Hey all,

Since the witer hit my part of the world a long time ago and my car is stored I decided to start my winter project. I was about to put my new shiny, sexy rollbar when I realized that I do not know how my to torque the nuts on it. So please someone must know a good ballpark that will be good to stay there and not too much to break the bolts tightening it....

Thanks in advance!!

<-- Rado, who guesses about 35-50 ft/lbs.....

 

There are several charts available that give the correct torque specs for nuts and bolts. The value will vary by grade and size. Do a search and the data will be there.

 

funny, i was thinkin the same thing when i installed my bolt in.

 

and should the bolts need to be re-tourqed after some amount of time? My autopower came with unknown bolts and were replaced with grade 8.

 

Probably not a completely silly idea to check them at the beginning of each season. One hint - put them in so the nuts are inside the car. (The nuts holding the cage in, Beevis.) This way, they won't be all rusty and grungy if/when you need to bolt-check them or remove the cage after you knock a corner off of your current tub. I have also seen rollcage floor bolts snag on curbs and do nasty stuff, if the poke down very far.

As far as quality, I would choose a GOOD quality Gr5 bolt over a Home Depot Gr8 any day. I was spoiled when I lived in Seattle and could go to Boeing surplus for real hardware but a lot of the Gr8 stuff that is readily available is crrrrap. Any bolt in a racing car should bend LONG before it breaks and much of the Chinese (et al.) hardware out there is Gr8 hard but brittle enough to snap before bending.

Check if I'm lying. Buy one of those Grade "8" bad boyz and do a quick-n-nasty engineering test on it - put one end in a big vise and whack it with a big hammer. The same goes for metric hardware that you use to bolt bits on your car. OEM Honda and VW hardware is pretty damned good - do a junkyard run for stock rather than buying out of the little baggies at Lowes.

Kirk

 

I thought that was part of the difference between grade - the higher the grade, the stronger it is in pull strength, but the weaker in ability to withstand shearing forces. Am I wrong?

 

In theory, you are right, but there are two issues - the load at which the bolt fails and HOW it fails. A commercial Gr8 bolt will carry a greater load than its Gr5 cousin but they may be brittle - snapping before they bend or elongate. Have you ever seen a stretched bolt, to the point that you can see it "waisted" - narrowed where it failed and longer than it started? I have, and it is really reassuring to know that when it did reach its yield point, it held the part on (a VW CV joint in this particular case.)

Kirk

 

Autopower sends the proper bolts with the kit right? So you should be able to just use what they send and not worry about it. I think you should call Autopower and find out the torque specs.

 

I've always heard it called necking but it's all semantics anyhow. And yes, when the bolt finally let's go in a tensile test, prepare to have the bejesus scared out of you. Anyways, back to the topic at hand...

I did a search on Yahoo for "bolt grade metric torque specs" and came up with these links:

http://dodgeram.org/tech/specs/bolts/M_bolts.html
http://www.geocities.com/MotorCity/G...q_spec_met.htm
http://www.spanishtrailrovers.com/Te...olt_torque.pdf


I also found this which looks to be a really cool link for engineers, and racers alike:
http://mdmetric.com/techindex.htm

 

Also, be sure to double nut and locktite everything.

 

Thanks guys for everything! I think i found what I was looking for!