DLC Coated Tool Steel Tappets

I am about a year and a half into these DLC coated tool steel tappets. This, like most projects, was a deeper rabbit hole than I intended to go down when I started this. I had a number of conversations with Jim Dour at Megacycle and several more conversations with Jim Schmidt on the functional needs of these to work across a number of different applications. Learning curve on these was steep, but I think these are starting to shape up to be one of the bigger developments for a british motorcycle.

The idea with these is to replace the worn internals in my engine with something like Jim Schmidt’s DLC wrist pins. Reducing wear and turning the surface into a low friction material that in effect removes the metal on metal contact with the camshaft.

At present Jim Schmidt is testing these now on a spintron. Jim’s initial tests are positive. I have a set I am going to put in a BSA shortly and I have another couple sets I am waiting to receive from DLC to put into my MK3 Norton.

I have prototypes in Triumph (R and STD) and BSA type. Weights are identical if not slightly lighter than stock BSA and Triumph tappets. Some details to work out still, but the development on these is finally getting to a place of putting these on the road.

Wow, they look seriously impressive !

What are you doing if anything for lifter blocks to support the use of these DLC coated tappets in Norton barrels?

Schwany said:

What are you doing if anything for lifter blocks to support the use of these DLC coated tappets in Norton barrels?

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Jim Schmidt has been supplying bronze lifter blocks to use BSA lifters in Norton cylinders for quite a few years now. There were other sources of them them in past years, but I don't know of anyone else who currently makes them for retail sale. I've seen a few others with machining skills who have made them for their own use. Anyone with machining skills and access to lathe and mill could do it, but Jim has already done the development work to sort them out. It's a lot simpler to just buy them from him. He has them made by a local CNC shop, and they are very high quality. I've used them on several race engines and one street bike, and I'm a real fan of them.

That's assuming that the DLC coated ones are dimensionally equivalent to the stock BSA lifters, of course.

Ken

Schwany said:

What are you doing if anything for lifter blocks to support the use of these DLC coated tappets in Norton barrels?

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If you look closely at the images in the top post you will see that there is a tiny radius and polish on the bottom edge of the tappet blocks to prevent gouging and wear of the bronze lifter blocks. The DLC is putting no wear on either the tappet block or the camshaft (some discoloration on the cam but no visible wear). Hard to believe but that's what the spintron shows so far. The image below shows a comparison of various lifters (including tool steel and so called "Stellite". The uncoated lifters all show some damage (one uncoated lifter is almost OK). But the DLC lifter is perfect and this is the 4th test on the same DLC lifter when all 4 tests showed wear on newly polished uncoated lifters. This is cutting edge Nascar technology.



Below shows the face surface that rubs against the bronze block. There is no metal to metal surface contact and there is no visible wear at all.


The spintron hard at work. Today I am trying cams of differenty materials from different suppliers. I've already tested an original stock cam and an aftermarket cam. Lots of time invested.

Nice work Jim !

jseng1 said:

Below shows the face surface that rubs against the bronze block. There is no metal to metal surface contact and there is no visible wear at all.

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That rounded off top edge on the DLC coated lifter shown in the figure above is a good addition. I should have done that with your Triumph lifters. Too late now though.

For the lazier engine builder like myself the DLC coating on stock flat lifters would be nice in a street engine.

Schwany said:

That rounded off top edge on the DLC coated lifter shown in the figure above is a good addition. I should have done that with your Triumph lifters. Too late now though.

For the lazier engine builder like myself the DLC coating on stock flat lifters would be nice in a street engine.

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I chamfered those bottom corners and polished them for you the last time I sent them to you. I do that on all the lifters I send out now.

jseng1 said:

I chamfered those bottom corners and polished them for you the last time I sent them to you. I do that on all the lifters I send out now.

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Didn't happen like you think it did. I never sent the lifters back to you. You never touched them again. I showed you pictures of the lifters and the damage to the lifter blocks and that is it. All I got from you was a new set of lifter blocks at a slight discount because the sharp top edges of the Triumph lifters ate the first set of blocks up. Any clean up work that was done to the lifters I did, but I did not do enough. It was me that told you the lifters were too sharp edged. Then you started doing more work to the future parts. That is what actually happened.

They look good. The Triumph ones Jim supplied scuffed quite bad in about 8,000 miles. It’s a shame the only worn parts were UK supplied, from LF Harris! I did source some NOS Triumph ‘R’ grind ones but decided to strip the lot out in the end and go back to stock.

Edit: I just checked my notes and the mileage was 13,018 miles before realising the cam followers where wearing badly not 8,000 miles. An interesting comment from Pete Lovell was that these mods are probably ok for racing where they don’t get a lot of useage.

Schwany said:

I never sent the lifters back to you. ...

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Shwany
I thought I had cleaned them up for you. I've been doing it ever since yours were too sharp and I thought I had done yours as well. That was a couple years ago and I forgot exactly what happened - sorry.

Mark Savage
I've talked to Harris about their lifters and their material. I'm testing them now and comparing them the Stock original equipt lifters. If they aren't up to snuff I will go back to original equipt (dwindeling supply) or preferably the DLC coating. That's what this project is all about - eliminating lifter/cam wear. Lifer/com wear has been an ongoing problem for everyone and there's never been a solution like this before..

I'm done with comparisons for now and testing the DLC coated lifter on a new polished cam lobe and things are looking good so far. No wear at all on the cam and a slight grey discoloration on the nose. The vertical lines you see on the cam are the original machining marks. This is after an hour + at about 3300 eng RPM. There is no wear on the DLC coating and under magnification you can still see the original machine marks and imperfections on the glassy DLC surface. I'll be running more hours on the spintron and hoping for the best.

Jim , what lubricant are you using with the cam to litter contact, or is straight metal to metal?

Brooking 850 said:

Jim , what lubricant are you using with the cam to litter contact, or is straight metal to metal?

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My first tests were with regular Castrol GTX with low zinc content and there was too much wear with steel to steel uncoated steel lifters. I'll be experimenting with high zinc content oil soon.

The DLC is pretty amazing. I just rubbed a sample HARD with 400 grit sandpaper and it wouldn't leave a mark.

I've sent some polished lifters for DLC coating and will be testing them on the spintron in a few weeks. Tests on polished BSA lifters and cam lobes show good resurts with witness marks but no real wear or galling after hours on the spintron. Its also important that there is plenty of zinc in the oil such as mobile 1 V twin or Vavoline racing VR1.

Here's a stock lifter comparison I forgot to post. Run on the spintron