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Discussion Starter #1
Does anyone know how many / what size the ball bearings are in the seat runners for the 05 Elise.

Mine only has a couple left each side, which means the runners have play.
 

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mine are loose on one side, is it even possible to free the balls ;)? I thought it might be sealed/crimped inside there.
 

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Discussion Starter #4
They are captive, but if the runner spreads a little then they can escape. I never found any in the car, but the previous owner may have cleaned them out, as the seat had play in it from when I got the vehicle.
 

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The play also causes the seat rocking (right?).

Would be great if someone could make a strengthened seat track that eliminates the rocking, but also keeps the ability to adjust the seat.
 

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Discussion Starter #6
Ok, upon further investigation I have found that the normal complement is two ball bearings per side of each track, one at the front, one at the back. ie there are 8 in total, 4 per side.

Each ball bearing has a limited run of about 10 cm, held in place by some crimps on the outer and inner runners.

The problem I am seeing is that if the balls get to the front or rear of its travel on both ends of the runner, then the seat is only supported on each side by two point contacts about 10 cm apart. This is why my seat always rocked back of forward a lot. Best case would be a much wider base of about 30 cm.

The bearings are about 6mm, but I'd need to extract one to measure, which may not be easy. If I added more per side, the same problem may exist as all the balls could group at the front or back of their run.

Other seat runners use a sliding carrier to hold the ball bearing where they should be.

I guess with the seat in place there is enough weight on the bearings to stop them sliding back and forward. The answer to the problem is to add sticky grease to prevent noise, then make sure the bearings are all centered in their travel before installing the seat.
 

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Discussion Starter #8
I measured the space between the runners as .310 to 0.320, so I think the balls are 8mm (0.315). There is a slight chance that they are 5/16 (0.3125).

The design is crazy. If all the balls end up in the middle, then there is only a 70mm 'base' for the seat, so the slightest play in the runners will cause the seat to rock around.

However, if the seat is moved fully forward and back with weight on it the balls should then move to the center of each of their tracks, making the seat more stable.
 
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