Building rear differential

[grousehunter 61]

I am rebuilding the rear differential in my 71 short box 4x4. I bought the center housing from Summit racing and am using my original ring and pinion. the housing they sent is a Yukon. I am having nothing but problems. using the spacers that came with the kit on the pinion I can not get the ring to match up with the pinion. If I put all the spacers on the center carrier on the left side I can get it close, but the carrier then hits the right side of the differential housing hard enough to lock it up, if I put the spacer on the right side it pushed the ring gear away from the pinion to the point that I have about 30 thousands back lash. The kit is YGA26052 that summit says is for that truck. I used all the spacers on the pinion that came in the kit but still no contact or no correct contact with the ring. Of course everything is closed for the weekend. any ideas on what I am doing wrong ?? this is a one owner truck and I am that owner, bought it new july 20 1971 so I know nothing has been changed.

[BASE]

I hate to ask but you are using the correct carrier for the gear ratio you have? I see lots of people get caught off guard by the carrier breaks. I think that axle has one around 3.73. It is 12 bolt right?

[grousehunter 61]

Yes, its a 3.73. Its like the flange that the ring gear bolts on to is to far to the left, as I said the only way to get it make contact with the pinion is to shift it all the way over to the right and then it hits the housing. waiting for Tuesday to call Summit and Yukon to see if I got the wrong carrier. My ring gear bolted up no problem, but something is not right.....

[Mbeef61]

Did you check backlash before taking it apart?

[BASE]

The carrier for the higher gears would be almost a 1/4” further away from the pinion to accommodate the larger pinions. Not sure if you are that far off but if it’s hitting the other side with the pinion all the way you might be.

[roboticjunky]

YGA-26052 is for use with 3.42 and numerically lower gear ratios, not 3.73 gears.

https://www.summitracing.com/parts/yga-26052

Here's the one by Yukon for 3.73 or higher gear ratios.

https://www.summitracing.com/parts/yga-26035

[grousehunter 61]

Thanks for the info, I am sure that is what happened, wrong carrier. I have been fighting this for a week or so. I contacted Summit and ordered the right one just now, they said that the part is out of stock and it will be 6 to 7 weeks before they can replace it. Great !!!! So now I go another month or two with out my truck, truck is not happy...its hunting season and I am not happy.

Sorry I didn't mention robotic for coming up with the correction for the problem. Something I was not aware of. That is what make sites like this so valuable. So thank you sir.

[MySons68C20]

Thanks for following up. I appreciate knowing the hows and the whys
Nice catch robotic!

[grousehunter 61]

Well the rear end got its revenge, yesterday I crawled under the truck to pull the center carrier to send back to Summit. the last time I worked on it I put only one of the end caps on to hold the gears in, remembering how hard it was to pull the carrier I took a short pry bar, removed the end cap and reached for the pry bar, turned my head to the right and the carrier dropped out of the housing and hit me on the left side of my face, now anybody that has worked on one of these knows how heavy they are, with the truck jacked up it fell about 1 to 1 1/2 feet and got me good, the wife saw me crawling out from under the truck with a face full of blood, she got a wet wash rag and cleaned me up. I think its going to leave a mark from my left ear to my chin with the cheek bone taking the brunt of it. Us 80 year old men should leave things like this to the younger guys.

[lil hoodlum]

Originally Posted by grousehunter 61

Well the rear end got its revenge, yesterday I crawled under the truck to pull the center carrier to send back to Summit. the last time I worked on it I put only one of the end caps on to hold the gears in, remembering how hard it was to pull the carrier I took a short pry bar, removed the end cap and reached for the pry bar, turned my head to the right and the carrier dropped out of the housing and hit me on the left side of my face, now anybody that has worked on one of these knows how heavy they are, with the truck jacked up it fell about 1 to 1 1/2 feet and got me good, the wife saw me crawling out from under the truck with a face full of blood, she got a wet wash rag and cleaned me up. I think its going to leave a mark from my left ear to my chin with the cheek bone taking the brunt of it. Us 80 year old men should leave things like this to the younger guys.

Oh jeez, I bet that did hurt something fierce.

Hopefully nothing permementally broken on your face and that you heal quickly.

[Jiggers72-GMC]

Oh crap, sorry to hear that, you'll have to grow a beard to hide the scars .....

[HO455]

Man just reading the post made my head hurt. But I'd skip the beard. Chick's dig the scars!
Please keep us posted on the progress.

[grousehunter 61]

The swelling is starting to go down, ya there will be a scar as stated by HO455 but at my age it doesn't matter, I have enough wrinkle's to cover it up, lol but thanks for the thoughts, one of these day I will learn to leave things for the younger crowd.

[72c20customcamper]

80 and still getting under the truck . My hats off to ya I'm 62 and still crawling around under cars and trucks dont plan on stopping cause that's when ya get old .

[grousehunter 61]

getting old is mandatory, growing up is optional.

[Steeveedee]

So true! I'm glad that the punkin didn't crack your skull. I dropped a driveshaft on my head in 2013 and my family tells me that I wasn't right for about 6 months. Guess I should have gone to the doctor. But then, I really haven't been right for most of my life.

I was at the doctor's office (doc looked young enough to be my grandkid) and started to wonder what she thought about all the scars on my arms. I have quite the collection, but none like you're going to get from that punkin!

[BigBird05]

If chicks dig scars, then I need to shave my head.

[grousehunter 61]

I am afraid that scars are a sign of a mechanic, my hands and lower arms look like a road map. I started working on cars before I was 14, bought my first at a wrecking yard, 1936 chevy, I was told that I should have it running by the time I was 16, 2 weeks later I was driving it while they were at work, got caught and it was taken away. My next was a 1937 chevy coupe then a 1939 chevy coupe, then to the dark side 51 ford convertible, and a woody wagon so as I say I have been doing this for a lot of years, but time is catching up with me. along with the scars I have a lot of memories.

[Lancialonnie]

OUCH! I hope you are feeling better grousehunter! I just ordered the parts to rebuild my axle. I wanted to run the Yukon dura-grip and 3.73 gears. I received the YDGGM12T-3-30-1 carrier and a Richmond 3.73 gear set 12BT373T. After reading this article I called the vendor asking if they shipped the wrong carrier and they explained that the gear set ending in T meant it would fit in this carrier even though the description states the carrier is for 3.42 and lower. Checking the description for the 12BT373T shows it fits this carrier. Sure makes this confusing!

[BASE]

I think most of them make “thick” ring gears that will fit on the carriers meant for the numerically lower gears. Very confusing. It was only dumb luck I got the right one on the first couple axles I rebuilt. I had no idea what a carrier break was when I ordered all of that stuff.

[tj1970cst]

Has anyone used the gears and posi diff that is for sale on ebay for $400-$500? Looks like deal. Wondering if the quality is good enough. Will properly set gears whine? Is posi rebuildable?

https://www.ebay.com/itm/GM-12-Bolt-...-127632-2357-0


Sorry to hear that thing landed on your face. When I worked at a Ford dealer, I rebuilt a ton of ifs explorers and expeditions. I put a majority in myself (no jack). Had an iron one I was putting in with a trans jack (feeling wussy that day). After thinking I secured it by starting 2 bolts, it fell out. I turned around in time to be a dummy and caught it with my hands, then put up a knee so my leg would stop it the rest of the way. I was sore all over, especially the top of my thigh for a month. I shoulda let it hit the floor. A couple fellas saw it, could not believe I caught it and said how dumb it was to try and grab it.

[Jiggers72-GMC]

tj1970cst, that's a great deal, I wouldn't hesitate to use it, if I wanted 4:10's
yes it's rebuildable & I don't see why it would whine if set properly.

sorry to hijack this thread.

[A1971Blazer]

OUCH...I've had a few mashed fingers and hands but never dropped one on my face...
I'm only 65...and I just can't crawl around under a vehicle very well...getting down is easy...getting back up is what's hard....
I broke down and put in a lift....it's a life saver

[grousehunter 61]

Jiggers, what size gears do you have now ?? and are you replacing the differential housing ?? My truck came with 3:43 gears and the chevy dealer told me that 4:11 would not fit in that housing and 3:73 was a low as I could go ?? I took there word for it and went with the 3:73 gears. I would have loved to put the 4:11 in it as I was cutting a lot of fire wood at the time and used my brakes way to much. If you get a different story please let us know.

[BASE]

Originally Posted by grousehunter 61

Jiggers, what size gears do you have now ?? and are you replacing the differential housing ?? My truck came with 3:43 gears and the chevy dealer told me that 4:11 would not fit in that housing and 3:73 was a low as I could go ?? I took there word for it and went with the 3:73 gears. I would have loved to put the 4:11 in it as I was cutting a lot of fire wood at the time and used my brakes way to much. If you get a different story please let us know.

Here is an article explaining the carrier breaks and the thick gears you can use to get around that: https://www.crawlpedia.com/thick_gears.htm

There is a chart there that shows the breaks for quite a few diffs.