I'm looking for advice on helping me choose a rear gear ratio. I have a '67 with a 383cu. in., 425 hp motor, 3.36:1 rear gear and a "close ratio" Trans with a 2.20:1 1st gear. Problem is, the car "bogs" too much when trying to pull out from a stop sign normally. I will be updating the trans with a new input shaft and cluster gear which will change this box to a "wide ratio" with a 2.52:1 1st gear. I don't feel that this will be enough change. So my problem is to change the rear to either a 3.55:1 or a 3.70:1 ring and pinion. Looking for someone's experience with the 3.55 combination. I don't want to end up with a "stump-puller" if I go with the 3.70's. Any advice? Boy it would be great if there was someone out there in the Spring City, PA area that has a car with a set of 3.55's that I could drive around the block a few times to feel those gears............Herb
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Re: Advice on Choice for Rear Gear Ratio
Herb-----
The change to the wide ratio gear-set is the perfect solution. Doing that, I would keep the 3.36:1.
For street driving, especially if you do some highway cruising, the wide ratio trans/3.36 rear gear combo is going to be perfect.
If you were going to stay with a close ratio trans, then I would recommend going to 3.70:1 but that would not be the best solution except if you were going to race the car a lot.
For the street, a wide ratio transmission is the best. Period.
One more thing: if the car currently uses a 12-3/4 flywheel, I'd recommend changing that to a 14" standard weight flywheel and 11" clutch. You'll need to change the bellhousing from a 3858403 to a 3899621 and also change the starter to a cast iron nose type to accommodate the flywheel changeIn Appreciation of John Hinckley -
Re: Advice on Choice for Rear Gear Ratio
I agree with joe. My 67 350 hp has M20 and 3:36 and it's just aboout perfect for all around street use.Comment
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Re: Advice on Choice for Rear Gear Ratio
Joe, thank you very much for your input. Actually I do have a 11" clutch in this car. We just purchased this car this past summer. The owner before me had a 11" Purple Hays clutch in it. I could hardly push it in. I immediatly changed it out to a "stock" 11" diaphram setup. I discovered the bellhousing was cracked, and needed to replace it with one of the newly GM liscened bellhousings sold by suppliers like Zip Corvette Parts. During all of this is when I discovered the M21 Close Ratio Trans. I bought the new Input & Cluster Shaft out at Corvette at Carlisle. Within the next month I will again drop the box to make the switch. Most of my driving is around our home base going to car shows and such. Occasionly we will need to go out on the Turnpike or Interstate and need to drive at 65 mph. Most of our driving is between stop signs and red lights which requires a lot of starting and stoping. I actually had several Camaros with 4.11 and 4.56 gears in them. They were "fun" but not meant for highway driving. Actually we drove our brand new '68 Camaro home from Ft. Bliss Texas in '69 with 4.56's in it. I Couldn't go over 60 mph all the way home!! But it sure could pull out "stumps"!!...HerbComment
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Re: Advice on Choice for Rear Gear Ratio
Herb -
Here's another vote for the wide-ratio/3.36 combination - I have it in my '67 300hp, and it's ideal for me.Comment
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Re: Advice on Choice for Rear Gear Ratio
Hi John, and thank you for your advice and support as well. I discovered that my car has a "AQ" Code rear. Which translates into an "Open 3.36" rear. However, an owner before me had a "posi" carrier put in. Much to my relief! I proved it by "lighting" it up just once in our driveway to see if I had Parallel Tracks. So it will please me quite well if I don't have to change out those gears..........HerbComment
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Re: Advice on Choice for Rear Gear Ratio
The '67 L79 I bought new was ordered with a close-ratio and a 3.70. As I remember, it was a perfect combination. When I built my current L79, I put in a 3:08 for cruising; bad idea. Wide-ratios; 3:36's I don't have any experience with, but I do know that a close-ratio 3:08 sucks.Comment
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Re: Advice on Choice for Rear Gear Ratio
how is your dist set up,lots of vacuum advance and if it is the bog comes when the vacuum goes away and the spark retards as you start out from a dead stop. try 15/18 degrees initial without vacuum advance and then limit the vacuum advance. easier than pulling trans
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Re: Advice on Choice for Rear Gear Ratio
Herb,
A 383 stroker should not bog off the start with 3.36 gears in a light weight car as a 67 vette with a 2.52 or 2.20 first. The problem lies in the power plant some place. Such as a bad camshaft, intake manifold selection or a carb that needs a tune.Comment
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Re: Advice on Choice for Rear Gear Ratio
When I bought my '65 w. L78 I had the same problem; poor part-throttle response with the 2.20 and 3.55. I switched to a wide ratio trans...all better. That combo is perfect for the way I use the car.
Try the wide-ratio and then consider more rear gear; I don't think you'll need it...Comment
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Re: Advice on Choice for Rear Gear Ratio
Herb
If you want the best of both worlds look into a Tremec 5 speed. With your 3:36 gears and a 5 speed it will be like having a 3:80 rear end around town but on the highway at 2000 rpm instead of 50 you will be going 75mph. Best thing I did to my 62 with the same motor as yours.
TerryComment
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Re: Advice on Choice for Rear Gear Ratio
I'm with Clem on this one. Get your tune right for the combination. I have a 3.36 w/close ratio in my 63 L-76 and I've lived with and enjoyed it that way since new. I can't count the number of 4.56, 4.11 and 3.70 equipped Camaros and Vettes I've left behind, or the money I've taken from them when they suckered for the 30 mph and up runs.
The only thing that slowed me down, which I had to re-tune for, over the years has been the lousy Ethanol laced gas. That had me going for almost 2 years until I figured it out.
I went the 4.56 route back in the late 50's early 60's with my post 57 Chevy at the drag strip. At the end of the season I blew the 4-speed and put the original (modified) 3-speed overdrive back in. At first I learned that when you topped out in high gear it is not wise to do a kick down for passing (tach needle pegs real quick). I then made a manual control arrangement so I effectively had a 6-speed, up and down. Now that was fun!
Stu FoxComment
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Re: Advice on Choice for Rear Gear Ratio
The wide ratio versus close ratio and various rear end gears has been tossed around about as about as much any subject I can think of in the six years or so I've visited the TDB. Always interesting to hear the personal perspectives.
In my mind, there isn't a "best" tranny ratio, ....only a personal preference that I would submit is affected some what by all of our unique driving styles, IMO.
As a general rule, I've found more "mild" drivers preferring wide ratios with mild to moderate read end gears.
In general, I find more "aggresive" (possibly a little more heavy-footed) drivers preferring close ratios and stronger rear gears like 3:73 or 4:11.
An interesting correlation comparison would be to tie it to white wall tires v/s black or red lines, and/or rally wheels v/s wheel covers on C3s.
Like political parties, study them all and go with the one you feel most comfortable being around........
Ridge,
owner 1966 Chevelle SS396 wide ratio with 3:08 gears
and .. 1967 Corvette 427/400 close ratio with 4:11 gearsGood carburetion is fuelish hot air . . .Comment
. Jimmy H. would approve.
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