Trans Question.
#1924309
10/02/15 05:49 PM
10/02/15 05:49 PM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
OP
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OP
master
Joined: Jan 2003
Posts: 2,924
A shed in England
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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
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1924339
10/02/15 06:35 PM
10/02/15 06:35 PM
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Joined: Jan 2003
Posts: 25,852 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
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Posts: 25,852
Rio Linda, CA
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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.
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Re: Trans Question.
[Re: Tig]
#1924381
10/02/15 07:24 PM
10/02/15 07:24 PM
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Joined: Oct 2007
Posts: 4,209 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,209
New York
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TransGo claims their valve body mods greatly reduce this.
Boffin Emeritus
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Re: Trans Question.
[Re: Tig]
#1924389
10/02/15 07:33 PM
10/02/15 07:33 PM
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Joined: Dec 2005
Posts: 11,602 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,602
Fulton County, PA
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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.
If the results don't match the theory, change the theory.
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Re: Trans Question.
[Re: Tig]
#1924757
10/03/15 07:22 AM
10/03/15 07:22 AM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
OP
master
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OP
master
Joined: Jan 2003
Posts: 2,924
A shed in England
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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.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1924945
10/03/15 03:34 PM
10/03/15 03:34 PM
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Joined: May 2003
Posts: 1,751 Graham, WA
Polarapete
top fuel
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top fuel
Joined: May 2003
Posts: 1,751
Graham, WA
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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.
Last edited by Polarapete; 10/03/15 07:57 PM.
1986 Dodge Ramcharger 440 2wd, Bracket Racer Under Construction 1998 Ram 2500 QuadCab, new daily driver. 2008 Honda Element 2014 Carry-On 7x14 Cargo Trailer
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Re: Trans Question.
[Re: Tig]
#1925115
10/03/15 07:48 PM
10/03/15 07:48 PM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
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OP
master
Joined: Jan 2003
Posts: 2,924
A shed in England
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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.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1925319
10/04/15 12:59 AM
10/04/15 12:59 AM
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Joined: Aug 2003
Posts: 43,218 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,218
Bend,OR USA
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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
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Trans Question.
[Re: Tig]
#1925370
10/04/15 02:00 AM
10/04/15 02:00 AM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
OP
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OP
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Joined: Jan 2003
Posts: 2,924
A shed in England
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Yep, it will also creep in neutral too.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1925649
10/04/15 04:11 PM
10/04/15 04:11 PM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
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OP
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Posts: 2,924
A shed in England
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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?
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1926031
10/05/15 04:28 AM
10/05/15 04:28 AM
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Joined: Jan 2005
Posts: 3,699 Newport, Mi
Evil Spirit
master
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master
Joined: Jan 2005
Posts: 3,699
Newport, Mi
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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.
Free advice and worth every penny... Factory trained Slinky rewinder.........
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Re: Trans Question.
[Re: Tig]
#1926113
10/05/15 10:56 AM
10/05/15 10:56 AM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
OP
master
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OP
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Joined: Jan 2003
Posts: 2,924
A shed in England
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1st to 2nd shift is barely noticeable at light load. Guessing this puts the blame on the clutch pack.
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1926296
10/05/15 03:31 PM
10/05/15 03:31 PM
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Joined: Jan 2003
Posts: 25,852 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,852
Rio Linda, CA
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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.
The INTERNET, the MISinformation superhighway
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Re: Trans Question.
[Re: Tig]
#1926325
10/05/15 04:07 PM
10/05/15 04:07 PM
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Joined: Jan 2003
Posts: 2,924 A shed in England
Tig
OP
master
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OP
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Joined: Jan 2003
Posts: 2,924
A shed in England
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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
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: Trans Question.
[Re: Tig]
#1926383
10/05/15 05:29 PM
10/05/15 05:29 PM
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Joined: Jan 2003
Posts: 25,852 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,852
Rio Linda, CA
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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.
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