American power train offers A body 6 speed manual

-
07raptorgytr

07raptorgytr

Well-Known Member
Joined
Oct 12, 2015
Messages
89
Reaction score
8
Location
Ohio
I know it probably doesn't belong here, but I just heard American Power train is now making a complete 6 speed conversion that fits the a bodies. I do not know if there is any tunnel mods that is done to make fit, but looks like a viable option over the passon 5 speed that looks like will never make mass production
 
6 gears,eh? I couldn't find a Mopar app.

With a double O/D, a 6 spd (4+2)is almost too much for a hot streeter.
This is because of the way the ratios play out, and how low the rpms fall in top gear;falling well below the cam's happy place.For most of us a 4+1 is more than adequate;especially if the ratios are progressively tighter as they approach Direct.
For a 4+2 to be effective,our cars would need to cruise at a pretty good clip, and for a pretty good distance, to make it worthwhile. With speed limits up here being 100kph(62mph) in most places, second o/d would put my rpm so low that the engine would be operating in a very inefficient zone. I suppose if first o/d was real tight, and strong enough, one could gear the car to trap in it. And then if second o/d was far enough away to put the sbm at around 2000@65 rpm with something like 4.30s,and 28s;now that would be something. Or, if the 6 was a 5+1, that would help our small blocks out a lot.

My car might not benefit with a 6 speed. I proved that with the GV behind the 3+1 A833. That combo gave me 5 useable, very tight, full-power ratios, plus 2 o/ds. The ratios were;
3.09(2.41)1.67(1.30)1.00(.78).55 and the splits were .78-.69-.78-.77-.78-.71 I ran this with 4.30s to be able to trap at 112@6000. Top gear was the equivalent of a 2.38 rear,making 65mph =1922rpm and the starter gear was 13.29.. That was pretty sweet. For a Strip/street car. But way too much shifting for a DD. I decided that for a DD,there really was such a thing as too many gears.
I currently run a 4+1GV, and am very happy. As a DD,with 3.55s,It has a starter gear of 10.97 and a highway gear of 2.77. This works very well with my 230/237@050/110 cam.
The ratios are 3.09-1.92-1.40-1.09-(.78od), and splits are .62-.73-.78-.71
 
I was looking at the tko 6 speed for my dart awhile back.
but i read somewhere that the gear spread was nuts. Either i would use the first three gears to get overdrive. Or use overdrive but not the first three gears. So i wrote it off that it was just a 4 speed with two overdrive gears.
This is stock ratios in vipers, corvettes, challengers. American powertrain may have a better gear spread.
 
Almost to much for the street?

Sorry, hard pressed to actually believe that. LMAO!
The GV-OD seems overkill.
 
I just seen it on facebook, mopar magazine did a article on it. The kit comes with crossmember and torsion bar crossmember parts to make work. As far as I have seen I do not know the exact details of what is included.
 
Buddy of mine has a Chevy w/ a 427 and he put a 6 Speed behind it. 4.29 gear and he can lift the front wheels and still gets 20mpg
 
07raptorgytr said:
I just seen it on facebook, mopar magazine did a article on it. The kit comes with crossmember and torsion bar crossmember parts to make work. As far as I have seen I do not know the exact details of what is included.
Click to expand...

Where on Facebook did you see it? On the Mopar Muscle page or the American Powertrain page?

I'm thinking that with 6 speeds you can run a numerically high number rear gear. That would be great for off-the-line performance AND it's cool to have 6 speeds.

I just want to know if I need to cut up my trans tunnel especially since I already have a 4 speed tunnel. That's something I would like to avoid.

I would love a bolt in kit where there's no body modifications and the shifter comes out of the factory 4 speed location. I wouldn't even mind a hydraulic clutch too.
 
07raptorgytr said:
I just seen it on facebook, mopar magazine did a article on it. The kit comes with crossmember and torsion bar crossmember parts to make work. As far as I have seen I do not know the exact details of what is included.
Click to expand...

I glanced at that, they made it look easy because the car had coil overs so they didn't have to address the torsion bar cross beam....

The only drop in for factory manual cars it Passion (if you can get one and have $4500ish laying around) or the soon to be released (sometime between now and never for Mopar, because you got to get those GM guys a 25th option for transmission before we get 2) the McLeod 5 speed.
 
JoesEdge said:
Where on Facebook did you see it? On the Mopar Muscle page or the American Powertrain page?

I'm thinking that with 6 speeds you can run a numerically high number rear gear. That would be great for off-the-line performance AND it's cool to have 6 speeds.

I just want to know if I need to cut up my trans tunnel especially since I already have a 4 speed tunnel. That's something I would like to avoid.

I would love a bolt in kit where there's no body modifications and the shifter comes out of the factory 4 speed location. I wouldn't even mind a hydraulic clutch too.
Click to expand...
On the mopar muscle page
 
there is a close ratio option for that Tremec 6 speed. Looking at the ratios, they aren't that bad.
2.66, 1.78, 1.30, 1:1, .80, .62.
 
rumblefish360 said:
Almost to much for the street?

Sorry, hard pressed to actually believe that. LMAO!
The GV-OD seems overkill.
Click to expand...

In my opinion yes, and here is why;
There are two 6 speed ratio sets, and here is the first;
2.97-2.10-1.46-1.00-.74-.50 and the splits:71-.70-.71-.74-.68 If you put 4.30s out back,you can trap from 5800(112) to say 6600(128). And your starter gear is 12.77
Now if you are down on power, and can only muster 112mph, then the 12.77 starter is a little shy. But if you can pull 128, you have a heck of a SBM. Hardly streetable. So what's it gonna cruise at? At 65 with 28s,1st over is 2482;the cam likes that. In 2nd over, 65 is 1688. Just try cruising that big motor at that. But you say dod is good for high speed cruising,right. Well that cam is barely cruisable at 2200, so what mph goes with that? Answer 115mph.So basically with a real motor and 4.30s, you have a 4+1, and 1st is kinda shy.
Now let's talk about those splits. An engine of this caliber will have a fairly narrow powerband.Unless it's a stroker, which it kinda needs to be to hit 128 at 6600.So lets assume it wants to be shifted at 6600. The drop-ins will be;4686-4620-4686, so that would be a powerband requirement of about 1950;so at least that's doable.
-But let's get back to a smaller engine. And let's run 4.88s. This engine might trap at 6600@112.7. Again that's a pretty big cam. So the starter gear is now 14.49. Well that's a little deep! First over will get you 65@2817, a little busy, but the cam is happy. And Second od will get you 65@ 1903; Doable, but just. So what exactly do you have for a streeter? A nearly useless first gear, and a nearly useless 2nd od. Thankfully starting in 2nd is easy cuz it is 10.25 ratio.Total answer for a streeter; you have a 3+1, and a driveshaft that is disparately trying to throw it's u-joints.And you paid how much to be able to say "I have a 6 spd!"
Okay so really what is a 6 speed good for?
To make the best of this tranny you will have to build an engine to use it. So let's back up the bus.Let's build a streeter.To use 2nd O/D, and to use the deep low, and let the rest fall where they may.Okay, from experience I know that a nice SBM starter gear is between 10/1 and 11.5ish tops.So 10.75 is a happy average and thus 10.75/2.97 = 3.62s; smack in the middle of 3.55s and 3.73s. I'll go with the 3.73s cuz Ima gonna need 'em for cruising.So now we have a starter gear of 11.1. Where will it have to cruise? Well, again with 28s, 65mph will be;2152 and 1455. So what to do?To pull 65@1455 and be easy on fuel,(I mean that's the whole big deal about having a Double Over-Drive,)will take a teensy,weensy, cam. We are talking 2bbl cams. Very short duration cams.Well maybe you live in a place where the speed limit is 85. Ok, I can dig it.85mph will bring the rpm up to 1903. So now you are into streetcam territory.Something in the range of 218 to 228 @050. But consider this; There is no good reason that I couldn't have selected 3.55s and then 85mph would be 2678 in First over; and we are back to a 4+1.
So,What have we learned?
It is my opinion,
that for;a normally aspirated V8 car, be it a streeter, a street/stripper, or a track-only car, in Canada at the very least; and if you never or rarely hit the interstate:The 6th gear is almost too much for anything, never mind; "almost too much for the street"

Now there is a second gearset;and
It is my opinion that it is much better for a streeter. The ratios are
2.66-1.78-1.30-1.0-.80-.64 and the splits; .67-.73-.77-.80-.80
-First notice the progression in the splits. Each successive ratio, carries a smaller powerband requirement. This works to keep the engine closer and closer to it's power peak, as she goes faster and faster, and has to fight her way through the air. Sweet! Next notice the total spread from the first gear to the last gear. It is much tighter. Then check out the 4-5 split;80%. This tranny begs to be used as a 5+1., But not as a dragracer.
-So lets check it out as a dual purpose car. Again shooting for a starter gear around 11.50max, we get a rear of 4.32; so 4.30 it will be. This gets us a starter gear of 11.44(perfect) and a trap gear of 4.30(also perfect).So we have a very nice 4-gear strip car. Now, soldiering on to cruise mode;65mph with 28s again will be 3123 in First O/D, and 1999in Second O/D.
Well, what do we have? Since First O/D is pretty much useless we again have a 4+1.
And again I ask;you paid how much to be able to say;"I have a 6spd"?
It is my opinion that you will be hard pressed to find an application in N.America, where a 6speed will be a benefit to a NA. V8. So far as I can figure out, there is just one place in all of North America where you could use it, and only at one time of the year. And it will cost you more money and time than you can imagine, to be able to run with the big boys.

-Any ways; as to my combo and overkill ............My combo has some real nice ratios;
3.09-1.92-1.40-1.09-.78 with splits of .62-.73-.78-(.71od) Notice the progressive splits, from first thru fourth. If I run it with 3.91s, I get a starter gear of 12.08, a trap gear of 4.26, and a cruise gear of 3.05 which gets me 100Kph(62mph)@2269 just about where my 230 cam vacuum peaks.
But hey, I have a splitter, I can split 1-2, and I can overdrive second.
The ratios thus are 3.09-2.41-1.92-1.50;splits; .78-.797-.78.. So what you ask? Well with 3.91s out back the track-starter is 12.08, and in the 1/8th, 2nd over will be 93.8@6600,Shazzam! But I want you to notice that;I'm in second o/d. That's right; I pulled the stick just once. And the powerband? 1450rpm. Overkill? You betcha. And,Ima crusin home at 2269rpm. Does it get any better?


So sorry OP, for the interlude;drive on thru....
 
Here's a shortcut, for streeters, to help select a manual trans; Take the first gear ratio in the box and devide it by the highest ratio in the box. A streeter likes this to be about 4.0 to 4.5tops

Mine is 3.09/.78=3.96,
The 6 speeders are 2.97/.50 =5.94. But notice that in first od it is 2.97/.74=4.01
and the alernate ratio is 2.66/.64 = 4.16;
The Tremek 5 spds are;3.27/.68 =4.81, and 2.87/.64 =4.48

For comparison; the A-833 family runs 3.09/1,and 2.66/1,and 2.47/1, and the superwideratio O/D box is 3.09/.73=4.23,right smack in the middle, of the target.
 
Well seeing that Iam going to run a 31" rear tire, with 4.88 gears this might be a viable option for me. If the math is done right I can run the tranny in 5th gear for my everyday driving and run a 2400 rpm at 55mph. Then when I hit the freeway where speeds are 70+ mph I can drop it in 6th and still be running at 2333 rpm.
My car will be a street/ strip combo build. So it would be nice to have the gearing to shred up the track and then cruise down the freeway getting descent fuel mileage.
 
Aj, depends on what Tremec you use. There are other ratios than that in o.d. at least. My 04 GTO has a .64 or .67 final with a 3.4 rear end gear. (Same ratios and trans for that matter as same year Z06 btw.)
 
mr68gts said:
Aj, depends on what Tremec you use. There are other ratios than that in o.d. at least. My 04 GTO has a .64 or .67 final with a 3.4 rear end gear. (Same ratios and trans for that matter as same year Z06 btw.)
Click to expand...

too bad someone doesn`t have an auto. 5-or 6 speed that`ll hold up to 700h.p. or so, and fit the stock a body tunnel !
 
Tremec can handle the power but it's costly and the trans is bulky requiring the tunnel mods as you mentioned. I'd have a hard time hacking my tunnel up for that myself. Also, I stand corrected, the gto is a .57 final
 
The T56 isn't overkill at all, especially with the close ratio box-

First Gear Ratio: 2.66:1
Second Gear Ratio: 1.78:1
Third Gear Ratio: 1.30:1
Fourth Gear Ratio: 1.00:1
Fifth Gear Ratio: 0.80:1
Sixth Gear Ratio: 0.63:1

Compared to 833's-

1964 thru midyear 1966 A-body: 3.09:1 - 1.92:1 - 1.40:1 - 1:1

1964 thru 1970 B/RB engine: 2.66:1 - 1.91:1 - 1.39:1 - 1:1 = (The "close ratio" V8 gearbox)

1970 thru 1974 TA: 2.47:1 - 1.77:1 - 1.34:1 - 1:1, = 1970 T/A & AAR 340s

Notice that the T56 close ratio box is very close to the gear splits in the T/A 833, with the exception of 1st gear. But even that isn't too far off. You already see where I'm going right?

The issue is, AJ stopped all his calculations at 85 mph. Yes, it's true, you shouldn't ever find cause to go faster than 85mph on public roads. But if you're not talking about public roads, you have a whole new ballgame. Like if you want to take your car out on a road course a couple times a year. Not to mention he did all his calcs with 28" tires, which is a street/strip or strip only kind of height. That's a drag race tire.

Run the close ratio T56 box with 3.91 gears and 26" tall tires. The result is perfection, if drag racing isn't your only goal and you're ok with the 1st gear ratio. Which you would be if you're an autoX or road race guy, because 1st gear lets you do 20 to 40 mph between 2,700 and 5,400 rpm. That's pretty darn good for most autoX courses, as they generally try to limit you to ~35mph. Keeps you right in your powerband, even with moderately hot cams.

And really, how many people have cams that start above 2,500 rpm? The T56 with the .63 6th gear, 3.91's, and 26" tall tires puts you at 2,500 rpm at 80 mph, which is not an uncommon speed to go on California freeways. In fact, it would be perfect for cruising down I-5 to the Spring Fling festivities, not to mention even better at Willow Springs, when the T56 will theoretically let me hit 160mph at 5k rpm. Which it won't because of air resistance, but again, perfect. I can probably hit 150 mph on the straights before I hit redline, even considering aerodynamics. So yeah, I probably won't use 6th gear a lot, most freeways could be handled with 5th gear especially on shorter trips.

But here's the thing, you have to cut the crossmember and the tunnel for a 5 speed TKO anyway. And the T56 magnums that American Powertrain sells will handle 700 hp, so it should be good forever in most street cars. And it really doesn't cost that much more. I've priced out my conversion for under $5k, which is all new parts through Summit racing. The only thing it doesn't include so far is the crossmember and tunnel work, but US Cartool is working on a conversion crossmember and tunnel for A-bodies as we speak, which should also work for torsion bar cars. For the amount of work it takes to get the TKO, you might as well go T56 and get the extra gear and additional strength. Even if you don't ever use 6th.

Also, you don't have to do the math. There's a really handy gear ratio calculator at vexer. This is the non-flash version of the one that gets listed all the time, but I use it because it's set up for a 6 speed.

http://vexer.com/automotive-tools/speed_nf.php
 
I will believe "it's available" when I see one in somebody's car.
 
RustyRatRod said:
I will believe "it's available" when I see one in somebody's car.
Click to expand...

http://americanpowertrain.com/i-23887137-1967-76-a-body-pro-fit-6-speed.html

M144051084.jpg
 
I'd rather spend the coin on a drop in Passon unit.
 
jos51700 said:
I'd rather spend the coin on a drop in Passon unit.
Click to expand...

Then feel free to sit on a waiting list for a year or maybe more. There are a couple Passon threads on here where people love to sit on waiting lists. Not my cup of tea.

I'm glad to see another company jumping in the mix. They also offer a 5-speed kit as well.
 
You must log in or register to reply here.
-

Back
Top