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 Post subject: Budget manual shift 904.
PostPosted: Wed Apr 14, 2004 6:44 pm 
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4 BBL ''Hyper-Pak''

Joined: Sun Dec 07, 2003 7:53 pm
Posts: 25
Location: Flint, MI/St. Marys OH/Loudoun, VA
Car Model:
OK, so our project car is coming along well. Installing the injectors and fabricating a fuel rail this weekend.

Since I have ditched the carb on this car, I'm wondering how to rig it so I can manually shift it with the colum shifter, or make a floor shifter. I'm not too sure how non-electronic auto transmissions work. Is there a way this can be done? Is there also a way to up the line pressure for firmer shifts, or should I go with a shift kit?

Remember... $2005 budget. Total investment so far $450. Still need suspsension, turbo, tires, and headwork.

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1971 Valiant, Bone stock
1993 Saturn SW2, Not very stock.


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 Post subject:
PostPosted: Thu Apr 15, 2004 10:18 pm 
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Guru
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Joined: Sat Oct 12, 2002 11:22 am
Posts: 3740
Location: Sonoma, Calif.
Car Model: Many Darts and a Dacuda
For a race car, just use a wire and tie the throttle pressure lever all the way back, full throttle pressure. This will make the tranny shift hard and at high RPMs.
If you want true, full manual valve body control, buy a reprogramming kit. (shift kit)
DD


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 Post subject:
PostPosted: Thu Apr 15, 2004 10:41 pm 
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Turbo EFI
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Joined: Sun Nov 03, 2002 1:49 pm
Posts: 2445
Location: Lubbock, TX
Car Model:
Whats wrong with just holding the lower gears longer by shifting manualy?


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 Post subject:
PostPosted: Fri Apr 16, 2004 4:58 am 
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Turbo Slant 6

Joined: Tue Mar 16, 2004 6:25 am
Posts: 831
Location: Tompkinsville, KY
Car Model:
Torqueflites rely on the kickdown linkage for line pressure control as well as kickdown signal, so you have to do something to turn up pressure if you don't have it.
A full manual shift valve body is the best way, if that's what you want, but that's $150 out of the budget.
Tying the lever all the way back definitely helps, but it might make the trans downshift hard when you're not ready for it ( not so good on the road course - makes for nice loops :shock: ).
How about this - drop the valve body and replace the accumulator spring with a short piece of pipe that will keep the piston right at the top of the bore.
Then, turn the line pressure screw (driver's side of valve body next to linkage - allen head screw under sheetmetal bracket) until the spring seat is even with the kickout in the bracket.
Finally, reinstall the valve body and tie the lever back no more than 1/2 way.
Hopefully, this will allow nice hard shifts, the trans to live, and you to manual shift without severe automatic downshifts.
Depending on how high you're going to rev it, you could still run into automatic upshifts; there might be safetys in the stock valve body that could rear their heads.
Of course, you could also rig a junkyard throttle cable (Fiero is nice and long) as a "pull" kickdown linkage from whatever throttle you have...You do have a throttle, don't you? :o


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 Post subject:
PostPosted: Sat Apr 17, 2004 9:41 pm 
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4 BBL ''Hyper-Pak''

Joined: Sun Dec 07, 2003 7:53 pm
Posts: 25
Location: Flint, MI/St. Marys OH/Loudoun, VA
Car Model:
We do have a throttle body. I didn't want to make the kickdown work with the TB, because I was afraid of hard downshifts under throttle. Also want to be able to use part throttle in a lower gear. Rare to hit 100% throttle in an autox.

I may consider running full line pressure all the time, but that would make this car suck on the street. And the street is going to be used for all test/tuning purposes.

_________________
1971 Valiant, Bone stock
1993 Saturn SW2, Not very stock.


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 Post subject:
PostPosted: Mon Apr 19, 2004 3:47 pm 
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TBI Slant 6
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Joined: Mon Apr 19, 2004 5:09 am
Posts: 132
Car Model:
I think what you are looking for is the Trans-go full manual valve body. Hard, crisp shifts. The ONLY draw back is that there is no engine braking in 1st gear. Soooo if you are in 1st rev up the car then let off then stab the gas down hard its like doing a nutral drop... Stuff go Boom

I have one in my car and love it...but its not a road corse car.


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 Post subject:
PostPosted: Fri Apr 23, 2004 9:29 am 
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Board Sponsor & Moderator
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Joined: Mon Oct 21, 2002 11:08 am
Posts: 17246
Location: Blacksburg, VA
Car Model:
You don't need a full manual VB per se, although it could be nice. They are pretty much all designed for drags, so don't necessarily have good downshifting qualities from what I've read/heard. Just set up the KD linkage so it reaches full travel when you're at WOT and manually hold it in gears using the column shifter. Works great for me.

Only trouble I've had is when things really get hot on a road course, the trans sometimes won't shift down to 1st with the shifter if you're over 35 MPH (3.23 gears). And, if you're closed throttle, it tends to not want to downshift, but you can blip the throttle.

Lou

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