4 speed questions

[70 sublime]

Has any one used a newer 833 4 speed transmission with fourth gear being over drive in their car ?
I have heard there may be some problems with the aluminum case hanging together with a bit more horse power

In my other thread there are some pictures of what I am working with
http://www.dodgecharger.com/forum/index.php/topic,135832.0.html

Can the short tail section off the transmission with the cast case be removed and replaced with the longer tail section from the over drive transmission ?
The over drive transmission tail piece is cast metal 

[RallyeMike]

I am using one from an 80's van in my race car. Has not broken yet but I am also not grabbing gears hard. I'm told the fix is to bore out the countershaft slot and put a sleeve in it. I figured it was just cheaper to buy a spare trans, so I have one sitting on deck.

Yes the long tail shaft will swap over.

[303 Mopar]

I have a Passon 833 OD in my '70 Cuda with a Gen III 6.4 Hemi and have no issues. 

[70 sublime]

I am using one from an 80's van in my race car. Has not broken yet but I am also not grabbing gears hard. I'm told the fix is to bore out the countershaft slot and put a sleeve in it. I figured it was just cheaper to buy a spare trans, so I have one sitting on deck.

Yes the long tail shaft will swap over.

Do you notice a big jump when you get into fourth gear with the over drive transmission or are the 1  2  and 3 ratios spread out a little more compared to the older 4 speed that 4th is direct drive ?

So if I put the over drive one in my car and manage to blow it up I can just take the tail section off and swap it onto my other transmission and be back on the road 

I figured out the other day that I have a 2.93 gears in my rear end and add that to an over drive transmission I should be able to have some nice rpms for highway cruising 

[c00nhunterjoe]

1 2 and 3 will be similar to a 727

[70 sublime]

So doing some math on this

I measured my tires and they have a circumference of 90"
My rear end gears are 2.93
And if I use the over drive transmission top gear is .73 over drive

I end up with motor RPM of 1254 to get 50 mph
                                         1505 to get 60 mph
                                         1882 to get 75 mph

I was out tonight with my 2018 Dodge Ram and it was around 1900 rpm at 75 mph

Think I would be happy with these kind of numbers
When I get the car done I want to be able to get out on the road and go places with it and not just fart around town with it

[Mike DC]

      
This calculator on Tremec's site is pretty easy to use.  


http://www.tremec.com/calculadora.php


It's intended to compare the Tremec transmissions but you can fill any other gear ratios into the blanks.  There's also a little section down at the bottom to compute tire diameters.

[RallyeMike]

Do you notice a big jump when you get into fourth gear with the over drive transmission or are the 1  2  and 3 ratios spread out a little more compared to the older 4 speed that 4th is direct drive ?

So if I put the over drive one in my car and manage to blow it up I can just take the tail section off and swap it onto my other transmission and be back on the road  2thumbs

I figured out the other day that I have a 2.93 gears in my rear end and add that to an over drive transmission I should be able to have some nice rpms for highway cruising

Yes there is big jump 2 to 3. You can find the various ratios from the ODs on the net. They don't vary much between them. Typically they all have a higher first gear ratio which is nice to get you moving, relatively normal jump to 2, big jump to 3....

It's a cheap way to get OD. You have to take the gear spread as a sacrifice for the low cost.

Another thing to plan for is the different input seal plate. It is bigger in diameter than a normal 833. You will need to buy an aftermarket bell, or machine either the stock bell or the OD input seal plate to fit.