What rubber grommet/spacer to get a bridge cover onto a 4001?

[DesolationBlvd]

I use the pickup cover on my Precision as a palm rest while picking, and I'd like to do the same with the 4001 that was missing its bridge cover. But when I bought the official replacement pickup cover, it sat way too low above the pickup. What's the size of the grommet/spacer to get it at the right height?

[espidog]

There is no rubber grommet or spacer used.

By the sound of it, I think you may be fitting the cover in the wrong way. The baseplate of the pickup goes at the bottom end of the adjustment bolts, then there's a long spring on each bolt. The pickup cover goes at the top of the springs (and they exert the upward force that holds it against the underside of the chrome surround).

I hope that description makes sense.

[DesolationBlvd]

There is no rubber grommet or spacer used.

By the sound of it, I think you may be fitting the cover in the wrong way. The baseplate of the pickup goes at the bottom end of the adjustment bolts, then there's a long spring on each bolt. The pickup cover goes at the top of the springs (and they exert the upward force that holds it against the underside of the chrome surround).

I hope that description makes sense.

OK, I just tried that...is the cover supposed to be this high?

[espidog]

Yes, that looks right.

[nov_1981]

http://www.rickenbacker.com/pdfs/bpickups.pdf
This may help

[DesolationBlvd]

Yes, that looks right.

Thanks. I actually tried that a long while back and thought it wasn't right, so I removed it. I'm keeping it on now.

http://www.rickenbacker.com/pdfs/bpickups.pdf
This may help

Funnily enough, that diagram threw me off in the first place. It showed base plate < grommet < pickup cover < spring < pickup ring < screw, as opposed to base plate < spring < pickup cover < pickup ring < screw which is working for me now. Maybe they changed it during the transition to 4003?

[jps]

The old cover on 4001 basses were "shorter in height" (Genesis reference) and fit just underneath the pickup surround (above the springs). Those did not move with the pickup when adjusting the PU height. Later ones are around 3/4" taller and do fit under the springs and ride up and down with the pickup as it is adjusted.

There should be some sort of spacer to provide enough clearance between the top of the pickup and underside of the cover. You can probably gauge the height required by how much clearance you need to avoid hitting the top of the strings with the pickup at the desired height.

[DesolationBlvd]

The old cover on 4001 basses were "shorter in height" (Genesis reference) and fit just underneath the pickup surround (above the springs). Those did not move with the pickup when adjusting the PU height. Later ones are around 3/4" taller and do fit under the springs and ride up and down with the pickup as it is adjusted.

There should be some sort of spacer to provide enough clearance between the top of the pickup and underside of the cover. You can probably gauge the height required by how much clearance you need to avoid hitting the top of the strings with the pickup at the desired height.

Thanks. That explains everything, including why the cover sits so high. But the cover didn't come with any kind of spacer, which is what led me to ask this question to begin with.

I'll live with a slightly high pickup cover for now.

[jps]

...the cover didn't come with any kind of spacer, which is what led me to ask this question to begin with.

I'll live with a slightly high pickup cover for now.

IIRC, on a couple of the 4003 basses I've had, there was either a spacer integrally built-in to the baseplate, or there were a bunch of black plastic washers stacked up that provided the needed height.

The washers make for a great way to tailor the height of the cover as desired. You should be able to buy nylons washers at your local hardware store. Get a bunch and experiment.

[espidog]

One factor to keep in mind if using plastic washers/spacers is that the pickup cover's chrome finish is conductive and thus should contribute to electromagnetic screening. Placing plastic spacers between it and the metal bezel will reduce the surface area of contact between the cover and the bezel.

[doctorwho]

FWIW, the spacer shown in the RIC exploded treble bass pickup diagram is a #10 nylon washer, the same that was (is?) used on the strap bolts to protect the finish. If the pickup cover is still too low with the pickup properly assembled, it might be possible to gain some extra height by using nylon spacers that are thicker than the washer (which is very thin). (I have used such nylon spacers as stand-offs for DIY circuit boards, but not on a bass pickup, but I think it could work.)

[DesolationBlvd]

Updating, now that I put the spacers in. I found that 1/2" spacers off the base plate helped lower the cover some compared to having it right against the pickup ring, but it's still a little high. But going down to 3/8" or 1/4" will have to wait until next string change.