1980's LP12 bearing bolt torque value

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vinyl4me
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1980's LP12 bearing bolt torque value

Post by vinyl4me »

Hello,

New to this forum, so this is my first post here.

I have a 1980's LP12 that have been in bits for quite a while.
Yesterday, I was trying to find torque values for the main bearing bolts, but failed.
The subchassis is the pre-circus expoxied steel one. The bearing has black, vented liners.

I have seen Linn recommend to tighten the bearing bolts "...as much as possible, avoiding distortion of the chassis...".
If anybody here could come up with a ball park torque value for these bolts, I'd be very grateful.

I'm a big fan of the tune-dem method and it still surprises me that it isn't more widespread.
I also happen to like the sound of the Valhalla, pre-circus, mid 1980's LP12 a lot.

Pete
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Re: 1980's LP12 bearing bolt torque value

Post by beck »

Welcome vinyl4me!

I am sure ThomasOK will find time to answer your question at some point. :-)
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Re: 1980's LP12 bearing bolt torque value

Post by vinyl4me »

Thanks!

I believe that I can appreciate what is meant by "as tight as possible", while avoiding "distortion of the subchassis", but I just thought I'd ask on this forum, since there seems to be a lot of experience/knowledge here when it comes to torquing various bits of the LP12.

Pete
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Re: 1980's LP12 bearing bolt torque value

Post by ThomasOK »

Pre-Cirkus can be a bit difficult so I'm not sure I can give you exact torques. Most pre-Cirkus bearings used hex head screws with domed heads and take a 2mm bit. I don't have a torque for them as any of the torques I have used on bearing housings would likely strip out the head. So I would recommend just getting them as tight as you reasonably can. The last version or two of the pre-Cirkus bearings use a bigger cylindrical shaped hear that takes a 3mm bit. These I torque to the same torque I use for a Cirkus housing/sub chassis which is 3.4Nm even. I haven't thoroughly tested this using tune method as I have only done a couple of them and didn't have the turntables for enough time. But as they are using the same size bolt and are attaching to a steel sub chassis (just not as thick a one as the Cirkus sub chassis) I expect it should be good. But it couldn't hurt to try some values around that one to see if it gets any more musical.
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Re: 1980's LP12 bearing bolt torque value

Post by vinyl4me »

Thanks for your reply. I'll try the 3.4Nm and see where that gets me, but I'm guessing it will be excellent and also glad that the bearing bolt torque doesn't appear to be all that critical - seems like "...as much as possible, avoiding distortion of the chassis..." might be an apt description after all ;-)

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Re: 1980's LP12 bearing bolt torque value

Post by ThomasOK »

Actually it can make a quite noticeable musical difference when it is able to be applied. It is especially important on the Karousel in my experience, but certainly audible on Cirkus bearings and also different on the Keel, the other aluminum sub chassis and the steel Cirkus sub chassis. In the past many things on the LP12 were over tightened due to the early Linn training to make things "Linn tight". So it is not unusual to find things over-tightened when working on older LP12s. This definitely leads to less that the best musical perfromance. Unfortunately, some Linn dealers still over-tighten things although I believe fewer as time passes.
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