K
Rearend gears
davidgonzales
+1y
I have an 86 crewcab dually, 3 speed, and I'm changing it over to automatic.
Do I need to change rearend gears? And if so, where can I find them?
Any suggestions on tranny I should use.Any help would be appreciated.
Do I need to change rearend gears? And if so, where can I find them?
Any suggestions on tranny I should use.Any help would be appreciated.
lc4carl
+1y
I'm assuming a 454.
The newer 4L80E requires a computer. Strong, with an overdrive.
I think the 700R4 can stand alone. Pretty strong, with an overdrive.
Of course there's the old stand-by TH400, three speed.
If the existing three speed has a 1:1 high gear and you go to an overdrive transmission, you have the option of staying with the presumably taller existing rear axle ratio for improved economy and lower highway revs or, in the pursuit of improved acceleration, you could lower the rear ratio while roughly maintaining your current economy and revs.
Tire height effects final gearing.
The newer 4L80E requires a computer. Strong, with an overdrive.
I think the 700R4 can stand alone. Pretty strong, with an overdrive.
Of course there's the old stand-by TH400, three speed.
If the existing three speed has a 1:1 high gear and you go to an overdrive transmission, you have the option of staying with the presumably taller existing rear axle ratio for improved economy and lower highway revs or, in the pursuit of improved acceleration, you could lower the rear ratio while roughly maintaining your current economy and revs.
Tire height effects final gearing.
monzter kuztomz
+1y
I'd go with a TH400 or a 4L80E. The 4L80E would cost more, the transmission alone will cost more than the TH400 not including the computer you'll need to run it. I would not use a 700R4, everybody says "I'm not gonna use it as a truck", next thing you know they're hauling a 14,000 lb 35 foot fifth wheel be hind that same truck. Besides Duallies are heavy empty. I got mine stuck in my front yard backing up to my back yard gate to drop off my new barbecue, and that was on flat ground. I drove around it and pulled it out with my lowered 2wd Suburban on 255/35-20s.
monzter kuztomz
+1y
Oh yeah, also you don't need to change the gears. My old 83 Dually had 4.10 gears with a SM465 manual transmission and my 93 has 4.10 gears, but also has an overdrive automatic 4L80E transmission. You'll tum the same RPM with the TH400 as you do with your manual transmission, but with a overdrive unit you'll turn less RPMs in overdrive. If you do change the gears I'd go to 3.73, maybe 3.54 ( Dana 70HD ) or 3.42 ( GM 14 Bolt ) if your running a smaller diameter tire.
skidrow
+1y
i have a 700r4 in my dually and am going to pull a 35 foot 5th wheel
it has a 700hp 502 in frount of it ive bilt 700 for a wile for street driving hotrods with no problems
but u have to know what to put in them and how to ajust them to work properly
and i jess it help that im a trans bulder with 20 years under my belt.
on a side note i was looking at my dually and all the shit i have going on under that truck and i dont think i ever want to pull that trans hehheh
erik
it has a 700hp 502 in frount of it ive bilt 700 for a wile for street driving hotrods with no problems
but u have to know what to put in them and how to ajust them to work properly
and i jess it help that im a trans bulder with 20 years under my belt.
on a side note i was looking at my dually and all the shit i have going on under that truck and i dont think i ever want to pull that trans hehheh
erik