Sniper Posted March 15, 2021 Report Share Posted March 15, 2021 Been thinking about putting an OD trans in. I have a couple of A833OD transmissions and there is an adapter made to put one of them in. The trans gear ratios are different for 1st and 2nd so I crunched some numbers to see what the effective gear ratio (trans gear ratio and rear axle gear ratio combined) would be for several rear axle ratios. Here's what I have. Stock A833OD Effective gear ratios Stock A833OD 4.10 4.10 3.73 3.55 1st 2.57 3.09 10.54 12.67 11.53 10.97 2nd 1.83 1.67 7.50 6.85 6.23 5.99 3rd 1.00 1.00 4.10 4.10 3.73 3.73 OD 0.73 ----- 2.99 2.72 2.60 Looks like the A833 with 3.55 rear gear ratio is the least objectionable change from the stock effective ratios. First gear being the biggest issue, imo. Now I know of someone making an 18 spline A833 gearset that is a lot closer to our stock ratios, but the vig is enormous. 1 Quote Link to comment Share on other sites More sharing options...
kencombs Posted March 15, 2021 Report Share Posted March 15, 2021 Yeah, 1st is steep. But since mine is a pickup and will see some trailer towing with the flathead, that's not a bad thing. I did mine (all bolted together but not installed in the truck) without an adapter. Using a 58-59 pickup/truck clutch housing and crossmember. Welded some bosses onto the housing where the needed bolt holes came to near the edge, drilled and tapped. All bolted up using a 79 van clutch disk with a 56 car pressure plate. I think the same could be done with other housings, after the front bearing retainer pilot hole in the housing was opened up to accept the big 833 version, assuming the housing was late enough not to use the enormously long Main Drive Gear that some early ones used. It will get a hyd clutch (stock for the 59 pickup) using the pedals from the same. Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 15, 2021 Author Report Share Posted March 15, 2021 Well, I do have an 8 3/4 rear end with 3.55 gears and a Sure Grip as well, so all is not lost for me, lol. Just mulling over the options. I kinda like to keep it all Mopar anyway. Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 15, 2021 Report Share Posted March 15, 2021 I only have opinions and no answers. I like how you broke down the gear ratios for same trans & different gears. My concern for using a stock manual 3spd and swapping the rear end is the torque. Example would be using too tall of gears, cruising 60mph on freeway & hit a incline, need to down shift to 2nd to pull the hill. Would be a disaster. You would hate driving the car. I wonder how this would affect a auto/od trans? Seems if all is working fine would be no issue. On the salt flats it would eventually top out. On the freeway on a hill it just shifts as needed? Without losing freeway speeds? Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 15, 2021 Author Report Share Posted March 15, 2021 Good points, LC. I am in the process of building up a warmer than stock 230 so that might help. 15 more ft/lbs stock vs the 218 I have. Not interested in an automatic. I like shifting. Quote Link to comment Share on other sites More sharing options...
Booger Posted March 15, 2021 Report Share Posted March 15, 2021 wow LC sure jogged my memory. and hes spot on. Back in the 70s when a had a Tradesman van with a slant 6 and a 3 speed I was sucking air when it came to a mountain grade in No Cal or Oregon. If your a flatlander then its chill and run at 65 all day. or a viable OD would be the smart option Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 15, 2021 Report Share Posted March 15, 2021 5 minutes ago, Sniper said: Not interested in an automatic. I like shifting. LC puts his red face of shame on ... thinking you were talking about a automatic ? Another forum, HAMB, a guy posted his results with 2 different B1B trucks with T-5 trans and rear end swaps. A stock 218 95 hp T-5 seems it likes a 3:73 gear. Cruises the freeway at a pokey 60 mph ... while breath taking for the driver with stock brakes/suspension. It will hit a hill and have enough torque to pull it. While same setup with 3:55 gears, it would cruise faster, but you hit a incline on the freeway & constantly shifting back & forth between 4th & 5th. A pita. Just not enough legs to pull the hill in high gear. I would think with a warmed up 230, you would probably be fine with a 3:55. So many variables in my example above ... were they both T-5 with same gear ratio? I have only heard of Mopar using the 3:73 gears, maybe the bigger Chrysler/Desoto used 3:55? Just food for thought ... my stock 218 I want to stay with 3:73 ... More hp I would want 3:55 or better. Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 15, 2021 Report Share Posted March 15, 2021 LC puts his red face of shame on ... thinking you were talking about a automatic ? Another forum, HAMB, a guy posted his results with 2 different B1B trucks with T-5 trans and rear end swaps. A stock 218 95 hp T-5 seems it likes a 3:73 gear. Cruises the freeway at a pokey 60 mph ... while breath taking for the driver with stock brakes/suspension. It will hit a hill and have enough torque to pull it. While same setup with 3:55 gears, it would cruise faster, but you hit a incline on the freeway & constantly shifting back & forth between 4th & 5th. A pita. Just not enough legs to pull the hill in high gear. I would think with a warmed up 230, you would probably be fine with a 3:55. So many variables in my example above ... were they both T-5 with same gear ratio? I have only heard of Mopar using the 3:73 gears, maybe the bigger Chrysler/Desoto used 3:55? Just food for thought ... my stock 218 I want to stay with 3:73 ... with more hp I would think the 3:73 would be more snappy from light to light, more fun to drive. While same time cruise well at freeway speed. If the warmed over 230 needs taller gears, may be taller then 3:55. The 3:73 sounds like a great starting point. your engine, your modifications ... unless you have a Dyno of torque & hp, you just guessing at rear end gearing .... IMHO of course, some people have real life experience. Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 15, 2021 Report Share Posted March 15, 2021 Sorry for repost my internet connection is going batty and causing many issues Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 16, 2021 Author Report Share Posted March 16, 2021 12 hours ago, Los_Control said: If the warmed over 230 needs taller gears, may be taller then 3:55. The 3:73 sounds like a great starting point. your engine, your modifications ... unless you have a Dyno of torque & hp, you just guessing at rear end gearing .... IMHO of course, some people have real life experience. Yes, without an idea as to the hp/tq requirements needed to make it over a given hill I am guessing, which is part of why I was looking at the effective gear ratios. Trying to keep 1 and 2 as close to stock as I could. Third is the same ratio for either trans so that's not an issue. OD may or may not be one though. Stock, the trans ratios seem to be fine for my driving style, just looking for an OD for the highway. I might look into the T5 ratios as well. Where I live is pretty flat, no mountains to speak of unless I drive miles and miles away, A few hills but nothing that is serious. If I took my 51 to go visit LC then I'd run into a few going the most direct route. I can avoid them by going an alternate one though. All said, moving the shift lever to accommodate the drive is something I do enjoy so I don't really see an issue, for me. Years ago I had an 86 Daytona, 2.2L 4 banger with similar HP ratings to the 218, less TQ but more RPM. I drove it from Chicago to San Diego, thru some mountains and such, I really don't recall it being an issue I shifted when I needed to and just carried on. Quote Link to comment Share on other sites More sharing options...
Adam H P15 D30 Posted March 16, 2021 Report Share Posted March 16, 2021 I've posted this before but my kid has a D150 with a stock slant 6, 833 OD and 3.55 rear gear. After driving that, I would go with a T-5 Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 16, 2021 Report Share Posted March 16, 2021 I guess I personally am more concerned with gear ratio because I want to stay with the 3spd. I would be a freeway hazard if I ran into a hill at 60 mph and then needed to downshift to 2nd. In your case shifting into 3rd is not as bad. you know here the speed limit is 75, everybody is driving 80 ... I never plan to drive the freeway with my old truck. I wonder what gears factory used on these old cars with od? Seems I may have read some used 4:10 or 3:90 when adding the od. Actually going to a lower gear instead of higher. Then 3:73 gears for the plain jane 3spd. <--- Not sure if this is true but is sticking in my mind. What ratio do you have now? Might be nice to have some baseline as a starting point, then choose gearing from there. Will probably need to have drive line built for trans, seems a good chance can re-use it for future rear end swap? I use to have a F**d Explorer, 300 hp V6 with a 5 or 6 spd auto & 4:10 gears. That was a kick in the pants to drive. Til it kicked my pants I believe my dd cheby truck 350 with manual 5spd has low gears for towing, maybe 4:10 I should check. had to learn to drive it without spinning the tires in 1rst & 2nd while just breathing on the gas it cruises at 80mph. Gets 16-17 mpg. Not terrible but think just low gears. Truck puts a smile on your face to drive it. 4:10 are fun if you got the right trans to go with it Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted March 17, 2021 Report Share Posted March 17, 2021 Live in San Francisco for a few years with a 139 inch wheelbase - 4900 pound desoto and you learn to love Fluid Drive! Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 17, 2021 Report Share Posted March 17, 2021 live in a rural area, winding roads that undulate.....drive a Porsche....really have fun.... Quote Link to comment Share on other sites More sharing options...
48ply1stcar Posted March 17, 2021 Report Share Posted March 17, 2021 On 3/15/2021 at 3:46 PM, Sniper said: Well, I do have an 8 3/4 rear end with 3.55 gears and a Sure Grip as well, so all is not lost for me, lol. Just mulling over the options. I kinda like to keep it all Mopar anyway. That's what I had installed last year and only regret that I didn't do it years ago. My rear brakes are 50 years newer and I installed front disc last year also. Now I just have to live long enough to enjoy the swap. 1 Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 17, 2021 Report Share Posted March 17, 2021 4 minutes ago, 48ply1stcar said: That's what I had installed last year and only regret that I didn't do it years ago. My rear brakes are 50 years newer and I installed front disc last year also. Now I just have to live long enough to enjoy the swap. drive faster........make up for the lost time..... 3 Quote Link to comment Share on other sites More sharing options...
Kahunah Posted March 20, 2021 Report Share Posted March 20, 2021 I'm very interested in this swap. I have the A833OD and an 8.25 with 3.55 gears from a Cherokee on the garage floor just itching to see the road. I really want to keep the flatty but want the OD to cruise. Quote Link to comment Share on other sites More sharing options...
Booger Posted March 20, 2021 Report Share Posted March 20, 2021 Ive had both, your better off with modern axle. youll cruise just fine' (IMHO) Quote Link to comment Share on other sites More sharing options...
48ply1stcar Posted March 20, 2021 Report Share Posted March 20, 2021 11 hours ago, Kahunah said: I'm very interested in this swap. I have the A833OD and an 8.25 with 3.55 gears from a Cherokee on the garage floor just itching to see the road. I really want to keep the flatty but want the OD to cruise. Unfortunately it took me 5 years to decide and pull the trigger on this swap. Cherokee 8.25 and disc brakes are by far the best thing done on my car. Quote Link to comment Share on other sites More sharing options...
derbydad276 Posted March 21, 2021 Report Share Posted March 21, 2021 I did the 8.25 /3.55 axle last year .... the swap was Night and Day for drivability ... last fall I picked up a R10 overdrive transmission from a 59 Plymouth.. it came with the bell housing I'm now waffeling on whether to install the R10 trans or get a A833 the second gear .. ratio in the 833 looks like it would be a better (around town ) gear match (aka) a long second Stock A833OD Effective gear ratios Stock A833OD 4.10 4.10 3.73 3.55 1st 2.57 3.09 10.54 12.67 11.53 10.97 2nd 1.83 1.67 7.50 6.85 6.23 5.99 3rd 1.00 1.00 4.10 4.10 3.73 3.73 OD 0.73 ----- 2.99 2.72 2.60 Quote Link to comment Share on other sites More sharing options...
Kahunah Posted March 21, 2021 Report Share Posted March 21, 2021 On 3/20/2021 at 7:37 AM, 48ply1stcar said: Unfortunately it took me 5 years to decide and pull the trigger on this swap. Cherokee 8.25 and disc brakes are by far the best thing done on my car. That is really good to hear. I have done the front disc swap, 12v conversion and new wiring harness throughout. I have a LA360 that I had considered swapping in but, the more I drive it with the flat 6, the more I love it. I really think the OD and rear swap will be the cat's meow for me. 1 Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 23, 2021 Author Report Share Posted March 23, 2021 (edited) Tremec has a new 5 speed out that has closer to stock gearing. 1st 2.87, 2nd 1.89, 3rd 1.28, 1.00, OD 0.81 or 0.68 Price is kind of up there though, MSRP is $2,795.00. The 86 and up S10 T5 gearing isn't really any better than the A833OD, might be worse in fact. 1st - 3.76 2nd - 2.18 3rd - 1.41 4th - 1.00 5th - 0.72 The 85 and earlier S10 T5 is worse, imo. 1st - 4.03 2nd - 2.37 3rd - 1.49 4th - 1.00 5th - 0.86 Edited March 23, 2021 by Sniper Quote Link to comment Share on other sites More sharing options...
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