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SM465 to TH400 2WD swap.....

xCaliK5x

xCaliK5x

1/2 ton status
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Yup.... here on the K5 boards since I figure you guys have ripped more into these then the street truck guys. Long story short, my SM465 shift lever has a ton of slop, and has started making odd noises on take off and while coming to a stop, or stopped with the clutch in. If I slightly move the shift lever, I can get it to stop, or happen.... so I think something is worn out.

I planned on building my 388, then getting a built TH400 to back it up. Shooting for around 500HP, I wanted a little more then a TH350, and don't want the expense of building a strong 700R4, plus as a weekend toy/cruiser, overdrive and mileage are a second thought. I planned on doing it in one fell swoop, but since the SM465 is on its last legs, might as well do it first. I can't find too much info for what I have planned. Seems to be lots of swaps going the other way but in 4x4's.

I plan on getting a box built from a reputable supplier. Any suggestions?

Length. I know I will have to modify the driveshaft, or swap to a one piece. No big deal there. I currently have a two piece I rebuilt about two months ago. Question is, Do I need to have the truck 9" tailshaft, or can I use the 4" car one? Does it matter since I will have to have the driveshaft modified anyway?

Next question is the cross member. Is the one I have now, the same as a TH400 2wd truck? Would all I have to do is move it back and buy mounts? Or do I need to find a cross member out of a parts truck? I plan on sourcing trans cooler lines this way.

I plan on using a Lokar kickdown setup.

As far as a cooler and lines. I figure I would get a decent one from Jegs. I won't be doing any towing, so I figure I do not need a t-stat/electric fan setup. Thoughts? I may either do braided AN lines all the way, or if my budget is tipping, I will source hard lines from a parts truck.

Thanks guys!

Mike
 
No replies eh? Here is what my research has found over the last few days.....

So looks like I plan on getting a built TH400 with a 34 element sprag, 1-2 shift kit with deep pan, upgraded steels and clutches.

2500 stall 11 inch converter.

Trans cooler I will order from Jegs with a fan and t-stat

Lines I will use braided hose with AN fittings.

Kickdown I will use a Lokar kit that has an actuator that bolts to the pan and uses a throttle switch.

Shifter, I do not know yet, thinking of a decent Hurst or maybe a Lokar auto that looks like a stick.

Cross member I can get from CPP.

This truck should go like stink.

Once this is done, I'm gonna back burner the motor, do Caltracs in the rear and new upper and lower tubular control arms. Might as well get it to point straight......
 
ya i would do a floor shift, cooler lines need to be addressed, doesn't matter if you do the short or long tailshaft, Dad always chases after the short tail shafts with the bolt in yoke. If you got the coin, supposidly the 1966 396/375 horse th400s have more straight cut gears and are a beaaast, but hard to find. Other than that I think they are mostly the same. Good luck cause ive never put a th400 in a 2wd for a swap, but the cross member location will change.
 
Is that the nice red short box? If it was me I`d put a super t10 in it. That would be easy and way cool.
 
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I'd omit the high stall speed torque converter,if it were my truck...they kill gas mileage and make the tranny run a lot hotter,and sound like it is slipping all the time...great for a 1/4 mile track,a poor choice for a truck,especially if it will see any heavy loads,towing or off road use...I would go the other way and use a lower stall speed obe like a diesel uses or an aftermarket one designed for towing...
 
Since you will be doing no towing and it is a weekend cruiser/toy as you say, do you know what height tire you will run, what gear ratio, what the weight of the truck is?

Fill in those blanks and we can zero in some more.

I have a 331c.i. in my Vette, it weighs 2850, has a 2600 stall t/c w/ 3.90 gears and 26" tires. It drives just fine on the street, without feeling like its slipping. With a set of 3.42's that might not be the case.



For tranny mods, for a T400 w/ 500hp....you should consider changing the output thrust washer to a torrington bearing conversion from a T350. A good tranny guy should know what it needs (a bearing set, and a shim) Also a heavy duty spacer in the intermediate clutch pack.
check this thread, post 328 for more info on mods to accept 500hp, and more torque:

http://coloradok5.com/forums/showthread.php?t=261694&page=7
 
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