It will be in a 500hp 6.1 with ported heads-219/231 camshaft, stock 6.1 intake and TTI headers-2.5" Super Turbo H-pipe exhaust, Sachs 10.5" stock replacement clutch, heavy steel Hemi 10.5 flywheel, a 1970 B Body 833, 27" tall tire and a 3.23 Dana or 8.75" with a Helical sure grip.

A 3500 lb 68 roadrunner that I'm going to daily drive again, and I'll likely pull the 833 and go T56 down the line. It's a pro touring car on a budget right now.

What thinks you all? Will it move in first gear properly? I need to drive my 20 mile one way trip to work in at least the middle lane. RPM's don't worry me, I'll keep a semi quiet exhaust.

If you don't want problems with the rear end don't use a 8 3/4 with any manual trans with a motor that makes some power in a car that can hook up halfway decently
That body can take a taller tire easily so I would look at buying and using a Dana 60 with 3.54 gears and a taller tire like 28 to 30 inches tall for cruising
As far as the exhaust size go to 3.0 or bigger now, not later
What year is your NP833? If 1970 and earlier non Hemi 23 spline it should have the 2,66 low gear ratio, if it is a 1971 and later(or a original 1970 AAR or T/A Challenger tranny) it will have the closer 2.4? ratio low gear set in it
You can check the low gear ratio with the tranny out of the car by putting in in low gear and mark the input and output shaft along with a mark on the front bearing retainer and the out put housing end by rotating the input shaft enough revolutions to make the out put shaft rotate exactly one full revolutions, if it takes 2 and a little more than 1/2 revolutions it is the 2.66 ratio, if the input shaft does not rotate pass 2.5 revolutions it is the closer 2.4? ratio
On your deal if you had access to a early A body NP833 with the 3.09 ratio low gear I would swap that entire gear set into your tranny cases
The NP 833 O.D. tranny have the 3.09 low gear but I wouldn't use one of them in application that I would beat on They will fail long before you may like it

You will be fine.

That Sachs clutch will slip long before you could ever hammer the 8 3/4 enough to hurt it.

Using your supplied figures at 75 mph you should be turning a hair above 3000 rpm.

Why did Chrysler come out with the 18 Spline unit? Wasn't the 23 spline good enough back in the day!
Comments/Opinions ??

The 18 spline unit came out for the Hemi and 440. It has a larger diameter input shaft then the 23 spline units.

The 23 splines on the 1" diameter input shaft look to have awful small teeth, where the 18 splines on the 1.25" diameter shaft look massive. (Shaft diameters are from memory and may be larger or smaller then stated, someone will correct the sizes.)

This would lead one to believe there may have been an issue on the shaft and spline size with the 440 and Hemi motored cars with good traction. Chrysler at the time overbuilt a lot of stuff. Gene

The 3.09 first gear set up is cool, however you will probably break it! Its not very strong. I know as I put a NOS set in my Cuda years ago. Had a 475 HP small block with a 3.55 rear. Ran good fora while then nocked lotsa teeth off on Woodward one night. Drive the regular 23 spline until you can swap trans. 18 spline will hold up better but bigger budget needed. Tremec trans don't shift under real acceleration unless heavily modifyed so don't waste your money there either. They break too. Cut the friggin floor and put a Richmond in. You only have to mod the left side of tunnel and move the crossmember. Big job but It will make you smile.

3.23 was pretty much the standard gear for most V8 manual trans Mopars unless ordered differently.

Kevin

Didn't Chrysler recommend the 3.09 - 1.00 gear set for drag racing back in the day? Hard to say if the gears were the problem or something else. Anyone know if the metallurgy has changed throughout the years?

I built a tranny for a friend who raced a 1970 340 Duster, it was a stock tranny to start with and I swapped the stock 2.65 gears and cluster to a set of stock 3.09 gears and cluster from a 1965 NP833 A body 4 speed, he had installed a Dana 60 with 5.57 gears in it with ladder bars and a slider set up on the stock leaf springs. I drove that car more than once at the track, you where really busy the first 300 feet
Let the clutch out at 7000 RPM and try and shift at 7000 RPM and wait for the 1/4 mile finish line to come up
He never broke that tranny or rear end

It will move properly, and it will probably be fine as long as you don't abuse it with sticky tires.

If you have rock hard regular daily driver street tires, no worries.
DOT slicks-It's a matter of when...Worry.
Drag Radials-probably worry, be careful.

The car has been down a long time since pulling my 440/727....I really miss it. The car had 2.94's-8.75" with the auto and the stock 440 moved it just fine.

I miss the simplicity of a carb and how it was with the big block and there is no going back now.

I can go as tall as a 28.6" tire in 200tw for the Nitto NT05 295/45-18. I've got a B body Dana 60 that needs perches moved back to B body location, new axles, gears and bearings to be useable again. I could do that for about what it would cost to get a nice 8.75" third built by Cass.

I've got this old muffler shop exhaust on it that doesn't fit that well and is compression bent, but I'm trying to not spend money for things that can wait. I want to do a 3" X-pipe system with Borla's and set of cut outs after the X pipe.

I'll check the tranny, but for now...its in there and it works. I want to just focus on keeping that combo together as one piece and selling it to someone who wants to swap this whole transmission combination into a g3 Hemi swapped car.


I like the last two ideas, but I need to just save towards a T56 instead of keeping the 4 speed!

It won't have an actual drag tire on it for a while. 200tw street tire in an 18". It will spin, but I'm just wanting to have some fun with the combination before I have to tear it all back up again.

Not many who have done what you have done, would admit that.

Hats off to you.

I think you'll be all right with the regular street tires.

I stepped off this ledge when there were not cheap and easy EFI kits, affordable redesigned BB heads and the aftermarket wasn't loving the BB's too much. But now, as long as it has taken me to get to this point...I would have rather just left the 440 in the car and added a T56.

I don't regret the end result, I just regret not having a hotrod to drive for a long time.

Once this car is up and running 100%, I think I'll quickly forget about those small details. These motors do run really great and make silly power for a modern motor.

The 3.23 will work fine in your set up....but.....if you are eventually going to a T56 why not install a 3.55? It will be better suited to the T56, and still be acceptable with your current set up, for anything but really long distance freeway work.

I don't mind re-doing the ring and pinion down the line, if it means that I buy some time before I have to spend even more money.

I have a 3.23 Dana 60 in my '65 Coronet with a Doug Nash 5 speed. I think it is just about the perfect combo. The Doug Nash has a steep first gear (3.27) and then fifth gear is 1:1. It takes some work to get the combination all dialed in since everything really depends on the camshaft and the torque curve. I'm not a fan of the double overdrive transmissions since 6th gear is almost useless. I had 3.54 gears in my car for a long time but it was just a little too deep for daily driving. Cass developed the 3.23 gears for the Dana 60 and so I took the opportunity to switch to a new Strange S60.

yeah, i was looking at what would be good if i put a t56 in my coronet, just looking at options. i remember thinking a close ratio t56 with something like a 4.1-4.30 gear would make 6th gear good for cruising.
probably for simplicity, i will just run a 451/727 with a 3.23 or 3.54 gear and just live with it.

I went from a 3.91 to a 3.73 [already needed the gear swap] with a close-ratio T56 and 28.6" tall tires. I wouldn't run a 4.30 on a 0.63 6th trans.