how do i make an auto shift hard?

my friend has a 69 firebird (yeah its not within the year limits) with a th350 and well it just doesnt shift worth shit. i mean it shifts at the right times and smoothly..but thats not really what he wants.

is there any way to make an auto 350 shift harder?

thanks guys.

 

Rub it a few times .... WWS

 

either do what he said, or put a shit kit in it.

unless it's worn out...then rebuild it and put a shit kit in it when you rebuild it.

 

I am scared to ask what's in that kit?

 

get a small straight screwdriver and pull the Vacuum hose off at the vacuum Modulator at the right rear side of trans pan....----INSIDE-----the tube on modulator that the hose fits on- is an adjustment screw that will firm up the shift.

 

not to steal his post but, tighten the screw= firmer shifts, loosen the screw= lazier shifts?

 

Get an overhaul manual,and aquaint yourself with the trans components.Remove the govener,there will be centrifical weights inside, remove a little weight off the weights, and it will shift at a higher rpm than stock. Remove the Accuumulator spring inside the acuumulator. That spring absorbs some of the pressure when it shifts.. remove the spring, and you will get tire chirping shifts,full pressure. You can also run a small gate-valve(plumming supply) beetween the vacuum modulator valve,and manifold vacuum tubeing. Less vacuum= harder shifts. They used to sell such a thing like that called"dial a shift". B+M's 'trick shift' fluid is good for firmer shifts also. Sparky

 

I could be wrong but I believe the vacuum mod controls when it shifts not how hard it shifts. Get a 50 dollar shift kit into it. Also, the trans will shift harder with a stock converter than with a high stall converter, the high stall slips more.

 

Screw it in Later/Firmer Screw it out Earlier/Softer.
Take the spring out of the accumulator and replace with a piece of broomstick about 1/4"shorter than the spring and it'll get a real big 1/2 shift but won't help 3rd much.
T.OUT

 

if you want to get real fancy, and leave the tranny working nice at part throttle but have nice firm shifts at full throttle, then open up the clutch feed holes a bit, and plug the accumulator passages with freeze plugs with a small hole in them, also shim the pressure regulator with a TH400 horseshoe shim. I can give you more specifics if you want.

A shit kit is a shift kit with a missing letter.

 

thanks a bunch guys, ill relay this info to him and we'll do some tinkering this weekend to see what we can come up with.

 

i put a shift kit in a fresh rebuilt c4 and now i dont have reverse

 

When your riding with him, you could also scream "ERCH" every time the car shifts.

 

I had a very hard shift kit in my roadster,,,,,It got old Quick but I kept driving it until the sprag gear broke in half,,,,

I had to replace it and took the kit out,,,now my neck doesn't snap ever time the gears change,,,,,,,,

If you use a shift kit,,,,go with a mild one,,HRP

 

Either a mild one, or else a good one...such as TransGo.

 

If you use a kit, i'd stick with a transgo, not a cheapie B&M. Alot more work to put in though.

 

That would be so silly on the way to the prom.

 

Shift kits suck...don't get one. Build it if you wanna get it to shift hard... and if you leave the accumulator spring out... your gonna wanna get a good quality sprag gear cause you'll break that bitch..if you drive like me anyways..

 

yeah, restricting the accumulator is much better than disabling it, you get comfy shifts until you put your foot down then it will shift hard...

 

been looking for this screw in the modulator tube thingy and cant find it ,please explain exactly where it is and what screwdriver i need in real easy to learn steps for the less abled please....................Marq

 

The factory modulators are not adjustable, but the aftermarket replacement (small) ones are.

Pull the vacuum hose off the modulator. In the hole in the nipple that you pulled the hose off, is a screw with a hole thru the middle of it. Use a 1/8" flat blade screwdriver, and turn the screw.

 

so ive been checkin out shift kits and that looks like the way to go, i had no idea theyre so affordable.

so for the transgo kits, which stage would be the best? 1&2 or a 3rd? im guessing 3rd is pretty rough, so maybe 2nd for a street application?

thanks for all the replies.

 

probably 2nd is what you'd want, you'll feel the difference but it won't be too harsh.

 

Slam it into reverse at 70 MPH....now there's a firm shift!!!

 

What he said.
T.OUT

 

The dude that rebuilt my TH350 told me to run Type-F fluid instead of the Mercron-Dexron stuff. He put a mild shift kit in it for me, and I have prolly around 70K miles on this tranny. It gives a nice kick in the butt when it shifts under medium acceleration... not that slushy stock GM stuff. Under hard acceleration (doesn't need to be WOT), it'll bark 3rd gear @ about 80-83 mph. (I have a SBC 350 in my 52 Chevy sedan with a one-legger 2.73:1 rear.)

All this, but it's really pretty tame in "regular" driving, so it's definitely not obnoxious like some are.

As for the Type-F, I have heard that you should never mix it w/ the M-D fluid, but don't know for sure. I put this into a freshly-rebuilt empty tranny.

 

Yup, shift kits want the type F fluid.

Don't mix it. Put in a new filter and screen while you're in there.