Exhaust gaskets at the head reusable?

[GS1000G Shopper]

I was finally able to get my new-to-me 1000G going for a short ride down the driveway. I noticed an exhaust leak. Turns out one of the bolts that holds the exhaust pipes into the head is missing (and stripped). I'm going to repair it with a heli-coil today. My question is, are the gaskets/packings between the pipe and the head reusable? Don't really want to wait a week or so to get them mail order (no bike shops around me).

Thanks.

 

[tkent02]

Try it, they usually seal. At least for a while. If you use nuts and studs with anti seize compound on them, it is easy enough to replace the gasket later if it leaks.

 

[Guest]

Order the gaskets. They're crush gaskets and may not seal well the second time around.

I'd say if ya have another bike to ride wait till they come in. If not you'll just wanna re-do it again when ya get em. The less ya have to do and re-do with those bolts the better.
If it were me I'd install some studs while you're there. Lots less wear on those threads.

 

[GS1000G Shopper]

Thanks. I like to do things for the long run, so I'll pick up some studs while I'm at it. I take it as reduced head flange type nut would work best here?

 

[tkent02]

Flange nuts are good, studs and copper exhaust stud nuts from BMW cars work very well and are cheap. 8mm x 1.25, they don't corrode, and they are locknuts. Good stuff

There is also a similar stud from Subaru for their exhaust manifolds which has an Allen head in the end of the stud, it's handy to keep the stud from bottoming in the hole as you tighten the nut, which weakens the threads.

 

[GS1000G Shopper]

I was going to ask about the nuts. It occurred to me after I posted that when I did work on my other air-cooled engine many years ago, the trick was to use a brass nut on the manifold stud since the studs had a bad habit of breaking off.

I'll do some shopping & post here what I find for the next guy.

Thanks.

 

[GS1000G Shopper]

For reference, the OEM bolt is 8mm x 1.25 pitch x about 50mm long (with the head). The hex is 12mm, and the lock washer under it is about 14mm.

Results:

Set of 16 BMW studs (unknown thread size & length) and copper nuts, $35. Studs have internal 3mm hex for installation.

8mm x 1.25 x 50mm long stainless studs with hex for install, $3.75 ea /$30 for 8
8mm copper plated lock nut, $1.95 ea / $15.60 for 8
Total cost for 8 each of both (plus shipping) $45.60. This place also sells on ebay & their shipping is listed as $10.

8mm x 1.25 2" long (51.4mm) studs and 8mm copper nuts $1 each, total cost $16 plus shipping.

Searched ebay, found a listing from seller goner19 titled "bmw 2002 / 318i M10 engine exhaust manifold sutd / nuts". It is a set of 8 studs & nuts for $22 plus $4.90 shipping. Studs use allen key to install. Unknown thread size & stud length.

Seller 53ragtop has a set of 8 VW copper nuts (unknown thread size) for $6.95 plus $11.23 shipping.

McMaster-Carr sells 8mm x 1.25 x 50mm studs in black for 56 cents each, 8mm black lock washers are $2.89 for 100, and stainless 12mm (hex size) nuts are $3.97 for a pack of 10. They don't sell copper nuts. These studs do not have a hex to install them. Total cost would be $11.34 plus shipping (they're really reasonable).

ARP 57mm 8mm x 1.25 studs, nuts, and washers set of 8 $65.60 plus $10.95 shipping. Stud has hex for install.

 

[tkent02]

The nuts are .40 ea here:

http://www.autohausaz.com/search/pr...9@Exhaust System Nuts, Bolts, Screws, Washers

They used to be .25ea a few years ago.
Studs are probably cheaper at Subaru, cheaper yet at any local metric fastener supply place. They probably have a bag of nuts for a buck or two.

The main thing is not to use bolts which wear out the threads in the head, use studs instead, use anti seize, and do not bottom out the studs in the hole.

 

[GS1000G Shopper]

Looks like they play the GM Parts Direct game- super low parts price, then they double or triple the shipping. I put 8 nuts in my cart & it said $14 to send them via USPS Priority Mail ($5.35 flat rate last time I mailed a small item). Same cost for 1 as for 8. I know there are handling costs with running a business, but that's rather high. I see they have free UPS ground on orders over $50, so it's one of those small orders not being cost-effective things.

I shopped the same thing at Pelican Parts (been a while since I bought any BMW parts, but I recall shopping there), and the nuts are 50 cents with $5.50 USPS.

I've done a lot of looking at Subaru parts (OEM and aftermarket) and can't find an applicable stud- for OEM, you really need a year & make. I tried several models from 1990-2009 and didn't find any listings.

The BMW seller on ebay is going to check with his supplier as to if he can get what I need.

 

[Guest]

I've reused them many times over except for the cheap ones that unravel.

 

[GS1000G Shopper]

I thought I had done well when we stopped by Advance Auto after church today. I found a set of 10 56mm 8mmx1.25 studs. they even had a hex portion on the end for installation. Turns out the studs need to be much longer than 50mm. When I had one of the 56mm ones seated, the hex end was even with the pipe flange- no room for a nut much less a washer. I estimate they need to be at least 60mm, probably 65mm for a good fit.

The worst news was after picking up a 21/64 bit, I found something was broken off in the hole. I got in maybe 3/8 of an inch and it was like drilling through hardened steel. I can see what looks like maybe a drill bit (much smaller than a bolt or extractor) in the hole. I hit it with several smaller bits but made zero headway. I have the hole deep enough to where I could grind down the end of the Helicoil tap and partially thread it. The insert went in about 85% of the way. I'm letting the thread locker set up and will see how it goes, but this more than likely will require replacing the head to do it right.

Being ever thankful (today's sermon BTW), I see this as a chance to make a stealth 1100. An 82 up motor should bolt right in, shouldn't it?

 

[Nessism]

Sorry you are having such a hard time with this project but please keep going. After you find the proper length studs, and the cheapest price, please post the info here so I can bogart some studs for myself after all your hard work. You're a good man....

 

[GS1000G Shopper]

Will do. I found some generic 65mm ones here for $2.13 each.

McMaster has some 65mm ones here (equal 20mm threaded each end) for $2.49 each, and some 65mm black oxide ones here for $2.42 each.

ARP goes to 57mm, which will be too short.

I think some of the unequal length threaded ones may work, and shorter, since they don't thread all the way in. Since I have it apart, I'll try & get a depth measurement later tonight.

 

[Mop Bucket]

Shopper, any update? Inquiring minds want to know.

 

[GS1000G Shopper]

My head is off the bike to be repaired. I won't have an update for a couple of weeks.

 

[GS1000G Shopper]

It occurred to me I can figure this out with what I have. I did some measuring today using the flanges from the pipes and one of the 8mm bolts. The flange is about 26mm thick. The bolt when inserted into the flange sticks through about 16mm. The hole in the head is deeper than this which is why the Advance Auto studs were too short. EDIT, I measured them and they are 20/8/22 with a 4mm hex extension, see below for what these numbers mean. I added a nut and lock washer to the top of the bolt to simulate it installed and got 35mm. Putting 35mm together with 16mm, I got 51mm, hence my original number.

Studs are sold either fully threaded, equally threaded, or unequally threaded. Our ideal stud would have a 16mm threaded side along with say a 20mm side, with the rest being unthreaded.

I checked McMaster, who give tech drawings for almost everything they sell. The closest one I saw was a 50mm broken down as 12mm and 20mm threaded, which left 18mm unthreaded (looking from the head, it's 12/18/20). It's part # 93210A030 and sells for $2.41 each. There was an equal length 50mm one with 20mm threaded on each end, but when it was scaled out in a diagram (attached) it was also too short.

I also looked at the next size up equal length, 65mm (20/25/20), and it stuck out too far from the head. The next size up unequal length, 60mm (10/28/22), either had less in the head (10mm) or did not leave enough threads past the flange when the 22mm side was put into the head.

Like most things in life, it's a tradeoff. The unequal length stud sticks out far enough to engage the nut is not as deep in the head, while the equal length one goes into the head further but does not stick far enough out to engage the nut.

Hope this helps.

EDIT #2
I re-checked the 50mm studs from 034 motorsports ($3.75 ea). They are listed as 16/10/21 with a 4mm hex, for 50mm overall. I scaled them in my diagram and if you use the BMW nuts (no lockwasher) they should be very close to a perfect fit for the GS (thread still not fully engaged). They have the benefit of the hex to install them, but cost a little more than the McMaster ones.

The AP Tuning studs and nuts ($16 plus shipping) look like the best fit and value when you factor in shipping cheaper nuts. They are stated as being .5/.25/1.25 for 2" OA length. In metrics, this is 12.85, 6.4, and 32.1. I've updated the diagram.

 

[Nessism]

Sorry to say but I don't think you are analyzing this correctly because the bolt holes are not in plane with the exhaust port exits. Plus, you have the thickness of the exhaust gaskets to consider.

Do you have any old exhaust bolts left? If so, measure the overall length, including the head on the bolt, add another 10mm and that should be the length you need. Am I missing something?

 

[GS1000G Shopper]

Good point about the gaskets. I did use one of the old bolts to measure past the flange, and I think your math should put it within range.

If anything, the studs could stand to be on the long side since my diagram shows the Advance Auto studs sticking out slightly. When I installed them (note: with gaskets in place), they were flush. This means the only ones that would work properly are the McMaster 50mm unequal or the AP Tuning ones. Possible fits due to this include the McMaster 60mm unequal length, which puts 22mm into the head (I don't have a head to measure for thread depth).

EDIT
Found this on my earlier post in this thread:
For reference, the OEM bolt is 8mm x 1.25 pitch x about 50mm long (with the head)

Adding 10mm gives us 60mm. The most secure fit would be the McMaster 60mm unequal length studs, assuming they fit all the way into the hole w/o bottoming.

 

[GS1000G Shopper]

I ordered both 45mm and 50mm studs from Allen's Fasteners (prices with shipping were good and shipping was quick), plus some flange and locking nuts (8 each, I was shorted 4 of the 45mm studs). These studs will go 10mm into the head.

I'm attaching a side-by-side photo of them with the Advance Auto Parts 56mm stud. I tried cutting some more bottom threads on one of the 50mm studs but only got another 1.3mm according to my caliper.

I should find out the status of my cylinder head this Friday, so I'll have more info soon.

 

[GS1000G Shopper]

The head is home, a $45 repair. Only problem is he drilled & tapped the hole for a 7mm thread (I was sure I said I'd do this, hence the low price). Repair looks good, and after test-fitting the 45 & 50mm studs with pipe, retainers, and packing, the 50mm is the one to use. I'd like to have more than 10mm of thread into the head, but am hopeful they will do the job.