[stoney 81ta]

What are the pros and cons on installing a shift kit in a thm350 tranny thats installed in a 81 Trans Am 305sbc mild build and 2.56 rear end ,would this help performance wise.Car is driven mostly on street and highways.Thanks all.

[327NUT]

Shift kits have their place but I think guys make a mistake by installing a race oriented kit that will break your neck everytime the trans. shifts. In your case I would change out that 2.56 rear end gear first to maybe a 3.42-3.73 depending on your mileage requirements. You would see a major difference in acceleration just doing that. I think a shift kit would be a waste of time and money without doing that first.

[stoney 81ta]

Thanks for the advise 327

[airworld2]

at 3 bucks a gallon for gas you would be better off with an overdrive transmission . you have a lower first gear for power and better top end with your rear gear. you would get worse gas mileage with lower rea gears and higher rpms at freeway speeds.
but shift kit wont improve torque and gear ratio
shift feel only improvement....

[427v8]

You guys don't understand shift kits aparently.

Any performance car shold have three things done to it immediately.

1. Total timing.
2. shipt kit.
3. performance tires

A stock auto trans is designed to shift smoothly. this is so the old ladies will be happy. The factory does this by engaging the clutches of 2nd gear while the 1st gear clutches are still engaged. this overlap softens the shift.

It also wears the clutches since the clutches are fighting eachother.

A GOOD shift kit reduces the overlap ( and a bunch of other things ) and makes the trans stonger and shift faster. Shifting hard is easier on it that shifting slow and still not as bad as a manual trans on the rest of the drivetrain.

I have a built TH400 in my Vette that shifts like butter at part throttle and like now at full throttle. It's a joy to drive around town, and a riot to drive at the track.

I do agree that an overdrive is better, of course.But a transgo shiftkit is cheap and fun.

Keith

[Crosley]

Originally Posted by 427v8

You guys don't understand shift kits aparently.

Any performance car shold have three things done to it immediately.

1. Total timing.
2. shipt kit.
3. performance tires

A stock auto trans is designed to shift smoothly. this is so the old ladies will be happy. The factory does this by engaging the clutches of 2nd gear while the 1st gear clutches are still engaged. this overlap softens the shift.

It also wears the clutches since the clutches are fighting eachother.

A GOOD shift kit reduces the overlap ( and a bunch of other things ) and makes the trans stonger and shift faster. Shifting hard is easier on it that shifting slow and still not as bad as a manual trans on the rest of the drivetrain.

I have a built TH400 in my Vette that shifts like butter at part throttle and like now at full throttle. It's a joy to drive around town, and a riot to drive at the track.

I do agree that an overdrive is better, of course.But a transgo shiftkit is cheap and fun.

Keith

the explanation of the over lap during a shift you've posted does not apply to a t-350 or t-400 trans in most cases.

When a t-350 or 400 with the shifter in "D"... shifts from 1st to 2nd gear another set of frictions apply, no clutch pack or band releases.

When the shift to 3rd gear happens..... the 2nd gear clutch pack stays applied. The sprag / roller clutch then over runs when in 3rd gear.

When these trans are manually shifted , slightly different things happen. In a t-350 the low /reverse clutch pack is applied in "1st" gear. This pack must release quickly for the 1-2 shift to happen and no tie up happens

[kwopper07]

i put a shift kit in my th 350 with a 2000 stall converter and i love it if you drive it part throttle it shifts real smooth at low rpm but if you nail it to the floor it shifts at 5200 real hard chirps the tires.some of the best money i ever spent

[kleen56]

A shift kits sole design is to reprogram the valve body of the transmission by changing flow and pressure of the fluid, thus increasing the quickness of the shift. There are several kits out there and I've heard good and bad things about shift kits. If your going to install one, I'd recommend using a name brand such as B&M or Transgo. They have been around for a while. If you ask several transmission guys, they'll usually tell you they can build a tranny that shift better than a shift kit can. I'm not running a shift kit and my tranny shifts nice and crisp. Most guys who install the kits are looking for that second gear chirp! That doesn't get you there any faster.

[airworld2]

Originally Posted by 427v8

You guys don't understand shift kits aparently.

Any performance car shold have three things done to it immediately.

1. Total timing.
2. shipt kit.
3. performance tires

A stock auto trans is designed to shift smoothly. this is so the old ladies will be happy. The factory does this by engaging the clutches of 2nd gear while the 1st gear clutches are still engaged. this overlap softens the shift.

It also wears the clutches since the clutches are fighting eachother.

A GOOD shift kit reduces the overlap ( and a bunch of other things ) and makes the trans stonger and shift faster. Shifting hard is easier on it that shifting slow and still not as bad as a manual trans on the rest of the drivetrain.

I have a built TH400 in my Vette that shifts like butter at part throttle and like now at full throttle. It's a joy to drive around town, and a riot to drive at the track.

I do agree that an overdrive is better, of course.But a transgo shiftkit is cheap and fun.

Keith

Well I know I can make a transmission shift smooth or hard enough to brake things . no engineer degree here but since 78 transmissions is what I do everyday. I had a Master tech at local GM dealer tell me in 93 that a 4L60E couldn't but altered to shift hard the next day I showed him he was wrong, that's before anyone had a shift kit on the market. So unless you know me don't spout off that I don't understand what A shift kit does.

[Crosley]

One other little trivia item....

TransGo is the only company that sells "Shift Kits". TransGo has the term shift kit trade marked. They have sued companies and won over the use of the term shift kit.

That is the reason you see terms like "Shift Improver" , "Shift Correction package" by various companies.

[briscoe]

Yes Crosley thats true. Transgo takes this stuff seriously, I heard that Gil Younger, the owner and founder of Transgo, and Steve Younger, his son actually sued each other, over a concept issue.

Now there's a piece of triva for you!

[Crosley]

Originally Posted by briscoe

Yes Crosley thats true. Transgo takes this stuff seriously, I heard that Gil Younger, the owner and founder of Transgo, and Steve Younger, his son actually sued each other, over a concept issue.

Now there's a piece of triva for you!

Actually, as I recall they split the sheets for a while back in the 1980's..... that is when they sued each other over the ideas and names of stuff.

[briscoe]

Actually, as I recall they split the sheets for a while back in the 1980's..... that is when they sued each other over the ideas and names of stuff.

I was sitting here thinking, man I hope that splitting the sheets didn't have anything to do with sex.

I know that one of the issues was the line to lube concept,but I don't remember the details now.

I was at AAMCO tech, early nineties, when I heard about their rift.