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Forged rockers

Posted: Wed Mar 13, 2019 9:47 am
by moggiegeek
Just building up forged rocker gear with new shaft.
Some rockers fine, no pitting on pad, a couple have deeper damage. Assuming they don't need rebushing
Is it possible to polish out slight damage without going through the case hardening?
And
If they're beyond saving can I mix new aftermarket forged rockers and old refurbished on same new shaft?

Re: Forged rockers

Posted: Wed Mar 13, 2019 11:57 am
by philthehill
The surface hardening is not that thick so care has to be taken if it is decided to clean them up with a slip stone. You do need to get the curve right as the end is not flat and if it ends up at the wrong radius it can put excess loading on the valve stem leading to rapid valve guide wear.

I would advise against mixing and matching the forged rockers they should all be the same and the new forged rockers may not give the correct mechanical ratio. There are several different types of forged rockers on the market.

The pressed steel rockers for normal and mild performance use are quite suitable.

Try and get the rockers central over the valve stem. Various sized shims are available from Mini Spare for the purpose of centralising the rocker over the valve.

If you have alloy rocker shaft pillars they should be ditched and the steel type fitted.

Make sure that No: 1 pillar has the oil transfer gallery through it as later shafts have the locking peg on No: 2 pillar.
Below is a set of rockers I have adjusted to sit central over the valve stem. The rocker shaft support pillars are forged steel and are of the type fitted to the Cooper S.
100_2636.JPG
100_2636.JPG (1.71 MiB) Viewed 1343 times

Re: Forged rockers

Posted: Fri Mar 15, 2019 9:57 pm
by moggiegeek
Been lucky enough to source used forged rocker arms from a fellow club member.
As the pads have been stoned I'm now wondering if restoring the case hardening is possible as a DIY activity!?
Also would it be necessary to press out the bearings before attempting heating and quenching?

Re: Forged rockers

Posted: Fri Mar 15, 2019 10:22 pm
by philthehill
I would not even attempt to harden the surface of the rocker pad as you could end up making the metal so brittle it ends with disastrous consequences.

If the stoning of the pad has not been seriously undertaken I would use as is.

If you do decide to harden the rocker surface pad the bush will need to be removed and refitted.

Use oil to cool the rocker after heating to the correct pre quench temp. There is plenty of information on the web.

Mark the bush/rocker so that the bush it is removed and refitted in exactly the same position.

You may find that you have to ream the bush afterwards.

Re: Forged rockers

Posted: Fri Mar 15, 2019 10:27 pm
by moggiegeek
I think I'll use as is. Good to decide on the basis of good advice. Thank you

Re: Forged rockers

Posted: Sun Mar 17, 2019 6:32 pm
by Declan_Burns
Phil,
That is a really good clear photo showing how it should be.
Regards
Declan

Re: Forged rockers

Posted: Sun Mar 17, 2019 10:33 pm
by oliver90owner
I would expect rockers to be case hardened, not through hardened. As long as they were cooled very slowly, they would not be brittle - and if a low carbon steel they would not harden with heating, anyway. There is always the chance that the material used might work harden in use.

Need to know the material composition in the first instance.

Re: Forged rockers

Posted: Fri Mar 22, 2019 9:32 pm
by moggiegeek
Decided to use rockers in current condition. They were all fitted with new bearings which need reaming in/honing.
First enquiry to machine shop produced an estimate of £30 plus VAT per rocker.
Does anyone have an engineering firm they could suggest - items easy to post?
I'm assuming that without a lathe plus expertise it's not a DIY option.

Re: Forged rockers

Posted: Fri Mar 22, 2019 9:32 pm
by moggiegeek
Decided to use rockers in current condition. They were all fitted with new bearings which need reaming in/honing.
First enquiry to machine shop produced an estimate of £30 plus VAT per rocker.
Does anyone have an engineering firm they could suggest - items easy to post?
I'm assuming that without a lathe plus expertise it's not a DIY option.

Re: Forged rockers

Posted: Fri Mar 22, 2019 9:44 pm
by les
You can buy new forged rockers for just over a tenner each, which apparently fit the shaft with no modification.

Re: Forged rockers

Posted: Fri Mar 22, 2019 11:09 pm
by Mark Wilson
I've been informed by a reliable source in a major supplier that at least some of the forged rockers now on sale, including the ones sold by his employers, are not really fit for purpose.