The Stovebolt Site Forums The Shop Area Engine Shop Saginaw 3speed OD for my 37

These are a few photos of the late 60's 3 speed Saginaw overdrive tranny I got off Ebay with shipping help from Ken Brown to get it here to NY from Washington State.
I disassembled the tranny, replaced the seals, all bearings and the brass syncro rings, the gears were all in nice shape. The OD controls, governor and solenoid, needed a clean up ,but work as they should.The shifter is an old Hurst, modified to fit,reworked the shifter rods and made a mounting bracket. Same with with the hand brake, drilled and tapped the case, welded up a bracket from scrap steel.
With 3.36 gears, my 37 Chevy pu's 261 engine was getting busy at 65 MPH and 2600 rpm.The OD will drop the revs 30 percent, to 1800 at 65, much nicer.
Shifter side
Tranny in my cellar

Tony,

There are some people here who would give up some very valuable parts of their anatomy to be able to turn the 2600 rpms at 65 like you do now! Now you're going for idle rpms at hwy speed. Hope you get at least 13 inch diameter disk brakes up front. You'll need it to help stop you from 2500 rpms at 100 mph! :p

-ftyler

Well, the 37 has Camaro discs on the stock front axle, good enough,lol. The 170 or so HP 261 would never pull 100 mph in OD, but has done 100 with the 3,36's ,about 4000 rpm.The OD is for calm hiway running, not land speed records
Ever since I put the A833 4 spd OD in my wife's 51 Chevy pu, I'm spoiled by low rpm cruising.The 51 has 3.40 gears, in 4th OD ,turns about 1800 at 60 mph.
You know what i'm talking about, your truck has the OD too.

Tony,

Not to twist your thread too much, but did I tell you that I finally got beyond that annoying vibration in my drivetrain? I don't mean got RID of it, just sped up past it.

Since my speedo doesn't work I don't have a clue as to how fast I was moving. But judging by the way I left the fast lane traffic on the interstate I had to be in excess of 90 mph. Easily!

-ftyler

Fred, so your truck's vibration is limited to a certain speed range?Sometimes a worn differencial or it's bearings will cause that.You eliminated all the other causes?

Haven't eliminated differential bearings. I guess it would have been a good idea to replace them when I had the axle bearings replaced, 3 years ago. :mad:

I hate the thought of tearing the rear end down. Ugh! :rolleyes: It'll have to wait. In the meantime I'll just drive under the vibe speed.

-ftyler

Hello Ftyler-I have just installed an overdrive in my 62 1/2 ton Chevy truck behind a rebuilt 235 six. Now the speedometer won't work. Suggestions as to what the problem is? The cable seems to be o.k.

Wish I could help out dude. Mine still doesn't work.

Since my temp gauge doesn't work, and I would like a better lit dash than the stock 66 anyways, I've decided to build a custom gauge panel. I'm going with 6 Autometer gauges. Now I can add the tach in dash and get a MUCH brighter dash and interior. All at a cost of around $400.

-ftyler

Tony I have the same tranny and o'drive in my 61 Apache with a built 261 (272 now). I have 4:11 gears and in O'drive I can flat haul the mail but 30% is a bunch.With 4:11's at 60 mph. your turning 3000 rpm. So you're turning 2600 at 65 sounds more like 3:73's and if that's what you have and 3:36's make it even worse I doubt you're going to like what you get. I found that 4:11's and a 30% o'drive are about perfect.Most O'drives today are 17% because the cars can't deal with any more. Good luck.

I had the same problem on my truck when I replaced the clutch. The inner part of the cable slid out of the back of the speedo unit. I had to disconnect it at the speedo, then hook it up at the tranny, then hook the speedo back up.
David

Well, The OD got it's first road test yesterday, works just dandy. The 261 just burbles along at 1800 rpm at 60 mph.
Wrench, my 37 does have 3.36 gears and the rpm is around 2500 at 60 mph in direct drive.I like the 30 percent drop in rpm, no problem at all.
17 percent OD on new cars? Most stick trannies in rear drive vehicles have around a 30 percent reduction.My 4.3 powered S10 has 2.73 gears and a .73 OD ratio in 5 th gear, runs along at 1500 rpm at 60,great for fuel mileage anyway.