transmission went bad (1 Viewer)

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Mar 5, 2002
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I just started hearing some bad noises in my 73 40 3 speed. Stock motor, transfer sua. Only first and second are making noise, possibly reverse but have not heard anything yet. I need advice. Really poor these days. How much longer than my 3 speed is an SM465? How much for a 420/ 465 swap w/o driveshaft mods (if possible)? I was planning on machinig a 3/4" spacer up front on the transfer case if I use a 420. Also thinking about a toyota drivetrain swap for a 4 speed if I can find parts for cheap. What do you guys have laying in your garage? Most interested in the adapter kit costs. Also concerned about the larger GM clutch friction disc not fitting well with the toyota flywheel and pressure plate..
Thanks
Pablo
 
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Jan 14, 2003
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I will have a 4spd bell housing/4sp trany/4spd t-case at the end of next week hopefully. Trany shifts smooth and the t-case was rebuild last year. Let me know if interested. I am just outside Sacramento.
-Brian
 
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Brian,
What year of transmission, 74? &nbsp:Domestic? What month? Clutch?
 
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I am guessing 74, but I am not sure. domestic. no clue on month, possibly 6/74 (production date of my 40). I know the engine was not the original so I am not sure on the drivetrain. I am keeping the flywheel and pressureplate for my SM420/3spr conversion, but the clutch disk will be sold. It was new (OEM) last year and I do not drive the 40 often. I also have a spare 4spd tranny and tcase. I am not sure of the condition of the tranny as it has been sitting around for a while and the tcase has a crack, but the internals are good. If you are interested let me know soon, as I am going to be unreachable after next week for 3 weeks (vacation).
 

woody

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price-wise, the 420 is the 2nd-cheapest swap, with IIRC no driveshaft changes needed, but only a minor driveability improvement.

The 465 requires driveshaft changes and the adapters are more $$.

The FJ40 4-speed swap is a good one, but you'll need the driveshafts too.

IMO, 3-speed tranny's are boat anchors and you should be able to find one for $25 plus freight or less....I've tossed all mine away as useless, sick of kicking them around...
 
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Bella Vista, AR
My 3 speed tranny clutch is nearing its final days. That will be the excuse that I need to swap over to an SM420. For the money and the end result (low first gear) it's definately worth the swap. Just my 2 pennies... :G
 
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Dec 31, 2002
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That sucks the 465 adapter should be cheaper.If everyone used the 465 the prices may come down for when I do mine It would be a lot cheaper. :G


Pablo I have 2 of the 3speed trannys laying on the garage floor.they were spares for my cruiser so I asume they work
 
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This is somewhat relevant-
Are the parts available to rebuild a 420? I've been going back and forth between Toy 4 spd and 420 for months. My 3rd gear synchro ring is wearing so its about time. I guess I should call some tranny shops nearby and see if they would rebuild? Should I just call it a SM420 and say it was in 1/2 to 1 ton GM trucks from '47-'67?
 
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Feb 19, 2002
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This is somewhat relevant-
Are the parts available to rebuild a 420?  I've been going back and forth between Toy 4 spd and 420 for months.  My 3rd gear synchro ring is wearing so its about time.  I guess I should call some tranny shops nearby and see if they would rebuild?  Should I just call it a SM420 and say it was in 1/2 to 1 ton GM trucks from '47-'67?

I talked to Inland Truck here in Missoula about the sm420. 3 variations depending on year and application. There are subtle differences in the synchros and possibly countershafts, input shafts, and main shafts. Also, they used it in up to 2 1/2 ton trucks, so you'll need to know more specifically what it came out of. He said the interest from off-roaders is mainly what's keeping the parts available. You know, enough people ask and they dig deeper to find what we need. Beyond that, "I know nuthingg"

I do have a 420 that I'll rebuild some day. Maybe I should start sooner than later!

ps - I rebuilt my 465 last year and had no problems with parts if that helps. 6.55 instead of 7.05 granny is only about 7% higher. Oops, wait, 5" adaptor, probable driveline changes and/or engine relocation. Not nearly as easy then as switching to a 420. My bad. :-[
 
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for sm420 rebuild check out PinHeads website:
http://members.cox.net/cglabe1/SM420/sm420.html
It is pretty easy to do yourself. I swapped out the main shaft for my sm420 adaptor (old AA style) and I didn't have a manual and had never taken a tranny apart before. Just lay the parts out in the order you removed them. You can basically get new seals, gaskets, bearings, and 3rd and 4th syncros. The web site has all the info.
 
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Any special tools? I don't have any gear/bearing puller type specialty tools. I guess if I get off my now lazy summer a$$ and find one, I could go ahead and rebuild while I drive the 3 spd into the ground. I remember someone saying the 420 is 1" longer then the Toy 3 spd? If so then my rear shaft should be fine, since its pretty extended right now after the lift, but I may be 2wd only until I get the front extended some?
So what should I ask for when trying to find one? Just ask what the oldest chevy truck in the lot is and if it has a 4 spd? And then go from there?
 
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Reverse on the 420 is left and back. Reverse on the 465 is right and back. Easy. Should be 420 in '67 and older.
 
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Read Pinheads write up. It explains which 420's are better and what vehicles to look for. The later ones don't have an oil slinger so you don't spill the tranny fluid out the front onto the clutch when pointing down a steep grade. When I pulled mine apart I did not have a bearing puller. I just used a chisel and a hammer and just tapped around the bearings until it came off or went on. Takes a while but still works. Pinhead goes over what is needed and the basic process.
 
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basically the "newer" ones are better. The older one's have an oil slinger which can let oil leak out onto the clutch. Not sure of the cut-off date though. PM Pinhead as he knows much more than I. If you look hard enough you can find pretty good deals. I got mine off PBB for $40. It was produced in 1964 and does not have the oil slinger.
 

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