Drag racers -- stainless case bolts OK?

[bwringer]

I'm working on rebuilding my spare GS850 engine. It's a 1980 engine with very low mileage, but I plan to paint it black (with polished side covers, natch) to mimic the look of my 1983 GS850's dearly departed original engine. Unless you count the valve cover bolts or know which clutch cover to look for, you'll never know the difference.

Anyway...

When I split the cases, I was appalled at the rusty, corroded, shoddy junk bolts used to hold the cases together. I'm very lucky I didn't break any.

I'd like to replace these bolts with stainless socket (allen) head equivalents for maximum bling and ease of maintenance. I hate cleaning motorcycles.

Would there be any problems with this plan? I'm not worried about the strength -- the stainless goodies are far stronger -- but I wonder if the cases might warp or something. Maybe they were designed around stretchy bolts that would allow the aluminum to expand or something.

It'll pretty much be a stock engine with no modifications, so there's not an excess of explosive ground-pounding power to worry about.

Please keep in mind I'm asking about the assortment of bolts that hold the upper and lower cases together. I am NOT talking about the bolts that hold on the case covers (alternator, clutch, and secondary gear covers). I know stainless is OK for these. My bike is wearing stainless allen heads on the case covers already, and I've got another kit ready to go for the "new" engine.

[Commodus]

I can't be of much use here, I'm afraid, but stainless is not necessarily stronger than steel bolts.

[bwringer]

A related question, while we're on the case topic:

What's the Right Stuff to use these days when putting the cases back together?

The manual mentions a certain sealant, but have there been any recent advances in polymer technology I should know about?



I know stainless is not as strong as a high-grade steel bolt, and it's more brittle. Could these disgusting lumps I pulled out really be high-grade bolts? The 8mm bolts are marked with a mysterious "7" on the heads. Does that mean anything?

[Mike_H]

Yes, its probably a grade number...but what, exactly, it means escapes me. If you can be patient, I will look tommorrow when I have my Machine Desgin textbook handy (I have that page tabbed out )

[Commodus]

It's a weird way of labelling it, but assuming it's a 'grade 7' :

http://www.engineersedge.com/hex_bolt_identification.htm

[NATEO]

I thought I read somewhere that the number refers to the torque when assembling the part...
I dont know though...

[Dink]

If you look in a genuine Suzuki service manual, you will find in the torque table, that they mention bolts with either a "4" or a "7" on the heads, these are a torque guide NOT a representation of grade!!!
DO NOT use stainless bolts to hold the cases together!!!!
Stainless gets brittle under heat and stress, you don't want broken studs holding the cases together.
Try an ARP stud kit.

Dink

[Mike_H]

Yes, its probably a grade number...but what, exactly, it means escapes me. If you can be patient, I will look tommorrow when I have my Machine Desgin textbook handy (I have that page tabbed out )

Well, I just check the book, and "7" is not a valid grade number for metric bolts. Beyond that, I would not have the foggiest ides what "7" means

[bwringer]

Hm. Looks like I'll be ordering up a passel of new bolts from Suzuki after spending some quality time with the world's fuzziest and most vague microfiche.

Lots of good info on bolts and metallurgy on ARP's site:

http://www.arp-bolts.com

It looks like my suspicion was correct -- bolts clamping aluminum parts must be designed with a certain amount of stretch and rebound capability to cope with aluminum's expansion rate when heated. This would not be a good place for stainless.

On another note, I do live in Indianapolis (there are several Indycar and NASCAR teams headquartered within 1/2 mile of my house), and I hear that you can find a huge variety of necessary motorsports materials from a variety of shops near Gasoline Alley. I bet one of them is an ARP distributor.

New Suzuki bolts would work just fine, though. And I am definitely replacing the cylinder head studs, too.

Any ideas on case sealant?

[Hap Call]

Any ideas on case sealant?

Yamabond 4 or Gasgacinch.


Hap

[RacingJake]

High temp rtv gasket maker works good too

[courier11sec]

If you look in a genuine Suzuki service manual, you will find in the torque table, that they mention bolts with either a "4" or a "7" on the heads, these are a torque guide NOT a representation of grade!!!
DO NOT use stainless bolts to hold the cases together!!!!
Stainless gets brittle under heat and stress, you don't want broken studs holding the cases together.
Try an ARP stud kit.

Dink

Hit it right on the head. Stainless is in my opinion a terrible material for fastener. Sure it's pretty and all, but it's hard, brittle, does weird things when heat is applied to it and most of all it is much more prone to galling than steel. Whatever you use, make sure anti-seize is on hand. Studs would be the way to go as aluminum get more upset with you the more times to remove and install a fastener in it.
Working as an exhaust mechanic the past four or five years has seen me fighting lots of broken stainless junk.
Now I'm getting angry just thinking about it...

[madjack57754]

Use the yamabond 4. Best stuff out there.

[Nessism]

Most of those Yamabond, Kawibond, etc. materials are made by 3-bond. It's the correct material for the job. Make sure you get the proper grade for case assembly and you are good to go.

[tomcat24551]

Bolt Head Symbols

Here's a little info that may help:

In June 1977, Suzuki issued a Service Bulletin Called "Bolt Head Symbols"

Here's what it says, in part:

"Notice:

In the past, hex head bolts used in Suzuki motorcycles were either an ordinary style bolt (plain head), or a special bolt ("S" head). The "S" symbol indicates that a special heat treatment had been applied to the bolt and its tensile strength is much higher that that of an ordinary bolt (plain hex head).

The "S" symbol is now being changed to a "7" symbol embossed on the top of the head. The ordinary strength bolt now has a "4" embossed on its head."

(There followed here a table of torque values for the "ordinary" and "High Strength" bolts with "bolt dia." of 5 mm thru 12 mm. As an example, in the table, the "ordinary" 10 mm bolt, whether plain or marked with a "4", should be torqued to 14.5 -18.1 ft lbs. The high strength "S" or "7" bolt in 10 mm takes 21.7 - 26.8 ft lbs.)

The bulletin ends with this statement about part numbers:

"The part number prefixes of the new style bolts are "01000" series for the ordinary bolt, and "09000" for the special bolt."

I looked at my microfiche for the '83 850 and, yes, some bolt part numbers begin with 01 and some begin with 09. Ditto for P/Ns for nuts.

One personal comment: I've never been a big fan of allen bolts. The '83 850 used chrome plated side case bolts with hex heads--not phillips-head screws. They look better, have a high shine, don't collect dirt/grease, and you ain't gotta search around for a special tool to get 'em out. They might not fit real good on cases that originally had phillips-head screws, though.

That's my opinion (and it ought to be yours!).

Tomcat