Welding a rear diff

mudnmud · March 3, 2002

I have a 1975 GMC 1/2 ton pickup that I am making into an off roader. It has a stock open rear end. I have read about people welding the rear end gears as a cheap way to make it a locked rear end. I do have to drive it one time about 3 hours up to our cottage but then it will be used mostly for muddin. Has enyone ever done this and does it hold up. The only thing I am worried about is if the weld doesn't hold I have a feeling the rear end will be trash.

95Yukon · March 3, 2002

This article shows a 14 bolt welded modification, but you would probably be able to apply the same principal to a non-14 bolt, then just swap the spider gears if you want to switch back.

http://coloradok5.com/welded14bolt.shtml

March 4, 2002

I always welded the spider gears up on dirt cars if locked rears were allowed. if you are/have a good welder, it's pretty bulletproof.

I found a new trick when I was at a track that didn't allowed locked rear ends;

On each side of the third member, fill the space between two spider gear teeth with metal. Basically, just fill it in with welding rod material. It will allow a very small amount of slip.

It was enough to get it through tech inspection and will probably be enough to make driving on the road a little less painful.

This method will allow the spider gears(each) to slip almost one complete revolution. When a gear tooth hits the filled space, PRESTO!, locked rear end!

The inspectors at our track would jack up one rear wheel and spin it one revolution by hand. They never caught on to what I'd done. You could sure tell on the track that it was locked up, though!

One more note;

Don't lock the front. You will not be able to turn at all.

chevy4x4trucks · March 4, 2002

Glad to see you made it over here, I told you these guys should know a bit more than I do

Kansas Kid · March 4, 2002

The inspectors at our track would jack up one rear wheel and spin it one revolution by hand. They never caught on to what I'd done. You could sure tell on the track that it was locked up, though!

Hey, thats a pretty good idea. I am going to file that trick away, never know when it might come in handy.

mudnmud · March 8, 2002

It sounds like the best way is to fill in the gap between some of the teeth and not weld the gears to each other. I just hope it holds up and I don't break anything when turning on dry pavement. I will just try to make wide turns. Does anyone know what a spool rear end is and if is a cheap way to lock the rear diff? Thanks.

March 8, 2002

A spool simply eliminates the spider gears. It turns the rearend into a straight axle. It does exactly the same thing that welding the spiders gears does, it's just more expensive.

March 8, 2002

It sounds like the best way is to fill in the gap between some of the teeth and not weld the gears to each other. I just hope it holds up and I don't break anything when turning on dry pavement. I will just try to make wide turns. Does anyone know what a spool rear end is and if is a cheap way to lock the rear diff? Thanks.

I think you'll be okay if the truck isn't loaded heavy. A truck rear is pretty light and will just chirp the tires in a turn.