Rukee

I just replaced a 3.90 with a set of 3.55s and couldn`t be happier. The car feels alot faster too as it seems to have longer legs between each gear and goes down the highway excellent.

 

ppurfield001

Point taken -- with the close ratio four-speed and the 3.90 gear ratio, the time between shifts on my goat is very short. Any idea how much it would cost me to go to 3.55 gears from 3.90 gears if I got a mechanic to do the changeover for me? Thanks.

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Rukee

I would expect to pay about $300-400 with parts and labor included depending on which set of gears you go with. You can pick up brand new gears from $227. I bought the Richmans myself, though the ones I bought didn`t say "Richmond Gear is not recommended for quiet applications." like these do, mine run quiet.
Auto Parts: YG GM8.2-355 - High performance Yukon Ring & Pinion gear set for GM 8.2 in a 3.55 ratio. Yukon exclusively uses 8620 steel in all their Ring & Pinion sets for high strength and long life. They use the latest designs and manufacturing tech
Auto Parts: RG 49-0015 - Richmond Gear ring & pinion gear set for GM 8.2 in 3.55 ratio. Richmond Gear has long been a staple in the performance gear market place with products geared towards the racing market. Their gears are made strong to withstand

ppurfield001

Thank you Rukee. I will investigate the parts supplier described above. By the way, in determining my current gear ratio according to your methodology, I also confirmed that my goat has posi-traction.

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CJD

Hi, I've got a 68 goat that I bought in Mid-Michigan and I am trying to find out what gear is in it. I read your response and I went out with a wire brush and I could not find the W/Y designation. Is it close to the pig or more outboard?

Thanks,

CJD

Rukee

Welcome to the forums.
As described above, to find your rear end ratio jack up the rear off the ground and rotate the tires one full revolution(for a posi unit), count the # of times the drive shaft turns to make the tires roll over one full turn. If only one tire rolls(open rear end) then block the one wheel and turn the one tire over two full revolutions and again count the # of drive shaft turns for your ratio. If you had a 3.90 gear the drive shaft will turn over almost 4 full revolutions (3.9 times to be exact), if you had a 2.73 ratio then the drive shaft will turn 2 and almost three quarters revolutions for every time the tires turn over once. It`s a very effective way to find your ratio.

rick3452

Having the 390's taken out and the 323's put in my 66 next Tuesday.Looking forward after almost forty years of driving this car to cruising the highway. Thanks for all the great info!!! Rick

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1966 GTO tri-power 4 speed competition-plus, Tubuler Automotive competition headers. 58 thousand miles. Owned since 1969

geeteeohguy

Rick: You're gonna kick yourself for not putting in the 3:23's 30 years earlier!! You'll love 'em! Good luck with the swap!
Jeff

Rukee

I know going from 3.90s to 3.55 was a world of difference in my `65! I just swapped out the rear gears in a `71 Challenger 440 six pack car from 4.10s to 3.54s and that guy is sooo freakin happy he almost kissed me.

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Restoration pictures password is 'GTO'

rick3452

Thanks Jeff....

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1966 GTO tri-power 4 speed competition-plus, Tubuler Automotive competition headers. 58 thousand miles. Owned since 1969