TH350 2nd Gear launch - Pros Comment
10-07-2008, 07:30 PM
#1
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TH350 2nd Gear launch - Pros Comment Is it more harsh on the trans launching of the trans brake in 2nd gear then it is in 1st. Please don't ask why, just need to no. It is a built th350
10-07-2008, 09:11 PM
#2
It's a lot of load on the intermediate sprag.
If it is truly a "built" TH350 it should have an upgraded sprag element. I use a 36 element sprag on a modified drum and this makes it much better than stock.
However the best setup to do this would be to use a "spragless" setup where the drum is solid and the VB is setup to release the 2nd clutches on 3rd apply.
That way there isn't a sprag to break.
If it is truly a "built" TH350 it should have an upgraded sprag element. I use a 36 element sprag on a modified drum and this makes it much better than stock.
However the best setup to do this would be to use a "spragless" setup where the drum is solid and the VB is setup to release the 2nd clutches on 3rd apply.
That way there isn't a sprag to break.
10-09-2008, 12:52 PM
#6
I think I pretty well covered it...
I build GM automatics for exclusively performance usage so I have an in depth understanding of the dynamics involved here.
The TH350 has PLENTY of clutch apply and friction area in 2nd gear, so there isn't an issue there, the planets are pretty stout, I don't see an issue there. There isn't anything else to hurt.
You should be fine to do a 2nd gear launch.
The things I would caution,
your converter is going to build more heat, take care of that.
You do NOT want to backpedal it in 2nd. If you let off then get back in it, the sprag will go from locked, to over-running, then back to locked, and going from overrun to locked under heavy power with good traction is brutal on it.
A few racers are running Glides in high gear only. This would be like running a TH350 or 700/4L60E in 3rd gear, same ratio.
What you are proposing is being done with TH400s which work on a very similar priciples of operation.
I build GM automatics for exclusively performance usage so I have an in depth understanding of the dynamics involved here.
The TH350 has PLENTY of clutch apply and friction area in 2nd gear, so there isn't an issue there, the planets are pretty stout, I don't see an issue there. There isn't anything else to hurt.
You should be fine to do a 2nd gear launch.
The things I would caution,
your converter is going to build more heat, take care of that.
You do NOT want to backpedal it in 2nd. If you let off then get back in it, the sprag will go from locked, to over-running, then back to locked, and going from overrun to locked under heavy power with good traction is brutal on it.
A few racers are running Glides in high gear only. This would be like running a TH350 or 700/4L60E in 3rd gear, same ratio.
What you are proposing is being done with TH400s which work on a very similar priciples of operation.
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10-13-2008, 12:55 AM
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It's a lot of load on the intermediate sprag.
If it is truly a "built" TH350 it should have an upgraded sprag element. I use a 36 element sprag on a modified drum and this makes it much better than stock.
However the best setup to do this would be to use a "spragless" setup where the drum is solid and the VB is setup to release the 2nd clutches on 3rd apply.
That way there isn't a sprag to break.
If it is truly a "built" TH350 it should have an upgraded sprag element. I use a 36 element sprag on a modified drum and this makes it much better than stock.
However the best setup to do this would be to use a "spragless" setup where the drum is solid and the VB is setup to release the 2nd clutches on 3rd apply.
That way there isn't a sprag to break.
