Re: [DML] Modified Trailing Arms For 1/2" Bolts

["content22207" <brobertson@xxxxxxxxxxxx>]

I am fully aware that TAB torque values are quite low. They have to be -- pivot tubes in the trailing arms themselves are only made from cheap Grade 2 steel!

Toby Peterson calculated his OEM bolts to have 103,000 lbs yield strength: http://autos.groups.yahoo.com/group/dmcnews/message/21114

I haven't been able to find Barnes' yield strength online. Tensile strength is 180,000-200,000 lbs, which should be at least 160,000 lbs yield strength: http://catalogs.barnesdistribution.com/WebProject.asp?CodeId=7.5.1.4&BookCode=bar&from=2#
Bowmalloys get glowing reviews in the rock crawler and racing forums. I am familiar with them from my railroading days as Lawson's perennial competitor (Tru Torq, which was advertised as a more affordable alternative, not a stronger alternative).

Lawson has upgraded their Tru Torq line to now include Supertanium, advertised with 162,000 lbs yield strength (180,000-200,000 lbs tensile strength): http://www.lawsonproducts.com/webimages/vert/Fastener-Torque-Book.pdf

Fastenal certifies their 1/2" Grade 9's to be 159,500 lbs yield strength: http://www.fastenal.com/content/product_specifications/HCS.GR9.YZ.pdf

My local Lawson rep is long gone (along with all our manufacturing). I am still trying to get an online account set up to determine pricing and availability. Same with Barnes. My local Fastenal store can order in two Grade 9's no problem.

Bill Robertson
#5939


--- In dmcnews@xxxxxxxxxxxxxxx, "Martin Gutkowski" <martin@...> wrote:
>
> Tensile strength is only part of the story, you have to be careful with ductility, aka "brittleness" and in general with steel the higher the tensile strength, the more brittle it becomes. A suspension component should have a degree of ductility, but not to the point of fatigue or elastic limit. The torque spec for the TABs is far lower than would normally be applied to such a bolt.
> 
> Martin
> 
> ------Original Message------
> From: content22207
> Sender: dmcnews@xxxxxxxxxxxxxxx
> To: dmcnews@xxxxxxxxxxxxxxx
> ReplyTo: dmcnews@xxxxxxxxxxxxxxx
> Subject: Re: [DML] Modified Trailing Arms For 1/2" Bolts
> Sent: 7 Feb 2012 05:12
> 
> You are absolutely correct -- both trailing arms are currently off my car in the process of being sanded down and repainted (in fact the entire rear suspension is currently off the car for sanding and painting).
> 
> If I use Grade 9's to reattach my trailing arms, they will be 3.5% stronger than the Grade 12.9's you sell (and less expensive). If I use Bowmalloy's to reattach my trailing arms, they will be up to 15% stronger than the Grade 12.9's you sell, although probably similar in price (Bowmalloys are up to 200,000 lbs tensile strength, average 190,000 lbs, and Made in USA as always).
> 
> Trivia: rear suspension uses 1/2-20 bolts for all pivoting parts, not metric (trailing arm bolts and bolts that hold the rear hubs to them are 12mm).
> 
> Bill Robertson
> #5939
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, Martin Gutkowski <martin@> wrote:
> >
> > Well this one slipped the net....
> > 
> > Surely to drill out the trailing arm, you have to remove it from the 
> > car? That means disconnecting the brake hoses and reconnecting and 
> > bleeding afterwards, and the rest. It's a lot of effort to go to in 
> > order to save not a lot of money.
> > 
> > (advert) don't forget I stock geomet coated 12.9's made in the correct 
> > M12 hex-head just like the originals, $49/pair shipped to North America. 
> > (/advert)
> > 
> > Martin
> > 
> > On 31/01/2012 18:15, content22207 wrote:
> > > This should definitely cause some wailing&  gnashing of teeth:
> > >
> > > I just modified #2508's trailing arms and bushings for 1/2" diameter bolts (removed slightly more than 1/64" of material). Big snub washers have to be enlarged as well. Stock shims slip right over a 1/2" bolt no problem, as do the serrated lock washers.
> > >
> > > 1/2" bolts open many more possibilities than do 12mm. Bare minimum I will install Grade 9's (3.5% stronger than Grade 12.9, 20% stronger than OEM). I also am going to try to find fractional Inconel 718's (same material as Toby's bolts). Whatever gets installed will have proper hex heads rather than socket heads (Grade 9 heads are much taller than standard heads, about the same size as a nut). It's easier to find zinc or cadmium plated 1/2" bolts in TAB lengths than 12mm. And they're less expensive too (TAB length Grade 9's are about $7 per bolt).
> > >
> > > Bill Robertson
> > > #5939
> > >
> > >
> >
> 
> 
> 
> 
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> 
> 
> 
> Sent from my BlackBerry®
>




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