Pumpkin switcheroo

[JENSHAMMER@HOTMAIL.COM]

I've seen and posted a few times about this, and I know a good number of
CAC-ites have done a gear ratio change... What I need to know (since dealing with mechanics around here without knowledge beforehand is wallet suicide) is how much is it (ballpark figures) to either -switch a new pumpkin with 3.73's, or have someone drop in the new gearing into my old punkin. Thanks for the help!

 

[81 Corvette]

it cost me about 2k for labor and parts.

parts included
gears
stub axles
strut rods
u joints
bearings and seals
carrier
bushings

one of the best mods you can do

 

[Glensgages]

My bil, for swapping the '82s 2.87s for 3.73s, was:
ring & pinion: $135
speedo gear/recalibration: $75
miscellaneous parts and labor: $325

Total bill: less than $550

As 81 Corvette says, best mod you can make for an under-powered stock C3.

 

[JENSHAMMER@HOTMAIL.COM]

so glen, are you suggesting that if I have absolutely no reason to think my posi needs to be replaced (true) then I could go your route? $550 or even $700 would be such sweet music to my ears... crate motor draws near

 

[Glensgages]

so glen, are you suggesting that if I have absolutely no reason to think my posi needs to be replaced (true) then I could go your route? $550 or even $700 would be such sweet music to my ears... crate motor draws near

JENSHAMMER:
I'm not trying-to-suggest anything:
just stating what it costed me for the 3.73 swap in October of '03.


A local Corvette-guy, with 30+ years of building hot-rods, drag-cars, and bad-azzed C1-C3 Corvettes, performed the install for me (he'd done ring & pinion work in my drag-car Z28 in the past), does VERY good work (often washes my cars before I tow them back to my home), and gave me the following advise that I'll pass-along to you, and anybody else considering high-horespower applications in '80-up C3s:

My '82 is box-stock, other-than the 3.73s, with a wimpy Cross-Fire motor, and with just 19,000 miles (at the time), the rear-end shown no wear or fatigue, yet my rear-end guy claims the '80-up Dana-44s are the worst rear-end he's seen, as far as taking abuse, and STRONGLY advised me to not put even soft street tires on the '82 for my twice-a-year trip to the strip, for fear of busting the rear-end.

If YOU are contemplating a high-horsepower crate motor in the future, with an eye towards drag-racng on soft, sticky tires, be fore-warned:
the Dana-44 type rear-end is prone to breakage if you can accomplish a 'dead-hook' at the strip.

If you just want a high-HP motor to cruise or 'show-off', keep hard, non-soft/sticky tires on the rear, and you should-be OK.

 

[JENSHAMMER@HOTMAIL.COM]

is there another rear diff, maybe from another C3 year that will drop in as a replacement? With one thousand junkyards and pick-a-parts near me, it would probably be easier... and safer... to get a different pumpkin and rebuild it and drop it in.

I am looking at 400 hp, eventually, with 99% of the driving just as a street rod, so no super-sticky tires are necessary for me. I might take it to the drags every now and again, but just for fun.

Right now just saving money, working on the small things, planning everything out and price finding everywhere I go, trying to plan the car with just the right amount of go (lots) and a bit of unique show, hopefully to make my 80 stand out in a crowd of c3's, but not obnoxiously so.

 

[Glensgages]

is there another rear diff, maybe from another C3 year that will drop in as a replacement? With one thousand junkyards and pick-a-parts near me, it would probably be easier... and safer... to get a different pumpkin and rebuild it and drop it in.

From what I have learned in the few years I've had my '82, no, there is no 'bolt-in' replacement for the '80-up Dana-44 type rear-end.
While the '68-'79 cars are almost identical, the earlier iron rear-ends are mounted differently, with almost NO (at-least EASY) inter-changeability, unless changing mounting-points is your idea of 'fun-and-easy'.

I've heard some guys absolutely abuse this type of rear-end, but with my 'luck' (or lack of same), and my years of racing at the strip, I'm just waiting until I can afford to put a solid-axle in an '80 Vette I have ear-marked for dedicated bracket-racing during my retirement years.

Maybe (hopefully? ) others of this Forum will prove me wrong.....

 

[WayneLBurnham]

All the Dana 44's and even Dana 36's on some are "weakish"

Even in cast iron over the lightened aluminum.

I'm sure the decision to do this was a engineering efficiency one. The medium power of the early C3's and C2's and the lower power of the mid and later C3's as stock with the tires of the day would gain little from a much heavier unit with a much heavier rotational mass - so the Dana 36, then Dana 44 then lightened housing Dana 44 was adequate.

This was not adequate for the use my '75 was intended as a platform so I spent a huge amount (over $4K installed) on a Tom's Differential high strength 12 bolt rated at over 1250 ftlbs. I do not know if they are available for the later C3's as a drop in or not. They cost $2300ish as a part, as compared to $800 or less from a regular vette house.