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MG MGB Technical - Seat Height

Following on from my captive nut post, ( thanks for the help ) I'm now ready to fit the seats back in. But with new carpet and felt, I now found my eye level is at the top of the windscreen, and when I've got the hard top on, my head is jammed against the roof. ( I'm 6' 2" ) I'm thinking of cutting a channel in the carpet and felt. The seat height without these is just about OK. Are there any other solutions?
c cummins

That's exactly what a friend of mine did. Not because he's tall. Since he made the cuts all the way to the back of the carpet, he can easily slide the carpets from under the seats for cleaning and drying, as they're no longer "trapped" by the seats. I'll be following his lead and I'll also trim an inch or so of the seat foam when I re-trim my seats with new foams. I'm 6'-2" as well and don't want to be sticking up in the slipstream.
Derek Nicholson

These seats originally ran on wooden 'slides', each drilled to hold an aluminium spacer for each of the four securing bolts. I understand some owners have upgraded the wooden slides to aluminium.

I assume the original idea was to keep the sliding mechanism clear of possible jams with carpet and, possibly, to provide some degree of spread of the distributed weight (seat plus load) given flex through the floor pan as the body responds to road conditions. Without this there would be additional stress on the steel of the floorpan at the mounting points. Perhaps not a great issue where the front bolts pass through the crossmember, but interesting at the rear points, especially in cases of rust affected floor surfaces.

I can understand your frustration but it might be wise to consider whether you want to install the original set-up and look to reducing height by making adjustments to the seat base structure to gain the additional space you need.

I am assuming you have maxed the rake of the seat back?

Regards
Roger
Roger T

C. The seat rails are 1/4" thick. I do not have new carpet and jute, so I am not sure how deep that is. When compressed by the seat rails, and over a period of years, the factory carpet is about 1/4"-5/16" thick under the seat rails. Thus, if you are to do away with the seat rails (packing strips) completely and cut out the carpet to allow it to fit around the seat, but not under it, you can pick up about 1/2" of lowering. Not sufficient, in my experience.

What I did, after consulting friends in the upholstery business, was to take about 1" off of the bottom of the new seat foams. A common cross-cut wood saw is used to remove the bottom of the seat foam. A series of marks are made along the front, 1" above the bottom and a mark at the rear about 1/2" from the bottom. The lines are connected using a magic marker, or similar instrument. The cut is made with the saw and any trimming needed was done with an electric carving knife. The seat covers were re-installed and a seated height difference of about 1.5" was noted. Actual change is seated height/view out the windshield was affected by the removal of some foam, the remaining foam being slightly softer, and the slight angle change of the upper face of the seat cushion. These items, in combination, will affect both how high you are above the car floor and the point at which you see through the windscreen.

This provides you with a basic reference/starting point. If there is insufficient lowering of the line of sight, one can decide whether to cut the carpet and do away with the seat rails to gain additional lowering.

Angle of the rear of the seat should not be used to make for a lower line of sight--if at all possible. The seat is adjusted-fore/aft, to allow one to comfortably reach all of the pedals and exercise proper control over them. The rake (angle) of the seat back is adjusted to allow the proper hand position on the steering wheel when the seat is positioned for proper pedal access. The, the purpose of the two adjustments is to optimize the position of the seat so that the driver will have the maximum ability to control the car.

When viewed from that perspective, excessive adjustment of the rake of the seat can be considered undesirable and something to avoid. If possible.

Les
Les Bengtson

I am also tall (6'1"), and found that I can see quite well under the windshield frame in my current MGB. But I have noticed on friend's MGBs that I usually have the windshield frame right in my line of sight. In my car the membrane under the seat cushion has given way alittle, which seems to make for perfect seating height for me. If it gives way fully, I plan to use some lawn chair webbing and custom-make the seating height so that it is right for me. Les, Cutting off the bottom of the cushion seems like a good way also, but does it not cause the seat covers to look "empty"?

Derek - further to the point about the carpet - Both my cars came with rubber floor mats with insulation material under them. The foot well area mats were removeable, the under-seat mats were sandwiched between the seat rails and the floor, with the wooden spacers in there too. In my first car, the floors were somewhat rusty, way worse under the seats, because you couldn't easily remove the mats to let the floor dry, and the fact that they were rubber meant that they sealed any moisture in.
What I did is cut the rear mats in half, cross-ways about mid distance from front and back edges of the seats, and slots in each piece from the centre cut. This way, I could slide each half out from under the seat, and let the floor dry when needed. The mats looked totally stock, because it was hard to see the cut between the seat and the frame rail, and impossible to see it between the trans tunnel and the seat. I find it absolutely necessary to dry these areas from time to time, because any driving in the slightest of rain seems to lead to water coming in (at least in my roadster).

Erick
Erick Vesterback

Erick. No, the seat covers do not look "empty". They still fit, perfectly, the upper portion of the seat foam. The material at the bottom, even with the standard foams, is wrapped around the bar that forms the bottom of the frame and attached to it with circular clips. On the three cars we have done this simply results in a little more material being gathered at the bottom. If there is too much excess material, it is trimmed off the bottom before fastening it down.

I might mention that one of the cars was a GT which, having a higher windscreen, might be perceived as not needing this modification. Untrue. With the new foams, my head was in contact with the roof of the car. (But, I could see outside fine.) We used new diaphragms, new foams and new covers, two covers from Moss and one set custom made. All fit well.

Les
Les Bengtson

Les - of course - that makes perfect sense that the material gets wrapped around tighter - forgot for a moment how the seat material gets attached. When I need to, I will replace the diaphram, forget the lawnchair-style webbing, and remove some of the foam from the bottom. Thanks for the tech-tip.

Interesting about the GT headroom. In my roadster, I have a good 3-4 inches of headroom with the top up, yet if I sat an inch higher, I'm sure the top of the windscreen would be in the way. Even as it is, I find myself ducking down to see traffic lights.

Erick
Erick Vesterback

The seat rails in my 69 are in direct contact with the floor. The carpet is cut to shape around the rails. Can't see any advantage to having carpet intefer with the seat attachment to the floor panel.

My reference to maximising the rake of the seat back assumed to the point of driver comfort/convenience only. I was not suggesting it be laid flat just to gain room.

Regards
Roger
Roger T

Was sitting in the backyard an hour ago and thinking MG and this board. Had a sudden mild panic attack realising I might possibly have caused some confusion in my last post. There I said (in my car) 'The carpet is cut to shape around the rails'.

Two points of clarification are needed:

1 its the wooden 'slides' which are cut around, and
2 its the underfelt which is cut to shape around those slides. The carpet fits over the slides, the seat rails sitting atop that.

The effect though is to both avoid the heightening effect of the underfelt sitting between the slides and floor, and to maintain the slides/spacers in direct contact with the floor steel.

Regards
Roger
Roger T

This thread was discussed between 24/03/2007 and 27/03/2007

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