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| Crank maching question https://www.slantsix.org/forum/viewtopic.php?t=68152 |
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| Author: | Charrlie_S [ Thu Apr 10, 2025 3:27 pm ] |
| Post subject: | Crank maching question |
Pretty sure some members have had the converter pocket at the rear of the early crank opened to the late crank diameter. I have been trying to find a shop to do this, without success. I have tried auto machine shops, crank specialty shops, and "general" machine shops. I would prefer a shop close enough to drive to, but at this point any referral would be appreciated. Not an issue with my 225 cranks, but different story with my 170 cranks. All but one have the small pocket. The main crank I would like to get done is my Lunati hard chrome crank. It was done by Lunati "way back when". It is stroke equalized, indexed, hard chrome standard size journals. But has the small pocket. |
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| Author: | slantzilla [ Thu Apr 10, 2025 3:42 pm ] |
| Post subject: | Re: Crank maching question |
Seems like any shop with a medium sized lathe could handle it. Unfortunately machine shops are dying off. |
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| Author: | Greg Ondayko [ Thu Apr 10, 2025 3:45 pm ] |
| Post subject: | Re: Crank maching question |
I suppose you are intending to run it with an automatic? |
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| Author: | Charrlie_S [ Thu Apr 10, 2025 3:53 pm ] |
| Post subject: | Re: Crank maching question |
Quote:
I suppose you are intending to run it with an automatic?
Correct. The plan is to have a "special" converter and nobody likes to build the small pilot converters. Even Andre complained about the last one he did for me.
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| Author: | Charrlie_S [ Thu Apr 10, 2025 3:56 pm ] |
| Post subject: | Re: Crank maching question |
Quote:
Seems like any shop with a medium sized lathe could handle it. Unfortunately machine shops are dying off.
We have several "general" machine shops in my area, but when I take the crank there to show them what I want, they decline.
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| Author: | slantzilla [ Fri Apr 11, 2025 7:33 am ] |
| Post subject: | Re: Crank maching question |
Quote:
We have several "general" machine shops in my area, but when I take the crank there to show them what I want, they decline.
WOW! Seems to me like that would be easy money.Maybe I've just been watching too many YouTube videos of Pakistanis making offset shaft using an ancient lathe, a steel rule, and chalk. 
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| Author: | mcnoople [ Fri Apr 11, 2025 10:16 am ] |
| Post subject: | Re: Crank maching question |
As stupid as this suggestion is.......you could do it yourself in a very very sketchy undercar experiment. It would require a manual trans bellhousing and flywheel with no clutch/pressure plate. You would have to make a jig to bolt the tooling directly to the transmission mounting surface on the bell. You have to do the machining on the crank while the engine is actually running. If you can make a solid enough mount for the tooling it can be done. With the crank mounted into an actual idling engine the bearings should maintain a close enough tolerance for the process. On a lift this would be much much safer than doing it on your back under a car.....of course this is just a theory and a crazy one at that. And this is probably the stupidest thing I have ever thought up for a forum. |
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| Author: | ceej [ Fri Apr 11, 2025 6:22 pm ] |
| Post subject: | Re: Crank maching question |
I'd think the fixture to indicate it in would be a pita. Make it easy. Build a fixture out of caps and bearings so they have a way to hold it. My lathe would do it, but my tail stock would need to come off. Actually, they could use a driven Dead center, maybe a drive dog then the rear main equipped with bearing fixture. (Two caps and some lube.) Put the bearing fixture into a steady rest, true it up, and go to town. Mike's lathe could do it and leave the tail stock on, but he has ten feet between centers. and a taper attachment ..fancy pants. CJ |
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| Author: | Charrlie_S [ Fri Apr 11, 2025 7:29 pm ] |
| Post subject: | Re: Crank maching question |
Quote:
I'd think the fixture to indicate it in would be a pita. Make it easy. Build a fixture out of caps and bearings so they have a way to hold it. My lathe would do it, but my tail stock would need to come off.
I have a lathe, and could do it if the lathe were just about a foot longer. I think it is long enough to mount a steady rest to support the crank at the rear seal surface, but the bed is not long enough to mount a tool holder at the rear. I think I might have found a shop about 3 hours from me that specializes in crank work. Spoke to the shop this morning and was told he should be able to do it. Couldn't give me a price but said their labor rate was $90/hr. I will wait a little while to see if something turns up closer. If not I will take my Lunati 170 crank, a stock 170 crank and a good 225 crank down, and possibly get all three done while he is "setup". Will depend on pricing. I'm thinking once he has the lathe setup, it shouldn't take more than 30 minutes each for the actual machining.
Actually, they could use a driven Dead center, maybe a drive dog then the rear main equipped with bearing fixture. (Two caps and some lube.) Put the bearing fixture into a steady rest, true it up, and go to town. Mike's lathe could do it and leave the tail stock on, but he has ten feet between centers. and a taper attachment ..fancy pants. CJ |
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| Author: | ceej [ Sat Apr 12, 2025 7:06 pm ] |
| Post subject: | Re: Crank maching question |
Cool! Let me know how it goes! CJ |
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