I have a T bucket with a GM rear axle 7.5 gears 2.73. I want to change the gears to 3.73s. I bought a 1994 S10 axle with the 3.73 gears, coded GT4. I hope to swap the carrier with the ring gear and pinion from the S10 axle. I read somewhere about some pinions having different diameter shafts. The axle under the T is 54" from inside to inside on the backing plates. I cannot find any stampings on the axle tube, like the GT4 numbers. My question, Do all 7.5 inch gears interchange or am I taking a shot in the dark on swapping this out?
If I understand right, I think you're going to need to change the carrier as well. The 3.73's won't work with the 2.73 carrier. I think as long as you swap the r&p along with the carrier from that set, you should be ok. I believe the 7.5" and 7.65" use the same axle diameter and spline count. At least, all the one's I've used have.
I believe they will fit, use the whole carrier, if not the old side gears should swap. It is the new axle shafts that have the larger splines. Check this catalogue out it should have all the info you need. http://www.neapco.com/pdf/2002axleringandpinioncatalog.pdf
Changing the carrier also is the plan. I checked the web site and it shows all the same specs back to 77 on cars and 82 on S10s. Maybe I will luck out. Thanks for the replies.
Well, the new pinion is different than the old one. First indication the pinion yoke nut is 1 1/8" on the old one. The new one is 1 1/4". The old one has 25 splines. I did not count the new one, but I think I saw 27 spline somewhere. I guess I'll just buy a new ring, pinion and spacer. Maybe the info will help someone doing the swap.
It is about 3 inches narrower than the 1994 S10 axle. At least I know how to determine the correct gear set.
With the 7.5" rear-end, you cannot put a 3.73 gear from a 3.73 carrier into a 2.73 rear-end. It won't fit. You need to buy an aftermarket 3.73 ring & pinion for the 2-series carrier, which will be wider and bolt right in...
I was going to use the 373 carrier while doing the gear swap. I was told this was possible, but could be wrong on this. I am going with the after market gear swap, unless I find one before Monday. Also noticed GM uses the 41 tooth ring and gears the pinion like 11 teeth for 373, 12 for 342, 15 for 273. I know the gears are matched sets, but thought it unusual compared to 9" Ford gearing. thanks,
You probably have an 8.2 1964-70 Chevy II housing not a 7.5 housing You will need a 3.08 or higher carrier to put 3.73 gears in it. You can check the Richmond Gear Catalogue to confirm this.
I think you are right on the 8.2 inch gear. It is the only GM I can find with a 25 spline pinion. Aren't some of the after market gears thicker to make them adaptable to the lower numbered carriers?
Not for this particular low performance diff, that I am aware of. In my opinion it is probably better to find something like a 96 s-series Jimmy or Blazer rear with the gear ratio you want and maybe free limited slip. It should be about the correct size for your T-bucket and swap it in for less money. In fact if you get 2002 or newer you get free rear disc brakes too. Get the master cyl for it while your there. There must be a million of these in the scrap yards for cheap. You may also want to consider an Explorer 8.8 instead they are as strong as a Chevy 12 bolt rear end and also come with the ratio you want, rear disc brakes and limited slip. Do a google there is a ton of info on them. Just have the axles and rotors re-drilled for 4 3/4 bolt circle to mount your wheels. Good luck.
I would really like to take any of those approaches, but the present axle has the buggy spring brakets and radius rod brakets welded to it. I would also have to stay with the GM wheel bolt pattern for my wheels. I already have a 7.5 axle out of a 94 S10, very low mileage, original brakes, 373 gears, only 3 inches wider, but don't want to get into that big of a job. I found a spacer listed at Randys Ring and Pinion for the 8.2. If I move up to just a 3.08, it would be a big improvement, but the 3.73 would put me in the sweet spot for cruising. Thanks for the information. I don't know if I would have been able to figure this out without it.
Not really a fan of spacers but if it is what works for you then go for it. Make sure you carefully watch the run out of the ring gear with the spacer on. Use a good synthetic gear lube for the diff, it will keep the diff temps low for you. Good luck.
I got the spacer. Guess what, it is in a Mr. Gasket package. It came with new bolts, longer I guess. Ordered the gears from my brother, should be coming in this week. I'll spring for the syn lube, even though I keep thinking I am going to quit working on this thing and get something else to keep me busy.
If you get a chance, throw a couple of pictures on here, of the ring gear with the spacer on it. Just interested on how it turns out. Thanks
I went to the Red Neck Rumble and did not read any sites until after I had the gears in. The spacer went in easy and works fine. The spacer came with longer bolts, was .250 thick. All the original bearing were good and was able to use the original crush sleeve. It was between 2 and 3 inches long. Pre load was easy. Carrier needed more preload and moving over some. After backlash, tooth pattern was good. Bucket T ran out good. Has good pep now. I have not had it on a highway run, but street driving is good. Speedo has dip switches, so should be good there. Thanks for the info, which helped so much. I hate I did not get you some pics.
Went through this same scenario with my Austin gasser. Got a narrowed 10 bolt from a friend who took it out of a mid 80's Canadian Peresienne(sp?) and had it narrowed for his project, but then changed direction. Price was very right, but I should have done more research. I knew it had an open carrier, and 2.73 gears, but figured it was a 8.5" 10 bolt being from such a large car, and the axles were such huge diameter. Turned out to be a 7.7" and a real bastard to get upgrade parts for. I ended up finding a 2 series carrier that was posi, and a set of 3.73 gears from another source, then had to go with a spacer as you did. Was told they didn't make them for this rearend anymore, but found them easily at Summit Racing online catalog. Only $60, and had it the next day. The rearend is holding up good so far, but I've only got a few thousand miles on it.
I found a good supplier while searching, Randys Ring and Pinion. He had the spacer I needed and it was on the door step the next day.
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