600 ft GRP Rods

Friday night at Norwalk (Summit Motorsports Park)was a night I would like to soon forget. This was going to be our first race of the season seeing how IHRA screwed all the roots blower funny cars. Two weeks prior though we did make two shake down runs at Norwalk 300 ft each. Ran it to the the top of first gear shifted into second (8700 rpm) and shut it off, engine ran great. 4.04 in the 8th and shut it off at 3.24. Went home checked the bearings they looked new. Everything was new pistons rods etc. even had the L-19 bolt option. We warmed the car in the pits on Friday and gave it the standard 5000 to 5500 rpm rev no problem. Got called up, started the car, rolled forward, got the thumbs up to start the burn out, eased into the throttle and BANG! The car didn't go 15 feet and put number 1 & 2 rod out the bottom. Punched a hole in the block and pan, bent the cam, bent 4 valves, 2 guides, Ruined 3 pistons and 2 liners. This is the first time we've thrown a rod and it sucks. Does anyone have any insight on what could have caused this? I'm not bashing anyone but $1000.00 plus rods should last longer than 600 Feet.


Thanks,
Paul
330-328-6318

 

I was there friday night (without the car... read another post) and im not qualified to give you any answers but i know how you feel , my damage came from the Mid America event in pittsburg last year. we were two pits over from you.

Sorry to hear it was that bad...

 

Where did the rods break? If the bolts were out are there signs of the threads being pulled out of the rods? I'm assuming the bearings look good (other than likely being munched).? What do you torque them to hot/cold?

We've been running GRP's for years now, the only problem we've ever had was when our torque wrench went way out of calibration. Kicked the rods out of a few motors that way.

 

Nathan,
I think your assumption is correct that the threads pulled out. We pulled it apart in the pits and found a rod cap with one bolt still in it and the threads wrapped around it like a spring. We have a snap-on torque wrench and had it calibrated last year. We torque the rod bolts cold with oil to 90 ft lbs.

Alcoholic,
Sorry to hear about your deal. We ran that combo for two years, if you need help cal me.

 

Yeah sounds like the threads pulled if they're wrapped around the bolt like that. I'm no expert by any means, but we've had our share of parts breakage. Sounds like you do pretty well what we do. We torque ours to 90 cold as well. Inbetween rounds we dump the oil and remove the pan then let the top end guys do their thing first to give the rods as much of a chance as we can to cool a little, then we check the bearings and torque to 85.

Not sure what would cause the threads to pull then, might be worth getting the torque wrench checked again - costs a lot less than rods and all the other damage. Do you torque the rod bolts in stages?

 

Well, well, well. This sounds awfully familiar. We are running GRP rods and had no problems all last year and we ran mostly in the 6.70's and 6.80's. Things were good and we began to think we could actually walk on water. Over the winter we changed the pistons and had the rods and crank checked. Everything looked good.

So we go out to the first race of the year in Woodburn Oregon and ran a 6.79 and a 6.80. We went home and made a gear change from a 410 to a 398 to prevent engine problems and then the reverse happened. We Went to the next race, the season opener and on the first pass I windowed the block at about 3/4 track.

After we tore it a part we found that the crank broke and the no. 3 rod broke right in the middle. One of the bolts stayed in the rod the other one I believe was found in the bottom of the pan. All of the bearings other than no. 3 looked like new. The No. 3 bearing was mangled big time. The head had moderate damage as we have some bent valves and the top piece of the pan's frame rails are beyond repair.

I know what you mean about this sucking big time. It's hard enough racing this car with limited funds it's even worse when you have to build another motor too. I'd don't know how guys do it.

 

Sounds familer if bolts are in the bottom of pan or with alloy around threads but pulled out or semi pulled out of hole.
We have had issues with torques wrenches , and failures because of it.
Respectfully Snap on Torques wrenches are nice but the fall out of calibration readily. Have found the most reliable are the Warren and Brown and they stay calibrated for years unless dropped or used incorrectly.
i have a nice little Snap on Torque wrench that now reads over 15% out, that is a catastophic failure waiting to happen.

have your torque wrenches calibrated by labority approved or ISO endorsed calibration provider on a regular basis. minimum 12 months but if high use, every couple of months.

 

Does any one sell a calibrator for the torque wrench , that a racer can afford?

Increments 50#-70#-90# use black anti seize,don't get carried away, heat increases torque, lube keeps it right. Gene

 

does using the rod bolt stretch gauge take this out of the equation?
we have used grp forever and torque the rod to whatever the right stretch is ,as advised by brian at grp, regardless of what the torque wrentch says if we need to go over 100ft/pd we throw a new bolt in it.
Brian at GRP once said it is impossible to pull a thread the bolt (SHOULD) fail first

 

Here's a tip, dont let the guy thats always drinking beer 24/7 touch your car.

 

Eli , Paul and Dave are not your 24/7 drinkers..very meticulous in what they do...i've gone thew three motors in the early 80's before i found out my torque wrench was off 18 lbs...always crank them back down to zero when finished using...have not broke a motor since...

 

Don't get me wrong i didn't mean any one in particular, just any one that drinks to much, i saw what happened to Micky's & my Brothers car, when i was tuning it. one bolt was bent in half, wonder how THAT happened.

 

I don't make rods for a living, so I probably don't know what I'm talking about...but to me, aluminum versus steel bolt?

When we were having torque wrench problems we noticed the rod bolts coming out with resistance all the way with the speed handle. Run the bolt back in and out then it seemed fine. Should have seen that as a sign of the threads moving. Funny though, the bolts always look like brand new....

 

If the bottom end was serviced and the rods went back together there is no way they just "broke" on a burn out. Someone forgot to tighten a rod bolt. Plain and simple.

 

I have 5 wrenches that are constanly being rotated out for calibration but sometimes I have little faith in the results and dig out the old craftsman beam wrench for confirmation. I sure don't mind trying something else.

I had not heard of these before so I did a little google research. Pretty neat deal. So far I haven't found anyone in the states carrying these.
Do you know of a source?

Dave Koehler
http://www.koehlerinjection.com

 

Gene, are you suggesting to step torque rod bolts? I know I did that in the old days but since running MGP rods for about 5-6 years now, I've followed Michael Giannone's instruction. Torque rod bolts in one continues pull.

Blessings.........Ron Clevenger.

 

If you do it in increments, it lets the bolt cool between torquing, a little common sense.

 

Hears a tought Will is over there have him bring back 10 of them, anyone that wants one. send him the money.

 

I knew as soon as I hit the Submit button that this would a hot topic. Here's the bottom line. We are a two man operation on a half of a shoe string budget. But we are not afraid to spend money on good parts. We do everything ourselves, from mounting the body to building the engine. We can't afford to make a costly mistake. The two of us service the bottom end and have had a consistent routine for 15 years. I don't believe we left a bolt loose.

 

We've only lost one rod in 10 years of racing....and it broke on the burnout at KCIR 2007. Sent the rod particles to GRP for evaluation....and Brian thought that we had oiling problems...but with a dry sump System One pump and 20 quarts on board we have never seen any signs of bearing problems...our crew guys Larry & Randy do the bearings at the shop (not at the track) and have an anal routine of making a mark with a black Sharpie on each rod cap when they torque and then make another mark (complete the "X") when they run through all 8 and double check them...so NO WAY a rod bolt was left loose. I pulled the engine apart and noticed that the top part of the rod was still attached to piston and the pin hole was real egg shaped. I did not include the upper rod when I sent the bottom to GRP, so they did not have all of the evidence to make a good evaluation. My thought is that we pinched a ring on #5 the week before and I slapped a new piston in that hole....and probably did not notice that the wrist pin hole had a little slop in it....and it took several more events to beat the rod and bearing to death....all other rods and bearings were perfect...I do think that the bearing pin hole on #5 had a little bearing material smeared over the hole before the catastrophe, so that should have been a signal when we checked bearings that there was a problem....this is just my experience with a broken rod and I wish I knew for a fact what actually caused the failure...I check the pistons & pins every 10 runs now...