Thanks chook, I've been looking at all options that avoid double declutching as my clutch leg is a bit wonky. I presently run a sequentially shifted 4L85E behind the LS3, it works OK and certainly helps when racing but at 116kg it's just too heavy. The alternative choices have been narrowed down to a Powerglide auto with a Gear Vendors over/under drive which in total is about 50kg lighter, four speeds with the right spacing are fine.
Problem yet to be solved is how to sequentially shift such a combo with a single lever and nothing else.
If you go manual, you are going to have to get a box with Dog Rings. A 4 or 5 speed Jericho and Haltech can take care of flat shift on up-shifts no problem. . There are sensors that work on the shift lever that detect when you pull on the gear lever. They are very accurate. You can get either Torque load sensors or linear motion sensors. They work on both sequential and H pattern shift levers. This is what the Aussie V8 Supercars use.
You can pick up a good used Jericho 4 or speed from shops that sell used Nascar parts. You can get some pretty good deals if you shop around. All the major Nascar Teams sell off used parts. The junior leagues such as Infinity series are a bit cheaper. For the 5 speed, check out SCCA used forums.
If it's in your budget, a used 4 speed Jerico from a Nascar team may be your best bet. You can use a sequential or H pattern shifter. Sequential would naturally be preferred, but could be added later. Then a shift sensor on the shift lever. Transmission with dog rings is going to be the biggest expense.
Downshifts just manually blip with your right foot. Note: Make sure you over rev and catch the change on the down swing of revs. A dog box will just fall into gear when you do it properly. No need for fancy Rev-up software. Your right foot and brain are more adaptable than any software programming.
The secret to clutchless downshifting is the over rev. Most people don't give a hard enough blip. You have to get the engine RPM range ABOVE the engagement RPM for the lower gear. A slight but swift pressure on the lever, and the gear will just fall into place. Swift movement of shift levers with a dog box is essential. Dog boxes are made to with stand a " Crunch " on gear changes. What they don't like is too slow of a shift, that gives you some " Fine ground coffee " and 10 cents change. Dog boxes take commitment on gear changes. But when you get it right they will literally shift like butter.
For upshifts with no clutch, it can be easy. You don't really even need the flat-shift hardware and software. Just do a quick, slight lift of the accelerator and pull the shift lever. Speed of shifting is the secret. Do everything quick and with commitment, and the Dog Box will be happy.
One other thing. Always try and shift ( up and down ) at the top of the Rev range. This is where you will have minimal shock loads from Torque differential between gears. Dog boxes don't like to be shifted at low or medium RPM's. Fat part of the torque curve is the worst place to shift a Dog Box.
I have some links for shift lever sensors for flat shifting. Gotta run right now, but I'll post them up later this evening.
Edited by Chickenman, A week ago.