Phil1305

I searched but didnt find anything, just wondering how much of a possibility it could be to swap an older 722.6 into our m156 cars? More so for the reliability for drag racing and forced induction setups. I see they offer stand alone kits for older cars to convert but would the coding be that hard to get it to work some what normally in our chassis, using paddle shifters etc.

You can build a bullet proof 722.6. This is more of a drag racing question but with still having functionality of being able to track the car on a road course if desired.

G_Money

I think the 722.9 MCT can hold about the same power as the 722.6. Plus it's faster.

Phil1305

I'm pretty sure mr 747 said hes gone through 3 weistec built trans, plus with the 722.6 you can do valve body upgrades and install a trans brake.

As long as the gearing is decent you can modify most other things to match the 722.9 mct.

I like taking my car on back roads but I live 10 minutes from a drag strip, and honestly even though I get 1.8 60' times that's not really acceptable to me.

I think the 722.6 has a better chance at being an all around trans...... maybe I'm wrong.

G_Money

Iirc mr747 has the non-MCT 722.9. Built, I know.

Phil1305

Ok, I was unsure of his trans then. I thought mct.

I will be going stage 3 weistec more than likely the end of winter and when my trans goes just looking into something that will leave the line a little harder.
I mean I make 473 whp and it just doesnt leave hard enough for me, at least on race start. I'm going back to the track in a couple weeks and going to test lifting the brake and smashing the throttle for the hard launch I want.

Also though I do want to do a few road course events as my supporting mods are done. I know oxy moron with a whipple but this car can handle.

Adi-Benz

The 722.6 has a valve body upgrade because it shifts slow compared to the 722.9. It'll ruin your shifts completely.

Probably no point.

deadlyvt

Ya a 722.6 for a road course would be a downgrade. The shifts are so slow

roadtalontsi

What makes you think the 722.6 is better or stronger? because a lot of 55K guys with a pulley, tune and headers have them? I feel like most people dont realize they used a 722.9 transmission in v12's, and all the m157 cars etc....
When are we going to have a 725 retrofit kit thats why I think the people want. new 9 spd is a bad mother thus far.

mr747

Yes i have been through 3 trans this one seems to be good but again i dont think it has much more left in it

The problem with 722.9 is you have to row through too many gears when running ovver 140mph im having to change into 5th and even with a gear change in the rear we are having to rev to 7600rpm past line
722.6 is more suited to drag racing then 722.9

BalanBro

The MCT 722.9 may be different with updated clutch packs, but initially, the 722.6 was the higher rated transmission for input torque, and is why the "65" series V12s kept the 722.6 around for a while. I wonder if the 722.6 trans as a whole is stronger, clutch packs aside. Fewer gears mean more real estate to make component beefier if transmission cases are kept equal.

https://www.transmissionrepaircostguide.com/722-6/

mr747

Correct it can handle more TQ then 722.9

Phil1305

This is what I was thinking, with less gears you can let the power of the engine accelerate the car not the excess gears. And with the valve body upgrades I dont see why it couldn't shift as fast if not faster than a 722.9. Plus installing a trans brake is a plus for drag applications.

If you could also code it so the paddle shifters work like stock that would be awesome. Just an idea that could make the car perform better I think.

Lastly my MCT at the track with 473rwhp just doesnt launch hard enough. I went 11.69 @121mph with 1.8 60'. If I could cut 2 tenths off my launch with decent 1.6's that would help tremendously. I'm going back friday and going to pedal brake it to get a harder launch we'll see what happens.

Phil1305

This is exactly what I thought, alot of guys chime in about shift speed but that can be enhanced or modified on the 722.6. I want torque capacity so the trans can take more than i can throw at it.

G_Money

They actually started using the 7 Speed MCT in the 65s starting in 2013 model year.

mr747

Even in this new gearboxs in C63s the cars dont launch they make up the times in the top end

No c63s has gone even close to 1.5 60ft

Moral of the story here is these gearboxes belong in the bin

Jasonoff

For your particular application...

mr747

Out of all european brands AMG is behind the 8 ball with there gearboxes

Its a fact they are slow and dont change when you want them to

deadlyvt

they are but the 722.6 is probably the slowest “performance” transmission ever built it’s super slow at shifting. Would be going back by using it. You would be better off trying to get one of the newer zf units to mate up and work imo

mr747

You are 100% right 722.6 is a dinosaur lol but lets face it my car once its back on the road wioo not be a street car we will see how long the 722.9 lasts before i put a powerglide in it

Phil1305

Agreed, even doing roll racing against cars I should beat. I have to wait till my top end kicks in to pass them.

I dont think the mct is all bad but certainly not for drag racing even a little bit. I was just thinking that with the 722.6 you could build an awesome all around transmission for drag or road course etc.

G_Money

What are you rolling from and in what gear? What cars are beating you that you think shouldn't be?

Also for the 722.6, that trans brake and the valve body upgrades are for the Dodge cars that used the 722.6 in the Daimler-Chrysler years right? Have you read up on upgrading the solenoids?

Jasonoff

Fair play, in comparison to other brands, sure.

I took this car to the road course once when my track rat was between engines and it did a surprisingly excellent job with shift points in sport mode.

Phil1305

I'm not saying this trans is bad, I love it when taking back twisty roads or road course style driving. It just doesnt perform when drag racing and with swapping a 722.6 and building or upgrading it I could get th ed best of both worlds. I fully agree a stock .6 would be a slug. But building it and upgrading the valve body I'm sure could bring it on par pretty easily.

Phil1305

Most of my rolls are roughly 40mph. But I have been pulled on by a few cars that get me in mid range then my top end will shine. I will admit I'm not one of these dumbasses that thinks the holy grail c63 is the fastest on the streets..... hell most of my friends are in the 700-1100whp range and a few close to 1500.

And I looked at a company in Florida that did the Chrysler 722.6 trans builds fir the srt8 and track hawk but they also offered mercedes builds. And there was a guy I think on benz boost or somewhere that offered the trans brake for mercedes 722.6 although not cheap but I'm going to have to build it anyway.

Phil1305

just a screen shot I took of 722.6 upgrades offered.