My 1990 R80GS was very "tappety" on the right hand cylinder. Removed the rocker arm assemblies for inspection, (rocker arm end float was ok, shimmed to spec. Needle rollers ok too) but the rocker arm section which rubs on the valve tip was unfortunately quite pitted, on both inlet and exhaust. So, just wondered if any one knows of an engineering shop (preferably near Nottingham) who can re-profile and re-harden (if necessary) these rocker arms? Alternative course of action is to contact our usual suppliers and buy a pair of new arms, of course - but they're not cheap!! Just out of interest, I swapped the offending rockers with a different pair, which cured the problem completely - but I need those on the donor bike! PM me if you have any recommendations. Many thanks!
Re-profiling (and re-hardening) rocker arm?
- Thread starter Rothgs80
- Start date
Reprofiled mine , think they are through hardened.
Made a little jig up to hold them and hand ground the surface carefully.
That was 3 k miles ago , still good.
Im sure there is a video on you tube that shows you how to do it.
Made a little jig up to hold them and hand ground the surface carefully.
That was 3 k miles ago , still good.
Im sure there is a video on you tube that shows you how to do it.
Normally the rocker face will be surface hardened. Time for some new rocker arms I'm afraid.
There’s a vid online showing a guy reprofiling his using a bench grinder. He’s made up a jig that holds the arm square to the side of the wheel but still allows him
To rotate it to keep the curved profile. No mention of needing to reharden. No link I’m afraid but I found it with a simple google search.
To rotate it to keep the curved profile. No mention of needing to reharden. No link I’m afraid but I found it with a simple google search.
Thanks for the replies so far. I'm chasing up one lead - a guy who re-profiles rockers for Triumph race engines, but will have to see if the airhead rocker can be done in his workshop. I'll need to discuss the hardening issue as well, although it looks as though the ends of the rockers are heat treated right through, judging by the heat discolouration. This could, of course, cost as much as a new rocker though, so may well end up contacting the usual UK suppliers!
The rockers are case hardened which is only a surface treatment.
Think the hardness depth is quite deep.
Mine have done 3k miles since i ground them and ive taken them off to check them, the surfaces are still perfect.
This is what Snowbum says , he is usually right -
" The tips of the rockers usually can be seen to be heat treated by their colorization appearance. The heat treatment is usually fairly deep, and contrary to BMW School teaching, the rocker tips often can be lightly resurfaced if need-be "
Mine have done 3k miles since i ground them and ive taken them off to check them, the surfaces are still perfect.
This is what Snowbum says , he is usually right -
" The tips of the rockers usually can be seen to be heat treated by their colorization appearance. The heat treatment is usually fairly deep, and contrary to BMW School teaching, the rocker tips often can be lightly resurfaced if need-be "
Beemerboff
Registered user
https://tttg.org.au/Content/Docs/Articles/CaseHardening.pdf
A little light reading re hardening and powders.
Just make certain you find a brand with no cyanide!
It seems that a single treatment gives around 20 thou depth of hardened material, so taking any more than 15 thou off depends on knowing for certain that the rocker received more than one treatment.
Just how you find out that is not clear!
A little light reading re hardening and powders.
Just make certain you find a brand with no cyanide!
It seems that a single treatment gives around 20 thou depth of hardened material, so taking any more than 15 thou off depends on knowing for certain that the rocker received more than one treatment.
Just how you find out that is not clear!
My experience with Kasenit is that the length of time it is left to soak at the desired heat, the deeper the case hardening.
The method that I use for small parts is to place the item in a piece of 3mm wall tube just larger than the item and pack it with kasenit, then weld a piece of 6mm plate over both ends.
I then put it in the coal fire over night . in the morning cut an end off and tip out the case hardened item , crush the kasenit up and re use it.
By heating it in a sealed container it excludes oxygen so stops any oxidation and blistering.
It normally has a 12 hour soak this way so deep hardening.
On rocker arms ( which I have not done ) try putting enough Kasenit in one end of the tube and standing the rockers so only the tips to be hardened are in the Kasenit powder.
Many years ago it was common practice to build up worn parts such as rocker arm tips with Stelite then re-grind them. Not sure if anyone still does this in this throw away era.
The method that I use for small parts is to place the item in a piece of 3mm wall tube just larger than the item and pack it with kasenit, then weld a piece of 6mm plate over both ends.
I then put it in the coal fire over night . in the morning cut an end off and tip out the case hardened item , crush the kasenit up and re use it.
By heating it in a sealed container it excludes oxygen so stops any oxidation and blistering.
It normally has a 12 hour soak this way so deep hardening.
On rocker arms ( which I have not done ) try putting enough Kasenit in one end of the tube and standing the rockers so only the tips to be hardened are in the Kasenit powder.
Many years ago it was common practice to build up worn parts such as rocker arm tips with Stelite then re-grind them. Not sure if anyone still does this in this throw away era.
Something to consider if simply reprofiling the rocker pad and hardening is you'll be changing the angle it makes contact with the valve slightly and possibly enough to cause valve guide wear.
I would just fit new ones and be done with it in this case
I would just fit new ones and be done with it in this case
Re-hardening could be an issue as the shaft will undoubtedly move out of alignment..... when manufactured, these will have been rough machined and finished ground after hardening and heat treatment so everything is in alignment and true. I reckon these will be case hardened but may be wrong.
Newman Cams in Farnborough Kent will re profile cams, followers etc.
http://www.newman-cams.com/
Mick
http://www.newman-cams.com/
Mick
Well, that's so simple! Thanks for the link. My rocker arm tips are showing exactly the same wear as the one in this video. If I lived in Costa Mesa (like my uncle once did), I'd be knocking on his door! Further to the latest message, I ought to contact Newman Cams. Obviously if they want £300 or more, then I may as well buy new.
Beemerboff
Registered user
M/Wks might have a good secondhand set.
Newman have a price list that shows them refacing curved Triumph cam followers for 50 quid the set.
But that probably wouldn't include building up if they are consider that is needed to maintain the geometry.
FWIW Tri followers were usually well worn, and any attempt to build them up and regrind them using the tools and rods found in the ravager workshop usually ended up with a wiped cam! DAHIK!
Newman have a price list that shows them refacing curved Triumph cam followers for 50 quid the set.
But that probably wouldn't include building up if they are consider that is needed to maintain the geometry.
FWIW Tri followers were usually well worn, and any attempt to build them up and regrind them using the tools and rods found in the ravager workshop usually ended up with a wiped cam! DAHIK!
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