What Bolts to use?

Its Art · **Joined:** Sat Jan 23, 2010 11:52 pm **Posts:** 329

Hi -

I broke-off or sawed-off most of the bolts in my front and rear suspension. Putting the front together the last few nights I've been using what I have, but have a sneaking suspicion I should be using grade-8 bolts for the ball-joints. I can't tell by what is written on the few remaining ones I have. I got all new H-T bolts for the back.

Same question for the drive-shaft.

Sure feels nice to put all those shiny pieces back on the sandblasted and undercoated car. I found my camera too - pics coming-up.

James

Volvord · **Posted:** Sun Apr 18, 2010 6:33 am

YES James, all suspension should be grade 8.
Don't cut corners and use a lesser grade, you don't want a suspension failure while driving.

CANCER MAN · **Joined:** Tue Apr 22, 2008 5:43 am **Posts:** 387

I would say grade 10 for suspension.Especially ball joints.

Tha VZA · **Posted:** Sun Apr 18, 2010 1:30 pm

seriously though you can get grade 10? where's this? all I have ever seen are Grade 8 or like L7M codes, which is sour (H2S) service stuff hardly for vehicles.

Gasbrick · **Posted:** Sun Apr 18, 2010 5:36 pm

I suspect that grade 10 was actually for metric grade 10.9 which is pretty much equivalent to imperial grade 8.

RT

Volvord · **Posted:** Sun Apr 18, 2010 6:50 pm

The bolt grade system goes from Grade 1 to Grade 8, that is not to say there are not bolts stronger than grade 8, what you are looking for is a bolt with high strength but not too brittle.

Ugly Duck · **Posted:** Mon Apr 19, 2010 7:48 am

During a discussion I had once with an engineer friend, he told me that at his school (Concordia, where he went through mechanical engineering, participated in Formula SAE, etc) he was instructed to only use grade 5 on suspension bits. According to the prof involved, grade 8 was too brittle.

Not sure I buy it, but whatever. What the hell do profs know anyway? :wink:

woodenshoes · **Posted:** Mon Apr 19, 2010 8:47 am

Ugly Duck wrote:

What the hell do profs know anyway? :wink:

Wait for it....

Ugly Duck · **Posted:** Mon Apr 19, 2010 1:05 pm

Tongue firmly planted in cheek, Jim.

woodenshoes · **Posted:** Mon Apr 19, 2010 1:36 pm

Ugly Duck wrote:

Tongue firmly planted in cheek, Jim.

Oh I know, just trying to build the anticipation. :mrgreen:

Gasbrick · **Posted:** Mon Apr 19, 2010 5:25 pm

Ugly Duck wrote:

During a discussion I had once with an engineer friend, he told me that at his school (Concordia, where he went through mechanical engineering, participated in Formula SAE, etc) he was instructed to only use grade 5 on suspension bits. According to the prof involved, grade 8 was too brittle.

Not sure I buy it, but whatever. What the hell do profs know anyway? :wink:

Not sure either, maybe they had really thin wall bushings and wanted the bolts to yield before crushing the bushings? Maybe they were "shear bolts" to protect more expensive components??

Me thinks Mr. Prof may have been confused...

RT

rockmonton · **Posted:** Mon Apr 19, 2010 6:50 pm

concordia....

Its Art · **Joined:** Sat Jan 23, 2010 11:52 pm **Posts:** 329

I went with Grade 8 bolts. Of course you can make something that is hard but not brittle. Yeah, or shear-pins/bolts, that are deliberately brittle.

What Bolts to use?

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