Will a 1955 3 spd OD fit my truck?

[MikeN]

Originally Posted by Isaiah92260

Thank you @61K10 and @MikeN for the info! I just got the overdrive. What do you guys think?

Sweet! I have a later model OD that I'm planning to install in my 64 this summer.


My brother-in-law put the same OD unit that you have into his 65 C10 several years ago. He loves it - works great. And he did swap over the shift arms and use his factory column shifter.

[MikeN]

Originally Posted by Isaiah92260

Looks brand new

That looks amazing. Did you have to polish the solenoid to have it look that nice? Or just clean with some type of solvent?

[Blue666(2)]

This video was just posted today. He always does a really great job of explaining through the teardown & rebuild of transimissions. https://www.youtube.com/watch?v=o2tFwBTrLRQ

[Isaiah92260]

Originally Posted by MikeN

That looks amazing. Did you have to polish the solenoid to have it look that nice? Or just clean with some type of solvent?

Awesome you gotta post a thread when you install yours, I would like to see how it turns out for you!
I’m happy to hear that you know someone with one and that the love it! Sounds like I’m on the right path with this tranny!

I polished/cleaned with steel wool and then I sprayed a light coat of metallic spray paint I got from Home Depot. I figured paint would protect the finish for a few more years

[Isaiah92260]

I pulled my old 3 speed today. Yes I will need to change the shift plates. Besides that. Everything seems good ,the rear shaft and front shaft are identical.

The old 3 speed is actually 21 1/2” in length and the 1955 OD transmission is about 21 3/8+ in length, so they are about 1/16+ in length of a difference. I’m sure that doesn’t matter but I felt like putting it out there for anyone information.

[Railroader]

Attached is wiring diagram for the OD setup. If you don't want to fool with kick-down switch, solinoid can be wired to a switch you cut on or off. On on the highway / off in town. For tranny to shift into OD, just let off the gas pedal above about 30 MPH and it will shift into OD.

I'm sure you'll love it. I can confirm that 65 - 70 MPH at 2100 RPM with 390 gear is a reality.

OD Wiring Diagram.pdf

[Railroader]

One more thing. After installation of OD, I upgraded to disc power boost on front brakes. Stopping quickly from 70 a lot different than 55 with stock drums. Just me. May be different for you.

[Isaiah92260]

Originally Posted by Railroader

Attached is wiring diagram for the OD setup. If you don't want to fool with kick-down switch, solinoid can be wired to a switch you cut on or off. On on the highway / off in town. For tranny to shift into OD, just let off the gas pedal above about 30 MPH and it will shift into OD.

I'm sure you'll love it. I can confirm that 65 - 70 MPH at 2100 RPM with 390 gear is a reality.

Attachment 1996397

Thank you so much for the Wiring diagram! Man that is probably the most simplest diagram I’ve seen so far haha.
Yes I am pretty lost on how I should mount a kick down switch, how would you suggest I could connect the 4 wires that would connect to the kick down switch to a on/off toggle switch?

That’s great to hear! I’m looking forward to getting her on the road!

No I strongly agree that is a good idea to upgrade the front brakes. I’ve heard drums in the front is dangerous anything over 65

[dschmit]

This is the diagram I found on the H.A.M.B forum. It is a little more involved and uses a second relay, but by doing so you can use a momentary switch on the dash within reach for your "kick-down". It works good. I like it, you don't have to mash the throttle to go to direct drive. When you want to go to passing gear/direct drive, just touch the button and it shifts down and stays until you lift the throttle. I put a small momentary switch In the bracket that I made to hold the push pull O/D cable.



Diagram credits to ChicoDave of the HAMB!

[Isaiah92260]

Originally Posted by dschmit

This is the diagram I found on the H.A.M.B forum. It is a little more involved and uses a second relay, but by doing so you can use a momentary switch on the dash within reach for your "kick-down". It works good. I like it, you don't have to mash the throttle to go to direct drive. When you want to go to passing gear/direct drive, just touch the button and it shifts down and stays until you lift the throttle. I put a small momentary switch In the bracket that I made to hold the push pull O/D cable.

Attachment 1996482

Diagram credits to ChicoDave of the HAMB!

So the 2 relays allow you to have a switch on the dash and have a kickdown switch?

[Isaiah92260]

So I changed out the shift arm shafts today and noticed this. The one with the o ring seal is from the truck? Interesting right? I put both shafts on from the truck that had O rings

[dschmit]

No. I only use the switch on the dash, nothing is activated by throttle pedal.
On the diagram where it shows "kickdown switch" is what I have wired to the dash switch.

[Isaiah92260]

I just picked up a wire harness, gaskets, seals, and the overdrive lock out cable.
I basically have everything I need.

So far I just mounted the overdrive cable. I’ll put more on the wire harness I have when I have a chance

[MikeN]

Please share what harness you bought when you can. Been thinking I'd fab up one from scratch, but if there's a better option I'd be interested for sure.

[Isaiah92260]

This is the harness I got

[Isaiah92260]

https://orangecounty.craigslist.org/...089012988.html


Contact him, really nice guy, very helpful

[Isaiah92260]

Installed my overdrive finally. It Ran great first Test drive. You can feel it engage the OD after 30 mph. It shifts very smooth, and Hauls ass. Feels like I’m riding in a roller coaster lol.
The max I hit was 65 Mph at 2,100 RPMS. I had my pedal dumped all the way to
The floor though. I’m thinking of doing one of those 2
bbl carburetors adapters and doing headers on the truck next.

The paint got scuffed up when I was installing it. I’m gonna get some pictures of the harness in stalled under the hood tomorrow

[Isaiah92260]

Overall what I had to do was

Swamp over the shift arm shafts
• 1st and reverse shaft was longer on the truck and the arm was bigger as well.

Replaced Rear Output shaft seal and bushing.
• I had to take apart the housing the remove the bushing.
• A experience gentlemen that was familiar with taking part these transmission helped me take it apart and we re greased all the gears in the OD and replaced an the gaskets

I tested the solenoid and governor, they both worked great.
• Replaced the seals for the solenoid

The Original Overdrive cable from a 62 impala I had was a 47” cable. It was at least 5” too short to reach the free wheel lock out lever. So what I did was welded a 5” cable to it.
It does not look nice but damn works well and the weld did not break when I tested the freewheel lockout. (I’ll get a picture of that on here soon)

Finally, I routed the wire harness with the starter wire harness and ran the OD harness as neatly as possible. I will post pictures on here as well tomorrow. I also mounted the relay on the firewall on the passenger side right above the plug for the starter harness. Then just zipped tied the kickdown switch to the choke cable for now until I fabricate a bracket and weld a bumper onto the throttle linkage.
(I will leave that project for another weekend)