manual tranny options

[mollyman]

I have an 81 1/2ton sub. I have put a 60/14blt under it with 4.56 and I am gonna run 38inch tires. It came with a 350/th350/208 combo, I have bought a rebuilt 205 for behind a 350 but now am thinking about changing to a manual tranny just for toughness. My question is what would be better a 465 or nv4500. I will be rebuilding the 350 (maybe make it a 383) but I was just looking for some input for the swap. I have followed the threads about how to do it, I am just was wondering what combo would be best for me?? And of coarse I spent some a decent bit of money on the 205 that I thought I was gonna just leave behind a th350 and now i am stuck with it. And I know nothing about either of these trannies, any help would be great, thanks

 

[Hogback Fabrication]

The gear ratios in the two transmissions are pretty similar except that the NV4500 has a fifth (overdrive) gear.

The SM465 has a lower first gear and is MUCH cheaper to swap into your truck.

The NV4500 will be a bit better for highway cruising, otherwise the 465 is the way to go.

 

[surfinmurfin]

Not tryin to thread jack or anything. But I'm a total noobe and don't know anything about these trucks. My pops has a 72 I think it might be a 3/4, I need to ask him. But anyway its in prety bad shape. If I bought a 69-72 k5 would the tranny be interchangeable? I'm wanting to tow with this thing too. I read that the Blazer is only a 1/2 ton. So can I put all the 3/4 ton into the blazer?
And in an attempt to relate to this topic. Is the 5 speed more expensive to swap, but better for towing on the highway? Would the 4spd be a bit more rapped out at highway speeds, wasting gas? Could I use the 4spd and change the rear end to better the towing on he highway? Or would that just be a bad move?

 

[tRustyK5]

The parts of a 3/4 ton truck that are different than a 1/2 ton Blazer are mostly the axles, brakes, and springs. Engines and trannies don't change much.

The stuff from your Dad's 72 should swap over easily enough, but you could use parts from a wide variety of years without much trouble. The 5 speed swap is more expensive because the availability of the 5 speeds is so much less. They didn't start making them until '92 and by that time it was a minority of trucks that got manual trannies. Less supply = more $$.

The overdrive 5th gear does make it rev less on the highway, but depending on tire size and gearing you might not be able to tow in 5th.

Onto towing...a K5 is not a great tow platform due to it's short wheelbase. You really asked a lot of questions all at once and there isn't just one answer to any of them. I'd suggest you keep reading and learning while you continue searching for a K5 or pick-up...and when you have more specific questions post em up then.

Rene

 

[surfinmurfin]

The parts of a 3/4 ton truck that are different than a 1/2 ton Blazer are mostly the axles, brakes, and springs. Engines and trannies don't change much.

Ok now all I have to do is talk him into it lol

Onto towing...a K5 is not a great tow platform due to it's short wheelbase. You really asked a lot of questions all at once and there isn't just one answer to any of them. I'd suggest you keep reading and learning while you continue searching for a K5 or pick-up...and when you have more specific questions post em up then.
Rene

Hmm well I would like a truck to tow but the idea of the blazer just seems soooo much better. With all the benefits of having a back seat and removable top.
How bad would the K5 really be to tow with? I currently tow with a Jeep Liberty, That thing is a pig with a trailer behind it. And Gets the same mileage as a v8 would with a trailer, so it can only get better in my eyes
ps I hate the liberty lol

 

[tRustyK5]

I've towed with my old K5, it's not impossible...just not the preferred tow platform. How big/heavy a trailer are we talking about?

Rene

 

[bp71k5]

I have to preface this with the fact that I don't do much towing at all. I think I've towed something 2 or 3 times in my life.

But I have read that it's not the best idea to tow when using overdrive on any transmission. Maybe someone can school me on why or if it's even true. If you plan to tow much at all, I think the 465 would be the better choice for a manual in that case.

If that doesn't sway you, plan to shell out a big chunk of change for the nv4500.

 

[tRustyK5]

Well the OD is the weakest gear in any OD tranny...but mostly what I recall is it's a definitely no-no with a 700r-4 due to heat build up etc. The NV4500 should be OK towing in OD (when possible) however, behind a high tq engine and with a heavy load it can cause 5th gear to fret on the mainshaft (throttle on, throttle off the gear will rock slightly back and forth on the splines). This works the gear against the 5th gear nut, eventually loosening it off and then 5th gear falls off the splines.

Some NV4500's have a damper between 5th gear and the mainshaft nut (mine does) and this does prevent 5th from loosening the nut...

Lighter towing behind a small block, or NA diesel it shouldn't be a problem though. Most small blocks and NA diesels don't have the cojones to keep road speed up at that low of an rpm anyways...so the point is moot.

I towed a 21 foot camper trailer a total of about 10,000 miles behind my K5 (4" lift and 35's at the time). I did use a weight distributing hitch though plus the electric trailer brakes made it not too bad. Still, longer wheelbase is much more stable when towing.

Rene

 

[surfinmurfin]

I've towed with my old K5, it's not impossible...just not the preferred tow platform. How big/heavy a trailer are we talking about?

Rene

well its a small homebuilt car hauler that I bought. And the car the I tow on it weights about 2200. Plus all my race gear(tires,tools,canopy,ect), I'd say the whole package is somewhere around 3500lbs ish. But the Liberty probably has the same if not smaller wheel base as the blazer right? And its puny v6 would cower at the 350. I think the 3.7 in my liberty only has like 237hp, so I should be way better off right? I also don't have brakes on the trailer. I want to buy a better one but its all I got for now.

 

[tRustyK5]

3500 is max legal trailer wieght for no brakes in a lot of states, and too heavy for no trailer brakes in a lot of states. You'll have to check the laws in your state to be sure...

It's not the HP that is important for towing, it's the torque and the rpm's the torque is made at. The Libby's V6 makes the same or more hp than a stock 350, but it doesn't make as much torque, and it doesn't make that torque at low R's like the 350 does. Gearing can help overcome the lack of torque though.

3500 lbs behind a K5 isn't that big a deal. Our old 21 foot camper trailer came in at near 5500 lbs loaded and a lot of our towing was through the mountains here.

Rene