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454/sm465 help

Magikal

Magikal

1/2 ton status
Joined
Nov 25, 2007
Posts
402
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Location
North Idaho
So I currently have a 7.4 liter in my blazer that came made it to a 4 L 80 e. Today the pump failed on that transmission. I'm so sick of automatic Transmissions. I have a sm465 kicking around from a 72 Chevy. What's all involved in getting this made it to that motor? I'm looking for a specific parts and part numbers. The other end of it will be meeting to the 203 range box for my Doubler.

A lot of this will be done on a budget so whatever Parts I can Source from the junkyard would be a big help. I don't mind buying the essentials though
 
Im not going to hand you part numbers as I don't care to do that much research for a project that isnt mine but I know a bit about putting manual transmissions behind engines. its a pretty simple bolt in swap for the most part

7.4l came from the factory with a NV4500. SM465 clutch setup is no different than the NV4500 clutch parts so use those. The only thing that may or may not take any work is throwout bearing height. There are two main ones in GM applications, short and tall. depending on the shift fork in your sm465 bell housing and clutch pressure plate design you end up with you will need one or the other. since its a 72 trans going into a 79 truck you can stick with the z bar clutch linkage if you want or update to a hydraulic setup form a newer truck, that will take a new bell housing from a hydo clutch 465 along with the other hydo parts. Or rig up an after market hydo slave if you want.

Go buy a flywheel and pilot bushing for your engine from the local auto part store. Use the application that the engine came out of. Get a clutch for the 79 k5 and a small block or whatever, doesnt matter they are the same. just find a 12" one at the price point you feel comfortable with. I have a part number for a luk in my 1980 build. The only reason why we are using a 79 clutch and not the one for your engine is to get a throwout bearing. The 97 7.4l would have had a bell housing mounted hydro one in the nv4500.

Bolt the trans to the engine. that's a simple bolt on job. Clutch linkage and pedal box for your truck from the junk yard, or make a custom hydro clutch release. while you're at the junk yard grab a stock 465 cross member to bolt on or fab your own.

The transfer case side I know nothing about. That sm465 probably has a 205 adapter on it I'm guessing. That would make it a 10 spline output, or its a 2wd with a 32 spline output. Ill also guess that your 203 box is not 10 spline. Someone better than me can help with that.
 
454's changed over the years so you need to identify the year and/or generation of your motor as this will determine the flywheel and pilot bearing you need to use. TreeFarm is right, the 454/465 combo is very common so pick an application and gather parts for it, up to '84 used the more common mechanical linkage pedals and '85+ used the preferred but more expensive hydraulic pedals. Pick a square body truck and buy everything for it to cut down on confusion later.

The '72 transmission will be 10 spline if 4wd or 35 spline if 2wd. A 2wd 35 spline unit will have to have the tailshaft swapped to either a 10 or 32 tailshaft to work with any tcase combination.
 
Older 454's were externally balanced and required a flywheel with balance weights cast into it and a harmonic balancer that was made with some of it missing to act as a balance weight.

I don't know if this carries over to the newer 454's after they went to fuel injection and gen 4,gen 5 engines,I would be sure you get the correct flywheel for the year the engine is..

I did one TH350 to SM465 swap in a '72 K5 I had,it was a tough job ,despite me having every part I needed from a smashed up K5 the same year,it was a week of six pm to midnight wrenching to get the clutch pedals,brake booster (mine was junk so I swapped that too),and getting the old transmission out and all the 4 speed parts installed ,with a new clutch,was enough for me to swear off ever doing another automatic to manual transmission swap..I'd buy a truck with a manual already in it if I wanted a manual..(though finding one up here is tough,few folks bought any with standard transmissions)..

Oh yeah..I had three Borg Warner rebuilt 12" pressure plates fail in less than a month after it was back on the road,and I never once burned rubber or abused the truck..

I tried going with a 12" diaphragm type one instead of the junk 3 finger type,which had such a strong pedal resistance you felt like you were pumping iron on a universal gym every time you put the clutch in..that one started failing to release fully after 2 months..
Pulling the transfer case & transmission out 3 more times sucked!..

I ended up using a used Centerforce 11" diaphragm pressure plate & disc,that held up good ..but overall I was unsatisfied with the swap,the truck had 3:08 gearing and that combined with the wide gear spacing in the SM465 made it a dog,especially up hills...and the splined coupler between the transmission and transfer case rattled and eventually stripped its splines,the output shaft on those older SM465's often had the splines wear out,that is why they went to the 32 spline ones in the 80's..despite their supposed "bullet proof" reputation,the SM465's have their problems too,like popping out of third gear when a snap ring breaks..

I'm not a big fan of automatics either really,but one that was built right usually holds together for at least 100,000 miles provided you keep it cool ...much easier to drive on & off road too..
 
All 454's are externally balanced. There are 3 generations of 454's, early are 2 pc rear main and later are 1 pc so the flywheels changed accordingly, this is why you need to identify the motor by casting number to know exactly what you have.
 
Thanx all. Great info. I will get engine cast numbers tonight after work. The sm465 has the 10 spline output. I think i even have the coupling sleeve with it although it's gonna be wrong.

I got a guy coming to check out my tranny also tonight and. He is an old tank mechanic from the army and does trannies like you and i would change a tire. So i will see what he has to say about my current one.

Will keep ya all posted.
 
Good deal on the 10 spline. The 203 will use a female 10 spline input, easy swap if yours isn't - I'm pretty sure ORD sells them.
 
Sadly, my 203 originally was a 27 spline and i swapped in a 32 spline so it could mate to the 4l80e. I still have the 27 spline shaft although it doesn't help needing a 10 spline one.
 
10 spline NP203 inputs are rare birds, haven't been available new for 10+ years. As used parts, they wear just as bad as the 10 spline NP205 stuff.

The 465/203 was a rare options only for a couple years (supposedly because the full time 4WD 203 was finicky with a manual trans), finding a good 10 spline 203 is really tough.
 
Think i will swap in a 32 spline main shaft into the 465. Novak has then relatively cheap. Any reason i shouldn't? Gotta figure out a way to connect 465 to 203 gearbox (doubler). What's everyone generally do for this? Im all ears....

Considered a 10/32 sleeve coupler but cannot seem to locate one anywhere. Not sure if it even exists...
 
ORD offers a custom 32 spline shaft for the 465 that allows you to use a factory 465/203 adapter. ORD May also have an adapter.

Another alternative is to use a factory long 32 spline output and 465/208 adapter and redrill the 203 face.
 
I'm leaning more towards the factory long 32 spline shaft for the 465 as I already have a 208 adapter and the 203 is already drilled for it. I presume the length of that shaft isn't the problem as it's considerably longer than the other shafts for the 465. I imagine it's doing away with the sleeve hence the increase length
 
Magikal said:
I'm leaning more towards the factory long 32 spline shaft for the 465 as I already have a 208 adapter and the 203 is already drilled for it. I presume the length of that shaft isn't the problem as it's considerably longer than the other shafts for the 465. I imagine it's doing away with the sleeve hence the increase length
Click to expand...

Yeah, the shaft length is ok when used with the 208 adapter and the drive sleeve is eliminated since the 32 spline 203 input is female.
 
From Off Road Design's Doubler tech page -

Off Road Design said:
GM SM465 4 speed Manual Transmission:
If you have an SM465 transmission there are 3 ways to mate it to the NP203.

1: Use a factory configuration. GM mated the NP203 to the SM465 in 1973-1975 using the 10 spline output in the 465, a 10 spline female input in the NP203 and a 4.25" adapter housing between the two. This configuration was used in a wide range of GM trucks but is somewhat rare. Problems are the 10 spline connection tends to wear in the long term and it's difficult to find. Positives would be the short length and the ability to use the common 10 spline output in the transmission.

2: Use a SM465 that was originally mated to an NP208 transfer case. This 465 will have a 32 spline output shaft with a 8 3/8" adapter housing. You'll use a NP203 gearbox with a 32 spline input gear and the face of the 203 drilled and tapped with the GM round bolt pattern to match up to the factory 208 adapter housing. This works very well if you have the available length in the vehicle since the parts are commonly available and the 32 spline connection is very strong and durable, we have brand new adapter housings.

3. Use the factory SM465 to NP203 adapter housing or a brand new adapter housing that we can provide with ORD's new 32 spline SM465 output shaft and a 32 spline input gear in the NP203 (click here). This allows the shortest overall length with the highest strength, most durable spline connection.
Click to expand...
 
nvrenuf said:
From Off Road Design's Doubler tech page -
Click to expand...

Yeah, i read that. Odds of locating one of those 203 are pretty low. Plus i already have my doubler installed so it's ready to go if i use a 32 spline shaft.

So, in summary i am looking at

Flywheel (match engine year and model) $100

Clutch, pressure plate, throw out bearing (match tranny year and model) $200

Main shaft, 32 spline for sm465 $100

Pedal, mounting bracket (any year from early 70's to late 80's should work) $20 from salvage yard

Last issue, cable or hydraulic connection from pedal to clutch?

Other thoughts:

Relocate/ fab crossmember (after briefly playing with tape measures last night it looks like i will be around 10in shorter)

Drive shaft length? Angles?
 
Magikal said:
Pedal, mounting bracket (any year from early 70's to late 80's should work) $20 from salvage yard

Last issue, cable or hydraulic connection from pedal to clutch?
Click to expand...

All of that falls in to 2 categories; your choices are '84 and older with mechanical linkage or '85+ hydraulic, they don't interchange without some fab work.
 
Junkyards and craigslist prices for a manual pedal setup here run about $100-$200...they are getting scarce..never was that many trucks with manuals around here,most that were are 1 ton dump trucks..
 
diesel4me said:
Junkyards and craigslist prices for a manual pedal setup here run about $100-$200...they are getting scarce..never was that many trucks with manuals around here,most that were are 1 ton dump trucks..
Click to expand...

No problem finding that stuff around here as this area is a little behind in the times plus everybody and the brother too has a 4x4 here.

I like the simplicity of install with a hydraulic setup for the clutch. Linkage is a mechanical connection with which i have never had much luck with. But, the 465 i have is from a 1972 k2500 and was linkage originally. If it is a headache to make it hydraulic then i will just stay with linkage. Guess it could be changed later if i don't like it or whatever.

Off subject (kind of). Does anyone know if a 4l80e from a 2002 is a direct swap with mine from a 1997? I know somewhere along in there they have some changes.... not sure on the timeline of it....
 
More thoughts overnight. I originally had the harness and pcm tuned by @Team208Motorsports. I wonder if switching to a sm465 will require any re-tune of the pcm as the would no longer be any computerized components in the tranny? VSS signal could be an issue to contend with ....ughhh
 
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