Reground desmo cam

[amartina75]

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I sent my desmo cam and rockers to Newman Cams in England for refurbishment. I just got the parts back today and I’m not sure what to think. The rockers look fine and as I expected but the camshaft looks faceted. I expected it to look almost polished. I have never had a cam reground before so I’m not sure what is normal. I’m wondering if I should say something to them. I’d appreciate some opinions as to what to do.

Thanks
Aaron

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[Eldert]

Hi Aaron

with regrinding you brake thru the hard surface so the camshaft need hardening again .

i just had some Mach 1 camshafts nitraded and they look like your camshaft

i would not worry about it

Eldert

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[amartina75]

Hi Eldert,

They did harden the cam, and I realize the metal darkens from that process. I’m not concerned about that, I’m wondering about the fact that the lobes are not smooth exactly, they look like they have many small facets.

[el_guru]

mmmmmm....... from an engineers viewpoint it doesn't look right at all. The followers would be hammering against the ridges until they wear down, i have never seen a cam with "facets".

Have you contacted the company and sent pictures.?
Can you actually feel the ridges with your nail.?

[amartina75]

Yes you can feel the ridges, i have not contacted them yet I wanted to get some opinions on here first, before I accuse them of shoddy workmanship.

[double diamond]

It looks like they ground your cam by making many passes to grind the profile. When I got the tour of Webcam, Steve showed me how they grind the profile on, basically, a specialized grinding lathe. The grinding stone follows a template that describes the profile of the cam. Your cam looks like it was ground on different equipment. I’ve seen information on CNC grinding machines that can grind cams based on CAD drawings. Maybe this is what you received. The coloring you see is probably a low friction coating. Webcam coats their regrinds with some sort of low friction Moly-whatever for break in. It wears off when the cam s run. Webcam won’t touch a desmo cam for hardweld/regind but Megacycle catalogs a desmo 450 cam. Their product is ground on a new billet.

Thanks for posting.

Matt

[Rick]

I'd say you're right to question the workmanship. They may have used a probe to digitize points on the cam, and then just drawn straight lines between the points instead of interpolating a curve, or they might have good data on the profile and their software broke the nice curve into small segments- doesn't look like it was ground to a master profile.
It's hard for me to visualize how it would perform- might be OK, I'd ask them to explain why it's segmented- let us know if they come back with a good answer.
Rick

[amartina75]

Thanks for your replies everyone, I value your opinions and wanted to see what you all thought before I asked Newman Cams to explain. I do think it was ground on a CNC grinder.

I just emailed David Newman and I’ll wait and see what he has to say, I’ll let you all know.

Thanks
Aaron

[amartina75]

Well I finally got a response from Newman Cams, not sure how I feel about it. They didn’t offer any explanation why the cam has the finish it does, but I guess the reason is someone did a poor job. I’m not sure what to do now, they say it’s ok to use as it is or they can grind it again. I don’t see either option being ideal. I measured the lobes before I sent it to them and after. Before and after measurements varied by .004-.007 if they grind it again that’s just making the lobes even smaller.


Hello Aaron,
Yes the ripple is not good but I can assure you that it will work without any wear or performance problems.
We will warrenty the cam for 5 years. Or 50000 Miles.
I can regrind the cam without ripples if you return it to me it will take 2/3 days.
Once again sorry for the problem.

Regards
David Newman

[el_guru]

Hopefully they can just remove the actual tiny ridges and not any more from the base..... Might just be a thou..?