Author Topic: TH400 to SM465 swap, many questions  (Read 14110 times)

Offline cwest

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TH400 to SM465 swap, many questions
« on: June 18, 2012, 09:58:38 PM »
Just bought an '86 Chevy K-20 350/TH400/np208.  I'm trying to create a copy of my Grandpa's truck from back in the day.  One big problem is his was a manual, the one I bought is not.  Literally everything is the same on the truck, except the trans.  I realize it would have been much easier to buy a truck already equipped with the SM465, just couldn't pass on the truck when I found it.  So anyway, I've done some reading and talked to an all Chevy junkyard guy, he informed me the bell housing for the hydro clutch(which was only offered in the '86-'87 models) is no longer being reproduced, and is very hard to find otherwise.  My only thought is to call junkyards until my ear falls off and just go on a wild goose chase.  Any thoughts on the easiest way to acquire this bell housing and really any thoughts on the trans swap as a whole would be very helpful.  Thx

   
86' Chevy K20
350/SM465/np208

08' Silverado 1500 4X4 WT

Offline Edahall

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Re: TH400 to SM465 swap, many questions
« Reply #1 on: June 18, 2012, 10:04:27 PM »
Instead of hydraulic, you could always use a bell housing from an older model truck and use manual linkages.  Or another option is use an NV4500 5 speed from a newer Chevy truck.
1990 ¾ ton 4x4 Chevy Suburban
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Offline Blazin

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Re: TH400 to SM465 swap, many questions
« Reply #2 on: June 19, 2012, 06:34:46 AM »
Your best option is to find a complete parts truck. That way you will have everything you need from the clutch pedal assembly to the driveshafts.
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Offline slammed79

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Re: TH400 to SM465 swap, many questions
« Reply #3 on: June 19, 2012, 08:01:40 AM »
There's nothing wrong worth spending time in the junkyard, I personally find it soothing.

Look on craigslist for someone parting out an 85+ with a stick. They pop up from time to time.
74 C10 Long bed 350/SM465 Lowered on 20's

Praise the lowered

Offline bake315

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Re: TH400 to SM465 swap, many questions
« Reply #4 on: June 19, 2012, 09:46:32 PM »
I'm doing the exact same thing with my crew - converting it from TH400 to SM465.  It's a '73, so it would have had manual linkages, and so I waited until I found a suitable donor truck - a '74 with an SM465 on Craigslist for $500.  I'm going to have to do something with the driveshafts though, since the length of the 400 far exceeds that of the 465.  I think I'm going to swap the trannies and linkages, then have two trucks - and then sell the '74.
• '73 Cheyenne Super C20 454/400 http://forum.73-87chevytrucks.com/smforum/index.php?topic=7672.0
• ’79 Scottsdale K10 350/NP208/SM465 “Oscar” http://forum.73-87chevytrucks.com/smforum/index.php?topic=37885.0
• ’87 Custom Deluxe R30 350/400 “Felix”

Offline slammed79

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Re: TH400 to SM465 swap, many questions
« Reply #5 on: June 20, 2012, 09:41:55 AM »
Also... I recently drove an 86 stick shift truck and liked the linkage clutch in my 74 better. The diaphragm pressure plate makes for a nicer feel to me.
74 C10 Long bed 350/SM465 Lowered on 20's

Praise the lowered

Offline cwest

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Re: TH400 to SM465 swap, many questions
« Reply #6 on: June 20, 2012, 03:35:40 PM »
Sounds like a complete parts truck is the best route.  I'm also not completely opposed to going the linkage route, sounds like they're better in the long haul anyway.  I like the idea too of having all the parts already assembled in one space, just moving them from truck to truck shouldn't be too difficult(in a perfect world of course).  I'll be sure to have a case of PB Blaster on hand.  Also, the junk yard guy said the np208 connects to the 400 and the 465 differently.  Is this accurate?  The transfer case I have now runs like a champ, I'd hate to swap it out for a junk yard piece that may not be as solid.  It is what it is though, I'll do whatever needs to be done.

Thanks for all the great info everybody, this is my first truck project and first forum, having a blast so far.  Keep the reply's coming, every little bit helps!
86' Chevy K20
350/SM465/np208

08' Silverado 1500 4X4 WT

Offline slammed79

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Re: TH400 to SM465 swap, many questions
« Reply #7 on: June 21, 2012, 09:32:27 AM »
It does mount differently, but with some searching, you can find the plate.

Now whats funny, is I currently know where there is a hydraulic bellhousing and a complete pedal assembly local. Its two different sources but kinda crazy that it shows up when I'm not looking for it.
74 C10 Long bed 350/SM465 Lowered on 20's

Praise the lowered

Offline zieg85

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Re: TH400 to SM465 swap, many questions
« Reply #8 on: June 21, 2012, 10:44:38 AM »
It does mount differently, but with some searching, you can find the plate.

Now whats funny, is I currently know where there is a hydraulic bellhousing and a complete pedal assembly local. Its two different sources but kinda crazy that it shows up when I'm not looking for it.

Very desirable in the midwest.  I could have sold at least 3 if I had them...
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1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline cwest

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Re: TH400 to SM465 swap, many questions
« Reply #9 on: June 21, 2012, 11:25:56 PM »
Don't suppose you want to hook me up with that bell housing and pedal source?   Would be a nice little step to acquire those pieces.  Also, what is the 'plate'?  I know the basics of how this stuff goes together, but definitely not up on the slang.
86' Chevy K20
350/SM465/np208

08' Silverado 1500 4X4 WT

Offline slammed79

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Re: TH400 to SM465 swap, many questions
« Reply #10 on: June 22, 2012, 10:38:03 AM »
There is a sm465 to NP208 mounting plate, I can dig around and see if I can find one.

Bellhousing
 http://phoenix.craigslist.org/evl/pts/3082876929.html

Clutch Assembly 1 (Michigan):
 http://67-72chevytrucks.com/vboard/showthread.php?t=524601

Clutch 2 (Arizona):
 http://67-72chevytrucks.com/vboard/showthread.php?t=524310

74 C10 Long bed 350/SM465 Lowered on 20's

Praise the lowered

Offline cwest

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Re: TH400 to SM465 swap, many questions
« Reply #11 on: June 22, 2012, 02:39:00 PM »
Thank you sir, much appreciated.  I'll let you know if I'm able to snag any of those pieces.
86' Chevy K20
350/SM465/np208

08' Silverado 1500 4X4 WT