Re: Installing 5 spd. x-mission in PW


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Posted by Charlie on November 11, 1998 at 15:42:54:

In Reply to: Installing 5 spd. x-mission in PW posted by Roy Sanders on November 11, 1998 at 13:41:10:

There MAY have been a few NP540/541/542s installed in W500s behind 251 or even earlier flatheads. I think there were, but specimens in running condition must be extremely hard to find. Even more common GM and Ford and newer Dodge bolt pattern 540 series 5spds with 5th overdrive (0.82:1) are very rare in running condition. The overdrive input shaft is out of stock and production. The NP540 is 13" long. the limit for putting a 5spd in an otherwise stock PW or M37 is 15", and that requires changing from flat flanges to yokes, in the case of the M37, at least. A Clark 280VO is 15" long, and 5th gear is 0.80:1. It can be bolted to the Dodge bellhousing with the following changes: the center hole must be enlarged to fit the bearing retainer. New holes need to be drilled and tapped in the bellhousing for at least 3 bolts. The usual Clark input shaft (which is 1.375"/10 spline) is a bit shorter than the Dodge input shaft, but still allows 0.50" of pilot engagement, enough to support it. The tip must be machined down to 0.750". A 1.375"/10 spline hub clutch disk must be used. A clutch shop can put this together for you. The floorboards need surgery.
There may be Spicer T5-250s and T5-290s around that are short enough, but I don't know anything about this gearbox and as far as I know they are only used on overseas mfg'd. trucks.
Another alternative is to use a Gear Vendors planetary overdrive (0.78:1 ratio in OD) mounted on the transfer case rear output. It works only in 2WD, shifts with a button (requires 12V), and requires shortening the rea r driveline 14". Randy Palmer, their engineer, states that he can make it work with their NP205 kit and a coarse spline coupler sleeve. A NV4500 5spd will NOT work in the stock application because of excessive length (18-20"). It should work with a V8 or 4cyl diesel re-power.
I would not advise the concurrent use of a 5spd and 4.89s with a flathead six. I think 5th gear would be unusable.
Charlie


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