Went to hardware store and bought grade 8 bolts to bolt power steering box to frame on 73 cutlass, after driving short time, I found one bolt broke! Went to local dealer, the parts guy told me, I could not use grade 8, bolt needs to stretch under load! And they can not get them. Has anyone else had this happen? Is this true? Were do I order right bolts for this , need 3 one is shorter then other.

 

Hi,
I just dismantled a '71 Cutlass shell & do have the bolts from that steering box to frame. I don't know if they are the same though? I guess I could measure them.
Scott

 

Scott, are 73 PS bolts the same as from 68-72?

 

I'm not sure, but from cars I have taken apart over the years, I think that no matter the model, they are darned near ALL the same.

If they're too long or too short, he can always send them back.

- Eric

 

Sorry, that's B.S. ALL bolts stretch under load. Lower grade bolts will NOT carry more load than a Grade 8 bolt. The Grade 5 bolts may be more ductile, but they will still break BEFORE the Grade 8 bolt starts to yield. I've had this argument on many automotive boards. Suffice to say that people who say otherwise are NOT mechanical engineers.

The parts guy may be talking about torque-to-yield bolts, which are used on new cars. Your 73 does NOT use that style of bolt and it is not necessary for your application. I've used hardware store grade 8 bolts on an Olds steering box with no issues whatsoever. A broken bolt could be due to a counterfeit bolt (sadly, more common these days with off-shore sourced fasteners) or a damaged bolt (nicked or cracked) or an improperly torqued bolt or a box that isn't seated properly on the frame due to rust or debris.

 

Joe. I'm with you. I thought the parts guy was nuts, but thought I would throw it out there, before I said he was. I'm just going to replace it with another grade8, I didn't use a torque wrench the last time, this time I will, and I will check the other two. As a side note, I didn't know the steering box had any movement once it's tight to the frame.

 

Um, I think we have a winner here...

The box isn't supposed to move on the frame, but the reality is that all structures flex somewhat under load.

 

Aw, c'mon, Joe.

I've put several of those on over the years, starting when I was 18, and I never used a torque wrench and I never had a problem.
I just always made them "REELYFRICKINTIGHT" and they worked out fine.

- Eric

 

X to the 10th order what Joe said. You likely purchased chineasium offshore junk fasteners, which is the only thing available to the general public these sad days. Even Fastenal is 99.9% china! Anything with a critical application, such as a steering box to frame bolt, has had some engineering behind it for safety and engineering compliance.
If you cant find good used fasteners look to ARP or a steering box vendor for guidance.

 

Tractor Supply sells grade 8 by the pound. I dont know where their made but they look good!

 

Stever, unfortunately I can almost guarantee China. Walk around the store and try to find something not offshore. Maybe the sodas in the pop machine?
T.S. has sold-out just like all the other big and small box chain and most other stores. You have to ferret out the good stuff...the rant
The help...Generally the aftermarket (higher end) will have USA ANSI/ISO cert fasteners. Why because they don't want the scourge lawyers gnawing at their heels.
Try Flaming River, AGR, Red Head etc...The Googler is your friend here.