NP435 problem, Help!

Clutch, transmission, rear axle

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bigtimbo
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NP435 problem, Help!

Post by bigtimbo »

I have a 1969 F250 4X4 4 speed. It has a np435 transmission. This is my first floor shift truck, my last 1969 was an automatic. Sometimes I have problems shifting it into gear, Mainly taking off from a dead stop I have to release the clutch almost all the way out or let the truck roll forward for it to go into gear.( even putting it in reverse) . Is this normal for old trucks or do I have a problem?
CrypticRacer13
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Re: NP435 problem, Help!

Post by CrypticRacer13 »

If you mean a slight roll like half a foot or so then yes, thats normal. my race car an highschool hot rods where all the same. Its just a matter of the gears sliding into place
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averagef250
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Re: NP435 problem, Help!

Post by averagef250 »

1st and reverse aren't synchro'd. In case you aren't aware, You don't use first gear for anything but driving very, very slow. 2nd gear is the gear you start off in 99% of the time.

It's hard to know exactly what the problem is, if there is one at all, but basically they shift great when you use the clutch properly and understand that it's anything but an on-off device. It should drop right into 1st or reverse if you're barely rolling along and you should be familiar enough with the clutch pedal to barely roll over the gears to line up the splines to drop right into 1st and reverse at a stop when you need to.

If it's not going into second gear easily at a stop and it's not grinding then you probably have a clutch disengagement issue. Adjust your linkage or replace your clutch. It's common for old diaphragm pressure plates to get bound up by rust and gunk and not release fully. 3 finger plates are not as prone.

If it's grinding as you're trying to pull it into second at a stop with the clutch pedal fully depressed you have a bad synchro and a mis-adjusted linkage or bad pressure plate.
1970 F-250 4x4 original Willock swivel frame chassis '93 5.9 Cummins/Getrag/NP205/HP60/D70
cep62
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Re: NP435 problem, Help!

Post by cep62 »

You aren't starting in 1st gear (creeper) are you?
For most driving you can start out in 2nd.

First and reverse are not synchronized and may need need a little finesse to engage.

Is your clutch disengaging properly?
bigtimbo
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Re: NP435 problem, Help!

Post by bigtimbo »

Thanks guys for all the advice. I start taking off in second gear. From a dead stop second gear and reverse is hard to get into.I will start by looking at the clutch.
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