So we've owned our '74 Challenger for a year now and couldn't be happier that we decided to get back into the classic Mopars that I had when I was a teenager and we were first married.
In any event, after a summer season of driving, I've decided that I definitely want to replace the Sure Grip 3.91 gears, with something more "highway friendly". I was pretty sure I wanted to do this when we first bought it a year ago, but thought I'd give myself a year of driving it to be sure, and I'm sure.
My thought was to go with a 3.23 Sure Grip. I'm thinking switching to 3.55 isn't worth the time, but 3.23 would be the "sweet spot" of still having plenty of take off kick, but also provide for a comfortable cruise at speeds of 60+ MPH, where the engine isn't working quite as "hard".
I have the 8 3/4 rear end. So what am I going to need to make sure of as far as rear-end compatibility? I know there is a number stamped on the housing assembly. Also, any suggestions as to where to get one?
Also, while I'm replacing the rear-end, is there anything else I might want to replace (other than seals/fluids)?
In addition to replacing the gearing, I noticed back at the beginning of summer that my car sits a bit "crooked" when you look at it from back. The driver's side seems to sit about 1/2-3/4" lower than the passenger side.
What might be causing that? As far as the rear suspension goes, I'm thinking things are pretty much stock, but once I'm done winterizing my garage (new entry doors and garage door seals, plus an install of a ventless, propane heater) I'm going to get her up in the air on jack stands and will start looking seriously at it.
What kinds of things could I do to improve the rear-suspension? I'm looking for any and every suggestion people can offer, just so I know what the possibilities are.
Thanks for any and all help!
I'd give some thought to keeping the 3:91 and going to an OD transmission :alan2cents:
Quote from: Brads70 on October 29, 2018, 06:14:29 PM
I'd give some thought to keeping the 3:91 and going to an OD transmission :alan2cents:
:iagree:
Quote from: Brads70 on October 29, 2018, 06:14:29 PM
I'd give some thought to keeping the 3:91 and going to an OD transmission :alan2cents:
It's a factory 4-speed. Is there a 5-speed manual? If there is, I had no idea such a thing existed, lol
Secondly, I think I would like to stick with the stock manual transmission to be honest.
Nothing special about the swap , you can order a new center section from Cass @ DR Diff , any center section will fit , axle splines are all the same , they are a simple diff , replace the inner axle seals while it is apart , they only real hang up is the U Joint size 7260 or 7290 so ideally you want to match the yolk up to the U joint but there is also a conversion joint available ,
I have done numerous swaps using the Mopar A833 alum OD from trucks , they are cheap & easy to find & will bolt in , you need to haver the front brg retainer turned down to 4.80 " & have a belhousing with the 4.80 opening to make it work , the factory shifter will work but you have to work with eh the 3-4 shift rod & levers , other than that it is a direct bolt in just another idea for OD
A better swap is the Passon OD 4 speed. It will bolt in and has better ratios and is a lot stronger than the original Chrysler OD 4 speed. Also Passon makes an OD 5 speed that bolts in however it is around $5k I believe. Honestly the Passon OD at $2k is not that much more than changing your rear end ratio by the time the smoke clears.
Overdrive with a 3.09 first and 3.91s.... Give me a break !
a set of 3.55s OR Passion 5-Speed.
Quote from: GY3R/T on October 29, 2018, 09:10:49 PM
Overdrive with a 3.09 first and 3.91s.... Give me a break !
a set of 3.55s OR Passion 5-Speed.
I have 3.06 first gear ratio and 4:10 ( 4L60) ? Works great for me? :notsure:
Quote from: Brads70 on October 30, 2018, 01:25:19 AM
Quote from: GY3R/T on October 29, 2018, 09:10:49 PM
Overdrive with a 3.09 first and 3.91s.... Give me a break !
a set of 3.55s OR Passion 5-Speed.
I have 3.06 first gear ratio and 4:10 ( 4L60) ? Works great for me? :notsure:
Works great for what ?? Pulling stumps ???
I ran a 3.09 1st with 4:30 gears for 9 years depends what yoou want to do , 1.4 60' or triple the speed limit .
3.91 with 3.09 OD gives you 2.77 final drive on the highway , seems about right to me
Thanks for the replies so far! I love the idea of the OD 5-speed transmission, but I'm not popping for an almost $6,000 dollar transmission.
I did a search for the new rear-differential through Dr. Diff, and $1,400 dollars is much more palatable. I would prefer a good, used one, maybe even one I could trade my 3.91 for, but I'm not opposed to buying a new one at that price.
Any suggestions on the slight sag to the driver's side (leafs?) and any potential upgrades in that area?
Quote from: DodgeGuy on October 30, 2018, 04:23:11 PM
Any suggestions on the slight sag to the driver's side (leafs?) and any potential upgrades in that area?
How is the front end for being equal side to side. I ask as when you adjust the torsion bars it also effects the rear heights some. How old are your leafs?
Quote from: RUNCHARGER on October 29, 2018, 07:22:22 PM
A better swap is the Passon OD 4 speed. It will bolt in and has better ratios and is a lot stronger than the original Chrysler OD 4 speed. Also Passon makes an OD 5 speed that bolts in however it is around $5k I believe. Honestly the Passon OD at $2k is not that much more than changing your rear end ratio by the time the smoke clears.
So after doing some research I understand what you meant about the Pass OD kit. This is a kit that allows me to rebuild my current factory manual transmission into a 4 speed OD transmission?
Quote from: Brads70 on October 30, 2018, 04:35:36 PM
Quote from: DodgeGuy on October 30, 2018, 04:23:11 PM
Any suggestions on the slight sag to the driver's side (leafs?) and any potential upgrades in that area?
How is the front end for being equal side to side. I ask as when you adjust the torsion bars it also effects the rear heights some. How old are your leafs?
I meant to comment on this the leafs are soft by comparison so if one side sits low it is the front torsion bar that is the problem it works in an X pattern
Yes: Check your torsion bar adjustments first to make sure they are even, that will effect the rear as well.
Yes: The Passon OD4 kit can be installed in your present transmission and is a great way to keep your current 3.91's but give you an overdrive top gear to get the best of both worlds.
For your rear stance, reduce your passenger side height adjustment on the front t-bar. OR, increase your drivers side.
IMO, if you can afford a 5 speed trans, go that way. If you can't, decide if 'lighting up' your tires is important to you. If it is, go with the od trans. If it isn't, re-gear to 3.23's. If it were me I would re-gear to 3.23 and preserve the nice shift spread of the original 833.
Quote from: Brads70 on October 30, 2018, 04:35:36 PM
Quote from: DodgeGuy on October 30, 2018, 04:23:11 PM
Any suggestions on the slight sag to the driver's side (leafs?) and any potential upgrades in that area?
How is the front end for being equal side to side. I ask as when you adjust the torsion bars it also effects the rear heights some. How old are your leafs?
I've never noticed the front leaning one way or the other. I'll have to take a closer look, but the back was so noticeable to me (because I notice stupid things like that) and I don't remember the front being that way.
I did wonder if the torsion bars might be a culprit.
Often you will not notice a difference in the front , as little as a 1/4 " in front can be very noticable in the rear
Quote from: Chryco Psycho on October 31, 2018, 10:30:49 PM
Often you will not notice a difference in the front , as little as a 1/4 " in front can be very noticable in the rear
Exactly. This is why a lot of guys don't look at the front as a solution with the rear. But, that 1/4" difference in the front over the 18' length to the rear can turn into a 2" difference when viewed from behind.
The thing about the 4spd OD unit that I think some people overlook is that if you are rebuilding it, you don't have to duplicate all of the original OD ratios. You can drop in the OD cluster to your existing 833 and retain decent spread between the other gears while getting the OD feature. Its certainly not an all or nothing deal unless you swap an original aluminum case OD unit that has not been changed in place of your iron case unit.
Quote from: DodgeGuy on October 30, 2018, 04:23:11 PM
I would prefer a good, used one, maybe even one I could trade my 3.91 for, but I'm not opposed to buying a new one at that price.
I sent you a PM.
Quote from: DodgeGuy on October 30, 2018, 04:23:11 PM
Any suggestions on the slight sag to the driver's side (leafs?) and any potential upgrades in that area?
Go on a diet??
Oh, that's with you out of the car, never mind. :haha:
[/quote]
The thing about the 4spd OD unit that I think some people overlook is that if you are rebuilding it, you don't have to duplicate all of the original OD ratios. You can drop in the OD cluster to your existing 833 and retain decent spread between the other gears while getting the OD feature. Its certainly not an all or nothing deal unless you swap an original aluminum case OD unit that has not been changed in place of your iron case unit.
[/quote]
@HP2 (https://forum.e-bodies.org/mlist/hp2_151) Are you talking about the Passon OD cluster or an original OD cluster from an aluminum case? Sorry if I'm hijacking this thread....just trying to learn
The gears sets are matched , it is all or nothing , you can swap od parts into an iron case either original A833 od or Passon OD will go in but you have to keep all 4 gear ratios , , you cannot just swap in the OD gear in 3rd gear position & use the original 1-2-4 gear.
Personally I like the factory OD 833 & have done numerous swaps , it is workable & affordable :alan2cents:
Definatly all or nothing. Can't mix-match gears. :stop:
Quote from: Chryco Psycho on November 01, 2018, 09:23:28 AM
The gears sets are matched , it is all or nothing , you can swap od parts into an iron case either original A833 od or Passon OD will go in but you have to keep all 4 gear ratios , , you cannot just swap in the OD gear in 3rd gear position & use the original 1-2-4 gear.
Personally I like the factory OD 833 & have done numerous swaps , it is workable & affordable :alan2cents:
I am aware that I can't mix and match gears.... sorry if I worded it that way. I have a factory OD transmission and I have a factory 4-speed from a 1970 e-body. I don't mind swapping the gear cluster into my iron case...just wondering if that would be pretty much the same as putting in a cluster from Passon?
:notsure:
Passon puts a 2.66 first gear in place of the 3.09 which bothers some. Otherwise second, third, and fourth are similar to the 833 OD.
https://www.hotrod.com/articles/a-833-the-ultimate-mopar-4-speed-fix-get-overdrive-and-strength/
That 3.09 isn't a bad thing to have in a heavy car, but if your motor won't rev you'll use up first gear pretty quick. My BMW M5 has a 4.22 first gear and with the 3.45 in the pumpkin it gets that big car moving quick, but that motor redlines at 7200 rpm. When I'm not in a hurry I just start out in second which is 2.52.
Thanks guys :cheers:
Quote from: Chryco Psycho on November 01, 2018, 09:23:28 AM
The gears sets are matched , it is all or nothing , you can swap od parts into an iron case either original A833 od or Passon OD will go in but you have to keep all 4 gear ratios , , you cannot just swap in the OD gear in 3rd gear position & use the original 1-2-4 gear.
Personally I like the factory OD 833 & have done numerous swaps , it is workable & affordable :alan2cents:
Quote from: GY3R/T on November 01, 2018, 09:54:49 AM
Definatly all or nothing. Can't mix-match gears. :stop:
You guys are kidding me right? With all the different ratios that came in the 833, you can't change gear clusters? That has got to be the first time I've been disappointed in Mopar engineering. Even POS saginaws can have the ratios changed within a range of ratios.
The counter shaft is a 1 piece unit , you cannot replace individual gears on the counter shaft so the 4 gears on the counter shaft have to match the 3 on the main shaft & the 1 gear drive pinion so it is all or nothing
Wow, what a downer. I've never been in the guts of an 833, so this is a surprise to me. That really sucks.