Link Pins loosen up

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Brad Ripley
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Re: Link Pins loosen up

#16 Post by Brad Ripley » Tue Nov 19, 2019 8:02 pm

In my experience one should always check the stub axel for straightness of the axle and the angle of the steering arm. Porsche tool P 69 is applicable for checking of parts of the axle; see photo below. The two bushing in the photo are adaptors for 356C axles. Also, another Porsche tool, P 70, is useful to check for parallelism and twist; I don't have a photo of that tool. All this can be found on pages S18 thru S22 of the B/C Workshop Manual.

I bigger problem is twisted and bent C-links. The C-link should be checked. There was not a Porsche tool for that but you could make one. I can send a photo of a homemade version of that tool if someone is interested. I guess as many as 20% of c-links are bent. You cannot straighten them with a big bar or hammer. Buy a new one. BTW, VW links must be machined to be used in the Porsche application.
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Juha Vane
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Re: Link Pins loosen up

#17 Post by Juha Vane » Wed Nov 20, 2019 2:18 am

Noted also loose link pins in my 356.

Brad, please send me a photo of the tool and could you tell
what need to be machined in VW links if it is not very obvious.
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Jon Bunin
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Re: Link Pins loosen up

#18 Post by Jon Bunin » Wed Nov 20, 2019 3:27 am

Brad Ripley wrote:
Tue Nov 19, 2019 8:02 pm
... Also, another Porsche tool, P 70, is useful to check for parallelism and twist; I don't have a photo of that tool ...
Here are both tools...
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Harlan Halsey
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Re: Link Pins loosen up

#19 Post by Harlan Halsey » Wed Nov 20, 2019 4:04 am

It won't be long before someone points out that the P 70 trailing arm tool doesn't work very well for the lower arm because the sway bar mount interfers with the long pin. We get around that in several ways, but it has ocurred to me that one of those laser bore sight cartriges could be mounted in a shortened bar and a target put on the other alignment pad.

As for straightening the C links, Ron does that as a matter of course. That's just part of the king pin/link pin bushing job.

BTW: Doug at Techcraft line hones the new king pin bushings for us. That does a better job than the VW reamer. Not that the reamer doesn't do a good enough job, but if you've got the equipment.....

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Joris Koning
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Re: Link Pins loosen up

#20 Post by Joris Koning » Wed Nov 20, 2019 4:52 am

Is there anybody out there who straightens control arms? I have heard of this being done. With the supply of straight arms getting less and less it would be a worthwhile service to the hobby
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Re: Link Pins loosen up

#21 Post by Jon Bunin » Wed Nov 20, 2019 4:55 am

Harlan Halsey wrote:
Wed Nov 20, 2019 4:04 am
It won't be long before someone points out that the P 70 trailing arm tool doesn't work very well for the lower arm because the sway bar mount interfers with the long pin...
Not true Harlan, the sway bar mount does not interfere. When the rubber bushing is removed, the pin passes through the mount.
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Re: Link Pins loosen up

#22 Post by Jon Bunin » Wed Nov 20, 2019 5:06 am

Jon Bunin wrote:
Wed Nov 20, 2019 4:55 am
Harlan Halsey wrote:
Wed Nov 20, 2019 4:04 am
It won't be long before someone points out that the P 70 trailing arm tool doesn't work very well for the lower arm because the sway bar mount interfers with the long pin...
Not true Harlan, the sway bar mount does not interfere. When the rubber bushing is removed, the pin passes through the mount.
Example from the manual, on a lower arm...
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Al Zim
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Re: Link Pins loosen up

#23 Post by Al Zim » Wed Nov 20, 2019 12:19 pm

The tool to check the offset on the "C" carrier is a VW 259. Remember you can easily bend the "C" carrier if you are using a heavy press to remove the king pin. I have mad a tool to TRY and straighten the trailing arms. One of the tools is a a solid thick round 6 foot steel rod. When I was 300 pounds I was able to do some small straightening. Now that I am 200 pounds that activity seems to have alluded me. al zim
 

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Re: Link Pins loosen up

#24 Post by Martin Benade » Wed Nov 20, 2019 12:52 pm

My old-school European mentor would heat and straighten most any suspension part, with good results. I always wondered what that did to the strength, but he never had a comeback.

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Re: Link Pins loosen up

#25 Post by David Jones » Wed Nov 20, 2019 1:53 pm

The "C" link or "dogbone" king pin carrier is a VW part that is machined on the inside face where it contacts the face of the suspension arms and quite frankly I do not understand why Porsche chose to do that. The only difference that becomes apparent on installation is that one must now use the Porsche rubber seal over the shims instead of the VW "O" ring that is I guess installed on the link pin to prevent incursion of water to the shim pack and link pin bushing. I have on more than one occasion used the VW part out of sheer laziness when I had more than a few VW parts lying around as I used to bend them occasionally when racing the F Vee. There may be a good reason not to use the VW part unmodified but someone with a higher pay grade will have to tell me why.
My to do list has the left side "C" link listed as an item to be taken care off this winter so I am still running an unmodified one as of now. I have one ready to go but for machining off the inside face. I can post a picture if anyone needs it.
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Vic Skirmants
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Re: Link Pins loosen up

#26 Post by Vic Skirmants » Wed Nov 20, 2019 2:16 pm

Porsche used the VW C link with no mods through 1955.

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Re: Link Pins loosen up

#27 Post by David Jones » Wed Nov 20, 2019 2:23 pm

Vic, does that mean that they just used a VW stub axle complete and the only difference at that time to a VW was the larger aluminum drum?
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Don Gale
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Re: Link Pins loosen up

#28 Post by Don Gale » Wed Nov 20, 2019 7:26 pm

In lieu of VW tool 256, one could accurately measure the straightness of the trailing arms with a surface plate, height gauge, a set of Jo blocks, and a precision ground hardened round, 18mm (approx. $20 on McMaster-Carr for a 12" length). Parallelism and skew can both be measured in 2 separate setups. As for straightening, I would avoid heat, not knowing the metalurgical state the arms were forged to and subsequently heat treat. (although there are numerous shade tree shops in the south valley who skillfully momentarily apply a torch to coil springs and leaf springs to create lowriders under their own weight).

If the arm is only marginally bent, I would probably fixture it and use Al's method with a beefy chunk of steel. One can reasonably assume if bent, it was the result of a curb, pothole, or minor crash. For impact loads such as that, the yield stress is effectively doubled, in which case it would be better to straighten it with a judicious whack as opposed to steady static muscle.
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Re: Link Pins loosen up

#29 Post by Vic Skirmants » Wed Nov 20, 2019 7:56 pm

David Jones wrote:
Wed Nov 20, 2019 2:23 pm
Vic, does that mean that they just used a VW stub axle complete and the only difference at that time to a VW was the larger aluminum drum?
David; that's pretty much as I see it. The tie rod hole was the small VW size, so all VW.

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Re: Link Pins loosen up

#30 Post by Martin Benade » Wed Nov 20, 2019 8:00 pm

Are the left and right upper arms the same?

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