Jump to content
SAU Community

Recommended Posts

If you are going to do your timing belt, then make sure you replace the idler bolt. It has not really got anything to do with power levels. It only has to do with the bolt already having cracks. If in doubt, take your old bolt to an engineer for a crack test or xray and you will find it is fubar.

We are using 10.9 grade bolts as 12.9 is usually a cap head and I have seen these foul on the lower cover as they sit too proud.

A breakage of a new geniune bolt is not a common thing so don't everyone start getting paranoid, out of the approx 80 timing belts I have done on skylines, this is the only new one to have broken. This is why I am taking on the experiment because we have the resources at our disposal and it will also help to clarify some cryotreating questions we have at the same time.

Hopefully it goes in for treatment this weekend. We are waiting in them having enough other jobs to warrant such a small one. We have also found that no bolt manufacturers will give any gaurantee on a bolt for any reason, so if a new one breaks, you are on your own.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-4893722
Share on other sites

Does anyone know the bolt dimesions to see if this could be cross referenced to any arp stuff..like an L19 bolt (260,000 psi tensile strength which is 1792 Mpa).

Overkill yes..but for peace of mind i wouldnt mind the extra few $$.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-4894381
Share on other sites

we looked at upgrading to a better/harder material bolt but were a little worried the stronger bolt without any sort of flex may actually cause the cast iron block to fatigue and possibly crack the casting.

new genuine bolts and studs are the go in my opinion.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-4894667
Share on other sites

I agree with Paul. I have done many timeing belts on GTR's of all power levels useing new factory bolts and have never had a problem. I would say that the bolt breaking in this case is just pure bad luck. And as Dan stated this is not a common problem so lets not all get paranoid.

we looked at upgrading to a better/harder material bolt but were a little worried the stronger bolt without any sort of flex may actually cause the cast iron block to fatigue and possibly crack the casting.

new genuine bolts and studs are the go in my opinion.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-4894826
Share on other sites

  • 3 months later...
If you are going to do your timing belt, then make sure you replace the idler bolt. It has not really got anything to do with power levels. It only has to do with the bolt already having cracks. If in doubt, take your old bolt to an engineer for a crack test or xray and you will find it is fubar.

We are using 10.9 grade bolts as 12.9 is usually a cap head and I have seen these foul on the lower cover as they sit too proud.

A breakage of a new geniune bolt is not a common thing so don't everyone start getting paranoid, out of the approx 80 timing belts I have done on skylines, this is the only new one to have broken. This is why I am taking on the experiment because we have the resources at our disposal and it will also help to clarify some cryotreating questions we have at the same time.

Hopefully it goes in for treatment this weekend. We are waiting in them having enough other jobs to warrant such a small one. We have also found that no bolt manufacturers will give any gaurantee on a bolt for any reason, so if a new one breaks, you are on your own.

How are the grade 10.9 bolts going? You haven't found them coming loose at that tension? or do you put some loctite on them?

Also so I can source the bolt before disassembly, is the M10 bolt a 1.5mm pitch?

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-5091635
Share on other sites

this is the only new one to have broken

Come on Dan I know of another one that caused a great deal of shite because I bought a turbo off the guy and because I am a friend he dicked me around no end. If I remember rightly an investigation was carried out and the bolt was found to be faulty.

A button head cap bolt is lower profile than a normal bolt and wont fowl.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-5098189
Share on other sites

Come on Dan I know of another one that caused a great deal of shite because I bought a turbo off the guy and because I am a friend he dicked me around no end. If I remember rightly an investigation was carried out and the bolt was found to be faulty.

A button head cap bolt is lower profile than a normal bolt and wont fowl.

Not sure what that means Terry but no, it was not a new bolt.

I was instructed by that customer to not replace the bearings...only the belt. The idler bolt was never touched and broke 3000km later. That was a factory bolt and yes it was tested and found to have multiple fractures throughout.

I have all of these grade 8.8 bolts here ready to send off for MPI, just waiting for the oportunity.

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-5099304
Share on other sites

How are the grade 10.9 bolts going? You haven't found them coming loose at that tension? or do you put some loctite on them?

Also so I can source the bolt before disassembly, is the M10 bolt a 1.5mm pitch?

You need an M10 x 1.5 x 70mm bolt.

As stated above, no problems with the grade 10 bolts being used. Cap heads sit proud and can touch the timing cover so stay away from the grade 12 bolts if you can. There is no need to go that high anyway.

Make sure the washer goes back under them

Link to comment
https://www.sau.com.au/forums/topic/290065-bolt/page/2/#findComment-5099614
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I swear at my GKTech ones every time I have to take them apart and replace a spherical. But I wouldn't swap them for anything else. They absolutely slay every other option, at least in terms of how they actually work. You sure you don't want to live with bearings? I mean, they don't have "ball bearings". They are rod ends and sphericals throughout. Tough as nuts, even though I have found more than one way to wear them out.
    • From when I was looking at getting the 86 engineered for the turbo, the joint said to put in a few euro 5 or 6 cats, then tune the car on a nice clean E85 tune When I was looking at a turbo for the MX5, it was basically the same thing, a couple of cats and a nice clean tune Although, it will depend on the year of the Jeep IRT emmisions standards required, and what mods are done, especially if it has a newer engine installed that requires a higher Euro
    • Yeah - but it's not actually that easy. There are limits for HC, CO, NOx and particulates. Particulates shouldn't be a concern in any petrol engine unless trying to comply to the very latest Euro standard. But getting a tune right so that all the others stay within limits AT THE SAME TIME is not a trivial exercise. You couldn't possibly get it right by just guessing at the tuner's dyno, unless he had a 4 gas analyser up the pipe, which is not often the case these days. It used to be. Every decent shop that did "tune ups" (as opposed to tuning) would have a 4 gas analsyer. Perhaps there's still quite a few of them around these days. But most "tuners" are only watching O2 and power readings.
    • Slight segway but the most expensive part of the whole thing which I would have thought would only be required for an engine size/type swap, not a VIV test, is emissions testing.  That's when you get into the big bucks.  I can't remember the exact price now but I got quotes for the GT-R based on swapping to RB30 (not that anyone bothers doing it legally anymore...) and it was around $4500 just for that alone.  The guy that does them manipulates the tune on the vehicle to make sure it passes.  The cheaper option is to book into Kangan Batman Tafe (I think that's where it was) and hire their tester.  Allegedly you're not allowed in there with the car though so not in a position to tweak anything to make sure the vehicle passes.  I'm sure in this day and age of ultra tuneable ECU's you could get the tuner to program a special efficiency (clean) tune that emits the lowest amount of particulates possible that would pass the test.  It might only make 50kW's but as long as it passed who cares!
    • I'm sure he has left signs, or, he is looking down, laughing That's my cunning plan for when I leave, lots of half finished projects, with no rhyme or reason of where I was actually up to, just to keep everyone on their toes
×
×
  • Create New...