[Jason@JacFab]

So after seeing a post in another thread about how great ford was, because they have magic toys and aftermarket support, I decided to research some of said toys. The main point on interest being the "trans brake" that is available from just a tune from Cobb. Well after digging a little bit, turns out JMS makes a wire in trans brake box, and even before that some home-brew guy came up with a way to do it externally with some wire splicing, a few relays, and a button... The big guys basically took that, and commercialized it. JMS made the box. Cobb, just figured out the tune programming to do it all internally. Even with the home-brew approach, it still needed some tuning tweaks to work right, but eh, doesn't everything? That should be attainable...

I started doing some research on how that Ford trans-brake worked, and while I'm still not 100% there, I under stand what they are doing, and am trying to figure out how we can apply the old school way of wires and relays to the GM transmission as it works on the same principal as the Ford 6R80 with both normally high, and normally low shift solenoids, swap some signals, and pow, maybe we've got a trans brake too....

I missed the JacFab'in Friday video because I was gone for 6 days for Christmas, but I discuss the theory in the video below...



https://youtu.be/hkKNSKUykDE

If you watched the video and picked up what I'm laying down, I think it very well may be doable to do the same thing on the GM cars? Disable a few DTC's and we're in business.

If you're interested in this project, feel free to watch the video because I explain how it works to the best of my knowledge there, and I don't feel like typing it all out, it was easier to talk about it.

But in a nutshell, they (Ford guys) are swapping the signal to two shift solenoids to engage reverse while in drive. My issue I can see with the GM stuff, is that especially in first gear they are already engaging 2 of the 3 reverse clutches in first gear, where as in the ford looks to not be using any of the reverse clutches in first. Very interesting stuff.

Do you understand Gm transmission, are you a GM engineer, or transmission builder by trade? Please feel free to chime in on the pieces of the puzzle that I am missing.

[dpelow07]

yes good job jason! this would be huge if you figure it out

[ChicagoTommy]

I'm game to figure this one out. I'd love to be able to do it without a 'box', but that would require some extremely custom and very trick programming, and the software to perform such programming doesn't currently exist for the LTG platform. One major hurdle that would need to be overcome would be communication with the BCM, if you wanted to involve the brakes in any manner, like setting up a line lock.

As far as glimmers of hope go, I have seen an LS1 car set up with a two-step that was done via HPT, and activated by the cruise control stalk.