The Camaro Club (UK)

Hi - anyone uprated their rear end from a 3.08 to 3.42 or 3.72? If so how noticeable was the improvement? Im considering it for my 73 with a muncie 4 speed and a big chevy 427. Maybe going from 3.08 to 3.73 is too much and the big block has enough grunt anyway- although its mostly around town driving so "highway" rpms less important. Maybe going from 3.08 to 3.42 wouldn't be a noticeable enough improvement to spend the cash on?
Also , choosing between a ram power grip or a centerfore dual friction clutch - opinions?
thnx

I went from 2.80 to 3.42, made it pretty nifty,
3.73s were looking good but the conservative in me won.

With a big block I would think 3.42 would work well .
Also is it a wide ratio ( M20 ) or the close ratio M21 or M22 ? Makes a difference in low gears .
Also RPM at cruising speed will be worse ( higher ) if you go for the 3.73.

For a big block 3.08 is plenty unless you have very good tyres and an overdrive box.

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My '80 progress thread - hugger orange! Now with LQ9 power - forged pistons, LS2 rods, 236/242, .621/.612, flowed and milled 317 heads. MS3X

4L80e, 12 bolt, 4.11, Moroso brute strength posi, steel shafts.

Subframe connectors, g-braces, solid body bushes, carbon hood and front bumper, custom door cards, Autometer gauges.

its an m21 if it helps. 2.2 1st gear

I went 2.56 to 3.42 and I've got a 5 speed overdrive, i definately wouldn't go higher, as cruising revs would just be crazy, fuel would be crazier, and I would be less likely to drive it....

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“You only live once, but if you do it right, once is enough.”

I'm going from 3.55 to 3.08 when my ride gets back on the road, with a wide ratio M20 the new ratio will provide a good compromise on cruising RPM and acceleration .

I would stick to 3.08 with a BB

otherwise you will be doing loads of RPM at say 80 mph = huge fuel bills.

better to fit an LSD with the higher ratio

Look at the RPM @60 mph per tyre size below:
Tyre Diameter Rear Axle Ratios
inch 2.73 3.08 3.55 3.73 3.91 4.11 4.56 4.88
24 2268 2587 2982 3133 3284 3444 3830 4099
24.5 2222 2534 2921 3069 3217 3374 3752 4016
25 2177 2484 2863 3008 3153 3306 3677 3935
25.5 2135 2435 2807 2949 3091 3241 3605 3858
26 2093 2388 2753 2892 3032 3179 3536 3784
26.5 2054 2343 2701 2838 2975 3119 3469 3712
27 2016 2300 2651 2785 2919 3061 3405 3644
27.5 1979 2258 2602 2734 2866 3006 3343 3577
28 1944 2218 2556 2686 2815 2952 3283 3514
28.5 1910 2179 2511 2368 2766 2900 3227 3452
29 1877 2141 2468 2593 2718 2850 3170 3392
29.5 1845 2105 2426 2549 2672 2801 3116 3335
30 1814 2070 2386 2507 2628 2755 3064 3279
All figs are RPM at 60 mph in top gear (1.00:1)

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Kind Regards
TopCat
Secretary
Classic Camaro Club
Member of The Association of American Car Clubs UK
Email :tboles@strathnoon.co.uk Websites: http://www.classiccamaroclubuk.com and:
http://www.youtube.com/watch?v=IdhLJtR_ZY4

I've got a 3.90 via a TH350. Great for the quarter mile, rubbish for anything else! My mpg is terrible and the engine is constantly buzzing, it's really off putting.