600 ft GRP Rods

Brian, if one doesn't have time to check each rod bolt with a stretch gauge, what torque wrench would you recommend??

Do you recommend stretching them each time or just the first time? If only the first, what torque thereafter?

Thank you,
EDB

 

a very good friend of mine who runs a top alcky dragster in New Zealand had the same problem. a new set of GRP's let go on just a couple of runs. the hole was BIG!. the few that didnt bust seemed to have loosened the bolts.
Not assigning any blame here, just stating what was found...maybe the threads pulled causing the cap to loosen.

always one of those touchy subjects. Ive run billet rods for 40 passes with one set of bolt replacements and no issues....and I know guys who have had rods go on pass #1.

cheers
Dave

 

You can use this to check your calibration and adjust accordingly.

http://buy1.snapon.com/catalog/item...group_ID=20359&store=snapon-store&dir=catalog

Brandon Booher
NHRA TAD #323

 

I don't want to start too much junk, but we just went through a big load of crap recently with big name steel rods. (A few different US made companies.) The rod bolts would back out until the bearing would start to bite and K-boom. The rod would read like it was an oiling problem, but the other rods in the engine would be loose. I know two engine builders here that asked to get all of the engines back with these new rods in them. EVERY ONE had rod bolts backing out and losing their clamping force. They were pulling bolts out of the old thrown away rods to save these big dollar engines. Many engine builders have been round and round for the last year on this deal. Lots of top sportsman type engines. The verdict is a new alloy in an old standard part number fastener. I just hope that this is not what is happeneing with this mess.
One of the signals was the torque numbers did not match the corresponding stretch numbers.

 

I just put a rod in the vise and turned the bolt until something happened........The threads pulled out of the rod.

 

Thanks Brian for replying. Will is right too. We should never just trash someone's product. I have worked with GRP's for about 6 years. I never took Brian's advise to check the bolts with the stretch gauge. Once you do you will never not do it. A top #3 car owner showed us how to do it and considering how many bolts are produced there are varying results. He had impeccable notes on each rod and bolts. Remember rod companies don't build bolts.

I am laughing Randy. I thought I was the only crazy one with a & b's etc on rods. With different lengths and rod cycles one better keep track or it will get expensive.

 

you know, sometimes things just break, bad batch of metal...etc. we broke a brand new M300 mag drive shaft....no one could explain that one. things happen

 

hmmmmm I was talking about the guy that said he thought he put the cap on backwards the night before, Not trying to be a smart a$$ LIKE SOME PEOPLE. My point was If it had a number on Rod and cap facing towards pan rail It may not have happend. I was just trying to be nice about it. I have seen a ton of fuel teams stamp them. I like your idea on the length a,b,c

 

hmmmm....Didn't he say ..."The bolt will break before it pulls the threads in the rod. "

Sounds like someone owes you a few sets of good rods to make up for the damage!

 

use a go no go tool..and remember always back off the torque wrench whe you are done with it.Dave
also if you have time when you knock off the pan set the wrench at what you put the rod bolts in at and see it it will tigten before it clicks if it does pull the rods out and put a new set in..Dave

 

Alcohol Paul
The next thing I would check on your rods is to machine half way through the threads on this rod and look at the cross section of the thread profile. If it had fatigue or embeding on the loaded face of the thread you should see this under magnification. I would be glad to do this for you and provide magnified photo's. I know what it costs to break a rod so I will do everything I can to help you figure this out.

Brian Scollon
GRP Connecting Rods

 

rods

Nitro4100, I do stamp my rods. It was late, sweating, tired, bad lighting, hungry, etc.
I make no excuses. I should have loaded it up and done nothing. I've been building engines and racing for over 35 yrs. That was only the 2nd time that I lost a rod.

Glenn

 

I don't care what grade aluminum you use, a freshly and properly drill and tapped aluminum chunk of metal will still have their threads stripped out if you insert a hardened steel bolt and over-torque it.

And a go/no-go gage will only check the entry point of the threads and only checks the pitch diameter. You can have an internal thread with minor oversize to almost the pitch diameter and if the pitch diameter was ok, the thread gage would check ok, but, the threads would be substantially weaker because of the oversize minor.

You can also play "tricks" to make the threads check good with a go/no-go gage on threads that are out-of-tolerance for their class.

Also, threads by design based on size and class, have approximately 80% contact area between mating parts and that is with both parts being at nominal tolerance, in other words, 2 perfect parts.

 

Ok apart from the added weight and greater clearance needed , why don't rods have a press in stud and nut that can't pull out ?

 

If you don't mind added wieght and clearence then you could use a 5/8ths inch bolt and it would be cheaper and stronger.


R/G

 

5/8ths !! Hey only asking

 

The quickest and cheapest would be to use heli-coils or threaded-inserts.

I still think a reversed-shouldered insert would be the best.

 

Brian,
Parts are bagged, tagged and will be on the way to you Monday. Thanks in advance for your help.

Paul,

 

Glenn very understandable, It happens