Torque Confusion

[hrosenthal]

I've been trying to figure this out since beginning the build.

At the beginning of the manual, FFR is great about telling the torque settings for every bolt.

But after the fist section, they don't make any mention of the torque settings.

At the end of the manual, there is a torque specifications chart, but I'm not sure if I'm using it correctly.

Right now I am bolting the steering rack to the frame.

As per the chart, I have a 1/2 inch bolt (Measured with calipers on the smooth section of the bolt close to the head) with 13 threads per inch (this is an estimate by hand counting the threads) - so the torque should be 75 Ft-lbs. I'm also assuming a zinc plated bolt in that it is magnetic.

Prior to beginning my build, I purchased a book "How to Build Cobra Car Kits" by D. Brian Smith as a supplement to the FFR manual, which says that the bolts should be torqued to 110 FT-lbs .

That seems like a very big discrepancy.

I'd like to know that I am doing my calculations correctly.

[Avalanche325]

Grade 5 is 75 ft-lbs, grade 8 is 110 ft-lbs.

Here is a quick reference chart that has both dry and wet. (It is a little scarey that the chart has "Torgue" at the top right). There are several fastener and engineering sites out there with the numbers, or the calculations if you are so inclined.

http://www.americanboltcorp.com/tech/techtorque.pdf

[hrosenthal]

Grade 5 is 75 ft-lbs, grade 8 is 110 ft-lbs.


How do I know the grade?

[CraigS]

Most of the FFR bolts are G5. The trick is the number of hash marks around the head of the bolt. The grade is two above the number of marks.
http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
BTW, look at bolts at HD and Lowes many of which have NO marks on them.I would use them on light duty house stuff only.
Also important in some of the suspension stuff is the material of the spacer sleeves. FFR has used aluminum for the coilover spacers, which, in my opinion, requires less torque on the bolts. Not sure if yours are al or steel.

[skullandbones]

One thing I like to do is find source that gives the torque reading for the application such as torquing your lug nuts or rocker arm bolts as the type of fastener is not always stamped on those items. I use Chiltons or Haynes to go to the actual application for that fastener and you can source it off the web if you don't want to buy one of those books. Of course, you will probably get torque specs with things like a new flywheel, clutch, and pressure plate. Mine is a Ram with very detailed instructions and specs. Lots of times they even go into step by step explanation on sequence, tightening details (e.g. torque to 50 then 60 and then 70 in a certaion pattern). So the devil is in the details. Usually, the number is on the head of the bolt or a series of dots that have a code that IDs the bolts grade. You're smart to get started learning the importance of these processes in your build. Good luck, WEK.

[hrosenthal]

Most of the FFR bolts are G5. The trick is the number of hash marks around the head of the bolt. The grade is two above the number of marks.
http://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
BTW, look at bolts at HD and Lowes many of which have NO marks on them.I would use them on light duty house stuff only.
Also important in some of the suspension stuff is the material of the spacer sleeves. FFR has used aluminum for the coilover spacers, which, in my opinion, requires less torque on the bolts. Not sure if yours are al or steel.

ok. 6 hash marks is grade 8. torque = 110.
Thanks. I never would have figured out the hash mark code.

I'm going to laminate the torque chart and hang it in my garage.

[hrosenthal]

One thing I like to do is find source that gives the torque reading for the application such as torquing your lug nuts or rocker arm bolts as the type of fastener is not always stamped on those items. I use Chiltons or Haynes to go to the actual application for that fastener and you can source it off the web if you don't want to buy one of those books. Of course, you will probably get torque specs with things like a new flywheel, clutch, and pressure plate. Mine is a Ram with very detailed instructions and specs. Lots of times they even go into step by step explanation on sequence, tightening details (e.g. torque to 50 then 60 and then 70 in a certaion pattern). So the devil is in the details. Usually, the number is on the head of the bolt or a series of dots that have a code that IDs the bolts grade. You're smart to get started learning the importance of these processes in your build. Good luck, WEK.

Thanks for the info.