Is a automatic trans possible for a 236 straight 6?

[Isaiah92260]

I’ve read a few past conversations on here but it was about going T5 and changing the read end

I’m hoping to learn something here.

I don’t know anything about gear ratio’s or transmissions.

Reason being for asking about a automatic transmission is because I really enjoy having the concept of column shifting.

I have a 1961 with a 235, 3 speed in the column and whatever basic rear end they put in a base model short bed Apache.

I could only go about 50 on the road without hearing the motor get pretty noisy and noticing the engine temperature starting to get warmer.

If I were to go automatic, what is the best tranny? Tom lagdon I read says no to a TH350.
But a 200-4R? What about a 700 r4?
Do I need to alter my drive shaft? And can I keep the rear end but just have to open it up and replacing it was a different differential ratio gearing?

If l have to go with a T5 because it’s just makes more sense I guess I will have to.

What ever is easier I suppose, I don’t want to go v8. If keep the 3 speed but changing the differential is good, that’s cool, transmission and differential swamp then? Okay which combination?

This is now becoming more of a priority because now that my 235 is running good and I have new tires, and brakes done, I’ve been driving it a lot more during the week and the weekends, I feel like I need to keep up on the road.

Any ideas and advice is greatly appreciated. Thank you all!

[62 Barnfind]

I did a a T5 on my 62 because I was having the same problem of the engine running at high rams when going down the road. The T5 totally changed the way the truck driver. i now can go 75-80 if the incline isn't too much. The 235 still won't have the power of the 350 but the T5 will let you go a little faster without the engine trying to blow up. Also you should have a 390 rear end in your truck. It's not an expensive upgrade but you will have to get a high hump for the trans to clear on a 60-62.

[oem4me]

My '62 C20 had the factory 235 three speed combo as well. In 3/4 tons the standard rear end ratio was 4.56, which is great for a work truck, but not great for the highway. I could hardly tolerate the high revs and noise, so I swapped in a 4.11 ratio center section for the rear end and also installed a rebuilt three speed transmission with overdrive. The basic feel or shifting characteristics of the truck are unchanged, but man what a difference it makes on the highway, especially with the overdrive engaged.
I can now talk with passengers without yelling at them, and actually relax a bit on the road.
Both swaps were fairly simple and no crazy alterations needed. Same driveshaft, and just the gear set in the pumpkin. Did it myself in the driveway.
I kinda doubt your truck is geared as low as mine was, but swapping gears is not that difficult, if you are so inclined.

[Isaiah92260]

Originally Posted by oem4me

My '62 C20 had the factory 235 three speed combo as well. In 3/4 tons the standard rear end ratio was 4.56, which is great for a work truck, but not great for the highway. I could hardly tolerate the high revs and noise, so I swapped in a 4.11 ratio center section for the rear end and also installed a rebuilt three speed transmission with overdrive. The basic feel or shifting characteristics of the truck are unchanged, but man what a difference it makes on the highway, especially with the overdrive engaged.
I can now talk with passengers without yelling at them, and actually relax a bit on the road.
Both swaps were fairly simple and no crazy alterations needed. Same driveshaft, and just the gear set in the pumpkin. Did it myself in the driveway.
I kinda doubt your truck is geared as low as mine was, but swapping gears is not that difficult, if you are so inclined.

That’s bad ass, that sounds like something I wana do for now. Where could I find a 4:11 rear end?
I also just found a 3 speed over drive that is probably gonna need to be rebuilt for $200. But it’s from a tri 5 Chevy it says. Would a mid 50’s over drive 3 speed work for my 62’ 235?

[Isaiah92260]

Originally Posted by 62 Barnfind

I did a a T5 on my 62 because I was having the same problem of the engine running at high rams when going down the road. The T5 totally changed the way the truck driver. i now can go 75-80 if the incline isn't too much. The 235 still won't have the power of the 350 but the T5 will let you go a little faster without the engine trying to blow up. Also you should have a 390 rear end in your truck. It's not an expensive upgrade but you will have to get a high hump for the trans to clear on a 60-62.

Did you change the rear end also along with your T5?

[cwcarpenter98]

I love the 3 speed overdrive I swapped into my truck. Same shift linkage, same driveshaft length (had to change the yoke because the trans output splines were different with the OD trans), and I can run all day on the interstate without worrying about straining my 283. If you go with one of these, try to get one in working condition with all the components

[papaw]

I have a 64 chevy short bed kept the 230 inline with 700r4. had to change front yoke and shorten shaft. fab and move the trans support, only problem i am having is connecting the tv cable.

[Isaiah92260]

Originally Posted by cwcarpenter98

I love the 3 speed overdrive I swapped into my truck. Same shift linkage, same driveshaft length (had to change the yoke because the trans output splines were different with the OD trans), and I can run all day on the interstate without worrying about straining my 283. If you go with one of these, try to get one in working condition with all the components

You had to change the yoke? Where do you find the one that is needed?

[Isaiah92260]

I also found a rebuilt Muncie sm319 3 speed with overdrive for $800.... is it worth it to pay that much in combination to add a 4:11 rear end?

[cwcarpenter98]

The tri 5 OD is the same as the truck OD length wise. Only thing that might be different there is the shift arm directions. My OD trans came off of a 65 c10, so the shift arms were the same as my old trans.

Only reason I had to change the slip yoke was because in 65 GM changed the output shaft splines on their transmissions. I went to a local driveshaft shop to purchase a new yoke, and they installed it for free. My Ujoints were still in good shape, so I wanted the shop to install it with the proper tools. I was in and out of the shop in about 20 minutes. I think the yoke was around 50 or 60 bucks, but don't remember exactly.

[cwcarpenter98]

If the rebuilt one has all the components, including the solenoid (most important) and governor, in working condition, it might be cheaper than having one rebuilt that needs new parts that aren't reproduced. Also, you need the wiring harness for it (can make one from scratch if you don't care about originality), kickdown switch, and relay to make it operate as GM intended. There are several good threads on here about how this trans works. Also, i mentioned some stuff about it in my build thread when I was installing mine (starts on page 6 of my thread)

[Isaiah92260]

Originally Posted by cwcarpenter98

If the rebuilt one has all the components, including the solenoid (most important) and governor, in working condition, it might be cheaper than having one rebuilt that needs new parts that aren't reproduced. Also, you need the wiring harness for it (can make one from scratch if you don't care about originality), kickdown switch, and relay to make it operate as GM intended. There are several good threads on here about how this trans works. Also, i mentioned some stuff about it in my build thread when I was installing mine (starts on page 6 of my thread)

Damn forget that Tri5 one the . It’s proably better for me to get that rebuilt one then. Cuz it comes with the wiring harness, a aftermarket kick down switch and the solenoid, governer, relay, switch and everything.

What kind of rear end do you have in your truck?

[cwcarpenter98]

That rebuilt one sounds like a decent deal. Mine was less than that, but it looked to have been rebuilt many years ago. I also did not have a kickdown switch, but used a new Studebaker switch to remedy that issue.

I have a 3.73 rear with 29" tall tires. Before the OD I was spinning 3k to go 70. With the OD, I am spinning somewhere around 2100 (don't remember exactly at the moment. Have not driven the truck in about a month because of college)

[Isaiah92260]

Originally Posted by cwcarpenter98

That rebuilt one sounds like a decent deal. Mine was less than that, but it looked to have been rebuilt many years ago. I also did not have a kickdown switch, but used a new Studebaker switch to remedy that issue.

I have a 3.73 rear with 29" tall tires. Before the OD I was spinning 3k to go 70. With the OD, I am spinning somewhere around 2100 (don't remember exactly at the moment. Have not driven the truck in about a month because of college)

Damn that’s really good! I’m gonna have to get that 3 speed over drive then!
Do you also agree that a 4:11 in combination with the over drive would also be a good idea ?

[oem4me]

Originally Posted by Isaiah92260

Damn that’s really good! I’m gonna have to get that 3 speed over drive then!
Do you also agree that a 4:11 in combination with the over drive would also be a good idea ?

First, research what ratio you currently have. The rear gears in C20's (like mine) are generally worse for the highway than C10's. You may already have a better highway ratio than the 4.11.
The overdrive trans is a big help, but another way to improve engine RPM on the road is with tire size. A taller tire means the axle will spin fewer times to cover the same distance.
By the way, my OD trans was directly from a tri five. Same basic trans since '39 or something. Gotta love Chevy's.

[Isaiah92260]

Originally Posted by oem4me

First, research what ratio you currently have. The rear gears in C20's (like mine) are generally worse for the highway than C10's. You may already have a better highway ratio than the 4.11.
The overdrive trans is a big help, but another way to improve engine RPM on the road is with tire size. A taller tire means the axle will spin fewer times to cover the same distance.
By the way, my OD trans was directly from a tri five. Same basic trans since '39 or something. Gotta love Chevy's.

Oh okay I will do some research then. All I know I have the base of all base models lol
My vin and lock panel tag says the truck was base model short bed. Original 235 and 3 speed. No trim, mouse grey original paint. That’s all I know I’ll look into it more.

Oh okay. I just got new tires too, I got 225/75R/15
I’ll have to go taller than that for sure then

[cwcarpenter98]

4.11 would still work well with an overdrive, just would be a little higher in the rpm range. A 235/75 r15 is just about 29" tall. Any GM 4 bolt side cover overdrive trans will bolt up, there's just a few small differences that I have noticed through my research. There are many informative threads on here and other sites about the trans

[Isaiah92260]

Originally Posted by cwcarpenter98

4.11 would still work well with an overdrive, just would be a little higher in the rpm range. A 235/75 r15 is just about 29" tall. Any GM 4 bolt side cover overdrive trans will bolt up, there's just a few small differences that I have noticed through my research. There are many informative threads on here and other sites about the trans

Seeet. Sounds like I could be in the right track then.
Oh okay I gotta find on the configuration with that rebuilt one I’m looking st then.
Was 4:11 just in HD trucks?

My buddy wants to sell me a rear gear from a 70’s el Camino that he’s got

[oem4me]

I looked up the 1961 rear gear ratios for C10 here: https://www.gmheritagecenter.com/doc...olet-Truck.pdf


It appears the ratio is already better than 4.11. If it were even possible to install one, you be going in the opposite direction from where you want to be with RPM's.
My choice for the 4.11 was based upon what would easily swap into the stock 3/4 ton axle. You are not as limited.
So, as bad as you think your highway RPM's are, mine was way worse.

[Isaiah92260]

Originally Posted by oem4me

I looked up the 1961 rear gear ratios for C10 here: https://www.gmheritagecenter.com/doc...olet-Truck.pdf


It appears the ratio is already better than 4.11. If it were even possible to install one, you be going in the opposite direction from where you want to be with RPM's.
My choice for the 4.11 was based upon what would easily swap into the stock 3/4 ton axle. You are not as limited.
So, as bad as you think your highway RPM's are, mine was way worse.

Thank you for looking that up for me! Okay then I’m assuming that all I would need is the transmission for starters!

Wow I can’t Imagine worse cuz I am already impatient with the trucks speed lol

[61K10]

if you have the org rear axle it's probably 3.90. I had the same setup in a 62 chevy tk and it was perfect.

[Isaiah92260]

Originally Posted by 61K10

if you have the org rear axle it's probably 3.90. I had the same setup in a 62 chevy tk and it was perfect.

Yeah looks like I have the 3:90 then!

[Isaiah92260]

So this is the transmission I’m looking at, what are your guys insight?
Looks like it is a older 4 bolt non synchro 1st, which isn’t a problem since I’m used to no 1st synchro.

It says something about it being a Muncie with a both Warner tail piece?

Chevy 3 Speed Overdrive Transmission
https://orangecounty.craigslist.org/...865337806.html


Chevy 3 Speed Manual Transmission with Borg Warner Overdrive. Muncie model SM319 with R10 BW OD unit. Fits 1955-1965 Chevy/GM cars and trucks. Reconditioned, new bearings, rear bushing, seals, and related components. Includes solenoid, governor, factory color coded wire loom, aftermarket kick down switch, relay, and pull cable. Installation instructions and wiring schematic also included. No Text Messages.

[cwcarpenter98]

For a rebuilt unit, that seems like a good deal. The trans in that add has the 16 spline output shaft, which should be the same as your current shaft. Another thing I noticed in the add on that specific trans is it looks like the shift levers are the same as my truck OD trans. That's good if that is the actual trans for sale in the pics. I noticed that his wiring harness is custom, therefore it does not have the original kickdown switch or relay. Both of those components are not cheap if you want originality (not reproduced, must find good used or NOS), or you could make it look original ish by using a Studebaker kickdown switch (can buy brand new for around $50 ish) and a blower motor relay from 70s GM trucks (brand new around $12 ish). I started a thread that has information about using the blower motor relay in place of the original relay. Looks a lot better than the new style plastic ones in my opinion.

I'm assuming that you have the long tail shaft trans in your truck currently? Have a pic of current trans?

The 3 speed case is pretty much identical with the exception of a hole drilled for the reverse lockout rod. The tail shaft of the OD trans (what the seller says is the borg warner part) is the actual OD unit.

If the cost is not a prohibitive factor, I would say go for it since it is complete and should be in good working order.

[Isaiah92260]

Originally Posted by cwcarpenter98

For a rebuilt unit, that seems like a good deal. The trans in that add has the 16 spline output shaft, which should be the same as your current shaft. Another thing I noticed in the add on that specific trans is it looks like the shift levers are the same as my truck OD trans. That's good if that is the actual trans for sale in the pics. I noticed that his wiring harness is custom, therefore it does not have the original kickdown switch or relay. Both of those components are not cheap if you want originality (not reproduced, must find good used or NOS), or you could make it look original ish by using a Studebaker kickdown switch (can buy brand new for around $50 ish) and a blower motor relay from 70s GM trucks (brand new around $12 ish). I started a thread that has information about using the blower motor relay in place of the original relay. Looks a lot better than the new style plastic ones in my opinion.

I'm assuming that you have the long tail shaft trans in your truck currently? Have a pic of current trans?

The 3 speed case is pretty much identical with the exception of a hole drilled for the reverse lockout rod. The tail shaft of the OD trans (what the seller says is the borg warner part) is the actual OD unit.

If the cost is not a prohibitive factor, I would say go for it since it is complete and should be in good working order.

Thanks man for the advice! In this circumstance I’m not too concerned with originality on the switch or the wiring. It does sounds like a good idea! I’m gonna start saving for it because I believe even though a 5 speed is better, I don’t wand change the hump and have to do a adapter kit or shifting on the floor.

I’m sure I have to modify my tube for the 3 speed over drive but I like it’s a direct bolt and I like shifting at the column. I’m gonna go for it