I'm confused exactly what the procedure on installing rod bolts useing a stretch guage. Like lets says bolts have a .005-.007 stretch /45 lbs of torque.Do you use a torque wrench to tighten them to 45lbs than use the guage and stretch them ? Or do you just barely tighten the bolts like hand tight than just stretch them to 007.

 

Stretch them to the specified value. Its more accurate then torquing and thus provides more consistent results/clearances.

 

so just put them on hand tight and than stretch them

 

Correct. Obviously you would need to put them on hand tight, install the stretch gauge, and then stretch them... but you get the idea!

 

I measure the free length first, then torque the bolt to whatever the manufacturer recommends, then check to see how much it stretched from that torque being applied to the bolt. You don't want to torque it then stretch it or else you'll ruin the bolts. If it's not enough torque, I'll break the bolts loose and repeat the whole procedure again, except I'll go up maybe 5-10ft-lbs to see what that stretches the bolt to. Whatever torque value works the best is what I use for assembly for those rods from there on out.

 

Bolt stretch is better but isnt nessesary. generally on a new set of connecting rods you want to torque and then retorque two more times. meaning do it once then loosen do it again and loosen and do it a third time. From my experience this gets you pretty close to bolt stretch specs, i never tighten more than manufacture specs on any of the times. This method has always worked for me but everyone has their own little things and tricks

 

No

even with new bolts, the stretch is different. You do check the stretch because not every bolt is made the same.

 

It just seems to me that If i torqued it to 45ft/lbs it just so much more tighter you putting more effort into it, Than if you snug the bolts up by hand and than used a box wrench and strtech it to 005 or what ever the specs are. Is this true if you just snug up the bolts with your hand/ rachet than stretch the bolts will it be tight enought.

 

well rod bolts arent supposed to be super tight, there are alot of forces at work trying to pull those end caps off lol.

Turbogixxer i dont dissagree with you but ive NEVER dont bolt stretch on my rod bolts and ive never had a problem

 

No.

The recommended torque usually puts you within the range of bolt stretch required for that bolt where checking the amount of stretch isn't required, but it is still a good idea. I've literally checked dozens of set of rods and I've never seen a new bolt stretch anymore than maybe .0001" more than the others of the same set, and I have never seen the recommended torque value stretch a bolt too much or too little with the correct lube.

If you're talking used bolts, then yes, I think it is absolutely required.

 

The tensile strength better be damn near perfectly matched in all the bolts. This is not 1958, the bolts are very consistent. if your getting different numbers you have problems with lube, dirt, thread issues etc.

 

Talk to a rod manufacture. They give you the rod stretch BEFORE the torque spec. I am sure you know more then them.

So, You say it is a good idea, then say only for used ones? Are you high?

you better tell honda that they were in 1958 with they did the rod stretch on the p73 rods.


Everyone of you are ASSuming the bolt was machined correctly. It takes 10 mins to check the stretch. You are just being lazy.

 

Don't be stupid. I said it's a good idea to do it with new bolts, but required with used bolts.

Before you go calling people lazy, how many bolts have you actually torqued and checked with a stretch gauge? Actually, what do you use to check bearing clearances, a mic and dial bore gauge or plastigage?

Like I said, I have torqued dozens of sets of rods and never have I seen one stretch more than the other. It's not a bad idea to use it, but in my experience, it isn't required.