Rear gear question

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Mar 17, 2010 | 01:22 PM

TWINRAY

Thread Starter

Melting Slicks

Joined: Aug 2005

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From: Working on the car NY

Rear gear question

Is a 3.36 gear to high to get my '67 with a 327/350 off the line with a 2.20 1st gear? I'm not talking drag racing it (as it has a

4.11 in it now) but just for general driving. Thanks.

Mar 17, 2010 | 01:35 PM

Plasticman

Race Director

Joined: Nov 2000

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From: Beverly Hills (Pine Ridge) Florida

The rule of thumb is multiply the rear end times the 1st gear ratio.
For you it is 3.36 X 2.20 = 7.392.
Generally a 10 or a tad higher is desired. Especially with a higher cam'd engine, like the L79 you have. My 66 327/350 had a 3.70 rear gear, which worked very nicely.

With the 3.36 with the 2.20 first gear, expect to be slipping the clutch (to get off from a stop).

Note that a 3.36 rear with the 2.56 wide ratio Muncie would = 8.60 total. Still not ideal, but far better than with the 2.20 close ratio Muncie.

Also note that my existing MY6 OD trans has a 3.09 first gear coupled with a 3.55 rear gear. That = 10.9695 and is a dream to launch smoothly (but 2nd gear does come up quickly).

Plasticman

Last edited by Plasticman; Mar 17, 2010 at 01:41 PM.

Mar 17, 2010 | 02:12 PM

Allcoupedup

Melting Slicks

Joined: Nov 2002

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From: Wheaton IL

I used to have a l76 with a 3.36 gear with a close ratio Muncie with a 2.20 first gear and it sucked. I swapped transmissions to a close ratio with a 2.56:1 first gear and it was a huge improvement.

Recently I changed from 3.36:1 to 3.70:1 rear end and it was another huge improvement.

To answer your question, yes I think the 3.36:1 is too tall for a l79. THe wide ratio is a great compromise because you will get a shorter total first gear ratio to the rear wheels but you will still get a 1:1 ratio out of the transmission in 4th gear for cruising.

Brian

Last edited by Allcoupedup; Mar 17, 2010 at 02:31 PM.

Mar 17, 2010 | 02:15 PM

TWINRAY

Thread Starter

Melting Slicks

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From: Working on the car NY

That's what I thought. I had a '68 GTO (360HP 400") with a 2.20 1st gear and switched to a 3.36 from a 3.90 after the latter went south. It was fine when you were rolling but it bogged like krap from a start. Oh well, it was just an idea

.

Thanks

Mar 17, 2010 | 05:21 PM

mhanley

Pro

Joined: Jan 2005

Posts: 644

Likes: 17

From: O'Fallon MO

Quote:

Originally Posted by TWINRAY

Is a 3.36 gear to high to get my '67 with a 327/350 off the line with a 2.20 1st gear? I'm not talking drag racing it (as it has a

4.11 in it now) but just for general driving. Thanks.

I have 3.55 in my 67 L79 and I just love the way it comes off the line, I think its the ideal gear for any type of driving. I also had it in a 67 L71 car it was great.

Mike

Mar 17, 2010 | 05:39 PM

w1ctc

Melting Slicks

Joined: Sep 2003

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From: Orange Ct

I have a 3.5 rear and 2.20 first. It's always been kind of lazy off the line but it pulls great with a street start ( 20 mph punch). I would gladly give up 10 or 15 mph peak in first for a better off the line feel.

Mar 17, 2010 | 05:50 PM

Tampa Jerry

Le Mans Master

Joined: Aug 2005

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From: Temple Terrace Florida

Gearing

I have a L79 in my 68 with a 3:70 and an M21. It is a great compromise for street and highway. The 3300 rpm on the highway at 70 MPH can be noisey on a long trip. I did put aTremec in my 66 L79 with a 4:11. Love that overdrive. Jerry