Cam cap bolts stretching
#1
Cam cap bolts stretching
Has anybody noticed an issue with the M8 cam cap bolts stretching? Specifically I'm talking about the 95701-08050-00 bolt (M8x1.25x50). I'm torquing them to the proper spec of 20ft-lbs and in the proper order from center bolt outward. I've replaced several new Honda bolts. I find the older bolts from an old head don't have this problem. Anybody else?
These bolts. The older black finish bolts dont have this problem. The new bolts have the clear zinc finish. They suck.
These bolts. The older black finish bolts dont have this problem. The new bolts have the clear zinc finish. They suck.
#2
Re: Cam cap bolts stretching
Interesting info. Worth noting that as far as hardware goes black coating is normally a hardened or grade 8 bolt and gold zinc coated are not hardened. This may not be the case here but it sounds like it may be.
#4
#7
Re: Cam cap bolts stretching
I knew someone would ask that. And yes I've had mine calibrated.
But most importantly, I'm not twisting off the tiny M6 bolts which are torqued to 7.2 ft-lbs.
Im only having issues with this specific bolt, repeatedly, and its only the new version of the bolt.
But most importantly, I'm not twisting off the tiny M6 bolts which are torqued to 7.2 ft-lbs.
Im only having issues with this specific bolt, repeatedly, and its only the new version of the bolt.
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#8
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Re: Cam cap bolts stretching
also muckman
honda might have changed part supplier. not sure what year your teg is but mine came from japan originally (1995) so the part supplier was most likely from that region. for a cost saving they most likely went with a US supplier for that part, so it may not be the 100% copy.
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Re: Cam cap bolts stretching
Hi Muckman,
Please check your torque data seems very high torque for 8mm bolts. I would expect the torque to be around 8Nm, or 6lbs/ft, or 5.8ft/lbs
Regards,
Kev
Please check your torque data seems very high torque for 8mm bolts. I would expect the torque to be around 8Nm, or 6lbs/ft, or 5.8ft/lbs
Regards,
Kev
#13
Honda-Tech Member
Re: Cam cap bolts stretching
Not sure if this makes a difference, as its only 1 ft-lb, but the H22 manual says 19 ft-lbs on the exact same bolt. I have noticed the bolts stretch on higher lift cams. I have not seen it on stock cams.
#16
Re: Cam cap bolts stretching
Kev - the manual states 28N.m or 20Ft-lbf-ft
Tepid - Im glad Im not alone, I'm wondering if its my higher than stock lift cams putting extra stress on the bolts. It would make sense...
JDogg - Long time no talk, Is that what you torque them too? Im shocked 20 would be so close to the maximum yield of the bolt. I think the tensile strength has decreased from the older black versions.
Tepid - Im glad Im not alone, I'm wondering if its my higher than stock lift cams putting extra stress on the bolts. It would make sense...
JDogg - Long time no talk, Is that what you torque them too? Im shocked 20 would be so close to the maximum yield of the bolt. I think the tensile strength has decreased from the older black versions.
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Re: Cam cap bolts stretching
wouldnt be surprised though if honda did switch suppliers. muckman, whats the lift on your cams?
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Re: Cam cap bolts stretching
I had the same problem about 3 or 4 years ago. I tried them and didn't like them so I pulled some older ones with the black coating from the old head.
The new ones are just sitting in a bag somewhere unused.
The new ones are just sitting in a bag somewhere unused.
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Re: Cam cap bolts stretching
Same I noticed this when i was running my pro 2 cams. just slightly. I hate these bolts. I've managed to brake 2 in the head. luckily for me, my engine builder is my neighbor.
#23
Honda-Tech Member
Re: Cam cap bolts stretching
Do you lube the bolts with oil or installs them dry? Also, I don't believe the marking on the bolt indicates a grade 10. Oem bolts tend to have strange markings that I don't believe correlate to the tensile strength. The hardware store stuff that is usually not JIS will have metric standard 8.8 or 10.9.
#24
Re: Cam cap bolts stretching
Runnerdown - I put a couple drops of motor oil on the threads. If that's true about not being a grade 10 then I might just get a real 10.9 bolt and be done with it.
eg6islife - I can always feel the bolts that are stretching. They are the ones that take more torque wrench angle than the others. I pull it out and you can feel the threads are skinny in the middle. Fortunately I haven't broken one yet.
eg6islife - I can always feel the bolts that are stretching. They are the ones that take more torque wrench angle than the others. I pull it out and you can feel the threads are skinny in the middle. Fortunately I haven't broken one yet.
#25
Re: Cam cap bolts stretching
Wow! That is an amazing observation. I am in the middle of a build right now and after reading this thread alone I will begin doing some research on the possability of studs for these bolts. Thank you very much for sharing your find and I'm sorry to here about your last motor.