Hi all. I haven’t posted on here in a while. I posted my 511 trickflow 270 combo several months ago that made 742/699tq on the dyno.
I plan to keep the car a stick shift and I plan to street drive it quite a bit. Car weight will be around 3500, and it has a strange Dana 60.
I am checking my options for a replacement for the 833. Id rather not go with the 6 speed magnum due to size weight, and no need for a 6th gear. My thoughts are If I can upgrade a tko to handle more than the 600ft lb rating would that be a option being I can get everything that just makes it a bolt in? Gforce is another option I’m checking into. I’d like to hear from some who have done it and what their experiences are. I don’t mind doing a little fabbing etc, within reason. Are there any other good streetable options?

Your most reliable and cheapest solution will be a 727 with a full manual valve body. Just tell yourself that you have a super high dollar clutchless manual when you drive it.

Liberty LSC5100. Have them install road race sliders, and it can be street driven.

American Powertrain offers an upgrade option for the TKX ... says it can handle 900 lb.ft. See: https://americanpowertrain.com/shop/transmissions/tkx-5-speed/tremec-tkx-extreme-upgrade/

I was on their website several months ago and they mentioned that they were working with Pfitzner Gear on an upgrade gearset for the TKX. I don't see that mentioned for the TKX anymore but they do mention this gear upgrade for the Magnum 6-speed at: https://americanpowertrain.com/amer...ear-upgrades-for-tremec-magnum-6-speeds/

I'm in the same situation needing an upgrade for my A-833 ... I've come to the conclusion as AndyF says that a race automatic with a transbrake is in my future. I've been rowing my own gears in the Cuda for 40+ years but its time for an automatic now. It will be tough to look in the console and not see the pistol-grip shifter handle in there.

Is the Gunslinger pistol grip still available for the console auto shifters?

It depends on if you want synchros in all the gears or not. If you want synchros, The G-Force GF3650 will more than handle your horsepower. Otherwise the t56 Magnum.
If a face plated transmission without synchros is okay with you, I agree with Jeff that the liberty LSc5100 would be a good choice.

I'm not aware of any modern, high torque capable transmission that won't require cutting the cross member. Just save the pieces you cut out. They can always be welded back in if you ever want to.

I would consider the TKX if you're going to be on a street tire.


Probably will need something stronger if using a drag radial or sticky tire at the track.

What's the torque rating of the Passon 5 speed? (though not sure if they are ever really available)

Comparing a transmission/gear manufacturer's torque rating to your engine dyno torque numbers won't tell you much. When you are actually going down the track, much faster engine acceleration and pulldown rates come into play which can have a huge effect on the input shaft torque numbers. Turns out it's actually the clutch that has the final say as to whether the typical street/strip manual transmission lives or dies, as the clutch controls the intensity of the inertia discharge spike that is created as engine rpm gets pulled down against WOT.

To illustrate the point, here's some dragstrip data...



Here's some averaged input shaft torque calculations for the above graph. It shows this example's 425ftlb engine only produces 204ftlbs at it's 1st gear engine acceleration rate, but when that same engine gets pulled down quickly against WOT by the clutch, the input shaft see the engine's full 425ftlbs + another 1046ftlbs that comes from inertia energy exiting the engine's rotating assy after the 1/2 shift...



Here's those calculated input shaft torque numbers, multiplied by the transmission's gear ratios, then compared to this run's actual Accel G trace...



When you reduce clutch clamp pressure it reduces the clutch's inertia draw rate, which in-turn reduces the intensity of the inertia induced torque spikes sent to the transmission's input shaft. For this example clamp pressure was reduced enough to double the clutch's slip time, and that increased slip time cut the intensity of the torque spikes in half...



Those smaller torque spikes now last twice as long, which will also boost that area of the car's accel G trace.

Here's a graph comparing the slower inertia discharge rate and the previous driveshaft torque numbers...



Notice the nice stair-step effect the clamp pressure change had on the torque spikes as it works it's way thru the gears. You could stick a 400hp shot of n2o between each of those spikes and still not exceed the torque applied to the driveshaft during that dead hooked launch

Grant

I have a 70 cuda that was at this power level and now is above 1100 wheel. I originally switched to a DR4 jerico, which didnt last. Ended up fixing it all the time, which pushed me to a G5R G-force. The G-force has been amazing. I use it for street driving and have even done some 100+ mile cruises and race, and cruise home without an issue. i also run a twin disc slipper clutch. Having the right clutch for the application is critical.

Grant,
That is a really excellent post.
Thank you.

Been a long time since I raced a stick, but I will go along with the clutch has to be right or it will kill the transmission. From my experience many years ago with a metalic three puck clutch disc, and a nash proshifted A833, if the disc had a sprung hub and it was set up to slip just a little, it not only 60 footed better Transmission lasted much better as well. I ran a four speed in a bracket car low 10's for 12 years and never broke a transmission.

The Liberty or the G-Force transmissions will hold what you have with the right clutch. They both use the Nash design that has been in use for many years and it's a race proven design that has been improved by both companies.
Like Joel said it will take some cut and fab work on the cross member with a custom built mount.

Gus

I agree. Very interesting and important info for stick cars. Thx

Thanks Grant. Very interesting information.

More good clutch info here:
https://youtu.be/wRRSPQ_FJUc?t=433

That's very good info Grant. But do you suppose that when the manufacturers of a transmission give it a torque rating they took a torque measuring device to the input shaft, locked up the output shaft, and leaned on it till it broke and then give it a torque rating accordingly? Or do you suppose they test it in cars of various torque outputs and see what it takes to break it? Or do you suppose they're just estimating?

I did call and leave a message with American power train. I am curious about the tkx upgrade. I will look into the Gforce as well.
What do you guys recommend for a clutch? Also do you recommend an aluminum or billet flywheel? Thx.

Call Hyatt Racing for your clutch & bellhousing

I wouldn't bother with AP if I were you. Been there done that.

Is Tim's son carrying on the business since Tim passed away? Haven't heard anything about the company since then.

Call Cale Aronson of Black Magic Clutches. and discuss your entire combo, and he can point you in the right direction.

I think oem torque ratings are more about the ability to handle long duration loads, not as much about impact. It would be fun to static test to the failure torque in each gear though!

Grant