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Mike68RS

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Discussion starter · #1 ·
I have 4.11's in my 8.2" 10 bolt rear end with a 700r4 trans. I am looking to replace the 4.11's with a set of 3.55's. Does anyone but Richmond sell the 3.55's for my 8.2 inch rear? I hear the Richmonds are a little noisy.

Thanks
Mike
 
#4 ·
I don't really know why, but I think it is because the 3.42 is such a popular gear in the other rear ends that they just set up the gear cutters to cut 3.42 gears for the 12 bolt and discontinued the 3.31 because it was close to the same ratio. That is just my idea of what happened. I may be totally wrong.
 
#6 ·
Eric, running a 8.2" 10bolt and 11's? give me a clue please. can't find a 8.5 and 12bolts are WAY too high. Any info on backlash ,ect. would be great.

2.73's fun on the hiway <1st gear to 80mph @6000) but have only driven on the hiway ??? 12 times in 5years?
 
#7 ·
There's nothing really special about my 8.2". I think the 12 bolts are overkill and the 8.2 and 8.5 are pretty similar strength wise. The 8.5 has beefier ring gear bolts, but I've never seen or heard of a ring bolt failing anyway.

The big no-no is doing burnouts without a line lock because you can tear up the posi if your back brakes aren't adjusted the same side-to-side. I burned up two Auburns in two years -- but I was not running a line lock. Sometimes I'm a slow learner
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I just run Timken bearings, a Richmond 3.55 gear set, stock axles, and an Eaton posi. Using 80w90 mineral oil and one bottle of limited slip additive. I'd like to add a stud girdle reinforced cover, but haven't got around to it ($$$$$'s).

My backlash is set at .011". I think the recommended backlash is .008-.012" (or is it .008-.014"?). I just set mine up to match the backlash exactly as it was when I pulled the Auburn out. DTS makes a nice shim kit that allows you to adjust the carrier in .001" increments.
 
#8 ·
Eric, Thanks for the info. I'll save money(I hope)by not spending 200+on an 8.5 housing(if I could find one).So BGH will be getting on order soon. S&H to Md. would be the decision maker.Glad I saved the 8.2" 3.08 open for the swap.
 
#9 ·
The 8.5 10 bolt has several improvements over the 8.2 10 bolt. The pinion is larger, the pinion bearings are larger, the ring gear is larger and the differential gears are larger. The axles are the same, but can be upgraded to 30 spline axles. If the axles are upgraded then the 8.5 is very close to the 12 bolt. The only difference between a 30 spline 8.5 and the 12 bolt is 3/8 inch difference in the ring gear diameter and the differential bearings. I have some 8.5 10 bolt Nova rear ends. I can build one for you, but the shipping will be a little high.
 
#10 ·
Now Freddie I know the 8.5" rear is pretty close to the 12 bolt strength wise. But have you ever seen an 8.2" rear fail because the pinion was too small or the ring gear was too small?

Not being a smart-alec, just curious. It seems to me that none of the local guys around here with 8.2 rears running 11's and 12's have had any "hard parts" failures. (in other words, just clutches in posi units, etc).

Have seen a few 7.5" diffs break parts though. Saw a case split in two last summer in a high 10 sec ride launching off the trans brake :rolleyes: should be a $ fine for that one . . . noone was suprised except the driver.
 
#11 ·
Most of the time they bust the gears inside the differential. I built a 8.2 for a '69 a few years back with a US Gear Torque Line posi and Moser axles that went behind a 383 and a Super T10 and it has survived well. If you build them right they will hold up pretty well.
 
#15 ·
I think the last set of 3.55 gears for the 8.2 that I sold was about $210, but it may have been closer to $180. I don't remember exactly. That gear is priced a little higher than most.
 
#16 ·
Originally posted by big gear head:
Most of the time they bust the gears inside the differential. I built a 8.2 for a '69 a few years back with a US Gear Torque Line posi and Moser axles that went behind a 383 and a Super T10 and it has survived well. If you build them right they will hold up pretty well.
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Freddie,

I assume that you are talking about the spider gears in the stock diff?

My 8.2 is set up with an Eaton Posi and US Gear 3.73's with stock "C" clip axles and Timken bearings throughout. What would be the most likely failure point? Would you consider this rear adequate for a street driven car with a moderately stout 383? ( A fear of mine is looking in the sideview mirror and watching the axle walk out of the housing)

Thanks!
 
#17 ·
Thanks Freddie. I'd hope the spider gears in the Eaton and Auburn units are little beefier than stock . . .

BPOS -- I've been keeping a close eye on my C-clips for that very reason . . . so far so good. I've been into the rear a few times over the last 3 or 4 years and haven't noticed any wear at all on them.
 
#18 ·
My 8.2 3.55 Richmonds, Eaton posi is holding up so far. No slicks but it's went through a few good burn outs.
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#19 ·
Originally posted by Eric68:
But have you ever seen an 8.2" rear fail because the pinion was too small or the ring gear was too small?

Not being a smart-alec, just curious. It seems to me that none of the local guys around here with 8.2 rears running 11's and 12's have had any "hard parts" failures. (in other words, just clutches in posi units, etc).
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Yes, I have killed one or two myself....and that was with a an open diff while driving on the street. But it doesnt have to do with the ring gear diameter, it has to do with the pinion shaft diameter.

I too have set up 8.2's and had them live. In fact a friend of mine had one in his 64 Duce with roughly 650 HP on the engine and another few ponies in a bottle....and he never broke it. But you have to remember that this car was around 2350 lbs and didnt really hook up all that well.....although it did run upper 9's on the street. Since then, a 9" was introduced for added strength and ease of gear ratio swaps.

Like Freddy said,
If you build them right they will hold up pretty well.
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But I dont recommend getting the chassis to hook up really hard as you will find out what it looks like when you blow the pinion head out of the bottom of the differential housing. Man, I whis I had a camera that day.......

The biggest thing about an 8.2 is avoid wheel hop PERIOD. That is the killer of the pinion shaft related failures.
 
#20 ·
The gears in the new Eaton posi are stronger than the originals. I don't know about the Auburn. The axles in the 8.2 scare me a little. I would replace them with some better aftermarket axles. Wheel hop can kill the best rear ends. I broke 7 ring gear bolts out of a 12 bolt on the street in front of my house because of wheel hop.
 
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big gear head
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