Hi All.
I have been digging around looking for info on the 8 3/4. (sorry if this is old news to some but I did do my homework before posting, so please keep the flames to a minimum if I missed something ;^) )
The OE 7 1/4 rear has 315000 miles on it and is noisy and sloppy. Leaking from the pinion, and maybe the axles. the engine is stock 273 2bbl so not much power to the wheels. My plan was to either rebuild the OE 7 1/4 ($500 - $1500 depending on need for gears etc.) OR for the same money (most likely the higher end +) replace it with an 8 3/4.
There is a shop in town who will build an 8 3/4 rear drum to drum for a reasonable price with 10 x 2 breaks, new (not OE) axles, green bearings, and refurbished or replaced everything else.
I have been looking for a good used assy and have some leads but need some advise. stick with the 7 1/4 that has held up so long or go 8 3/4 and the relative headaches it will give me collecting all the misc parts and swapping it in.
99% of my experience with rearends is with Ford 9" and Dana full floating 3/4 ton truck.
What I am learning about the 8 3/4...
1. Stock uses a two piece bearing and a pressed on retainer ring. there is a single adjuster on the driver's side to set bearing preload on both sides. This requires a "Thrust block" between the axles in the diff so one axle can push on the other.
2. Replacement "green" bearings are like the ones in the 7 1/4, and ford 9" where the bearing is a sealed bearing and is held in by a pressed on retainer ring. there is no preload adjustment so the adjuster is removed and replaced with a plate and the "Thrust block" in the diff would need to be removed.
3. there is debate about older "Green" bearings and newer "Snap ring" "Green" Bearings and OE bearings as to which is best. "snap ring" "Green" being seen as better than old "Green" But OE is as good
4. there is info to suggest that OE bearings have a weaker diff because of the "thrust block"
5. BREAKS ( OYE! ) there are 10 x 1 3/4, 10 x 2, 10 x 2 1/2, 11 etc. the backing plate needs to match the housing and the axle and the drum. In looking, replacement drums seem to be in short supply for most of these options. (not looking to go disk)
6. 3rd member there are various units and the pinion shaft dia being the major difference so as long as the pinion and the yoke are correct any will bolt into any housing. 489 being the stoutest of the stock oe 3rd members.
7. Housings ( the easy part!) A-body 66 (or is it 67) to 68 are same and hole for breather is in the correct 67 location. 69 - 72 the breather is moved. the length, spring perch, and pinion angle are all the same from 66(?) to 72
8. I'm not even going to get into locking or open diff at his point.
Thanks for the input.
I have been digging around looking for info on the 8 3/4. (sorry if this is old news to some but I did do my homework before posting, so please keep the flames to a minimum if I missed something ;^) )
The OE 7 1/4 rear has 315000 miles on it and is noisy and sloppy. Leaking from the pinion, and maybe the axles. the engine is stock 273 2bbl so not much power to the wheels. My plan was to either rebuild the OE 7 1/4 ($500 - $1500 depending on need for gears etc.) OR for the same money (most likely the higher end +) replace it with an 8 3/4.
There is a shop in town who will build an 8 3/4 rear drum to drum for a reasonable price with 10 x 2 breaks, new (not OE) axles, green bearings, and refurbished or replaced everything else.
I have been looking for a good used assy and have some leads but need some advise. stick with the 7 1/4 that has held up so long or go 8 3/4 and the relative headaches it will give me collecting all the misc parts and swapping it in.
99% of my experience with rearends is with Ford 9" and Dana full floating 3/4 ton truck.
What I am learning about the 8 3/4...
1. Stock uses a two piece bearing and a pressed on retainer ring. there is a single adjuster on the driver's side to set bearing preload on both sides. This requires a "Thrust block" between the axles in the diff so one axle can push on the other.
2. Replacement "green" bearings are like the ones in the 7 1/4, and ford 9" where the bearing is a sealed bearing and is held in by a pressed on retainer ring. there is no preload adjustment so the adjuster is removed and replaced with a plate and the "Thrust block" in the diff would need to be removed.
3. there is debate about older "Green" bearings and newer "Snap ring" "Green" Bearings and OE bearings as to which is best. "snap ring" "Green" being seen as better than old "Green" But OE is as good
4. there is info to suggest that OE bearings have a weaker diff because of the "thrust block"
5. BREAKS ( OYE! ) there are 10 x 1 3/4, 10 x 2, 10 x 2 1/2, 11 etc. the backing plate needs to match the housing and the axle and the drum. In looking, replacement drums seem to be in short supply for most of these options. (not looking to go disk)
6. 3rd member there are various units and the pinion shaft dia being the major difference so as long as the pinion and the yoke are correct any will bolt into any housing. 489 being the stoutest of the stock oe 3rd members.
7. Housings ( the easy part!) A-body 66 (or is it 67) to 68 are same and hole for breather is in the correct 67 location. 69 - 72 the breather is moved. the length, spring perch, and pinion angle are all the same from 66(?) to 72
8. I'm not even going to get into locking or open diff at his point.
Thanks for the input.
