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Buick36-49

1936 Buick High Way Speed Question

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That 95.6 mph top speed observed at the GM Proving Grounds for the new '36 Century rings a bell. I read that years ago. Thanks. However, a coupe or convertible would be no faster. Actually, a convertible would be a trace, perhaps a couple hundredths of a mph, slower due to drag from the cloth top.

Absolute or top speed= coefficient of drag (CD rating)/horsepower/final gearing

Acceleration=weight/torque/final gearing

And even if Buicks defied the laws of physics, Flint would still publicize the absolute highest speed they could wring out of their new car, regardless body style.

Thanks, sir, for confirming that figure.

Edited by Water Jacket (see edit history)

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since Buick used the torque tube for years ( I believe into the 60s ), can't you guys find a complete rear or just gears with suitable ratios that might interchange with your older cars ???...yes 4.44s and 4.33s are fine for chugging around town,the freeway is another thing....I think that mid to late 50s Buicks used a highway friendly 3.64 and 3.36 ratios...look into these gearsets.

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Seems to me people are often substantially out of proportion in their expectations of higher gear ratio obtainable from swapping the ring and pinion gearsets. The factory rear end for ford (model A) correspond to a 3.78 (OEM) ring-divided-by-pinion ratio. A weekend and several hundred dollars later, you can have the 3.54 ratio, if you are lucky enough to find the gearset. Stop and think about difference in these two ratios. Easiest way is probably just to divide 3.78 by 3.54 to find that 1.068 the high speed rear end is only about 6% gain! Say you are going 60mph with the lower ratio. Then, preserving the same rpm, you are only able to go only 3.6 mph faster, or about 63.6mph! I believe the reason for over-rating the effect of these ratios probably stems from drag racing, where a small change can lead to many thousandths of a second in elapsed time, which makes the change seem much more meaningful than it is with respect to engine rpm. Perry

Edited by prs519
mistake (see edit history)

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The Buick differential gear sets (pumpkins) are interchangeable from 1940 to 1955. When installing a taller ratio gear set you may need to use slightly longer bolts to hold the case into the rear end housing. The ratios that were made for the later years were 3.9, 3.6, 3.41, 3.36 and perhaps one or two more. You need to re-use your original drive shaft and torque tube. The rear cover needs to be positioned so the drain plug is at about 4 or 5 o'clock as the gear lube level should be about about 1/2 way up or just touching the bottom of the axle shafts.

Pay attention to the fact that while you can usually improve road speed with a gear change, you still have to stop these old Buicks, so leave enough room to stop.

Joe, BCA 33493

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As far as my Pontiac goes, since this car was (until I purchased it) in the mountains, then that would explain why the RPMs are so high when at 50. All I would be interested in, would be to find the higher-speed ratin that would have originally come with my car. This of course would be the gears that were designed for flat-ground driving. No mountains in Florida, so that wouldn't be a problem. I know that these cars were (for the most part) not designed for the highway speeds of today, but if I could drop the engine RPMs just a bit, going 55 mph wouldn't be such a strain on the old engine.

I spoke to a guy that also owns a 37 Pontiac with a 6 cyl, and he told me he has no problem going 55-60 MPH at a constant speed. His car has the flat-land gear ratio.

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when these cars were new, there wasn't any road called a "freeway". around town and country roads were all there was....40-50mph would have been just fine....now with every car equipped with overdrive, overhead cam high revving aluminum engines, every driver just suums to be in a great hurry to get to their destinations....why??...because they can !!...our old cars are now just "rolling roadblocks" to modern vehicles.

'

'

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Dynaflash I must admit that would be a ratio change wide enough to be highly noticeable, as you say. You gain better than 12% more roadspeed at any high-gear RPM. I think that is along the same lines as some overdrive units.

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A gear swap won't come close to matching an overdrive for RPM reduction. As someone pointed out above, the effect of a modest gear change isn't very big, but the overdrive in my Cadillac, for example, is a 30% reduction (the Cadillac's final drive ratio goes from 4.75 to approximately 3.33 with the overdrive). At a real 60 MPH, the engine thinks it's going 42 MPH. I don't think there's any real-world gear ratio out there that can deliver that much of an improvement.

This isn't to say that a gear swap isn't a worthwhile improvement, because even a 300-500 RPM reduction is nice peace of mind when you hear it thrashing away under the hood. I have a 3.60 gearset for my '41 Century that I intend to use in place of the original 3.90s, but that's really only economically smart because I already have the whole car apart. If I had a complete, running, driving car, I don't think I would have made the investment in money or effort for that small of an improvement. I believe The Old Guy has a set of 3.54 gears from a Dynaflow car in his 1940 Super, which is probably the ideal choice for any '30s or early '40s Buick, which have plenty of torque to pull a lower gear. If you can find a set THAT would definitely be a worthwhile upgrade.

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