Just picked up an 1980 4wd Toyota .... i've got the 4 speed manual and i do alot of highway driving .... my rpms are way up at 3 grand when i'm runnin' 80 kph.

I dunno what that is in mph 50 ? sucks ..... i figure toss on some taller tires might do it .... but does anyone make a bolt on overdrive for this rig ? ..... any more ideas?

 

Easiest fix is the tires like you mentioned. That 4 speed is notoriously weak but the 5 speed that replaced it is very good. I'd try to find a 5 speed before I considered putting in higher diff gears.

 

to tell you the truth i heard the exact opposite about the 5 speed. Don't know if he's really a reliable source though.

but i do know the 5 speed is 4 inches longer ? ... is there an adapter for that ? .... or do i cut and paste?

 

The early 5 speeds are to be avoided.

You would basically have to do some driveshaft alterations to make that work.

 

Damn your right. G series 5 speeds suck and W series are much better but those are for later trucks. You have an L series tranny which I have almost no info about. What axle ratio and tire size do you have?

I found this page but it doesn't list much info about tranny strength: http://www.4x4wire.com/toyota/faq/

Marlin's truck may be the best example of a first gen around so I'd ask him what is possible.

 

i believe you have that reversed. the 4 speed was a clunky bulletproof tranny, but the L and G series 5 speeds are pieces of junk that tend to blow up when you need them most

i'm thinking about putting in a w56 out of a 85+ truck and having my rear driveshaft shortened and front lengthened

 

thanks

If the truck is still runnin stock gear ratios ... i should have 4:37s in my axles .... i'm pretty sure i'm running a 255/75R at the moment (i'd have to double check) ....

I am looking at buying a used set of 30 inch mickey tompsons ...

how much of a change in tire size would i have to go to lower my 4th gear RPMs 500 to 1000 rpms less?

 

probably quite big...and as gutless as these trucks are you'd probably best spend that money on a 5 speed tranny

right now on my 31.5" tires, i push about 3000 at 65mph

 

Sounds like 31's would be about right. 4.56 and 31's is right for the newer trucks.

 

only problem is that the newer trucks have 5 speeds in them, while we're stuck with our 4 speeds from the days of 55mph speed limits...

 

So 4th gear in your 4 speed has no overdrive? I'd say you could do 33's if that's the case although that would probably make your truck slow as a slug.

I think a 265/75r15 is a 31 so you should consider at least 32 but then we have to start looking at clearance and lifting.

 

Yes, it's the metric equivalent of 31x10.50x15R.

 

always looking for another reason to lift

 

I've scooped a set of 31" 10.50 Rs off an old truck of ours, to test em out for fit .... should be a good time