Here's our first prototype of the aluminum low/reverse drum with upgraded 12 roller sprag. The factory sprag only has 8 rollers, this prevents the high gear drum from flying apart.
Here's our first prototype of the aluminum low/reverse drum with upgraded 12 roller sprag. The factory sprag only has 8 rollers, this prevents the high gear drum from flying apart.
What transmissions does it fit? Are you planning on selling any?
These are going to be for the 3 speed auto.
I can't remember right now...is the sprag used in all forward gears or only in 1st while in the "D" position on the stock automatic valve body?
As I understand it the sprag is a known weak point. I am also pretty sure that there is a way to hydraulically accomplish 1st gear without using the sprag. Besides adding to things that need to move to engage 2nd gear, is there any benefit to doing it that way and if so, why not just bypass the sprag all together and just make it as light as possible?
The sprag is only against the one-way in 1st, it spins I'm second. Your thinking low band apply, I'm currently working on a valve body using the newer cores. It will be reverse pattern, low band apply, 1-2-3-n, and ability to regulate reverse line pressure separate.
But you cannot get around the sprag, low band will help prevent the drum from flying apart but the sprag still slips tearing the race up and eventually sends the high gear drum flying. The only way to fix it is to add rollers.
Ah...ok. It's been a while since I really looked at it, so thanks.
Next part I'm working on is the forward drum out of aluminum. It will be splined to use 904 clutches for high gear drum which have a lot more surface area and will be more readily available.
I know these are race only type parts, so the transmissions get torn down for inspection "regularly". I am wondering how you are attacking any issues that might arise from the clutch spline teeth wearing away at the drum splines?
I will use 7075 which is about the strongest you can go. It's what everyone uses and they see little to no wear. Now for the forward drum I'll probably have it hard anodized.
2nd the question about - are these going to be for sale?
I will offer people a chance to get in on the batch once I get more of the details worked out. Still working on final price and quantity, I just didn't want to break any rules since I'm not a paying vendor.
The the drum itself does not wear, the rollers slip on the race and chews it up. Once they slip it sends the high gear drum 2-3x engine speed and the drum flies apart. Ill post pic of my trans after the drum exploded. Now if the car isn't leaving hard or stalling high then maybe you won't need it. I just wasn't chancing ever again, I don't want to be hit with drum chunks.
I guess if the sprag slips the drum is spinning the same speed it would in 1st gear which is ~2.6x engine speed. It would feel like a slipping condition but with such a strong motor it would go from sprag slipping to drum exploding so fast you might not be able to let out quick enough.
Dont push the red button.You hear me?
I couldn't tell that the sprag was failing, I was foot braking the car and let off the brake and a loud bang happened. Here's the aftermath.