: WILD BILL] #246228
03/07/09 11:58 PM
03/07/09 11:58 PM
Joined: Aug 2005
Posts: 751
Southington Ct.
T
turbobitt Offline
super stock
turbobitt  Offline
super stock
T

Joined: Aug 2005
Posts: 751
Southington Ct.
Since it is a manual VB, It could be something in the factory governor circuit. Some VB's looped the supply and return together to make the VB shift on demand. Check for internal fluid leaks. I once had a VB that would shift correctly and it was just one of the endplates was loose. Another thing it may be is sometimes a checkball may peen its way through the seperator plate. I had this happen before and I think it didn't shift into second.


1970 Challenger w/572 Hemi street car and my pride and joy. 1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno. 1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
Re: 727 question [Re: turbobitt] #246229
03/08/09 01:17 PM
03/08/09 01:17 PM
Joined: Jun 2004
Posts: 119
SE VA
hemibee69 Offline OP
member
hemibee69  Offline OP
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Joined: Jun 2004
Posts: 119
SE VA
Thanks for all the relpies. The response to put air pressure on the servo apply port helped me identify my problem. The kickdown band I put in over the winter was slightly larger than my previous one. When the band is clamped the ends tough before enough force is applied to stop the drum under power. I attached a photo. The Alum front drum has some runs, but is not worn much. It must be slightly smaller diameter than a stock one. I would have never thought to check this when assembling the trans. At least now I know what to fis, and the servo was sealing fine.

5078591-origclamped.JPG (70 downloads)

1969 Orig Hemi Super Bee Post 4 spd Red on Red (Sold sadly)
1970 Cuda Drag car 500" B1/BS 8.63 @ 155 mph
1970 Challenger SE 383 4 bbl A/C PB PS Leather
1971 Orig 440+6 Cuda 4 spd Shaker In-Violet
Re: 727 question [Re: hemibee69] #246230
03/08/09 01:36 PM
03/08/09 01:36 PM
Joined: Dec 2007
Posts: 10,542
BROOK PARK, OH
WILD BILL Offline
Senior Member of the Junior Dragster Club
WILD BILL  Offline
Senior Member of the Junior Dragster Club

Joined: Dec 2007
Posts: 10,542
BROOK PARK, OH







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