Fatboy Gimball Tonearm Install

Fatboy Gimball Tonearm Install

Postby Shep » Thu Dec 20, 2018 6:43 pm

Just received my Fatboy gimball upgrade for a 3DR unipivot (both 10") on a Prime Signature...Merry Christmas to me!!
Problem is that it came w/no instructions or tools and I'm already at an impasse. I've looked on VPI website but don't see anything there related to the Fatboy (other than the promo photo) so if anyone can point me to something there I'd be grateful.

In the meantime, the first step is to remove the unipivot from the arm borad. Per the dealer, it takes a hex key for the retaining nut underneath but it's impossible to see as the hex bolt head is concealed within the opening of the retaining nut. I've tried a dozen different sizes from tiny to anything that fits in the hole opening but no luck. None of the hex keys that came with the TT fit.

If there's anyone who's made this swap that can offer assistance, I'd be most appreciative. Will I need to dismantle the TT in order to make the swap?

TIA for any help.
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Re: Fatboy Gimball Tonearm Install

Postby Brf » Thu Dec 20, 2018 7:08 pm

I just installed mine, very easy. First, you must remove the old pivot spike off your existing dog leg platform.

Step 1 - loosen the grub screw which is located in the side of the dog leg platform beside the pivot spike
Step 2 - remove the threaded nut that holds the pivot spike. The retaining nut has a flat spot to allow the use of wrench. Remove the old spike
Step 3 - your Fatboy should have come with a little round metal bushing spacer. This spacer goes in the hole of the dog leg platform. Lightly tighten the grub screw to secure the spacer.
Step 4 - insert the Fatboy into the dog leg platform, install the retaining nut and tighten. Note. Before you fully tighten the Fatboy, make sure that the outer gimbal ring does not interfere with the full movement of the arm.

Good luck
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Re: Fatboy Gimball Tonearm Install

Postby jonathanb » Thu Dec 20, 2018 8:02 pm

Brent, will those instructions work with this type of arm base assembly?

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Re: Fatboy Gimball Tonearm Install

Postby Shep » Thu Dec 20, 2018 8:11 pm

Thanks jonathanb, that's my platform as well...no grub screws per Brent's Step 1.

I'm considering using pliers at the bottom of the unipivot base but afraid of damaging the finish.

I think after the pivot base has been removed, it's a breeze but....
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Re: Fatboy Gimball Tonearm Install

Postby 10ovr » Thu Dec 20, 2018 8:27 pm

A little duct tape around the base and remove with pliers,,Once you crack it loose you can remove it by hand ImageIMG_1357 by Tim Morgan, on Flickr
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Re: Fatboy Gimball Tonearm Install

Postby Shep » Thu Dec 20, 2018 8:40 pm

Bingo! Just finished the same and got it off. Installing the FatBoy should be no problem.
At least it's documented here now for those that make the switch in the future.

Thanks all for your prompt and useful assistance.
Merry Christmas!!
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Re: Fatboy Gimball Tonearm Install

Postby Shep » Mon Dec 24, 2018 1:43 pm

Just wanted to circle back with a couple observations re: the Fatboy after getting it installed and setup:

In the first photo, you’ll see the effect of using the washer/spacer with the Fatboy in my setup. With it in place, it makes the tonearm queuing unusable due to the large gap between the bottom of the tonearm and the queuing platform. It works fine and sets up well w/out the spacer but just wanted to make sure that it’s OK to use without?

In the 2nd photo, you’ll see that a single twist of the lemo connector in either direction removes the normal loop/arc in the wire. When configured this way, the effect is to push the tonearm straight up from a neutral, balanced position. Basically, it’s useless for anti-stake/bias compensation and I’ve not had this with either of my two previous VPI arms. I’m using the mechanical bias adjustment w/out issue but just wanted to check if this is a change for the Fatboy arm?

I've sent this to the dealer as well and will update here with their response but also wanted to include here for others converting to the Fatboy.

Any comments or insights re: these conditions would be welcome & appreciated.

Merry Christmas to all!!


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Re: Fatboy Gimball Tonearm Install

Postby Brf » Mon Dec 24, 2018 2:44 pm

The Fatboy spacer provided is not to be used as a tonearm riser as denoted in your first picture. The spacer is provided to reduce the diameter of the pivot spike opening in a dog leg platform that is not threaded (like most 12” vta towers).

The impact of the lemo wire twist can be mitigated with some manipulation, but I personally like a neutral wire harness and use the mechanical a/s device.
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