Hirth Cranks

Discussion of 4-Cam Type 547 engines (and all the Fuhrmann racing variants) and cars that powered them.
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Jacques Lefriant
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Re: Hirth Cranks

#31 Post by Jacques Lefriant »

Hi John
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Alan Klingen 2
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Re: Hirth Cranks

#32 Post by Alan Klingen 2 »

Just a note the rollers are sized for the journal they are on so don't mix them up!Alan The Stable.

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Re: Hirth Cranks

#33 Post by Alan Klingen 2 »

My dad's 356 super came with a roller crank an it was knocing badly my boss at the time, Juergan Kirberg said to me get that crank out of the and even gave me a new 356 C crank to use. They were known as Adolf's revenge. Alan The Stable.

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Re: Hirth Cranks

#34 Post by Alan Klingen 2 »

I would not recommend you trying to take apart a roller crank the rod journals are held together with what is called a diifential thread EG the pitch is off by one turn on the male vs female threads. Alan The Stable.

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Martin Benade
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Re: Hirth Cranks

#35 Post by Martin Benade »

Regardless of that, it takes a special wrench and they are REALLY tight.
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Jeff Adams
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Re: Hirth Cranks

#36 Post by Jeff Adams »

The rod journals on pushrod engine roller cranks, and early style 80mm four cam roller cranks do not use differential threaded bolts. The center main bolt on 80mm four cam cranks and all five bolts (four rod journal and one center main journal) on the later style 82mm four cam cranks do use the differential threaded bolts. Due to a condition Jim Wellington called "set and seizure", disassembly of the differential threaded bolts can be difficult since the torque needed to loosen the bolt will be much higher than what is used during assembly. My military grade torque wrench goes up to 1000 foot pounds for either tightening or loosening the bolts. While taking a crank apart, two people are needed: one to lean on the wrench, the other to watch the torque wrench dial and make sure 1000 foot pounds is not exceeded. Going past 1000 foot pounds risks breaking the special tools. I have been lucky and not broken any tools yet, but 1000 foot pounds sounds like a good number to stop at.

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James Davies
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Re: Hirth Cranks

#37 Post by James Davies »

Some visualization of the discussion here.
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Harlan Halsey
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Re: Hirth Cranks

#38 Post by Harlan Halsey »

in Santa Clara, Jim had his assembly tool/bench bolted to the floor in a corner. He would put a cheater pipe on the Hirth wrench, put his foot up on the concrete wall and pull! I watched him assemble a couple of rod journals using "chalk oil" changing rollers until the clearance, measured by rod end play was right. (I don't see how it is possible to rebuild a Roller crank without the selection of rollers Jim had. For us in those days it was simple, just have Jim do it. For a simple re rollering without different parts needed Jim charged about $ 300. A lot of money for me back then. The crank he built for me ran the MHAR for 15 years and still seems OK.)

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Re: Hirth Cranks

#39 Post by Alan Klingen 2 »

Jim Wellinfton was the last person I knew that rebuilt them My dad's 55 super had one and it rattled badly. When my boss at the time heard my car he told me to ge that POS crank out of there and gave me a 356C crank and all the info to change it over." he called it Hitler's revenge. Alan Klingen The Stable. BTW Jim WELLINGTON OF Rennsport Werke bought the crank from me because it was the only way he could get spare rods Etc. For his crank bussiness. Alan Klingen The Stable.

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Harlan Halsey
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Re: Hirth Cranks

#40 Post by Harlan Halsey »

Alan Klingen 2 wrote: Tue Oct 24, 2023 9:35 pm Jim Wellinfton was the last person I knew that rebuilt them My dad's 55 super had one and it rattled badly. When my boss at the time heard my car he told me to ge that POS crank out of there and gave me a 356C crank and all the info to change it over." he called it Hitler's revenge. Alan Klingen The Stable. BTW Jim WELLINGTON OF Rennsport Werke bought the crank from me because it was the only way he could get spare rods Etc. For his crank bussiness. Alan Klingen The Stable.
Bill Doyle continued to rebuild Hirth roller cranks long after he left Jim and started his own business. Bill rebuilt a couple of Carrera cranks for me. (I actually don't know if Bill did the work himself or whether he sub-ed it out to Garretson or Wellington.) Hirth roller cranks simply required maintenance at abut 40,000 miles. This wasn't a problem for the first, second, and probably third owners. They were " Adolph's revenge" for people who didn't understand that or didn't want to. Or who didn't like the cost of maintenance. I am amused at your mention of Kirberg. His son Harold had quite a reputation in the SCCA SF Region. At the very first race I attended after moving to California in 1968, there was a brand-new Alfa leading the race. It was also orange like Kirberg's Speedster. Kirberg couldn't quite get by so he simply crashed into the rear of the Alfa in the last turn. The Alfa owner was distraught over the damage to his new car, and I think Harold was disqualified. Later on, Speedsters running Bursch straight pipe stingers curved them over so that the stinger didn't project. We called the modification a "Kirberg preventer" because of Harolds way of crashing into them to kill the power. For a long time there was a Kirberg Motors German Auto repair shop on old County Road in Belmont. I passed it frequently but was never tempted to go in. I've no idea who Kirberg's customers were.
Jim was always looking for used 356 cranks, particularly the center section. And for Carrera cylinder heads. Those were the parts in shortest supply.
Last edited by Harlan Halsey on Wed Oct 25, 2023 6:07 am, edited 1 time in total.

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Joris Koning
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Re: Hirth Cranks

#41 Post by Joris Koning »

Hi Harlan,

You know if Jim is still around? I lost contact with him. Last time I spoke to Paul C. He also mentioned he had not heard of him in a long time.

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Harlan Halsey
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Re: Hirth Cranks

#42 Post by Harlan Halsey »

Joris,
Jim is still around but hasn't been reachable for work for a long time. I have a friend who grew up with Jim and could reach him if you have some good reason to do so.

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Re: Hirth Cranks

#43 Post by Alan Klingen 2 »

I remember Jim Wrellington gave me $500 for my dad's used roller crank because this was his only way of getting spare roller crank parts. My boss at the time Juergan Kirberg suggested that I remove that crank and use a plain bearing one instead he called them "Hitler's" revenge. Alan The Stable.

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Re: Hirth Cranks

#44 Post by Alan Klingen 2 »

I WAS AT THAT RACE AT Laguna. they both spun at turn!11
They were both cautioned about "over driving" Alan The Stable.

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Re: Hirth Cranks

#45 Post by Steve Douglas »

Speaking of Jim Wellington, I have some stickers from Jim's shop, one was for his rebuilt engines the other might have been for the V-4 Midget Race Engines. If anybody would like one or two let me know, I will put them in the mail.
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