Author Topic: Rear Gearbox Tail shaft seal  (Read 345 times)

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Offline kiwi428

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Rear Gearbox Tail shaft seal
« on: August 18, 2019, 10:36:49 pm »
I'm a little miffed that the rear seal on my 4 speed top loader is dripping. Box was reconditioned, new rear seal, but I get this annoying drip that appears under the end of the tail shaft housing. I have checked the oil level which is just below the filler plug. Should oil pass down the tail shaft housing, and fill the slip yoke space? Taken the drive shaft out and found a small amount of wear near the seal point( 0.002) but didn't think it was that bad enough. When I removed the drive shaft oil came out, about a 1/3 of a cup then stopped. Have I over filled the box?

Cheers John

Offline rockhouse66

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Re: Rear Gearbox Tail shaft seal
« Reply #1 on: August 19, 2019, 07:45:10 am »
I wouldn't say "fill the slip yoke space" but there is always oil in the end of the slip yoke when you remove the driveshaft.  I suspect the rear bushing is worn and lets the slip yoke push down on the seal, causing an escape path for the oil.  You probably need to replace both.

There is a nifty Snap On tool that will pull that bushing out easily with the trans in the car so try to find someone in the transmission business that will let you borrow or rent the tool.
Jim

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Offline stangperformance

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Re: Rear Gearbox Tail shaft seal
« Reply #2 on: August 19, 2019, 08:21:44 am »
+1 on the rear bushing and seal replacement.Something else to be sure and do when you re-install a new seal is to put some sealant around the outside edge of the seal to help make sure it is filling any places in tail housing casting that may have happened before. sometimes they will drip if oil is going around the outside of the seal. Just something I will do. Don't trust the little bit of sealant that comes on the outside edge of some of the rear seals. Roy
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Offline rockhouse66

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Re: Rear Gearbox Tail shaft seal
« Reply #3 on: August 19, 2019, 11:19:38 am »
FYI, the Snap-On tool is the same for C6 and big in/out Toploader so if you do ask around just get the one for the C6 as the shop may not know it works for Toploader too.
Jim

'69 Grande CJ

Offline lr68cj

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Re: Rear Gearbox Tail shaft seal
« Reply #4 on: August 19, 2019, 11:26:48 am »
What type of seal is it? IIRC the factory seal had a "boot" for when the rear rotated and pushed the driveshaft forward it would "compress" a little bit. The new seals are flat with no boot. I think the old ones are very hard to find today. But I could be wrong.

Offline rockhouse66

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Re: Rear Gearbox Tail shaft seal
« Reply #5 on: August 19, 2019, 01:34:11 pm »
Pretty sure the CJ style Toploader didn't have the boot style seal.  I think that was on the earlier cars and/or BW or C4 trans.

The SCJ car I had still had its original FoMoCo seal, though I had a little trouble getting it out ::)

Jim

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Offline kiwi428

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Re: Rear Gearbox Tail shaft seal
« Reply #6 on: August 19, 2019, 10:24:51 pm »
I'd be a little disappointed if the rear bush is worn since reconditioning, only done 400 miles since restoration,however its not to say it was replaced at that time? I don't have the rear seal number but it has the boot, so trust it is correct. When I removed the drive shaft I checked for excessive tail shaft movement and couldn't get much?
I'll keep looking and at worst change bush and seal.

Thanks guys

Offline 70cj428

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Re: Rear Gearbox Tail shaft seal
« Reply #7 on: August 19, 2019, 10:56:53 pm »
The original, day one, built with seal didn't have a dust boot. Most kits come with a C6 seal that has the dust boot and most toploader rebuilders use the seal with the boot.  I think Ed Meyers had some of the original style seals made. Here's a post over on the Concours Mustang Forum where they are addressed...

http://www.concoursmustang.com/forum/index.php?topic=18875.msg119218#msg119218

A lot of guys don't replace the bushing when they rebuild the box as it's a pain in the ass to get out of the tailshaft housing without making a special driver or using one of the tools designed for a C6. Snap on made a great set of tools that makes replacing the seal and bushing a 5 minute job once the driveshaft is out. They don't make them any more but they're always on Ebay.   Search for S-8687 (puller), S-8688 (bushing driver, seal driver (2 parts)), there's also a handle that screws into the driver.  all you have to do to use these is pull the driveshaft...

Hope this helps, John
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Offline ed meyer

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Re: Rear Gearbox Tail shaft seal
« Reply #8 on: August 20, 2019, 09:51:03 am »
All the replacements rear seals are nothing like the original assembly line victor dual type seal a rubber and a felt seal and that why we had them made.  Make sure u install seal with the victor # stamp end pressed to inside .

Offline preaction

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Re: Rear Gearbox Tail shaft seal
« Reply #9 on: August 20, 2019, 01:16:37 pm »
Is this what an original looked like ?
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Offline 70cj428

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Re: Rear Gearbox Tail shaft seal
« Reply #10 on: August 20, 2019, 06:13:03 pm »
No Paul, that's the C-6 style with the boot. I think Ed Meyers can sell you the correct seal ....
70 "R" code Mach1, Wimbleton White / Vermillion, Auto, AC,
70 "Q" code Mach1, Grabber Green / White, Auto,AC
70 "M" code Mach1, Med. Gold / Ginger, Auto, AC
68 "S" code GT Fastback, Wimbleton White / Black deluxe int.,4 speed, AC, (getting a 427SO..)

Offline Chris Teeling

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Re: Rear Gearbox Tail shaft seal
« Reply #11 on: August 20, 2019, 07:06:40 pm »
You can get the seals (along with a bunch of other nice parts) through Brown's Auto Body Services:

http://www.brownsautobodyservices.com/chassis/4-speed-transmission-output-shaft-seal
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Offline preaction

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Re: Rear Gearbox Tail shaft seal
« Reply #12 on: August 21, 2019, 12:32:28 pm »
No Paul, that's the C-6 style with the boot. I think Ed Meyers can sell you the correct seal ....
I thought they were the same.
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Offline ed meyer

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Re: Rear Gearbox Tail shaft seal
« Reply #13 on: August 21, 2019, 02:13:52 pm »
no  totally different seals from factory