Best Rear end

[forestb]

If I was to do a rear end swap on my 1962 c10. What wold be the best rear end to use. With the hope of keeping it 6 lug and maybe switching to disk breaks at some point. There is nothing wrong with my current rear end except that the pinion seal is leaking. But I have noticed that there are not a lot of replacement parts out there for my current one.
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[cwcarpenter98]

If wanting to stay 6 lug, you could easily get your hands on a 65-70 truck 12 bolt. Captainfab sells the trailing arm mounts that you can weld on to the outside of the stock perches so you can match the pinion angle and then bolt to your factory arms

[LostMy65]

I went from a 62 Eaton to a 65 12-Bolt. The trailing arms are a little farter apart on the 60-62 than they are on the 65-72's. I didn't remove the existing perches, I just welded the new perches next to the existing ones. Check out my thread starting here: . http://67-72chevytrucks.com/vboard/s...10#post7357010
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[forestb]

[QUOTE=LostMy65;8819572]I went from a 62 Eaton to a 65 12-Bolt. The trailing arms are a little farter apart on the 60-62 than they are on the 65-72's. I didn't remove the existing perches, I just welded the new perches next to the existing ones. Check out my thread starting here: . http://67-72chevytrucks.com/vboard/s...10#post7357010
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Was it wider than the original? Did you narrow it?

[LostMy65]

Originally Posted by forestb

Was it wider than the original? Did you narrow it?

No, they are the same width. I believe it's around 1971 when the C10's went to 5-lug (disc brakes in the front) is when the rearends got wider. I think from then on, they all are a total of 1.5 inches wider (3/4 of an inch further out each side).

[SCOTI]

Originally Posted by LostMy65

No, they are the same width. I believe it's around 1971 when the C10's went to 5-lug (disc brakes in the front) is when the rearends got wider. I think from then on, they all are a total of 1.5 inches wider (3/4 of an inch further out each side).

Late '70 is when the transition apparently started. There are 'wider' 6-lug housings under some of the '70 models. Of those, some migrated to other trucks as years went on.

The 5-lug pattern did coincide w/the '71's new standard front disc brakes.

[Captainfab]

I also make 2 different 6 lug rear disc conversion brackets for the '64-'82 truck 12 bolt and the '79-'87 truck 10 bolt.

[Paul Y]

You could always look at the Ford 8.8.

Disk brakes, LSD (if you pick the right one) and shafts are available from your favourite speed shop in the stud pattern of your choice.

Cheap and modern, especially if you are going to go to Disks

P.

[forestb]

Awesome thanks

[vince1]

I think you'll find that most 12 bolts are 3.73. IMO they would be good with an overdrive transmission. Otherwise maybe OK for city driving.

I have a 71 diff in a 66 with a 3.07 ratio and 6 lug axles that works well with the straight through manual transmission and 235 75 R 15 tires.

[forestb]

So it turns out that I have the 3.90 gears and it is a mess inside. Lost's of slop.

[verdell]

I went the same route as LostMy65 and used a 65-70 12 bolt, moving the trailing arm mounts out wider. Did it on my very first C10 which was a '61 and my current '60 Apache. 4.88, 4.10, 3.73, 3.42 and 3.08 gears are all easy to find and it can remain a 6 lug if you prefer.

[forestb]

It's at the rear end shop right now so we will see what they have to say.

[LostMy65]

Yeah, 3.90 is what my 62 Eaton was.
If you start thinking about what other gears might work for a 1:1 transmission (no overdrive). Here is a chart to give you some ideas depending.

[forestb]

I do have a 700r4

[LostMy65]

I think you just have to multiply by .73 for overdrive.

[SCOTI]

Originally Posted by forestb

I do have a 700r4

Originally Posted by LostMy65

I think you just have to multiply by .73 for overdrive.

Correct, multiply by the final trans ratio vs a 1:1 ratio. That being said, a 700r4's 4th OD gear is .70.

[forestb]

So does this mean I should be looking for a 2.73 Gear ratio, or are my calculations incorrect?

[SCOTI]

BBC's/SBC's like 21-2300 rpm but will work from 2k - 2500 easy enough.

2500rpm is about the limit for extended drives. Higher rpms get annoying @ or above 75mph. Below 2k would likely be lugging the motor & not beneficial.

[forestb]

So I have a 29 inch tall tire. So I should be looking at achieving a rpm of around 2377, 2485 or 2613. My 3.90 gear ratio would have been perfect if I had stuck with the 350 transmission I had in there before.

[AcampoDave]

Scoti nailed it. I had my carburated 283 cruising at 2000 for a few years just using an old rear end I had for a long time. Then I had it re-geared to cruise at around 2300 and I could tell the motor was happier. It didnt use any more gasoline (maybe less) and it was just "punchier" you know.....like it was in its sweet spot, breathing properly and saying, "let's go, I'm ready .
My thinking is a carbed motor needs a few more rpms to keep that mixture well atomized as opposed to my fuel injected work truck, for example, that can glide along all day with the computer in charge of everything.

[cwcarpenter98]

I have a 30" tire, 3.73s and a .7 overdrive. The engine really likes cruising at 65 and doesn't mind 70 at all either. I think I'm around 2200 rpm or so, but my speedo is off so kinda guessing off of the GPS on my phone. I could go 75 if I'm in a hurry, but with the stock caster, much faster than that is a no thank you for me.

[SCOTI]

Originally Posted by cwcarpenter98

I have a 30" tire, 3.73s and a .7 overdrive. The engine really likes cruising at 65 and doesn't mind 70 at all either. I think I'm around 2200 rpm or so, but my speedo is off so kinda guessing off of the GPS on my phone. I could go 75 if I'm in a hurry, but with the stock caster, much faster than that is a no thank you for me.

3.73's x 30" tires x.70 final gear is approximately 1900rpm @ 65mph & 2050rpm @ 70mph.
At 80mph, it calcs out to 2340rpm.

[cwcarpenter98]

Originally Posted by SCOTI

3.73's x 30" tires x.70 final gear is approximately 1900rpm @ 65mph & 2050rpm @ 70mph.
At 80mph, it calcs out to 2340rpm.

I'll have to check my actual numbers again once I'm back on the interstate. And I really need to fix my speedo, but I don't want to pull the back end off the transmission

[Blue666(2)]

Here is a chart of tire sizes & diameters from Tire America. Best to check your actual tires/wheel combinations. A good guide if you are considering a rim or gear swap.

https://www.tireamerica.com/resource...diameter-chart