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.

 

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.

 

They all say grade 10 on the heads as you can see (new and old). The 4 studs in the middle that the the spark plug cover screws into are also black - even the new ones. No problem with those as well.

 

Weirdest problems ever...

I don't see how you keep your sanity and wits about you to keep doing this much rebuilding

 

Im probably the only person who buys new oem bolts and notices a quality difference. lol

 

might seem dum
but is your torque wrench accurate at low spec's as most arnt
unless they are for a lower scale

 

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.

 

co-sign

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.

 

Thats what Im thinking too. I'm sourcing original bolts from a 95, 99 and a 2000 GSR head which have the black version.

 

This is the type of insight that only pro builders can offer. Thank you.

 

You're not alone. With the cams I run I notice stretch too. The bolts suck.

At least you're not pulling up threads from the head.

 

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

 

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.

 

I think I have a full set of the older black cam cap bolts if anyone needs them, willing to ship.

 

torque them to 16-18.. 20 will stretch the crap out of them every time

 

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.

 

yeah, i dont do 20.. you'll stretch the crap out the bolt or pull the threads out of the head...

 

interesting. ive been doing those bolts in 2 steps (12 then 20) for years. kinda got me worried a bit.

wouldnt be surprised though if honda did switch suppliers. muckman, whats the lift on your cams?

 

I think it might be more about valve spring pushing back than just lift.
GSC T1 cams with 12mm in /11.5mm exh peak lift (.472/.453")
Supertech H100DR with 85lbs seat press.

 

I just installed Gsc t1 cams with the Gsc valve springs and had no problems all torqued to 20 ft pounds

 

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.

 

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.

 

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.

 

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.

 

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.