how to change front seal- th350? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GMC 3 · 08-26-2003, 04:05 PM

have the tranny out of the truck and want to change front seal before I put in in my truck. How do I remove the seal and what is best way to put in new seal? thanks

**COBALT** · 08-26-2003, 04:11 PM

Piece o' cake. Use either a seal puller or a hooked slide hammer to yank that seal out of its bore from the center of the seal outwards. You don't want to dig next to it, and tear up the inside of the bore.

Once you get it out (it'll take a little bit) you can either use a seal driver made for the front seal (you can get them from Atec Trans-Tool or Kent Moore), or just carefully tap it in working around in a circle with a plastic or rubber hammer. Don't warp the seal body. It needs to go in straight and flush with the pump body.

You might want to replace the rear seal as well so they're both the same age. Remember to put a little vaseline on the seals before putting the converter and slip yoke back in.

crazy longhorn · 08-26-2003, 04:20 PM

Im a "cheap"player.....you can drive a screwdriver in the "front tin " on the seal & pop it out.....be carefull as Cobalt has suggested, not to scar the pump housing. I use a short lenght of the proper sized pipe to drive the seal back in. yes, & a little lube on the seal lips.....a dry seal will fail. Good luck,crazyL

OhioDan · 08-28-2003, 04:45 AM

I made a seal driver for that using a piece of exhaust pipe, and an old bearing race. Locate a race that will cover the new seal completely, and weld it onto a piece of exhaust pipe, wide flat side to the seal. Workie goodie. AND CHEAP ALSO!

08-26-2003, 04:05 PM	#1
GMC 3 Registered User Join Date: Dec 2001 Location: Philadelphia, pa. U.S.A. Posts: 87	how to change front seal- th350? have the tranny out of the truck and want to change front seal before I put in in my truck. How do I remove the seal and what is best way to put in new seal? thanks

08-26-2003, 04:11 PM	#2
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Piece o' cake. Use either a seal puller or a hooked slide hammer to yank that seal out of its bore from the center of the seal outwards. You don't want to dig next to it, and tear up the inside of the bore. Once you get it out (it'll take a little bit) you can either use a seal driver made for the front seal (you can get them from Atec Trans-Tool or Kent Moore), or just carefully tap it in working around in a circle with a plastic or rubber hammer. Don't warp the seal body. It needs to go in straight and flush with the pump body. You might want to replace the rear seal as well so they're both the same age. Remember to put a little vaseline on the seals before putting the converter and slip yoke back in. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

08-26-2003, 04:20 PM	#3
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Im a "cheap"player.....you can drive a screwdriver in the "front tin " on the seal & pop it out.....be carefull as Cobalt has suggested, not to scar the pump housing. I use a short lenght of the proper sized pipe to drive the seal back in. yes, & a little lube on the seal lips.....a dry seal will fail. Good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

08-28-2003, 04:45 AM	#4
OhioDan Registered User Join Date: Apr 2002 Location: New Carlisle, Ohio,USA Posts: 1,404	I made a seal driver for that using a piece of exhaust pipe, and an old bearing race. Locate a race that will cover the new seal completely, and weld it onto a piece of exhaust pipe, wide flat side to the seal. Workie goodie. AND CHEAP ALSO! __________________ LIFE AIN'T EASY WHEN YER FAT AND GREASY! GMC= Got More Class! 1970 GMC LWB, Fleetside, 350/4spd, Flowmaster "40's", 2002 GMC 16" Rallies, cowl hood,and added a bunch of options that weren't there when I started.



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