The Stovebolt Site Forums The Shop Area Driveline How to adjust rear axle gears

Hello all.

Ive been lucky to find a gear set for my 1945 cheby pickup. It will change the gear ratio from 4.11 to 3.50. Now is my question does any one have documentation or a manual on how to adjust the play etc?

Thank you in advance.

You will need to provide more information on the model of truck. Is it a BK 3100 or a BL 3600 ? This information will help others who read your post. I've attached a link to a 1947 Truck Shop manual that has a section on the rear axle that may be helpful. I don't know if the 1947 and 1945 Models used the same rear differential or not. Perhaps it will help. I'm sure others with experience will chime in. Best Wishes


http://chevy.oldcarmanualproject.com/shop/1947truck/index.htm

Ron

Unless they're brand new gears, I hope you checked the tooth contact pattern before removing them from the original housing they were running in. Once a wear pattern is established, any other adjustment, including setting the backlash to specification will set up a howl that would make a timber wolf jealous. Most service manuals have a section on what to do to establish a proper running fit on new gears which is far too complex to address in a chat room post.
Jerry

As long as you got things apart, it would be the time to replace seals and bearings too.

Rick

Thanks for the replies

@dusty53. I have a 1945 model.
@hotrodlincoln. The gearset i bought is new.
@rickmg i will also replace the seal and bearings too. Yiu know the part numbers by any chance

Thank you

Most bearings and seals will have part numbers stamped on them that can be cross-referenced to modern equivalents. Some of those bearing numbers haven't changed in decades, and will still be in use.
Jerry

The best illustrations and explanations I have found are in the older "Motors" manual. As stated the process has a lot of steps to get the right gear contact pattern. Instead of white lead I have used cold GOJO for years as it is more visible to old eyesight and cleans up easily for repeat patterns. Room temp GOJO gets brown, runny, and useless as an indicator. Buy an inch pound torque wrench or a fish scale to set bearing preload which is important.

Robby45 in the Netherlands.

This is one of those jobs where an experienced mechanic is best.
The link below provides pictures which may help you see a small portion of what happens during a conversion.
Click on "see all 32 photos".
Also notice that the owner elected to have the torque tube serviced (bushings and seals) at the same time.

https://www.motortrend.com/how-to/1003clt-chevs-of-the-40s-3-55-1-ring-and-pinion-swap/