Engine Mount Bolts

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MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Engine Mount Bolts

Postby MotoMike » Wed Sep 15, 2010 5:29 pm

talk in the "does your single vibrate" thread has turned in part to engine mount bolts. starting it fresh here.

emailed Joe Carter (euro trash Jambalaya) he stocks the narrow case engine mount bolts but not the wide case. He advised that they are on the way and expects them within 2 months.


Ok, this is what I have found.
the parts books in our tech section shows the front mounts on a wide case as being 8mmx100. the rear upper as 8mm x 225 and the rear lower as 10mm x 252mm.

I pulled my front mount bolts and found that two are indeed 8mmx100. One is 10mmx100 and one is 3/8"x4". the top rear mount is 5/16" x9" The bottom one I didn't take out but looks to be a 10mm bolt. The outside frame width where the bottom rear goes through is 215mm. this bolt also goes through the rear hole in the front foot peg mount. each of these brackets are about 10mm thick. In each case the stock dimensions leave around 15mm of thread protruding.

In each case on mine someone has affixed nylock type nuts. This would be fine, except not enough thread protrudes to engage the nylon in the nuts, so no locking is accomplished by these nuts.

so if I were to replace them all with washers and nylock nuts, the dimensions listed in the parts books are a bit short.

I think the following would be a better set of mounting bolts.

10mm x 110mm in the front on all 4 bolts
10mm x 235 for the top rear mount
10mm x 260 for the bottom rear mount.

If you have rear sets, then the two rear mount bolts would both be 10x235.

What are your thoughts on this? what grades should be considered? How about in stainless? I don't know if such a group of bolts exists in some venders existing stock or not. finding that guy might be tough and might be a place that doesn't sell by the piece.

Teckhardt
Posts: 394
Joined: Sat Oct 31, 2009 10:25 pm
Location: Pacifc Northwet USA

Re: Engine Mount Bolts

Postby Teckhardt » Wed Sep 15, 2010 8:37 pm

I like stainless for non-stressed items but I would be careful with engine bolts. Stainless is not as strong.

"It is a common misconception that stainless steel is stronger than regular steel. In fact, due to the low carbon content, stainless steel cannot be hardened. Therefore when compared with regular steel it is slightly stronger than an un-hardened (grade 2) steel fastener but significantly weaker than hardened steel fasteners. "

Source: http://www.boltdepot.com/fastener-infor ... rials.aspx
1970 450 SCR

Pete
Posts: 102
Joined: Sun Nov 01, 2009 1:00 am
Location: Walworth, NY

Re: Engine Mount Bolts

Postby Pete » Wed Sep 15, 2010 8:45 pm

You can try McMaster Carr for individual bolts.

http://www.mcmaster.com/#cap-screws/=8v0rdn

They only list up to 200mm, but you may be able to get longer ones if you call them.

Pete

MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Re: Engine Mount Bolts

Postby MotoMike » Thu Sep 16, 2010 1:38 am

Teckhardt wrote:I like stainless for non-stressed items but I would be careful with engine bolts. Stainless is not as strong.

"It is a common misconception that stainless steel is stronger than regular steel. In fact, due to the low carbon content, stainless steel cannot be hardened. Therefore when compared with regular steel it is slightly stronger than an un-hardened (grade 2) steel fastener but significantly weaker than hardened steel fasteners. "

Source: http://www.boltdepot.com/fastener-infor ... rials.aspx


I was thinking grade 10.9 but wanted others thoughts on it.

Mike

MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Re: Engine Mount Bolts

Postby MotoMike » Thu Sep 16, 2010 3:50 pm

Pete wrote:You can try McMaster Carr for individual bolts.

http://www.mcmaster.com/#cap-screws/=8v0rdn

They only list up to 200mm, but you may be able to get longer ones if you call them.

Pete


Hi Pete
I only found up to 120mm at McMasters. Maybe missing the right section as it is quite vast.

I did find that they have grade 8 zinc plated bolts in 3/8" out to 12 inch lengths that could probably fit the bill.

Teckhardt
Posts: 394
Joined: Sat Oct 31, 2009 10:25 pm
Location: Pacifc Northwet USA

Re: Engine Mount Bolts

Postby Teckhardt » Thu Sep 16, 2010 4:12 pm

If you decide to go with Ti...

http://www.mettec.com/category/m_ten_hex_flange_bolts/9

Per their site:

Titanium bolts can replace both grade 5 and grade 8 steel bolts which have minimum UTS requirements of 120,000 psi and 150,000 psi respectively. Metric bolts with an 8.8 rating can be replaced with titanium while bolts with a 10.9 rating can sometimes be replaced with titanium depending on intended use. Any bolts with a rating over 10.9 rating should not be replaced with titanium.
1970 450 SCR

MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Re: Engine Mount Bolts

Postby MotoMike » Thu Sep 16, 2010 5:15 pm

Teckhardt wrote:If you decide to go with Ti...

http://www.mettec.com/category/m_ten_hex_flange_bolts/9

Per their site:

Titanium bolts can replace both grade 5 and grade 8 steel bolts which have minimum UTS requirements of 120,000 psi and 150,000 psi respectively. Metric bolts with an 8.8 rating can be replaced with titanium while bolts with a 10.9 rating can sometimes be replaced with titanium depending on intended use. Any bolts with a rating over 10.9 rating should not be replaced with titanium.


Thanks techardt
but I did not consider titamium at all. cost being the main concern. I was operating under the opinion that titanium was springy and therefore not really a good motor mount bolt. I can only imagine the cost of having custom made titanium bolts made. titanium parts are more at home with the carbon fibre set than a 41 year old thumper. I'll go old school.. hardened steel.

interesting that the blurb says good for grade 8 but for grade 10.9 maybe. I thought they were pretty much the same specs.

MotoMike
Posts: 487
Joined: Wed Aug 04, 2010 3:40 am

Re: Engine Mount Bolts

Postby MotoMike » Tue Sep 21, 2010 7:40 pm

still looking for opinions.

Sourceing these 10mm bolts in the longer lengths seems to be a bit of a problem. I see that some of the modern Ducatis have bolts that might fit the bill, but will have to get into their parts books and check the specs.

Sourcing SAE bolts in 3/8 grade 8 seems do-able from stock in some places.

regards,
Mike

Jon Pegler
Posts: 459
Joined: Sun May 16, 2010 6:19 pm

Re: Engine Mount Bolts

Postby Jon Pegler » Tue Sep 21, 2010 7:50 pm

Whilst not strictly correct, you could fit a stud with a nut and washer at each end.
It could get you out of trouble in the short term, until you find the genuine bolts.
A good source of studs in the right length would be a car dismantling yard.
VW bug head studs come in the right sort of lengths. Pre-1970 bugs use 10mm studs, later ones 8mm. The head studs come in about three different lengths, so take a tape measure with you if you go to get some.

Jon

Pete
Posts: 102
Joined: Sun Nov 01, 2009 1:00 am
Location: Walworth, NY

Re: Engine Mount Bolts

Postby Pete » Tue Sep 21, 2010 8:38 pm

MotoMike wrote:still looking for opinions.

Sourceing these 10mm bolts in the longer lengths seems to be a bit of a problem.

regards,
Mike


Not that I am really pushing McMaster Carr, but we buy a lot of stuff from them where I work. If it is available and not listed in their catalog, they can usually get it. They are very helpful if you give them a call.

Pete


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