Cost is factor to sell a lot and make a profit, but to develop something that "fixes" a problem, cost is not a factor. The cost of failure is far greater.

I do agree and it seems quite clear that some of the Rockers being sold do seem overpriced.

When we started looking at rockers it was because we had experienced some failures with used Cast Steel Rockers.

When they failed due to fatigue the damage wasn't so bad but a typical 2 day European Rally costs around $6000 dollars and it is a lot of money to spectate.

It would be possible to shot peen used rockers and remove the prior fatigue damage but by the time you have refurbished, re-bushed and shot peened you may have arrives at more than 60% of the cost of a new part.

The price of used early forged rockers was quite high and now they sell for about the price of a new cast component and more often than not the hard chrome needs to be removed and re-plated adding more cost.

Add to that the fact that they still don't have the longer pad and we felt we needed a solution.

We looked at the 9M billet rockers and the converted 993 Rockers and the price just seemed high.

We had a number of interested parties looking for rockers specifically for Period F Appendix K engines which was our basic motivation and by copying the basic early design but with the RSR length heel we seemed to have a fairly 'scrutineer proof' component.

We used a 300-M VAR steel as this adds about $1.20 to the cost of each forging when compared to a commercial 4340.

We Vacuum heat treat, rough machine, stress relieve. finish machine and Isotropically Superfinish.

We selected a surface treatment technique that is a diffusion based process as opposed to DCL.

DLC is a bit of a 'Choc Ice' as it is a thin, brittle shell, it has very good hardness (2500HV) and low friction but I just don't think it can be justified on the basis of cost.

The original Hard Chrome finish is around 850HV hardness - there is some loss from the 'as-plated' hardness level due to the grinding process and these parts seem to last for more than 30 years without too much wear.

The cost of hard chrome and grinding is also quite high and there is the potential for hydrogen embrittlement and I just didn't like the risk.

An old colleague from my University days is the Technical Director at Hauck Heat Treatment and he advised the treatment we use for the surface finish on 'our' rockers.

It has a surface hardness of 1000HV and the layer produced is oleophilic so although it may not be quite as low a friction as DLC it is still exceptional.

The cost of this process is around 1/20th of the price we were quoted by Balzers for the Balinite C Star DLC treatment.

The metallurgy of this process is sound, the cost is affordable and to date performance has been excellent.

We also fit and hone an original specification Glyco bush.

In the UK an OEM Spec Aftermarket Rocker has a price of around $90+ including Sales tax. This means a set of new cast rockers is $1100

If you buy a genuine Porsche Rocker the price goes up to about $1500.00 per set.

We sell 'our' forged Rockers for this price which is $125.00 each.

I can't see much reason why the 906 Rocker we will make available early next year will be more than $150 each + Lash Caps.

When we produce this rocker we will not only forge but we will also stamp the rocker in a coining die to improve its basic geometry and finish. This coining operation makes a small increase to our cost which we will need to pass on.

I feel that these prices are realistic and they offer a sensible alternative to standard parts when considering costly race engines.

We really made them for use n our own engines and we have sold some to other Race teams in the UK and some have been shipped overseas but it was never our plan to sell large quantities on a commercial basis and we are happy with the results we have obtained.

We expect to sell more 906/RSR type rockers as there is a demand but at $600 each not many people are buying but at $1800 a set we think it will be worthwhile.

We have already started to manufacture the complete size range of lash caps that Porsche used to offer with the 935.

We also manufacture a Surface Treated Rocker shaft which is similar to the 'Porsche Motorsport' shafts used with the 906/RSR Rocker.

Not directed at you, just Porsche parts in general lately.

Porsche is really pricing people out of these cars, and it's really sad.

Then, aftermarket comes along, and takes advantage too.

Reproducing a factory part when you have it already on a silver platter has me scratching my head a lot.

I know what you mean. I thought they were really expensive also but when you look at a new set of stock ones it wasn't really a lot more. I'm getting mine reground lol.

Oh most definitely!

Scary prices when you think high end Gene Berg forged ratio rockers for a VW were never more than $500 for the set of 8 with shafts and hardware. :eek:

A set of new Pauter rockers, which BTW I've never cared for, in 1.3, 1.4 or 1.5:1 ratios are $525 retail. ;)

How can you legitimately compare a rocker made by Gene Berg or Pauter for a VW with a rocker designed and made ex F1 people? Of course the price will be reflective of this difference.

You honestly believe rockers should cost as much as a good, used DD vehicle?

There's nothing special about our rockers. If there is, please fill me in.

The real profits are being made by the guys selling the investment cast steel rockers.

If you manufacture and buy them in countries such as India or China they would have a total cost of about $5.00 each,

Mould costs would be around $500.00.

To spend $40-$50 dollars re-finishing a $5 part :) just doesn't seem wise and it seems to me that all you are really buying is risk.

If forged rockers were manufactured in volume, also in India or China, the cost would be around $12.00 each with die costs being around $1500.00

When you consider that Mahle now forge their pistons in Shanghai it increasingly likely that many 'OEM' parts are produced using a similar supply chain.

When Investment cast rockers were first introduced in the Sixties they provided the car makers with substantial savings as production components are costed to around $0.001.

Porsche must have saved a significant amount as their early cast rockers didn't have a bush and weren't chrome plated.

If we believed we would have been able to sell 3000 rockers we ,may have considered this approach but we didn't have $40 000 to invest.

We did invest around $6000 for tooling including machining fixtures.

We have used the 'best' quality material we could find and because of small quantities we have to pay premium prices. We also use quality suppliers for all of the secondary processes.

Forging costs are high as we only make batches of 250 parts.

Our complete supply chain is UK based but mostly due to the low volumes we make.

To simply compare one product to anther only on price can be misleading.

If you consider an M8 K nut for example, I can buy them 'uncertified' from Belgium for about $1.00 each but if I buy them with a full Release Certificate from Simmonds they cost around $14.00 each.

We still haven't recovered all of our tooling costs but I do believe we have produced some parts that have been useful in a specific category of racing.

Working in the automotive industry, it is possible to get good quality anywhere in the world with a certified supply chain and a good team. Unfortunately at small volume products establishing a certified supply chain is cost and time prohibitive, hence why you rely on suppliers you trust.

Increasing batch size is the obvious means to reduce cost by amortizing one off costs such as setup time and tooling. I imagine Chris isn't in a position to absorb the upfront costs for larger batch sizes or asssume the risk for holding significant stock, this is where either retailers such as pelican can get involved or group buys make a lot of sense. In fact a tiered price where; group buys pay up front before the manufacturing run and wait for the lowest cost, retailers can order and hold stock for a heigher retail price and the manufacture can hold as much stock as they'd like can be beneficial for all.

Unfortunately group buys here are frowned upon by Pelican. I am interested in the hard finished rocker shafts that Chris makes and the valve guides he is working on.
I spent more quality time with my rocker arm today. Finally got my measurements to repeat accurately. The radius of the pad on this rocker is 29.99mm I feel safe rounding this up to 30mm. I will work on a sketch tonight.
David

Have another glass of Koolaid. :rolleyes:

The Gene Berg rockers were forged swedish steel and I believe the raw forgings were made by the same company that made 911 cranks. They were bushed for the hardened centerless ground shafts.
BTW I own a Berg crank in an engine that produces 2.5 times the OE rated horsepower, 24 years one of my summer DD.
Berg cranks and rockers now command prices up to 10X there original retail on ebay.

BTW Berg cranks I know for sure was forged by the same outfit as all OE VW and Porsche cranks.
Gene Bergs son, Clyde Berg who was a long time employee at Gene Berg Ent. has started making/selling a reproduction of his dads rockers.
No doubt now made in China but $350 a set retail it's funny because I wouldn't think there's very high volume for aircooled VW ratio rockers anymore.

I'm not knocking Chris' price point, for a low volume production it's sounds quite reasonable, but $7-9K rockers just because it was made by EX F1 people is nuts.:rolleyes:
YMMV ;)

It is really interesting to look at how the world of manufacturing has changed in the last 20 years and the techniques that have been developed to reduce price and to improve performance so forgive me for drifting away from the main topic.

When I first started work in a Metallurgy lab 'Swedish Steel' was a premium product was made to the finest quality standards in terms of cleanliness and Motorsport Parts made from these material sold at premium prices.

I bought a Steering Drag Link for my 'Rally' Lotus Cortina and spent two weeks salary.

I am sure it was worth at least a second a mile :D

Today the only steel company in Sweden producing the type of steel used in cranks is OKAVO - they have 2 plants in Sweden and 1 in Turkey.

They have a range of steels known as OvaX and these differ greatly from the traditional Chromoly products that used to be used for high end cranks.

If we think of the 'anatomy' of a crankshaft then the main reason for forging is to save machining time and hence cost.

As is normal there many other reasons that are then stated - the classic 'grain orientation' and many other technical claims being made to justify prices.

In the early days of steel production the presence of non-metallic impurities in steel was a significant problem.

These impurities used to elongate during the rolling process and align along the length of a bar or through the thickness of a plate.

Forging causes these strings of defects to wrap around corners. The first well documented description of this process was first published in 1939 in 'Metallurgy for Engineers' by EC Rollinson A book which is very basic but still in print.

The presence of the strings of impurities caused significant planes of weakness and billet machined parts would often suffer from fatigue failures and as the process of metal fatigue was very badly understood until the late 50's and early 60's forging became a very important process to avoid these problems.

The production of steels in the modern era involving Vacuum Arc and Air Re-melting techniques has resulted in levels of cleanliness that really means that forging is now of much less significance other than to save cost.

The Anisotropy of mechanical properties of materials such as 4340-VAR and 300M VAR can realistically be ignored as these material produce a level of homogeneity that is unprecedented.

Modern ESR steels are also now producing similar results.

I would be interested to know the composition of steel used in 911 cranks as I had been led to believe that they were a Carbon/Molybdenum steel quite similar to Werkstoff 1,5411 (4072 in the USA) and had little in the way of Chrome or Vanadium.

The Tenifer treatment (Tuftriding or Melonite) used seems to hint at the lack of the more traditional alloying elements that are used in cranks that are nitride.

I do have some experience with original 911 Cranks that have been Gas Nitrided after grinding and they spall quite badly which again seems t suggest a lack of strong nitride forming alloy elements.

Unfortunately I don't have a scrap crank to cut up and analyse so some better would be really interesting.

Cast cranks have also improved significantly since the early days of Ford and the modern Austenitic SG Iron cranks produced by companies such as Darcast.

These material were developed at BCIRA in the UK and have equally good fatigue life to the more traditional EN40B gas Nitrided crank.

My company produced the fatigue testing machines used during the initial development stage of these alloys and the results produced were, at the time, astounding.

For low volumes billet machining cranks is now a good alternative to forging as fatigue life will be good and the huge tooling costs can be avoided.

As I get older it is tempting to cling to the past but I am sure we will soon be using Aluminium based Metal Matrix Composite con rods produced by powder metallurgical techniques and they will provide major improvements in performance.

At the recent Advanced Engineering Exhibition I managed to organise a sample of a material that has been produced in this manner and we are machining a rod for an XT 500 Yamaha engine as a trial.

The fatigue properties of the material look quite encouraging but I am not sure how to deal with the expansion of the big end and I don't know any UK manufacturer of aluminium rods.

We would also like look at making rockers from this material but then I will have to worry about valve spring resonances. :rolleyes:

A loose explanation of how grain structure looks in a forged part is to think of a chunk of pine (old style billet) that is cut into the shape of a crank, as opposed to a pine crank that was forced to grow inside a mold (forged).
Any woodworker knows that cutting through the grain makes for a weak part that is prone to splitting. The grain structure of the forged part flows around the corners thus making a much stronger part.

I know pretty simple but most laymen understand this grain explanation quite clearly.
Back in the day forged was the strongest (could still be), Billet wasn't quite as strong because of the grain issue and cast was downright poor

Casting (and billet, etc.) has come a long way now, if cast rockers is what Porsche used (I thought they were forged) in the past, wouldn't they be twice as strong today?

Been meaning to ask for a long time.

Why hasn't anyone made an AL rocker with steel facings??

AL rockers are the norm in the American V8 world, and have to push on springs that are far heavier than standard 911 spring.

Assume there's not enough real estate around the shaft area?

:eek:

:D

Sadly metals aren't wood and the grain behaviour you describing is only valid of you consider planes of weakness that are due to the non-metallic inclusions that used to be present in much greater quantities than we now find.

I would agree that the analogy is easy to understand but at a fundamental level it is inaccurate.

It is simply the presence of long strings of non-metallic impurities that produces the effect you are describing.

The basic crystal structure of steels doesn't resemble wood in any other respect and if you remove the inclusions you will have a more or less homogenous structure.

I would agree that this description made sense 50 years ago but with the steels we now use it is not really relevant and is becoming less and less relevant as process control improves.

Modern Ultraclean steels have very small and very short inclusions that don't produce any significant planes of weakness and you can really neglect their effect.

OKAVO provides significant amounts of data about the homogeneity of their IQ family of steels.

It is also possible to produce steel with a crystallographic 'texture' but this always involves complex fabrication techniques such as 'plane strain' rolling and is generally only applicable to relatively thin sheet materials used for press work.

Non-ferrous materials such as copper and brass can also develop significant texture but generally due to the use of specific rolling techniques.

Bar Products and heavy plate will not produce these effects and if they are clean or 'ultraclean' such as current OKAVO crank material you can consider them to be homogenous so forging will only save money and not improve performance.

Porsche only used forged rockers in their engines used in the 1965 and 1966 911.

We 'forged' our rockers on the advice of the UK's Motorsport representative on the FIA Historic Technical Committee due to his assertion that am billet machined rocker would be unacceptable for use in a Period F Appendix K Porsche 911 and producing rockers for this application was our overriding concern.

The 906 Rocker used in the 901/20, ST, RSR and 935 engines was always forged but the finish has always been quite poor and they always shows that they have been hand fettled.

By coining the forgings we hope to make a significant improvement in this area.

We chose to use an Ultra clean steel because it added around $1.50 to our base cost and it must produce a more reliable component.

It is fair to say that whilst some casting techniques have improved there is no real reason to assume that the Investment Cast Rockers are any different now to when they were first introduced.

The first examples of investment cast parts date back to around 2500BC and in reality little has changed.

We melt materials with better control, we have developed some better materials but broadly there is little that I believe can be done to significantly improve the strength of the existing cast 911 rocker.

The scatter in properties may have reduced but we are still melting a very basic steel, pouring into a ceramic mould and letting it solidify.

The main issue with cast steels is still the fact that the solidification process produces a material with inherent notch sensitivity and a fundamental susceptibility to suffer form the effects of fatigue unless alternating stresses are well controlled and below the critical threshold.

This is to do with the basic manner in which metals solidify and with small parts some of the inoculation techniques used to improve performance is tricky.

Xceldyne make them in their French facility in Vilbraye.

They don't keep stock and they quoted me $475 each in January.

Titanium rockers
 

I commend CHRIS for his efforts in producing a quality rocker.I used to buy early 911 rustouts just to harvest the forged rockers,cams & counterweighted cranks & early quick 2:8 to 1 steering rack with damper.Price is fair for his product which is obviously well thought out.I think Titanium rockers would be the bees knees.He should offer a buy in for a run of them.I use Ti valves in my street cars as they are just better.I am in for a set anytime.Ti valves run lighter spring which makes less drag & less face wear.I do not see aluminum holding up in this application.Titanium would remove over 2 lbs.off of the swinging weight at an important place & minimize over rev damage.Go for it Chris.Ciao Fred

Chris, what AL alloy would you use for the rockers? Assume there'd be a heat treatment after?

I could whip some up I think. Could you make the faces hard enough without steel? Assume not? If not, would a plating of some kind work?