4 speed transmission rebuild kit

[c10 custom]

hi guys i have a 1947 gmc advance design series truck and its a 4 speed transmission i was wondering where i would get a rebuild kit for the transmission thank you for any help

[63 & 64 Bowties]

You might try some of the vendors here:
http://67-72chevytrucks.com/vboard/s...d.php?t=392428
It's from the Pre-47 section, but many of them carry 47-59 parts.

[_Ogre]

as many of those transmissions being removed from old trucks on this forum
you might be better off buying one from a board member
they usually don't wear out or break
what's wrong with yours?

[OrrieG]

I'm with Orge, I have never broke or worn out an old granny 4 speed. Around here you can still pick them up for $100 or less (or the newer ones that will fit).

[arturo7]

Is this what you're looking for?

http://www.novak-adapt.com/catalog/t...m420_parts.htm

[c10 custom]

well i thought i would go threw the transmission and re do it but if i cant get a rebuild kit then

[mr48chev]

The link that Arturo7 gave has what most people consider the whole rebuild kit for that trans. You don't replace the gears unless they are so worn or chewed up that they don't work good or unless they are broken.

[_Ogre]

you can get rebuild parts, but unless the trans you have has a problem i'd use it as is.
if it's leaking out the front or the rear, those seals are easy to replace without tearing into the trans.
the only thing i've replaced on those old heavy duty trans are the rear seal and the speedo drive gear.
i've pulled covers off those trans and have seen chunks broke off the sides of the gears from jamming a gear and they still work fine

[1project2many]

Look for Transtar on the web. Find the catalog section and look for the SM420. They have major kits minor kits, seals and gaskets, individual synchros, and anything else you might need.

if it's leaking out the front or the rear, those seals are easy to replace without tearing into the trans.

Pretty tough... there's no front seal in that trans.

[sweet70beast]

Where is Lethbridge? I have the 4 speed out of my 53 Suburban I will make you a deal on if you're interested.

[dwcsr]

Originally Posted by c10 custom

well i thought i would go threw the transmission and re do it but if i cant get a rebuild kit then

I agree with you taking it down and putting a bearing kit in it. 60yr old trans has to need it. The issue may be finding other parts for the 47 version of it. SM420 was around a long time but in 3 different versions. The popular ones are the 60's versions. Its a simple rebuild I'd go for it and you don't have to worry about it again.

[1project2many]

Some of the bearings can be obtained from industrial bearing supply houses. It's possible some of the bushings can be obtained that way as well but I've never had to hunt them down outside of a bearing and seal kit.

[c10 custom]

i think i will just install a bearing kit and go from there maybe change the syncro's while im in there

[tttuba]

I talked to the guys at the Novak site, Nice people and will help you. I was going to buy that kit to do mine. Unless I am doing something wrong...I think my synchros could use replacing. I try to double clutch even and still grind them. They also have a way of putting in a front seal so when you park downhill you don't leak oil. I haven't used them yet but think they might work. Never thought about seeing if someone here might have one they took out. I too have a 47 gmc and was keeping it pretty much stock.

[DransportGarage]

Originally Posted by tttuba

<snip>... I try to double clutch even and still grind them...<snip>

Double clutching...now THERE's a lost art!

[tttuba]

And apparently I am not that good at it.

[vwjohnny]

These folks had a full kit for my 3 speed saginaw That we rebuilt last year. Very helpful and guaranteed it was the correct kit. I think the girl at the desk is named Michelle. She really knows her stuff. Good luck.

Transmission Products Inc
490 W 2nd Street
Tucson, AZ 85705
(520) 884-7134

[dwcsr]

Originally Posted by tttuba

And apparently I am not that good at it.

Double clutching only works if you have a clutch brake built into your input shaft. Otherwise its hit and miss and your better off shifting with no clutch and get the same results

[tttuba]

Originally Posted by dwcsr

Double clutching only works if you have a clutch brake built into your input shaft. Otherwise its hit and miss and your better off shifting with no clutch and get the same results

I never knew that...good to know...thanks

[1project2many]

The input shaft can leak oil just driving and the seal conversion is pretty reasonably priced. You shouldn't be grinding gears unless you're trying to downshift into "granny" when coming into a stop. And making that shift happen is a challenge to say the least because there's a significant difference in gear ratio from Low to 1st. If you're not trying to crash through the gears and you're getting grinding, the synchros are probably bad. Hopefully the gears haven't suffered too badly. They're pretty tough, though.

[tttuba]

Originally Posted by 1project2many

The input shaft can leak oil just driving and the seal conversion is pretty reasonably priced. You shouldn't be grinding gears unless you're trying to downshift into "granny" when coming into a stop. And making that shift happen is a challenge to say the least because there's a significant difference in gear ratio from Low to 1st. If you're not trying to crash through the gears and you're getting grinding, the synchros are probably bad. Hopefully the gears haven't suffered too badly. They're pretty tough, though.

Its the downshift that grinds. From fourth to third to second. I never use 1st as it is too low.

[Zach B]

Jim Carter (clasictruckparts.com) sells all the seals and bearings.
Posted via Mobile Device

[mknittle]

Originally Posted by DransportGarage

Double clutching...now THERE's a lost art!

Not around hereI'm an ex-log truck driver.

[DransportGarage]

Originally Posted by mknittle

Not around hereI'm an ex-log truck driver.

You got me there. I forgot about you professional guys!

[mknittle]

The SM420 is a tough transmission. It was used in up to ton trucks. The only reason I rebuilt the one in my jeep{the only one I run} is I had to replace the main shaft to adapt it to the transfercase.