Someone clarify shift kits for me?

[JollyGreen]

Yeah, it just depends on what part(s) are going bad. Mine wouldn't start slipping until it was warm.

 

[slippy3002]

If you think its funny check the fluid. My friend had that almost identical problem before and it would hover before it shifted. We drained yhe fluid and changed the filter and it was good.

Sent from my SGH-T989 using Xparent BlueTapatalk 2

 

[19Yukon97]

Just rebuilt my transmission with my dad. Has shift kits for each shift. A vette servo for 1-2 2-3 and a billet servo for 3-4. Has all the updates for the 4l60e also. The shift kit is what is making it shift hard. Mine does the same thing. Its not supposed to shift real hard while just at part throttle, it shifts hardnat wot and 3/4 throttle. It sounds like you pretty much have the same stuff as i do. The 1-2 shift is vert firm. The 2-3 3-4 shifts arent near as firm but they are felt.

 

[ridiqls]

Yeah I think it might be a shift kit then. I'm going to try and drive it again and floor it and see if the RPM goes up without the truck moving.

On a side note, would you guys buy an used tranny for $150? There's one on craigslist and he said he parted out his truck and it only had 72k miles on it. I asked to see the truck or the proof like registration or something to make sure it was the mileage he claimed and he said all he had was a bill of sale and the fluid is red and clean. Obviously a fluid being red can be faked cause you can just put new fluid into it and also the bill of sale you just write up something on a piece of paper. There's no way to test the tranny but IF what he is sayin is true then $150 isn't a bad price even with a rebuild right? He said the reason the truck was being parted out was because the engine burned so the tranny was unaffected.

Whether or not the truck needs a new tranny, I'm wonder if it's a good investment for my friend to get the one on craigslist at $150 for possible rebuild down the road. After all the truck has 220k miles almost with supposed 160k miles on new tranny w/ shift kit.

 

[sewlow]

A trans that shifts soft is slipping slightly between gears.
Most transmissions were designed with this so that the masses get a vehicle that shifts 'smooth'. But it's that slippage that creates heat, & heat kills transmissions. Smell the trans fluid. If it smells burnt, then the rest of the tranny is too.
The less time the transmission spends going from one gear to the next, means that there is a lot less heat being generated. Those firmer shifts can be a little harder on the rest of the drivetrain, though. Probably why the PO swapped the posi unit. Gov-locks don't like to be hammered like that. They go Boom!
If you think that the auto with an s-kit shifts hard, go for a ride in a vehicle with a high HP engine, a stick, & someone that can bang shifts! Now that's hard on a vehicle!
An automatic can shift faster, (constantly in gear) & it's a lot easier on the rest of the drivetrain!
If that 'clunk is pretty bad, or gets worse, I'd be checking those u-joints, the u-bolts, shackle & hanger bolts, & the engine & tranny mounts.

 

[ccreddell]

A trans that shifts soft is slipping slightly between gears.
Most transmissions were designed with this so that the masses get a vehicle that shifts 'smooth'. But it's that slippage that creates heat, & heat kills transmissions. Smell the trans fluid. If it smells burnt, then the rest of the tranny is too.
The less time the transmission spends going from one gear to the next, means that there is a lot less heat being generated. Those firmer shifts can be a little harder on the rest of the drivetrain, though. Probably why the PO swapped the posi unit. Gov-locks don't like to be hammered like that. They go Boom!
If you think that the auto with an s-kit shifts hard, go for a ride in a vehicle with a high HP engine, a stick, & someone that can bang shifts! Now that's hard on a vehicle!
An automatic can shift faster, (constantly in gear) & it's a lot easier on the rest of the drivetrain!
If that 'clunk is pretty bad, or gets worse, I'd be checking those u-joints, the u-bolts, shackle & hanger bolts, & the engine & tranny mounts.

Yeah, this. You keep saying slipping and hard shifts in the same sentence, and you cant have both. Either it slips, or it shifts hard. If youre hearing a real mechanical clunk, chances are its not the tranny.

 

[SAATR]

A little clarification: hard, fast shifts are good for the life of the clutches due to decreased slippage and heat generation. HOWEVER, tire chirping, neck snapping shifts kill hard parts, period. You may save the clutches, but take out the reaction shell, forward sprag, input drum, planetaries, or any combination of those in the process. If your buddy likes to drive with his foot in it, he may need that spare trans sooner than he thinks. You didn't mention what kind of truck he bought, but 400's can and do break reaction shells and planetaries when completely stock. With lockers and bigger/wider wheels and tires it's even easier. Food for thought.

To answer your question, yes, it sounds like a shift kit. Most kits will have you make several changes to the valve body to change shift timing and firmness. Automatic transmissions have accumulators in the valve body that cause a delay between the time a valve opens and when the clutches are applied. This serves several purposes, but primarily acts to make the shift smoother and to ease clutch engagement to reduce shock loading of the transmission and driveline. By opening up the metering orifices in the separator plate and/or changing the accumulator piston spring, you can reduce the delay and create a quicker, firmer shift. The problem is that too little delay serves no purpose but to make the shift feel harder and tear up hard parts without any performance benefit.

 

[sewlow]

A little clarification: hard, fast shifts are good for the life of the clutches due to decreased slippage and heat generation. HOWEVER, tire chirping, neck snapping shifts kill hard parts, period. You may save the clutches, but take out the reaction shell, forward sprag, input drum, planetaries, or any combination of those in the process. If your buddy likes to drive with his foot in it, he may need that spare trans sooner than he thinks. You didn't mention what kind of truck he bought, but 400's can and do break reaction shells and planetaries when completely stock. With lockers and bigger/wider wheels and tires it's even easier. Food for thought.

To answer your question, yes, it sounds like a shift kit. Most kits will have you make several changes to the valve body to change shift timing and firmness. Automatic transmissions have accumulators in the valve body that cause a delay between the time a valve opens and when the clutches are applied. This serves several purposes, but primarily acts to make the shift smoother and to ease clutch engagement to reduce shock loading of the transmission and driveline. By opening up the metering orifices in the separator plate and/or changing the accumulator piston spring, you can reduce the delay and create a quicker, firmer shift. The problem is that too little delay serves no purpose but to make the shift feel harder and tear up hard parts without any performance benefit.

Wisdom from a transmission guy! Good stuff! Great explanation!

 

[ridiqls]

A little clarification: hard, fast shifts are good for the life of the clutches due to decreased slippage and heat generation. HOWEVER, tire chirping, neck snapping shifts kill hard parts, period. You may save the clutches, but take out the reaction shell, forward sprag, input drum, planetaries, or any combination of those in the process. If your buddy likes to drive with his foot in it, he may need that spare trans sooner than he thinks. You didn't mention what kind of truck he bought, but 400's can and do break reaction shells and planetaries when completely stock. With lockers and bigger/wider wheels and tires it's even easier. Food for thought.

To answer your question, yes, it sounds like a shift kit. Most kits will have you make several changes to the valve body to change shift timing and firmness. Automatic transmissions have accumulators in the valve body that cause a delay between the time a valve opens and when the clutches are applied. This serves several purposes, but primarily acts to make the shift smoother and to ease clutch engagement to reduce shock loading of the transmission and driveline. By opening up the metering orifices in the separator plate and/or changing the accumulator piston spring, you can reduce the delay and create a quicker, firmer shift. The problem is that too little delay serves no purpose but to make the shift feel harder and tear up hard parts without any performance benefit.

Ah! Just what i was looking for. Learn something new everyday. Thanks. So it does look like it is a shift kit. Thanks everyone