[toobroketoretire]

After driving my '71 around for the past three years with it's TH700R4 and 3.08 gears I decided to treat myself to a set of 3.70's. I ordered them from Summit Racing and they should get here by Friday or Saturday. And I also ordered the speedometer gears needed to correct my speedometer.

With the 3.70's I'll be able to make full use of my lower three gears for 1/4 mile passes and still run only 2040 rpm at 60 mph in 4th. Can't wait to try them out.................

[fishslayer143@yahoo.com]

you will love the 3.70 gears with the 700r4 ..its perfect match.. I got a little different gift for Christmas... A Bushmaster M4 ... I was a good boy this year

[toobroketoretire]

Originally Posted by fishslayer143@yahoo.com

you will love the 3.70 gears with the 700r4 ..its perfect match.. I got a little different gift for Christmas... A Bushmaster M4 ... I was a good boy this year

From my calculations it appears a set of 3.70's is a perfect match to a TH700R4 as the lower 3.70's will allow the first three gears to be fully used for 1/4 mile passes and then still allow cruising at 120 in 4th at only 4100 rpm. The best of both worlds.

[fishslayer143@yahoo.com]

one of these days, I m gonna have to see just what mine will top out at.. I ve had it to 150+ and it wasn t near done.. its peak horsepower is at 6200rpm,with 6800 redline.. in 4th gear, with 27 inch tall tires, top end should be pretty high..problem is ,my Pro-Comp speedo stops at 160 !

[david78]

what type of ring & pinions do corvettes have, 2 series or 3
or are Corvette in a class of there own? I have 3.73's right now and i wanna try 4.10/4.11 (as long as I stay below 3,000 RPM's on the highway)
Nice Gift !

[crossflag]

Originally Posted by fishslayer143@yahoo.com

one of these days, I m gonna have to see just what mine will top out at.. I ve had it to 150+ and it wasn t near done.. its peak horsepower is at 6200rpm,with 6800 redline.. in 4th gear, with 27 inch tall tires, top end should be pretty high..problem is ,my Pro-Comp speedo stops at 160 !

Most GPS units will show your speed

[toobroketoretire]

Originally Posted by david78

what type of ring & pinions do corvettes have, 2 series or 3
or are Corvette in a class of there own? I have 3.73's right now and i wanna try 4.10/4.11 (as long as I stay below 3,000 RPM's on the highway)
Nice Gift !

After talking to the Summit sales representative I found the 1963 thru 1979 Corvette gears are only used by the Corvettes as they aren't used in any of the other G.M. lines. So they are a bit harder to find and also a bit more expensive.

As far as the "series" goes a "2" series means the carrier will only accept ratios in the "2's" like 2.72's or 2.87's. The "3" series means the carrier will accept any ratios in the "3's" like 3.08's, 3.31's, 3.55's, 3.73's, and 3.90's. Then the "4" series carriers will accept ratios like 4.11's, 4.56's, and 4.88's. There are spacers available so you can put the thinner ring gears used for the 4.11's, 4.56's, and 4.88's onto the "3" series carriers but it requires longer bolts and isn't recommended for drag racing usage. Some gear manufacturers offer thicker 4.11, 4.56, and 4.88 ratio ring gears that will bolt up to the "3" series carriers without having to use a spacer and longer bolts.

As I'm running a TH700R4 the 3.70's will be ideal as I can buzz thru the end of a 1/4 mile in 3rd gear at 5100 rpm but buzz only 2040 rpm at 60 mph in 4th; thanks to it's 30% overdrive. And with it's 3.06 1st gear my launch will be ultra fantastic. And with it's 30% overdrive I'll be able to cruise at 120 mph at only 4000 rpm.
As I have 3.08's right now the 3.70's will bolt to my carrier with no problems.

[david78]

Originally Posted by toobroketoretire

After talking to the Summit sales representative I found the 1963 thru 1979 Corvette gears are only used by the Corvettes as they aren't used in any of the other G.M. lines. So they are a bit harder to find and also a bit more expensive.

As far as the "series" goes a "2" series means the carrier will only accept ratios in the "2's" like 2.72's or 2.87's. The "3" series means the carrier will accept any ratios in the "3's" like 3.08's, 3.31's, 3.55's, 3.73's, and 3.90's. Then the "4" series carriers will accept ratios like 4.11's, 4.56's, and 4.88's. There are spacers available so you can put the thinner ring gears used for the 4.11's, 4.56's, and 4.88's onto the "3" series carriers but it requires longer bolts and isn't recommended for drag racing usage. Some gear manufacturers offer thicker 4.11, 4.56, and 4.88 ratio ring gears that will bolt up to the "3" series carriers without having to use a spacer and longer bolts.

Thanks for the info
found a set on jegs.com richmond gear was $300-400
but dont know if they have a thicker ring gear for 3 series

[Bucwheat]

Very nice can't wait to hear track time differences.

[fishslayer143@yahoo.com]

Originally Posted by david78

Thanks for the info
found a set on jegs.com richmond gear was $300-400
but dont know if they have a thicker ring gear for 3 series

Duntov has the 4.10 thick gear sets