Selection of Torque Converter and Rear Gears for Hot 340

[Garrett Ellison]

I like deep gears and avoiding highway travel, but that’s just me... now saying that, I can vouch that hot rpm happy small blocks in heavy vehicles work very well with 4.56 gears.

 

[AJ/FormS]

I like deep gears and avoiding highway travel, but that’s just me... now saying that, I can vouch that hot rpm happy small blocks in heavy vehicles work very well with 4.56 gears.

Hyup even with stock smogger-teens

 

[rumblefish360]

I totally get that;
I got me a GVOD so I could run any rear gear I wanted to, and I had a shed full of accumulated pumpkins.
My 367;blew up some ex race-gear 5.38s; and zinged off a couple of teeth on some used 3.91s; I traded the 4.10s for 3.55s,sold the nearly new 4.30s;and no takers yet on the 4.88s; so I totally get you,lol.
Finally I got the Commando box with the 3.09 low, and re-installed the 3.55s. Then it was , bye-bye to the byway blues, with a 2.77 equivalent overdrive gear.

What is the OD ratio again? Truck OD trans is different IIRC. I keep forgetting. CRS!
So since I have you this far, would you be so kind as to break out the calculator and do a quick figure on the ratio changes for the 4.10 & 4.88's please?
Thank ya AJ.

I like deep gears and avoiding highway travel, but that’s just me... now saying that, I can vouch that hot rpm happy small blocks in heavy vehicles work very well with 4.56 gears.

No doubt GE, no doubt.
Even better when you run a ride around 3K or less with a big cam.

 

[AJ/FormS]

What is the OD ratio again? Truck OD trans is different IIRC. I keep forgetting. CRS!
So since I have you this far, would you be so kind as to break out the calculator and do a quick figure on the ratio changes for the 4.10 & 4.88's please?
Thank ya AJ.

No doubt GE, no doubt.
Even better when you run a ride around 3K or less with a big cam.

The GVOD is .78. The F-car A833 is .73. But I found a second ratio in the A833 with a .71od; unfortunately it has only 18 teeth on it, and it likes to split into tiny pieces when it gives up.
I'm a lil clueless as to what you are asking about the ratio changes, but I'll try; Going from 4.10s to 4.88 your Rs will increase 4.88/4.10=1.19 so add 19%
With 26s(81.7 roll-out) and at zero-slip; the 4.10s will cruize at around 55=2915; while the 4.88s math out to 3470@55. To verify; 1.19x2915=3469, close enough,lol.

Second gears with a regular 1.92 ratio, come to 7.87 and 9.37, again a 19% change. At 60 mph with 26s, your Rs come to 6100 with the 4.10s,and ~7270 with the 4.88s, Bam!.

 

[rumblefish360]

OH! Like this!
Gear times OD ratio for final drive feel of.....

4.88 X .78 = 3.80 / now by .73 = 3.56 / now by .71 = 3.46
4.56 X .73 = 3.32
4.10 X .73 = 2.99

thanks AJ!

 

[AJ/FormS]

OH! Like this!
Gear times OD ratio for final drive feel of.....

4.88 X .78 = 3.80 / now by .73 = 3.56 / now by .71 = 3.46
4.56 X .73 = 3.32
4.10 X .73 = 2.99

thanks AJ!

Oh, now I see what you were asking ..... lol

Or
4.30 x .71 x .78=2.38, or
3.55 x .71 x .78=1.97
Hyup, ran both of those.
That Hughes [email protected] was fabulous, at 185psi, with aluminum heads.

 

[rumblefish360]

But I found a second ratio in the A833 with a .71od; unfortunately it has only 18 teeth on it, and it likes to split into tiny pieces when it gives up.

This would be the truck version correct?

 

[AJ/FormS]

I got it at a swap meet, at the close of the day for $50C in a F-body case.The guy said he was tired of hauling it around, so I offered the fiddy. To my surprise, he accepted it.
With the exception of the low gear, there is not one single gear in those two boxes (.71 and .73) that will swap over.
IIRC I bought two or three spares, or more lol,of those od boxes, and never saw another .71od.
The .73 box has a 20tooth od gear.I broke one of those as well. You know what happens when you are used to a 4-gear, and now you have 4.30s or more in the back? Hyup, Zing there goes another one,daymn she revs out fast with 4.30s.
I spent some time at a local wrecking yard. There I found an old school-bus with a number of od boxes, mostly Chevy pick-up stuff. But I never counted teeth; they had enough Mopar stuff in there to satisfy my needs.
I think I blew up three of those boxes: two od gears and the whole cluster drive on another. I think I still got a couple of good spares kicking around here somewhere. I'm done with those
If I had to guess, I'd say the .71 is likely a slanty ratio, while the .73 is likely a teener-box