typical breakage of a forged rocker?

[Astro]

Hi,

is this the typical breakage of a forged rocker? This one was a 1.3.

Best regards.

[mk1]

Yup, thats where they usually go if they are going to.

[Astro]

I have just been told to keep the hands away from these rebuild rocker arms. Either to look for original ones or to use pressed steel rocker arms.

[mk1]

I know of one supplier who has sold thousands of repro forged rockers with very few problems at all. I think the person who says simply steer clear is probably overstating the case a bit.

[Astro]

"This item is presently out of stock. See below for any alternative items."
Is this the same one? The problem seems to get ones are available and working!

[mk1]

Being honest I have not used any forged rockers for years so I have no idea as to the supply situation at the moment.

If you can't get them, & have to use "traditional" rockers, the old pressed steel ones are a good alternative IF you can find a decent set.

[Astro]

Yes, now I will get some reinforced pressed steel rocker arms. Otherwise such things could become expensive.

[12G940]

what is this rocker ? is it a repro ? looks more like a casting than a forging, a proper forged 'S' rocker will bend
between the pivet and the valve if it becomes coil bound and still it will not break.
I've seen brand new old stock genuine 'S' rockers on e bay this week somewhere if I find them I will come back
regards 12G940

[Astro]

Thank You! But if I will order them from eBay, how do I know that I will not get the same ones? These have been delivered from a big mini supplier.

[12G940]

pretty sure they were the real deal ,they were still in unopened Leyland packets. ask them what
number is on the beam section, if they come back with 12G1221 your almost there, if they say theres no number for sure there rubbish ,thats the best I can do for you, but they did have other genuine stuf as well,
didn't smell bad.

[Simon776]

here doesn't appear to be a number on the rockers in the picture and they look a bit lighter in colour compared to BMC ones.

[Toby]

http://www.ebay.co.uk/itm/220993854078

And the seller already has a bid on them, I didn't expect that to happen

[Ronnie]

I agree with Simon and 12G940, they dont look like S rockers and that break looks more like cast iron.

[12G940]

Hi Astro
If the rocker is cast,obviosly this is not what you expected when you purchased it, but even a cast rocker will need some encouragement to fail,
Check out your full lift isn't coil bound and also your top hat isn't coming into contact with your valve guide, I imagine you have a fair bit of lift there on that cam grind by the amount thats gone from the base circle judging by the excessive amount of pushrod ajustable ball pivet hanging out of the rocker.
There are a lot of things that need checking here as the geometry of the cam timing via the rocker movement as its all over the place, with the ajuster hanging out that far your 1.3 ratio is heading for 1.2. Could be many things, could be real bad design movement of those repro rockers, could be pedestal hight, and lots more, but you have to start somewhere, so start with the current movement before you put on some proper rockersn so they don't get damaged and then you can go from there.
Just of note I am not a Mini anorak, so don't know all the numbers, just a retired engineer, so I will give you what I know of the basics and you can confirm with others for any special tricks or reasons this dosn't aply to Mini ect
Best of luck 12G940

[36inter]

I have to agree with 12G940, thats a cast rocker, I am no metallurgist but I spent 33 years testing metallic materials for defects, forgings if they break do not usually look like that, but I have been known to be wrong

Pete

[almondgreen]

I think it would be fair to tell that the valve of the broken rocker was bent and made troubles before.
The question here is, why is the weak point the rocker and not the pushrod....

[Astro]

Thanks’ to almondgreen. It’s a bit more complicate. The car has been on a rolling test bed and the guy there sets the ignition much too early. The cylinder head gasket broke and water came into the first cylinder. We just installed a new head gasket for the head seemed to be all right. When starting the motor again, the first inlet valve got stuck and then a hit from the piston. We disassembled and installed new inlet valves and controlled the outlet valves. Everything seemed to be all right. I started the car and drove about two kilometres. Suddenly there was a noise. The rocker was broken but the pushrod still ok. This was why I asked how a broken forged rocker should look like. It was my impression that this one was not forged.

[12G940]

Almond Green is correct in that it is usual in this situation of restricted rocker movement we do expect the pushrods to buckle first, and then the rod is restricted by the tube in which it operates and if there is no more area for a reduction in the operation that is continuing something else has to give, this is normally the rocker between the pivot and the valve and a good quality forged rocker will pucker/bend on the beam. Almond Green makes a good point that the rocker was so poor that even the pushrod was subjected to very little stress before the rocker just plain broke.
Glad to see a bit more information, always a bit more to story, but I think this is now confirmed, the repro rocker was just not good enough
regards to Almond Green 12G940

[251 ENG]

They look like castings to me .

The flash line is very thin and even , just compare with the side of a con rod