The Stovebolt Site Forums The Shop Area Driveline Colorado rear

Hey guys I have an original ( Other than paint and body putty)1950 3100. I was thinking about swapping rear for one out of a Chevy Colorado.Bolt pattern seems the same but center hub is about 3/16”larger than my wheels. Should I get axle or wheel machined down or both ? Maybe a spacer the thickness of the center hub? Planning on t5 swap at same time

Forgot to mention I want to keep my original wheels
Thanks Rick

Rick - IIRC, the Colorado axle differential is offset significantly to one side unlike your existing axle. It will create a problem with driveline alignment and probably bad vibration and ride.

There have been other threads on this topic, but I’m not able to locate them at the moment.

Gdad51,Thanks for that information. I’m glad I checked here before purchasing.. I figured there was a post on it somewhere but I couldn’t find it I’ll have to come up with a new plan. Thanks a lot,
Rick

Dan, looking at the pics in this post, it doesn't look like the Colorado rear differential is that much offset. Even so, If you pay attention to getting the driveline angles correct, both vertically and horizontally, a horizontal offset isn't a big issue.

Many vehicles were produced with off-center pinion shafts without any issues. As long as the pinion shaft is aligned parallel to the crankshaft/transmission output shaft, no issues will occur.
If the pinion shaft is not parallel to the crankshaft/transmission output shaft, one of the u-joints will be articulating more that the other, causing undue vibration and early failure of both u-joints.

Look at a 55-57 Chevy passenger car rear axle sometime- - - -the pinion flange is noticeably off center to the transmission centerline.
Jerry

I installed a Colorado rear in my 40 gmc.The pinion is 2 inches to the right of center. 52Carl is right about the 2 different angles causing a serious vibration. Couldn't get the vertical angle to zero. The horizontal angle is pretty good.Vibrated like crazy. I used hose clamps to balance the shaft on the vehicle. Got rid of 95% vibration. Its not right but driveable. Keep checking u-joints.

Yes, driveshaft angles need to be within certain specs ideally. But if you were able to improve on vibration by modifying weight on the shaft, I’m guessing the straightness of the shaft being checked and having it professionally balanced, would be extremely beneficial.

The shaft was straight and balanced at a good drive line shop in Spokane, before I added the extra weight.

I would guess that the driveline shop Did an adequate job on the shaft. Just a little surprised It needed further modification because of a bit of angle misalignment.

Update!!,
I just finished my Colorado rearend and t5 transmission swap. WOW what a difference in the old truck. It rides great and so much quieter,should have done it a few years ago. Rick

Rick - Please post some pictures! Would be a big help to other Bolters considering to do this and give us a visual of how things look in functioning condition.

I've been following this thread waiting for an update. I'm going to be doing the same swap-Colorado 3.73 rear and T5. I'm assuming the offset yoke on the differential wasn't a problem for vibration?

RB, I don’t think the offset is a problem at all. I just drove my truck 67 mph on the highway..I have been running it the last couple of weeks on every type of road and it’s been doing great. I didn’t even have driveshaft balanced, guy charged me 40dollars to shorten the Colorado driveshaft. My donor rear was from a 2010 with 3.73 open gears.wheel cylinders have metric thread so I had to make new brake lines to connect to my line. It

That's great news. I bought one out of a 2012 that's in good shape, and didn't notice how much it was offset until I got it home. I was concerned, so I did some estimations on what the driveshaft angle would be in my truck and did some research. From what I found, I figured the angle would just barely be within acceptable limits for my expected drive shaft rpm's in all gears. Glad to hear yours is working out.