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Discussion Topic:
1951 Rearend Ratio
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supereal |
03-05-2010 @ 8:37 AM
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Senior
Posts: 6819
Joined: Oct 2009
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Many of us grew up with the old "crash boxes", and I still find myself "double clutching" now and then. It's true that overdrive units are not cheap, but given the rather narrow power band of the flathead engines, they do provide the means to travel safely at today's highway speeds when necessary without a screaming engine. My Ryan OD cost just over two grand about ten years ago, and has been trouble free, to date. For anyone considering such an installation, be sure that your steering and brakes are capable of safe operation at speeds above 50-55 mph. These cars were not designed for the 65-70 mph common today, and any handling deficiencies can produce disaster quickly.
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Mercman |
03-05-2010 @ 12:00 PM
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Member
Posts: 6
Joined: Oct 2009
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I have a '51 Mercury M3 pickup with the original 255 ci flathead coupled to the original 4-speed low geared straight-geared (no synchro) tranny fitted with a Power Take-off unit (PTO). The original wheels are huge 8-bolt 17" split rims which I've had to replace for '66 Mercury 8-bolt 16" rims for safety's sake. (No one will touch split rims anymore). Plus, it lowers the truck a bit. First gear is what I call "bull-low" for pulling extraordinary loads up steep hills. The truck used to be owned by a wrecking yard and had a 15-foot long A-frame with a huge mechanical winch on it. When I first bought the truck in 1982,I used it for hauling and lifting massive fir trees (16" dia by 100'long) for a log house building project. I've since restored the old girl and made a complete 8'-long pickup box for it. It's great, except for the really low gearing...probably that 4:27 ratio someone mentioned. I never use first gear except to demonstrate how it will only go 5mph with it! I have Canadian Collector Licence Plates on it, which essentially means that I cannot make a drivetrain change to a modern axle for the benefit of economy and highway speeds. I'm wondering if anybody knows of a way to change the original gearing (axle or fourth gear) to achieve highway speeds (60-70 mph), without the very expensive overdrive solution. For example, is there a replacement pinion one can acquire?
This message was edited by Mercman on 3-5-10 @ 12:07 PM
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37RAGTOPMAN |
03-05-2010 @ 1:23 PM
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Senior
Posts: 1943
Joined: Oct 2009
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some of the old trucks had a 2 speed rear axle,this also a option, if you can find one, a friend of mine had a roll back truck with a 2 speed rear and it travel down the road with no problems, I doubt that the law would know the difference,if you were stopped,not unless it gets inspected,and I highly doubt they would know the difference also. my 3 cents,37RAGTOPMAN
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supereal |
03-06-2010 @ 9:39 AM
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Senior
Posts: 6819
Joined: Oct 2009
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I agree with 37. I've never heard of an axle transplant being a factor in inspection, but I don't know about Canadian laws. It has been common for many years to have different rear axles in trucks. Some due to the variance between vendors, special orders, or junkyard repairs. As you have already replaced the "widow maker" split ring rims, it seems odd the type of rear axle would be a factor. I've never seen a pickup with a two speed axle, as the largest are the "tonners", and the two speeds were installed in the ton and a half and larger.
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JebNY |
03-06-2010 @ 3:45 PM
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Member
Posts: 44
Joined: Nov 2009
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I had an 1950 F5 with 2 speed axle and it worked out nice for a road driving, BUT. It was a very heavy axle assembly and it had a much larger wheel/tire size than the smaller model F1-3. The larger tire diameter was important since the axel was 5:14/5:83, not much help with pickup tires.
Jim... 1950 F1 Stake
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Mercman |
03-11-2010 @ 8:08 AM
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Member
Posts: 6
Joined: Oct 2009
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Thanks for your helpful comments. I guess I'll just give in and do the "axle transplant".
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