Paper vs metal?

[BMCMOTO]

I have a question. Metal vs. paper gaskets. In this case, between the Breva 750 transmission and bell housing. It came with paper. Does it make a difference? What about thickness differences, etc? I don't think there is any end clearance set by this housing. Any experiences, opinions, obsevations to share?

Brian

[73 sport]

     What is the advantage, one over the other?

[73 sport]

    I'll answer my own question. Metal gaskets are used in high temp.- high pressure situations, paper gaskets are used to seal two mating surfaces to prevent wate.r intrusion and to keep the joining surfaces from corroding together. Someone may think of more reasons.

[guzzisteve]

I have never seen anything on that spot, nothing. No oil in there & no set end gap that you must have. Never seen anything since smallblocks have been made back to 78. I wouldn't put anything there, you may get the little hole plugged up for draining a leak.

Here is another Q------------Does the parts book show anything? I think not! Carry on w/your discussion.

[BMCMOTO]

The smallblocks are different than the big blocks. There is a gasket between the transmission and bellhousing / clutch housing / reduction gear housing or whatever name you wish to assign to it. Guzzi calls it a clutch drum, I didn’t think that was a very clear description. That area carries gear oil lubrication for the reduction gears. There is no gasket for the dry side between the engine and bellhousing / clutch housing / clutch drum etc . I ask because, both styles are offered. I was looking for input on which might be better in any given situation and why. Guzzi made the change at some point to metal gaskets in several places, like timing covers on big blocks and apparently even valve covers etc.. I have used a few of the timing cover metal gaskets. I liked that they were easier to install and less prone to kinking, but did not like that once kinked, they were unusable. I was just looking for some info if anyone had any.

Brian

[Dirk_S]

I’m guessing the metal version supercedes the paper. Looking at some parts fiche, I see GU23200370 as one of the first gaskets, superceded by 887005.  Not sure if that’s of any help other than hey—metal gaskets are reusable!

[guzzisteve]

Now I get it, the primary section of trans, yea paper.

[BMCMOTO]

Steve, so it came with paper but as Dirk says, the steel appears to be a supercession but the paper is still available. Why do you say paper in this case? I'm trying to reason this out. For instance are the steel gaskets truly reusable or is that just somebodies guess? I posed the question quite broadly to garner others thoughts. I have ordered both and will make my decision after they arrive. There is a great difference in price with the paper around $4 and the steel over $30. Sometimes cost isn't the deciding factor for me. So why is the paper your choice?

By the way I'm not trying to start an argument I really just want to learn.

Brian

[Dirk_S]

Is this the gasket?

[BMCMOTO]

Yes it is.

Photos.












Maybe this makes it clearer.
I Could not get that image to post. Thank you!

The question remains, if given a choice between paper and steel which to choose and why, in any given situation, not just this one.

Brian

[guzzisteve]

Steve, so it came with paper but as Dirk says, the steel appears to be a supercession but the paper is still available. Why do you say paper in this case? I'm trying to reason this out. For instance are the steel gaskets truly reusable or is that just somebodies guess? I posed the question quite broadly to garner others thoughts. I have ordered both and will make my decision after they arrive. There is a great difference in price with the paper around $4 and the steel over $30. Sometimes cost isn't the deciding factor for me. So why is the paper your choice?

By the way I'm not trying to start an argument I really just want to learn.

Brian

Mostly cost, not a spot that normally leaks. I don't know if they make a thick green or red one for that spot. Metal ones should have a rubber stripe on it, then it is reusable. I have even used a smear of Pro Black silicone. It is much like the back cover on a 4 or 5 speed trans. Always been paper. I have not used the metal gaskets made for valve covers & such. May try next time I have a failure. I wet the thin paper ones w/water to stretch so holes all lines up.

[BMCMOTO]

Thank you Steve. I do have both ordered. There is a spot on the top of the case exhibiting some minor corrosion evident of moisture intrusion, I think I will seal that area with a flowable silicone product just before assembly. This flowable silicone is very thin, thinner than Yamabond or any other silicone sealant I have found. I just want to seal the exposed porosity of the erosion.

Brian