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Backwards swap -- SM465 to 700r4

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4thgenceli

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Recently acquired an '87 K5. 305, 465, 4x4 blah blah blah. Last decade or so it's been 80% hunting rig in some route AZ territory. Its been owned by one family (happens to be my inlaws) since new and has been passed from father > son > father > brother > son > father > son > father > brother inlaw (me). Now doing the same thing and getting my oldest in it for his first rig.

I see there's tons of posts about going the other way around and swapping into the 465 manual -- but I want to do the opposite. Currently have an '87 K5 with a 305/465 in it. The 305 is coming out for a teardown/mild build (most likely just headers/cam/etc). Nothing too wild, my 16y/o will be daily driving it. I'm all for him learning to drive manual transmission (and he will learn if he wants to use my truck or track car).

From what I can tell, I'll need at bare minimum the transmission (including flywheel/torque converter), crossmember, shifter (undecided on floor vs. column), xfer case and rear driveshaft. The last two I know may not be needed depending on the xfer case I have onboard already. I've only had this thing a few weeks and haven't had a chance to really dive into it.

Anything else I'm missing that'll be needed for this? I'm moving my other project into the garage this weekend so this one can get into the driveway, pull the plant and go to town on it.
 
I don't deal with the automatics once they went EFI, you'd need at a bare minimum the ECM, and I suspect it requires adding the park/neutral switch and/or wiring. Also guessing there is some wiring from 700R4 to ECM, probably to control TCC.

Don't think your crossmember or drivelines theoretically need swapped...GM changed adapter length (apparently so driveshafts would all be the same length regardless of trans used) but not design after '85, so the crossmember will be the same, and I believe same location.

You'll need another column, linkage to the trans, and parts for the cluster if you want to keep from butchering the floor.

I'd seriously consider leaving the manual in the thing until it is determined whether or not he wants to keep it that way, at least until after he learns and can make an educated decision. That's a lot of work to go automatic when ~90% of the trucks out there are already automatics. The 465 with it's ultra low 1st is very easy to learn on, and if you put it in 4 low, almost impossible to stall. Not to mention that hydraulic setup often has much better "feel" than the earlier mechanical setups.

Note that modding the 305 may cause problems for the injection as well.
 
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I've been pouring through all I can. I'd imagine he wouldn't have a hard time learning it as he knows the fundamentals of it (dirtbike and my truck has a nv3500 in it) If we decide to not go through with the auto swap the 465 will be torn down and rebuilt. I have no clue how many miles are on it. All I know is the stick is uber loose and occasionally slips outta 4th. Since I'll be in there to take care of that cir-clip may as well do the rest.

Good to know about the performance work. I haven't been a domestic beast for many years. The last domestic I was seriously wrenching on was a couple old S10/S15 Blazer/Jimmies. Sounds like I'll just be limited to letting it breath a bit easier.
 
I found a pretty good series a guy did rebuilding a 465 on youtube. He was wrong about a couple of things, but they weren't critical. This guy: https://www.youtube.com/user/GebBuilt

The shifter design on the 465 is pretty bad, but the problems are known and fixable, and generally related to the stick itself, not a design flaw in the trans.

Popping out of fourth is a weird one, I think it's normally 2nd that does that...
 
There is very little electronic control on an '87 TH700R4. I believe the torque converter lock up would be the only thing to worry about. It is absolutely necessary to install the setup for the TV cable (throttle valve cable......goes from throttle body to transmission).

Personally I am a fan of the 700r4 and it makes a much nicer daily driver as compared to the clunky old school 465 manual.
 
There is minimal control of the trans, but it's more the other way around...the transmission determines a few things with the computer...timing and fueling is different manual to auto, the automatic uses the P/N switch to govern idle RPM, I believe some of the anti-stall strategies were different, probably some other things I'm forgetting.
 
If you do swap I'm looking for a couple parts you'll be pulling
 
My crew cab had the SM465 and I put a 700r4 in it. The TBI didn't seem to care about the difference; it never gave me an ounce of trouble.

I found the TV cable bracket at the junkyard. The stud for it was already on the TBI linkage. There's a TCI kit for the torque converter lockup that will use engine vacuum to trigger it. The TCI kit also had provisions to use a switch. I never hooked up the vacuum, just used the switch. That's probably not ideal for a new driver tho; I would use the vacuum switch.

As @dyeager535 mentioned, in theory all the crossmembers and driveshafts should be the same for 80's trucks. I figure that's why the NP205 got a front flange and slip yoke rear output in the 80's K30. I would say if your current setup and the donor tcase both have front flange and rear slip yoke, you should be fine.

I know when I was a young man I thought floor shifters were cool so that would get my vote. You could do a B&M ratchet shifter or the venerable Winters gate shifter. I use the latter.
 
I think he'd need a matching transfer case for the 700R4,as the SM465 will have a 32 spline output shaft and the 700R4 will have a 27 spline output shaft..

I have swapped a SM465 in place of a TH350--it sucked,took me a week of six to midnight's after work to take the truck apart and re-assemble it using all the needed parts from a donor truck..putting the clutch pedals in was the worst part probably,and I had to replace the power brake booster while I was "in there",the master cylinder leaked into the booster and trashed the diaphram..

Going the other way from a manual to an automatic is easier,you'll need a radiator with a tranny cooler in it or have to risk using an external one alone (may not keep it cool enough)...to me this is a downgrade,I'd stick with the SM465...
Why you ask ?...granny low in low range for crawling,you can push start it if the starter croaks or battery goes dead,and unless your in stop and go city traffic constantly,shifting and clutching isn't that annoying..
 
BowTie Overdrives and TCI have the cable and linkage you'll need. I like BTO's adjustable cam linkage that attaches to the throttle arm, helps when stuff isn't exactly OEM.

Get a stand alone torque converter lock up kit. Mine locks in 4th and will allow it to slip in 4th as well. I wasn't able to slip 4th with my '85 700r4 but when I had someone rebuild my '89 700r4 they were able to use a different valve body I think. So...aside from the TV cable and bracket, brake pedal switch for lock up, wiring kit and lock up solenoid... that's all I know. For sure like mentioned it will need a 27 spline xfer case input and maybe a flywheel. There isn't much to controlling the 700, I don't have any vacuum reference for it either. Has 8k brutal miles on it so far.
 
I learned how to drive on a 465 and believe me, if he can master driving that. He can drive anything.
 
put a manual valve body in the 700r4...tell the TV cable to suck it and shift it like a stick when you want to..bolt the 700r4 up to a SYE'd np241
 
So the ECM in a manual truck doesn't provide a TCC lock up signal? Too bad, because that's by far the cleanest way to get lockup. Can it be flashed to the PROM? DON'T run without lockup.

I think the year of the 700 decides which method is best. The ones from a TBI truck have the simple set-up. If you get an earlier one, skip the aftermarket stuff and run a factory vacuum switch and brake switch.
 
I've read the early 700R4's had problems with the pump splines that were upgraded along with a auxiliary valve body and other internal upgrades to prolong the life of the transmission..

Nearly every thread I read about a 700R4 swap suggested using only a 1987 or newer one for that reason..there must be some aftermarket device (or backyard hack ) ,to make the overdrive kick in thats not overly complicated..

This is just a few of many reasons I dont like 700R4's,they are not the greatest automatic GM ever made..unfortunately all the newer automatics with computer control and solenoids all seem to fall short of their early 3 speed non overdrive automatics when it comes to reliability and durability...but GM isn't the only one who hasn't had a really good automatic for the last 20 years,with the exception of the Allison maybe..
 
You can reprogram the prom or get a manual prom, but for a 305 the latter isn't likely easily found, and the former is a bit pricey.
 
Loads of information guys... Thanks.

While I'd like to do it just for ease of use (namely letting the wife get to drive it) my son had an epiphany overnight and wants to keep the 465 and drive a manual. I think we'll keep this in a back-pocket burner to return to later if this every becomes desired. It doesn't seem like it's much and everything I read seems very straight forward.
 
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