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TR2/3/3A TR3A Seat Tracks Binding

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71TR6

71TR6

Jedi Hopeful
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I planned to install the driver seat in my 59 TR3A today and it didn't go as planned.

I installed the new Moss floor tracks over the carpet and used a piece of plywood ripped to 12" to maintain the spacing between the floor rails while I tightened the screws. I checked the seat rail fit on the tracks to make sure I didn't warp the tracks when tightening the screws to the floor and they slid back and forth easily.

When I positioned the seat rails on the floor tracks and positioned the seat on top, I noticed the posts didn't match up with the holes in the seat pan. I expected this since I heard that replacement floor pans have the cage nuts in the wrong position. I elongated the holes in the seat pan to fit the seat rails, put a light coat of lithium grease on the tracks, placed the seat on the rails and tightened the 1/4-28 nuts. After doing this, the seat was locked in solid and wouldn't move. I've disassembled and reassembled multiple times and can't figure out what is causing the binding.

Does anyone have any words of wisdom on what might be causing the binding?

Ron
 
Try loosening the seat nuts and see if the seat moves. Then tighten them up progressively until you find the offending nut/nuts. Its really easy to put the seat in a bind.
 
I remember something similar on my MGB. Turns out that after installing the tracks over the carpet, the bolts were then just high enough to catch the seat, and prevent movement.
 
The MGB's had a wood spacer with holes, to lift the tracks above the carpet.There was also METAL spacers
that dropped into the holes in the wood to prevent crushing. IMHO it was a nice touch that could help in
a Tr3.....
Mad dog
 
Thanks for everyone's suggestions. I spent a few hours today dissecting the problem and I think I figured it out. It isn’t a seat rail issue after all.

I checked the floor tracks and they were flat as a pancake and completely parallel to each other due to the plywood board I used to set the spacing. Since I used 1/4" heavy washers to space the tracks and minimize carpet caused bending, I didn't expect any but nonetheless I used a digital angle gauge and a straight edge to see if there was a difference in front to back angle between the two tracks. Both tracks read zero degrees so there isn't any angular difference between the two that would cause binding. At the same time I looked for a gap between the track and the straight edge and didn't observe any.
IMG_3347.JPG
IMG_3371.JPG
IMG_3372.JPG
IMG_3374.JPG


I then looked at the seat bottoms. I put a straight edge spanning the holes and discovered one hole location was lifting the straight edge by over a 1/16” and another had almost an 1/8” gap. Hmm, this could be a problem.... so using a hammer and aluminum plate I beat the ribs on one side or another until the straight edge was flat spanning the holes as shown in the image.

IMG_3375.JPG


Before I reassembled everything, I draw-filed a radius on each of the mating edges of the rails and floor tracks, taking care to remove the shear burr that was on the mating sides of the track an rails. I had to use a needle file on the inside edge of the rails that mount to the seat bottom to remove that burr since a standard file was too thick. The radiused edges were then sanded with a few passes using 220 grit emery paper. All the mating surfaces were brushed with a light coating of lithium grease before reassembling everything.
IMG_3376.JPG


Once I tightened all the nuts, I was really happy to see the seat moved like it was on a stick of butter. I don't mind spending a sunday afternoon doing this when the results turn out positive.

I'm guessing the difference in the plane of the holes on the bottom of the seat, despite the tinfoil flexibility of the seat bottom, caused the seat mounted rails to warp when the nuts were tightened. On to the right seat to see if I can replicate the fix...

Hope this helps someone in the future!

Ron
 
Excellent. This is one example of the Brits actually under-engineering something. The seat slides are so simple they are affected by anything that is out of alignment. Later, the rear of the seat will depress from the force of the seat back...which then interferes with the slide. I went to the trouble to weld reinforcement into the bottom of the seat, to extend the life of the slide.
 
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