ARP Bolts - torques

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1

Hello again,

I just need some advice on torquing ARP bolts on my K series build.

Having just bought some ARP flywheel bolts, what should the torque be? Is there any need for Loctite? Im guessing no as you torque to yield??

And…conrod bolts. Again ARP bolts on Farndon rods. Bolts are 3/8UNF, am I correct in thinking that I torque to 42-45 Ft/lbs?

None of the bolts came with lube (?) should these be torqued dry?

Thanks in advance

Ben.

2

I was only trying to find exactly the same thing very recently!

On the flywheel bolts I used a tiny amount of loctite 243 and torque to 115Nm/ 85lb/ft OR you can use moly grease and torque to 78Nm/ 58lb/ft. Torque and slacken each bolt a few times as below first too…

Rod bolts should definately be lubed. ARP lube is simply moly grease. Torque each bolt up to 25Nm (18-19lb/ft)and then slacken it off, repeat about 5 times (essential as it polishes threads to get more reliable readings) before doing the final torque of 25Nm+45 degree turn. This is actually in effect a slightly higher torque than 42-45lb/ft.

Hope that helps

3

Thanks for the info Azrael.

The torque figures that you gave, are these for ARP bolts or standard Rover fixings? I spoke to Farndon (they supplied the bolts as well you see) today and they told me just to torque the bolts with no angle?! Im confused!!!

Thanks once again


Ben.

4

Ben,

I totally understand your confusion, I got mixed messages from everywhere I tried too.

Utlimately ARP say that to get these bolts correctly tight they should be stretched by a specified amount. A stretch gauge is the most accurate way to do this, a torque plus an angle next best and using a torque wrench is the least accurate…

The 25Nm plus 45 degrees method just happens to be the same as standard rod bolts because 5/16unf (standard) and 3/8unf(ARP) have the same thread pitch and it works off the principle :-

  1. Torque the bolt to a lowish value to remove all slack
  2. The angle is then worked out from thread pitch so say if the pitch was 1mm and you turned the bolt 90 degrees it must stretch 0.25mm as there was no slack in the system etc.

Steven



See, now this is why no-one talks to me anymore…