I have a 55 Chevy rear with 3:55 gears in my Model A, I'd like to change to a more highway friendly gear. Thinking 3:36 or 3:08. Do I have to change the carrier to put either one of these gears in?
@scoop Hello, When I was a teenager, my brother had a 58 Impala. The rear end set up was interchangeable between anything from 56 to 58. So, we were changing rear gears for easy street driving on long distance trips versus the short quarter mile acceleration races we did every weekend and sometimes during the week. It came with a 4:11 Positraction gears and to be fully competitive with the top racers in the class, we got a complete 4:56 gear third member section to change out for the weeks school, work and longer cruises than a quarter of a mile. Yes, it sounds like a lot of work changing one complete unit for another. I was given the job of doing that to get the 58 Impala prepped for the Friday-Saturday races. So, I spent my Thursday after school until late evening taking apart everything and installing the new 4:56 carrier. But, the competition was hectic and the top racers were using 4:56 gears. So, we had to be competitive. @scoop “I have a 55 Chevy rear with 3:55 gears in my Model A, I'd like to change to a more highway friendly gear. Thinking 3:36 or 3:08. Do I have to change the carrier to put either one of these gears in?” Jnaki 3:55 to 3:08 is about the same as our 4:11 to 4:56 exchange. It was a lot of work, but I did not drive at the time and that was a way for me to get a “free” ride to anywhere I needed to be. Basketball practice, sports events, beach, downtown, etc. so, I did not mind doing the exchanges. So, when it came time to change the gears, it was out with the old and plop in the new. But, for a couple of weeks, I exchanged my 4:11 Positraction for a friend’s 3:55 gears from his 57 Chevy 283, dual quad, Bel Air hardtop sedan. He had a match race challenge coming up and wanted to have a little extra in store. With the 3:55 in my 58 Impala, we drove down to La Jolla (100 miles+one way ) and the next week, up to Santa Barbara (+ 100 miles one way) just for a little break from our normal stuff. The road smoothness was outstanding and we still had the 280 hp+ if any necessary “things” popped up. So, if you use the either gear you listed, then want to go back to the 3:55 gears, it would be easier to just get a whole 3:08 complete rear center section to slide in and out. The 3:36 to 3:55 may not be worth the effort in taking out the compete ring and pinion each time, or even getting a complete 3rd member unit. You probably won’t notice any difference in performance or road feeling. But, that is your choice. I was lucky for the 3:55 change with the 4:11 gears. I still had the 4:56 Positraction gears in the backyard garage if/when the Impala needed more traction and power acceleration. YRMV Note: When we finally got the 1940 Willys Coupe together, the rear end was a 56 Chevy unit. Strong and fit our needs. It also was able to interchange with the existing 3:55, the 4:11 Positraction and the 4:56 Positraction third member unit from our 58 Impala usage. convenient and less costly in the long run. Once the 4:56 Positraction was installed, it stayed there until we sold the whole rear axle housing in a garage parts sale. The person who took the ad information over the phone read it back to me. But, when it was published in 1961, we realized she had a spelling/hearing problem with many of the items. A 56 not a 55 Chevy rear end, a 292 c.i. motor – not 283 c.i. Hedman not headman, adapter-not adaptor, a 40 Willys motor and trans – not a 49 model as mistakes. At least she got the correct name and phone number for the ad. Luckily, the prices + parts were valuable and a good deal for most. All parts stayed in So Cal. Except for the complete 292 SBC 671 motor that had the buyer come out West, to ship it back home to his Midwest location. They were all purchased within a month and all was good, except for our “psyches…”
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