Transmission Options
Thread Starter
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Cross-Country
Joined: Mar 2009
Posts: 62
Likes: 1
From: San Diego, CA
Transmission Options
Hello, My NP 435 4spd started to grind shifting in to 3rd and the same down shifting from 4th, so it has to be taken out, torn apart to diagnose and overhaul. The truck is a 76 300 i6 2wd stepside LB it is my daily driver, freeways mostly. I am thinking thating a 5spd would be a little better on gas and a couple times a week I do hual stuff and sometimes trailer so nothing real heavy(city living). What are some good 5 speed trans options out there, is there a 5spd that would drop in to the 4spd place without much mods to the trans tunnel or is keeping the NP my best bet? All opinions and replies are appreciated. Thanks
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Joined: Apr 2004
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The cheapest option for a 5 speed would be the Mazda 5 speed found in F150s behind 300s and 302s.
The ZF is stronger with the low first gear, but more expensive. Behind 351s in F150s, and in F250s behind the 300, 302 and 351.
The big problem with these is they are integral bell transmissions, and use an internal hydraulic throw out bearing. That means you have to convert to a hydraulic clutch. PITA
The cheapest route to an OD for your set up is the 4 speed OD box used late '70s to mid '80s. First up here:
Domestic Truck Tranny Guide
These are not strong transmissions, light duty only. The iron cased unit is the strongest, but check shifter location. Also found in vans.
After the strength issue, the gearing is the biggest annoyance. The 2nd to 3rd gap is huge. Light duty, flat land use will be OK.
Another option is to fix up the NP435, and then use the low first gear to pull some tall gears in your axle. You probably have a 9 inch rear axle? You can put some 2.79s in there and get basically the same effect. Not as cheap as it used to be, but doable. New gear sets are about $200, add bearings and labor. Or try to find a good pumpkin that you can just slap in there--
Auxilary ODs exist, but $1500 for one or $3000 is a bit steep.
Ranger Overdrive
Gear Vendors under/overdrive transmissions the most awarded auxiliary transmissions.
The ZF is stronger with the low first gear, but more expensive. Behind 351s in F150s, and in F250s behind the 300, 302 and 351.
The big problem with these is they are integral bell transmissions, and use an internal hydraulic throw out bearing. That means you have to convert to a hydraulic clutch. PITA
The cheapest route to an OD for your set up is the 4 speed OD box used late '70s to mid '80s. First up here:
Domestic Truck Tranny Guide
These are not strong transmissions, light duty only. The iron cased unit is the strongest, but check shifter location. Also found in vans.
After the strength issue, the gearing is the biggest annoyance. The 2nd to 3rd gap is huge. Light duty, flat land use will be OK.
Another option is to fix up the NP435, and then use the low first gear to pull some tall gears in your axle. You probably have a 9 inch rear axle? You can put some 2.79s in there and get basically the same effect. Not as cheap as it used to be, but doable. New gear sets are about $200, add bearings and labor. Or try to find a good pumpkin that you can just slap in there--
Auxilary ODs exist, but $1500 for one or $3000 is a bit steep.
Ranger Overdrive
Gear Vendors under/overdrive transmissions the most awarded auxiliary transmissions.
Thread Starter
|
Cross-Country
Joined: Mar 2009
Posts: 62
Likes: 1
From: San Diego, CA
Thanks for the info. and links. I don't think i'm willing to tackle a hydra cluch conversion just yet. OD unit sounds cool, going to have to save my pennys though LoL. I also saw that you replied to this thread in the trans forum covering the bases, thanks.
