79 Convert Rear Seal or Flange gasket

[JayDee24ca]

Here are a couple of photos of the rear flange on my 79 Convert. It was leaking a puddle every time I stopped, and the rear of the bike was getting pretty grimy as well. It was definitely not the transmission, torque converter, or crank breather.
It appears that the leak is from the rear seal only, but I am not 100% certain that there is nothing coming from the flange or the two bottom flange bolts. Should I, while I am in there, pull the rear flange and replace the gasket, or just leave it alone? Do the photos look like the flange gasket is leaking? There is motor oil at the juncture of the flange and seal, and a fair bit across the face of the seal. The back of the flywheel was dry.
JD





free unlimited photo hosting

[Chuck in Indiana]

Just MHO, but when I'm "there" I replace gaskets, seal, epoxy the plug.. you know the drill. Besides that, it's much easier to replace the rear main with the bearing carrier on the bench. That way, you'll never have to go there again.

[JayDee24ca]

Thanks Chuck. I'll pull the flange. Any sealant (grease) on the flange gasket or just put it in dry?
JD

[Chuck in Indiana]

You'll get all kinds of answers on that one. I, personally, use a light wipe of aviation permatex on one side of the gasket. Others will tell you to use their spooge of choice on both sides of the gasket. Others say dry.  It's kind of like an oil thread.. <shrug> 

[JayDee24ca]

Chuck, are you talking Hylomar? The blue stuff? I have a tube of that, and this MIGHT be a good spot for it.
Got the bearing carrier/flange out with no alarms, but boy is that gasket ever stuck to the backside of it! Worse than snot to a doorknob. Managed to get it off finally with a few coats of paint remover (burnt my fingers with it, the old fashioned gel stuff) and a bit of red scotchbrite.
JD

[Antietam Classic Cycle]

I use a light application of Permatex 300 or Permatex Aviation on both sealing surfaces (case and flange) and on the outer diameter of the seal too. Seal the bottom two bolts holding the flange to the case or they're leak (I use Hondabond 4). I'd recommend replacing the breather pipe gasket (Permatex 300 there too), and the aluminum crush washers on the oil return banjo bolt (I apply Hondabond there too). As Chuck said, JB Weld the cam plug while you're at it.

[rodekyll]

Just MHO, but when I'm "there" I replace gaskets, seal, epoxy the plug.. you know the drill. Besides that, it's much easier to replace the rear main with the bearing carrier on the bench. That way, you'll never have to go there again.

I use a light application of Permatex 300 or Permatex Aviation on both sealing surfaces (case and flange) and on the outer diameter of the seal too. Seal the bottom two bolts holding the flange to the case or they're leak (I use Hondabond 4). I'd recommend replacing the breather pipe gasket (Permatex 300 there too), and the aluminum crush washers on the oil return banjo bolt (I apply Hondabond there too). As Chuck said, JB Weld the cam plug while you're at it.

Micro-picky?  Maybe.
Overkill?  possibly.
Really good advice?  Most definitely!

Covers the bases, CYA, and after 35 years or so, good preventive maintenance, imo.

Since you've got the gearbox out, doing the hydraulic drive seals and O-rings might not be a bad idea, either.  You can lose the torque converter snout seal and not show a leak.  I just did a rubbers refresh on one.  Found the stuff at NAPA, less than $20 for everything.

If you REALLY want to get picky, I'll bet your shift shaft o-ring is leaking, too.

$0.02

[chuck peterson]

P.S. i casually got rid of the aft fluid during a seal and oring excursion only to discover the newer fluids suck for a vert. RK put us onto the mil spec fluid, but things changed when I starting using that. A little less push it seemed, but...I'd keep and reuse any old atf fluid that's stil clean and red if it's been working well for you.

[JayDee24ca]

RK, the hydraulic seals and orings in the trans and TC were all done a few months ago in my second tear down. I did not at that time go deep enough apparently, and that is why this third teardown has me chasing a bad rear main seal. Oh, and as a result of forgetting to refill the resealed transmission on the second teardown, and driving it for 109 miles, I am also now replacing the transmission with a freshly resealed used one......

The cam plug got a fresh coat of JB Weld this afternoon. Shift shaft has a new oring.

What is Hondabond 4? Is there a more common sealant that can be used? I have a drawer full of permatez varieties, and Hylomar, but no Yama or Hondabond.

Is the aviation goop that you guys are speaking of a non-hardening type? I ask simply because I wonder if it is the same thing as Hylomar, which is also used in the aviation industry I am told.
Thanks

[Antietam Classic Cycle]

RK, the hydraulic seals and orings in the trans and TC were all done a few months ago in my second tear down. I did not at that time go deep enough apparently, and that is why this third teardown has me chasing a bad rear main seal. Oh, and as a result of forgetting to refill the resealed transmission on the second teardown, and driving it for 109 miles, I am also now replacing the transmission with a freshly resealed used one......

The cam plug got a fresh coat of JB Weld this afternoon. Shift shaft has a new oring.

What is Hondabond 4? Is there a more common sealant that can be used? I have a drawer full of permatez varieties, and Hylomar, but no Yama or Hondabond.

Is the aviation goop that you guys are speaking of a non-hardening type? I ask simply because I wonder if it is the same thing as Hylomar, which is also used in the aviation industry I am told.
Thanks

Hondabond 4 is virtually identical to Yamabond, both likely made by Threebond. Grey, non-hardening sealer. If you have a Honda or Yamaha dealer nearby, you can get it there, it's also available on Amazon.
https://www.amazon.com/Genuine-Honda-Hondabond-08717-1194-applications/dp/B00STVCWYY/ref=sr_1_1?ie=UTF8&qid=1502769020&sr=8-1&keywords=hondabond+4

Permatex 300 or Aviation are both brown liquids, come in a little bottle with a brush on the cap. Also non-hardening. I buy it at my local NAPA.
https://www.amazon.com/Permatex-80057-Super-Gasket-Sealant/dp/B000HBI9DM/ref=sr_1_1?s=automotive&ie=UTF8&qid=1502769490&sr=1-1&keywords=permatex+300
https://www.amazon.com/Permatex-80019-Aviation-Gasket-Sealant/dp/B000HBM3QQ/ref=sr_1_1?s=automotive&ie=UTF8&qid=1502769599&sr=1-1&keywords=permatex+aviation

I've used Hylomar a few times, always on British stuff (Land-Rover and Matchless G11CS). Not a fan of it.

[JayDee24ca]

Thanks Charlie, I'll head don to the hardware store in the morning and see what I can find. Yes, the reason I have the Hylomar was for the Jensen I had a few years back, a British car.
thx
JD

[chuck peterson]

P.S.S. My more experienced guzzi friend and mechanic Mike Duphiney, "Iron Mike" guessed a porous rear main bearing. And used the Hylomar to coat the flats there after a second excursion crabbing to replace a rear main seal was unsuccessful....wor ked

[Wayne Orwig]

Any more, when I go that far in, I seal the case and pressurize it with a bit of air. Clean it well, and spray powder on the case. In a few hours, the leak will be very visible.

[Chuck in Indiana]

Any more, when I go that far in, I seal the case and pressurize it with a bit of air. Clean it well, and spray powder on the case. In a few hours, the leak will be very visible.

A bit meaning maybe 5 psi?

[JayDee24ca]

I was unable to locate either the Honda bond or the Permatex 300 (only two possible outlets here in town), so I went with what I had, the Hylomar and a white Loctite thread sealant. Unfurtuantely, the small and only bike dealer in town (Honda) has taken his usual summer break for three weeks and the shop is closed until September.
I got things back together alright, no issues, however I am unable to determine if there are specific torque specs for the flange. I looked through the manuals for the Convert and SPII, and don't see any. What are your recommendations in that regard?
Thanks!

[Chuck in Indiana]

Just use a generic torque value for the bolts being used. I don't remember what they are. Torque evenly in a cross pattern, and you'll be fine.

[JayDee24ca]

Just use a generic torque value for the bolts being used. I don't remember what they are. Torque evenly in a cross pattern, and you'll be fine.

Done. Thanks Chuck.