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Joined: Jul 2003
Posts: 264
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Jul 2003
Posts: 264 |
Can anyone help please?
'David I am in problems trying to track down a pinion gear for my car. The GM
number stamped into the gear is 346215 this is a 11 tooth gear that mates
to a 46 tooth crown (or ring ) gear. As my car is as you know a Canadian
built car I do not know if the ratios are the same as U S production. My
History of Pontiac , which is a American book shows the 26 to mid 28 as
being a 4:18x1 reduction. I have also been told that a Chevrolet
differential is the same however the ratios seem to differ. Are you able to
cross reference the above number as to what year of Chev may use this same
number?
I hope you may be able to put some insight to my problem.Thanks Pete Watson'.
Cheers,
David Hayward
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Joined: Jan 2002
Posts: 242 Likes: 1
Backyard Mechanic
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Backyard Mechanic
Joined: Jan 2002
Posts: 242 Likes: 1 |
Hi david yes the 28 and 29 chevs had that combination 46 tooth over a 11 tooth pinion and yes the 346215 part number is 1928 the 1929 part number is 355414,However these pinions and ring gears were matched sets and should not be swapped around there is a differance in the gears as the 29 is slighly larger in the outside dimention this gave the gears a greater surface area to handle the power of the six cylinder all the internal dimentions and the mounting holes are the same .As a note the 42 tooth over the 11 tooth combination will give a better cruse speed.
Jim
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Joined: Nov 2001
Posts: 273
Backyard Mechanic
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Backyard Mechanic
Joined: Nov 2001
Posts: 273 |
Yes - but remember the first two months of 1928 production - Jan and Feb - still used the 42/11 tooth combination [3.82 to 1] which was standard on 1925 thru Feb 1928 models. But because of the big shift to those heavier Fisher sedan bodies, most early '28 Sedans had a slow acceleration problem [not as pepi as the 27 models?] So the fix was Starting in March 1st 1928, all 1928 passenger cars switched to the Pontiac gears that were the 4.18 to 1 ratio [46/11]. KenK
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Joined: Jul 2003
Posts: 264
Backyard Mechanic
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OP
Backyard Mechanic
Joined: Jul 2003
Posts: 264 |
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Joined: Feb 2003
Posts: 39
Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Feb 2003
Posts: 39 |
Does anyone know how hard it would be to mount a late 20's rear end into a 490 frame? A friend offered to give me a Pontiac rear end which I gladly accepted, but I want to build a speedster using a 490 frame.
Stephen Sebastian
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Joined: Dec 2001
Posts: 217
Backyard Mechanic
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Backyard Mechanic
Joined: Dec 2001
Posts: 217 |
Starting in March 1st 1928, all 1928 passenger cars switched to the Pontiac gears that were the 4.18 to 1 ratio [46/11] My 1928 coupe (manufactured after March) had the 4.18 gears and it would pull stumps. I switched to the 3.82 gears and it drives a whole lot better. -R 
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