74 High-boy shifting problem

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Apr 25, 2006 | 07:20 PM

Trailcat

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74 High-boy shifting problem

Hello everyone, I just acquired a 74 F-250 that runs pretty well but I have run into a problem with down shifting. The clutch seems fine as far as up shifting and starting but when its from 2-1 or 3-2 it grinds unless I get to a slow enough speed. Any suggestions? Thanks in advance.

Apr 25, 2006 | 07:51 PM

KubotaOrange76

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From: GA

sounds like an np435....i rebuilt mine and i fixed teh same problem....key is the syncro shims and the endplays.....dont expect this tranny to shift like a zf-6 or something though

Apr 25, 2006 | 07:52 PM

ken selvy

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Try running red line synthetic , I did and I have 340000 miles on a borg warner 4 speed , goes into gear smoothly.KFLORD77. Just a suggestion!!!

Apr 25, 2006 | 07:57 PM

KubotaOrange76

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From: GA

whats the api rating or whatever its called on the red line??? ive always heard th 435's syncros dont like the newer gl5 gear lubes but i cant find anything gl4 or older

Apr 25, 2006 | 10:16 PM

Trailcat

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Thanks, will try the fluid first and the rebuild if that fails.

Apr 25, 2006 | 11:07 PM

FordPickup460

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From: Cab of a truck

The tranny shouldnt go into 1st gear without double clutching and/or matching the rpm's unless you are stopped as its non-synchronized, the grinding is normal there. Most of the NP435's ive seen, and my own, dont like to downshift to 2nd unless you double clutch or match the rpm's.