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Topic: Auto Tranny help needed

in Forum: C3 Driveline Components


Auto Tranny help needed

Posted: 6/5/06 9:12am Message 1 of 5
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Edgewood, KY - USA
Joined: 10/26/2003
Posts: 339
Vette(s): 1981, Black/Black, Engine bumped to about 400HP.Ext/int mostly stock.

After a long winter of getting the engine, tranny and front suspension rebuilt, I now have everything all reassembled and running.  I also installed a Transgo shift kit in the 350C transmission.  (I have an '81, so the transmission has the computer controlled lock-up converter.)  I also installed a B&M shift-point kit with lighter governor weights, so that the wide-open-throttle shift point would be higher.  My problem is that the transmission now never shifts down on it's own.  In other word, I put it into "Drive" at a stand-still and it is in third gear.  Even when I stomp on it, it will not shift down.  Any thoughts on the possible cause?

a) kick-down cable not properly adjusted (I haven't tweaked with it much yet)

B) new adjustabole modulator valve stuck or not working

c) I dorked up the govenor when I installed the shift point kit

d) or none of the above?!

Thanks!




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Auto Tranny help needed

Posted: 6/5/06 11:53am Message 2 of 5
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Irving, TX - USA
Joined: 8/21/2004
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Vette(s): #1 -1969 Corvette Coupe Riverside Gold, black interior,MN,A/C,350/350,PS,PB,window cranks. #2 -2000 C5, black/black, 6 sp, Bose system & lots of buttons.
Joel.......where are you?  Your help is needed!!


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Auto Tranny help needed

Posted: 6/5/06 6:03pm Message 3 of 5
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
What?!!!

John, the answer is...
c) I dorked up the govenor when I installed the shift point kit     ("dorked??" )

Does the trans work if you manually shift it?
I would start by putting the gov. back the way it was. While you're doing that, make sure the valve in the middle of the gov. is free. It should flop back & forth if you shake the gov. If the gov. valve is stuck, it will take off in a higher gear, either 2nd or 3rd, depending on where the valve is.

What T-Go kit did you use? Are you sure it wasn't a kit that made it a "manual shift"? Some of them do. If that is the case, it is working the way it was designed. Also, some T-Go kits put a small orificed "cup plug" in the gov. passage, to limit the amount of lube oil going to the tailhousing. If the plug is installed in the wrong passage, it could cause this.

I've never been a fan of the gov. "shift point" kits. They are more of a pain than they're worth, IMHO.

Start with the gov., and let us know what happens.


Joel Adams
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Auto Tranny help needed

Posted: 6/6/06 9:10am Message 4 of 5
Former Member
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Edgewood, KY - USA
Joined: 10/26/2003
Posts: 339
Vette(s): 1981, Black/Black, Engine bumped to about 400HP.Ext/int mostly stock.
Yeah, the transmissions works fine if I manually shift it, starting in first gear and running up to 3rd.  It just will not shift on it's own at all.  My 1st job os to go back and re-read the Transgo shift kit directions and maybe even call them.  I installed an optional spring that was supposed to allow me to downshift at any speed.  However, I did not read anything about that spring choice making it a completely manual shift, but I may have misse it or mis-read it.


Auto Tranny help needed

Posted: 6/6/06 5:32pm Message 5 of 5
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
No, the mod to allow a downshift at any speed will not be the problem. The kit would have different instructions if it was designed to make it a manual, and would state, "Do this ONLY if a manual shift is needed", or something to that effect. The fact that it will upshift to all gears tells me the problem is gonna be in the gov., or possibly the modulator. Did you install the "pink" spring on the mod. valve?, If so, take it out, and throw it in the garbage!
Do this; take off in first, and drive to about 18mph, shift into second, drive until about 20 mph, and move the shifter to 3rd. If the trans downshifts back to first(it may feel like neutral), it is a mod. problem. If it does upshift to 3rd, I'd go with the gov., and put it back stock.


Joel Adams
C3VR Lifetime Member #56    

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(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

in Forum: C3 Driveline Components


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