R32 Gtr Broken Camshaft

[jonnyo]

Hey guys

Was getting my HKS camshafts that have done 5000klms in my mates r33 GTR yesterday installed in my 32 GTR when I got a phonecall saying that they had installed the inlet 256 8.7mm lift but while installing the exhaust 264 8.7mm lift it broke. Now they are saying that HKS camshafts are of poor quality and that this happens all the time and they are passing the buck to HKS.

What I want to know is this the case? are HKS camshafts poor quality and is it like the lottery- some snap and some dont? any help on this would be appreciated.

[RPMGTR]

All RB cams are easy to snap regardless of brand. A little care and attention when installing is all that is needed. Get your installer to replace the cam FOC, and I bet he will never snap another.....

[BHDave]

Tell the workshop to cough up.

If they can't install a cam shaft without snapping it then they are are obviously doing something wrong. You can also point out that someone obviously managed to install them correctly once before as they were in your mates car.

[mokompri]

what BHD said, just another pathetic workshop not taking responsibility

whats more common, workshops passing the buck, or HKS cams failing

[jonnyo]

Guys went to the workshop today and they are going to replace the broken cam with a new one.

Cheers for the replys on this.... hopefully should get some good power.. just for interest sake does anyone know how these cams inlet 256 8.7mm lift and exhaust 264 8.7mm lift will change the power? car has fc and 34 n1 turbos + injectors etc?

Edited November 23, 2006 by jonnyo

[rev210]

Easy to break the cams.

Even easier if your doing it on the cheap and didn't replace the cam retaining bolts/studs with new ones.

Hopefully you did replace them because that new cam/s may let go (along with the motor) later on thanks to a fatigued old bolt that breaks. You dont have much lift on those cams so you might be lucky. Then again.....

[MR331307]

From what i have learnt off all Serious RB Engine builders is

If you havent smashed an oil pump or Snapped a cam your not a serious rb motor builder

[mokompri]

From what i have learnt off all Serious RB Engine builders is

If you havent smashed an oil pump or Snapped a cam your not a serious rb motor builder

this sounds pretty ridiculous, so your saying unless you have broken a cam whilst installing them your not a serious engine builder ??

if the torqueing procedure and order isnt followed correctly sure they will break, but thats because your either being lazy or dont know what your doing, i dont see how this makes you better/smarter somehow ?!

with that sort of logic, im finding it hard to understand what exactly went wrong in this case...

Edited November 23, 2006 by mokompri

[rev210]

The cams are so long that they are very fragile when being torqued down.

I blame the nissan torque steps being too few. I didn't trust them when I first un-torqued and then retorqued mine the first time and I had no issues. I threw in 3 extra steps in between to be sure.

I think if you do enough of them (cam changes) you are likely to break some, especially when customers aren't willing to go for the extra expense of new bolts. Add to that big cams and beefy springs and it doesn't help. 90% of the time old bolts might work could be even higher as a percentage but, that still means you do enough and you get a few broken ones.

[MR331307]

The cams are so long that they are very fragile when being torqued down.

I blame the nissan torque steps being too few. I didn't trust them when I first un-torqued and then retorqued mine the first time and I had no issues. I threw in 3 extra steps in between to be sure.

I think if you do enough of them (cam changes) you are likely to break some, especially when customers aren't willing to go for the extra expense of new bolts. Add to that big cams and beefy springs and it doesn't help. 90% of the time old bolts might work could be even higher as a percentage but, that still means you do enough and you get a few broken ones.

Thats comming from hi octane

anyways

we made longer studs to help tension larger lift cams in straight

[blur]

That happened to my car. the cams i was about to put in looked almost brand new. they were installed but fortunatly they broke before the covers went back on. the crack in the metal was there for a while, oil that was to lube the cam had penetrated the crack quite some way through which makes me think they were damaged or broken already. got tomei poncams now, all good!

[rev210]

Hi MR331307,

Who are Hioctane? Do you mean the company over east? or some sort of mag?

I initially did the torque steps because I took the cams off without a manual, so I was carefull and used a bit of logic to guestimate the sequence, kind of easy to do though. Then a friend let me have a look at the manual he had before I put the new cams in and I just decided there needed a few more steps.

[mokompri]

The cams are so long that they are very fragile when being torqued down.

I blame the nissan torque steps being too few. I didn't trust them when I first un-torqued and then retorqued mine the first time and I had no issues. I threw in 3 extra steps in between to be sure.

I think if you do enough of them (cam changes) you are likely to break some, especially when customers aren't willing to go for the extra expense of new bolts. Add to that big cams and beefy springs and it doesn't help. 90% of the time old bolts might work could be even higher as a percentage but, that still means you do enough and you get a few broken ones.

lets stop for a second and see what your saying implies. "if you do enough cam changes you are likely to break some", now this begs the question... what about the ones that didnt break ?? why DIDNT they break ?

and so what seperated them, from the ones that broke ? if the problem is not with the installation, then it goes back to being the product, and i dont think a company like hks will have random quality control of their camshafts.

if nissans torqueing procedure isnt sufficient, then a "serious engine builder" should know better. either from experience (which the workshop in this topic claims to having), or knowledge.

and as for replacing new bolts, i dont see how this will affect breaking the cam, if the bolt is too fatigued/stretched to be reused, and is used, then it will snap/shear. it should not have any bearing on the breakage of the cam. i know this, because i snapped a bolt when i did my cam change

Edited November 24, 2006 by mokompri

[rev210]

Mokompri,

The world of mechanics is ruled by Murphys law as well as those physics ones.

One of the most common misconceptions about using a torque wrench to tighten bolts like these or on a head is that the torque reading on the wrench indicates how much load is on each bolt. The reading on the wrench only tells you how much twisting force is being applied on each bolt. The actual clamping load will be much, much higher, and will depend on the friction in the threads, the size, pitch and diameter of the treads, and the length of the bolt, temp (good to do it on a hot day but, not for the person) and things like how long the stupid cam is and the bending forces it goes through on the way to sitting nicely in there.

For example a stretched bolt might bottom out at a different height to a healthy bolt from and therefore can give you issue. Sometimes not right away but, maybe the next week or next month it goes or you get lucky and nothing happens for a year till you go racing.

These bolts are run of the mill units that acheive maximum clamp at thier yeild point which if exceeded has them deform to some extent, permanently. Unlike a TTY style of head bolt these don't spring back up to it's yield point as they deform. So if they have had some use you are best to ditch them. It also means even new ones can cause grief as the leverage along such a long stick of metal makes for a bigger margin for error.

So change those old bolts and cross your fingers.

Hope that sheds some light.

Then again maybe an engine builder or two would like to put thier hand up for a record number of RB cam changes without a breakage?

Edited November 24, 2006 by rev210

[mokompri]

physics i agree, but murphys law is philosophy - i dont think it belongs here. murphys law is something thats used when shit happens and the real problem cant be explained, but i believe theres a reason for everything.

friction on the threads should always be around the same, as your supposed to oil the bolts and the holes so that variation doesnt occur, and all those other variables stay the same anyways (size, pitch etc). the temperature variation you get in aus is probably around 20 degrees celcius through the year, hardly something that will have much affect in the process.

in my engine i had the snapped bolt removed, and replaced with a new one. the engine ran thousands of km's after that, then i sold the car. but anyways, with all that you have said it practically puts the cause of inconsistency here to murphys law, which doesnt really say much at all does it

[CRD]

physics i agree, but murphys law is philosophy - i dont think it belongs here. murphys law is something thats used when shit happens and the real problem cant be explained, but i believe theres a reason for everything.

friction on the threads should always be around the same, as your supposed to oil the bolts and the holes so that variation doesnt occur, and all those other variables stay the same anyways (size, pitch etc). the temperature variation you get in aus is probably around 20 degrees celcius through the year, hardly something that will have much affect in the process.

in my engine i had the snapped bolt removed, and replaced with a new one. the engine ran thousands of km's after that, then i sold the car. but anyways, with all that you have said it practically puts the cause of inconsistency here to murphys law, which doesnt really say much at all does it

Hey Guys,

Just for your info we have built over 1000 RB engines and have never had 1 breakage.

[rev210]

Hey Guys,

Just for your info we have built over 1000 RB engines and have never had 1 breakage.

Excellent!

Do you just follow the Nissan manual or do you take some other precautions?

[T04GTR]

thats what happens when you dont know what ya doing

you have to GRADULY wind down the bearing caps conmcentrating on the loaded areas. (lobes opening valves)

it should take about 10 mins max to do each one properly

[mokompri]

Hey Guys,

Just for your info we have built over 1000 RB engines and have never had 1 breakage.

now this is a more suitable attribute to someone thats a 'serious engine builder'

[BHDave]

hooray! (thats a lot of built rb's)