Looking for transmission advice, TH350 or SM465

[big dan]

I'll go against the grain and say automatic. I swapped a truck of mine to sm465 and drove it for about a year before I went and got a th400.

I hate the shifting on the sm465, had some the wouldn't go in gear, some that popped out of gear and some that got stuck in gear. Had one truck with a 465 that would break the starter every time I cranked it. I tried various things from retarding the timing to a new flywheel. Crank the engine and as soon as it would start it would break the case on the starter. Never figured that one out. Oh and I absolutely hate pulling those heavy akward bastards to change a clutch. Plus my wife can't drive one if she needed to.

I was always scared of the durability of autos and the cost of replacements so I learned how to build them myself. Learned how the internals work and how to modify them for durability. Personally I like th400s even though they rob power, the case strength is better than the 350s and they are supper easy to build.

I've got a th350 in my shop that I've broken the case on 4 times now and welded back together. The last time I broke it half right down the middle and it was still working till I lost all the fluid. On the other had my friend with sm465 lost many clutches while wheeling due to mud getting in it.

Guess what I'm saying is they all have a weakness when you pound on them in ways they were never meant to take. Pick what your comfortable with and go.

 

[diesel4me]

Nobody?

I'm on record as tolerating it, but not a fan. I've driven nice transmissions, and I don't consider the 465 to be one of them. This is the primary reason.

Add me to the non-fan list of the SM465's gear spacing..

The "granny low" was nice,would be better if it were syncro'd though..."second" was geared pretty good,it was compareable to first gear in any other tranny...but third..ugh...way to big a leap from "second"...GM drops the ball there..

The one coupled to 3:08's in my formerly TH350 equipped '72 K5 was quite irritating to drive,you'd get a nice "blast off" in granny low or second,but the jump to third made it lay an egg and lug badly until you got it up to 45-50 mph..going up steep hills in third was a challenge between 30 and 50 mph..
--(and when it started popping out of third,it really sucked,I had to use only second and fourth till I was able to find another transmission and swap it in..picture living in a town with steep long hills,and having to redline it in second,then dump it in fourth !..and listen to the spark knocking....it was not bad at 70-75 mph though,it cruised at about 2650 rpms and got decent highway mileage..

Another truck I had with an SM465 with 3:73's was not so bad with stock sized tires,but it felt like you were in third going 70 mph compared to the K5 with 3:08's..

With all the other transmission choices available in other trucks GM had,like Clark 5 speeds and some others,usually reserved for larger 2 ton trucks,I often wonder why they never put one in a later 4x4..

I knew a guy who owned a rare '60 Suburban 2wd that had a factory Clark 5 speed,with a 235 straight six,it also had torsion bar front suspension...
I rode in that truck and the gearing seemed a lot better spaced than a SM465..it still had a "granny low",but the other 4 speeds were nicely stacked...a lot of school busses used those transmissions too,and it was rare to hear of any problems with them..putting one in a half to one ton truck would be bullet proof..

 

[blazinzuk]

Automatics are for women and children.

Martin

Well my wife says I'm a child soooo.

Without a doubler or decent gears ( with smaller tires) 465.

I really like my 700/241 combo.

But a th350 with either a 203 or a 205 is awful for wheeling

So given the choices it's a 465 all day long

 

[skunked]

All depends what the truck is being used for.

I get those that run a sm465 for the first gear budget crawl ratio but I don't like driving them.

 

[6872xtc]

I agree with blazinzuk about a 350 with the 203 or 205, not good.

 

[skunked]

I agree with blazinzuk about a 350 with the 203 or 205, not good.

I had that, it sucked

 

[Bent77]

SM465 + 205 works just fine

 

[82355]

I get those that run a sm465 for the first gear budget crawl ratio but I don't like driving them.

I thought that is why people bought automatics? So they could magically claim double their crappy crawl ratio.

I don't know, I just don't like letting them drive me.

Martin

 

[wetoolowdingbangow]

SM465 + 205 works just fine

I know a guy with a crew cab that wheels that setup with 38s and 4.56s i think and hes pretty happy with it. With my better gearing (208 and 5.38s) im think im in the territory of being able to drive with the clutch out and minimal throttle.

 

[handloader90]

Here's the specs.

'78 K5
Currently has a 383 stroker but dropping my 355 SBC in until I go through the 383 (fawker pisses oil I think from the rear main seal).

So...
355 SBC, mild cam
CUCV 1 tons - D60/14BFF, 4.56's, Detroit in rear, disc braked rear, doing 3/4 ton brakes up front also to have all the same brake stuff and to bea able to run a 15" wheel without grinding calipers

Currently has th350/np203

Looking into th350/205 or sm465/205 (definitely leaning towards the latter with all the motivation in this thread).

Planning on running a 37" tire on a 15" beadlock and if I can't find something big for a 15" wheel then I'm going to a 17" beadlock.

Gonna be driven daily some days out if the week with a max speed of probably 60 mph. and it's gonna hit the trails hard.

I plan on going double but have to figure that out with the SM465, I did some research into ORD's double kit since it seems to be the best one and from what I've read it's only for autos (but I didn't dig into it that much.

 

[82355]

I have an ORD doubler kit.

Behind an SM465.

Martin

 

[82355]

I would look for an SM465/NP208 (or better yet, and SM465/NP241) before using an SM465/NP205. Especially a ten spline SM465/NP205.

Martin

 

[wetoolowdingbangow]

I got a 32 spline 465 with a 208 attached to it...kinda the best of both worlds....Its nice to eliminate the power coupler. Its going in my trail truck so its pretty much all battle and a few freeway jaunts now and again so i could care less about the long throws or spacey separation of 3rd to 4th.

Its hard to beat the simplicity and strength if those are what youre looking for.

 

[skunked]

I thought that is why people bought automatics? So they could magically claim double their crappy crawl ratio.

I don't know, I just don't like letting them drive me.

Martin

Probably should ask someone that's preaching that.

 

[82355]

Let me know when you find someone using an SM465 for a budget first gear crawl ratio.

Martin

 

[Bent77]

Hey, I do that. Bonus it has 3 pedals

 

[wetoolowdingbangow]

Hey, I do that. Bonus it has 3 pedals

Just wait. I have 4 pedals...extra clutch between the 465 and 208

 

[blazinzuk]

What it really boils down to alot is personal preference. Autos don't just magically blow up for no reason. Manual trans do break.

A 465 and a 205 with a hand throttle can crawl as good as a th350 with a doubler cause in reality the gearing is very similar.

I will say this. I have never had to stop for 15 minutes or longer to let my clutch cool down. With most manuals you are eventually gonna heat that clutch up to a point you should stop.

But once again my assessments are very specific to the terrain I commonly wheel.

There isn't much non obstacle space on our trails. It's very hard on rigs and it might be something you never have an issue with.

If a doubler isn't in the cards right now a 465 is a great way to go. But I would not use a 465 over an auto if a doubler was an option.

Even if the 465 had a doubler.

 

[skunked]

Let me know when you find someone using an SM465 for a budget first gear crawl ratio.

Martin

That's not a benefit to you or other sm465 users? Maybe I don't understand your question.

What it really boils down to alot is personal preference.
If a doubler isn't in the cards right now a 465 is a great way to go. But I would not use a 465 over an auto if a doubler was an option.

Even if the 465 had a doubler.

I debated a manual and decided against it, we have a variety of trails and the thought of slugging around in a 4 speed on the street to the trails isn't something I wanted to deal with. So I decided the Th400 with a doubler (241/205) was the best solution. Like you said, it's about preference and there isn't really a wrong answer when comparing the two.

 

[Hoss7979]

Auto for speed and manual for cruising! Had a SM465 w/ mechanical clutch when I bought mine after breaking 2 stubs, 1 inner shaft, 3 sets of lockouts I switched TH350 and haven't had an issue since. When your in the mud I mash the gas and hold on.....only shift if ya need to. With the SM465 there was no shifting if needed...very fast that was....