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Seat diaphragm replacement

Posted by 2-74mgbs 
Moss Motors
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2-74mgbs Avatar
John Galvao
Haddon Heights, NJ, USA   usa
I'm redoing my seat upholstery and need to replace the diaphragm, actually I think this is a weak point in the seat. Has anyone replaced it with wood or metal? or even jute webbing?
I think the foam and additional foam cushion that I'm using is more than sufficient to make it comfortable. Any ideas on this subject???. Thanks.John G.

ClayJ Avatar
Clay Johnston
Mt. Olive, MS, USA   usa
1972 MG MGB
You would notice the lack of webbing on large bumps. IMHO, do the webbing.

RAY 67 TOURER Avatar
Ray Marloff
Fort Bragg, CA, USA   usa
1967 MG MGB "My Girl"
The diaphragm design is actually quite strong. They are a bear to replace due to their inherent strength. Heating with a hair dryer makes them pliable and much easier to install. Doing away with them will result in a very hard ride. RAY

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spikemichael Avatar
Michael Caputo
Aberdeen, WA, USA   usa
1973 MG MGB
1973 MG MGB "Freebie"
1974 MG MGB "Spike"
1979 MG MGB "MegaBeanie"    & more
I did a how to thread on gaining leg room. In it I tried 1/2" plywood and it was a BAAAAD idea. I settled for pegboard that a driving season later I still enjoy.

Michael J. Caputo
'79 RBB and '73 CBB owner with extensive experience in 12v Audio System design and installation.
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2-74mgbs Avatar
John Galvao
Haddon Heights, NJ, USA   usa
I appreciate the suggestions and ideas... I think at this point I might just order new rubber diaphragms. The ones I have now are ripped at the stretching hooks, beyond repair.
I'll be looking for additional input. The pegboard idea seems good! Thanks guys.

CDBaker Avatar
Christopher Baker
Daphne, AL, USA   usa
1974 MG MGB GT "Libby"
1975 MG MGB "Little Green Car"
When I redid the front seats for my 66BGT I took all of the parts to a local upholstery shop and asked for the oldest guy there. Out walked a 75 year old guy that new immediately what car and the year range they came out of. I understand that stretching the diaphrams is a PITA and if it is not done correctly means you rip them and have to buy more. Because of that and because I did not want to rip my new leather seats and have the piping straight I had the shop assemble them. I think it was about 100 for both of them and in my opinion is money well spent.

Fairfield, CA, USA   usa
You need a bottom.

I have used lawn chair plastic webbing in an early car. Worked just fine, a bit stiffer than the straps that car used, but easier to install and lasted quite awhile too. A pain to fasten and I can't recall just how I did it back then (about 40 years ago)

1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed

2-74mgbs Avatar
John Galvao
Haddon Heights, NJ, USA   usa
I was checking Moss Motors catalog and sure enough, I may have older seats. The MGB is 1974 and should have webbing. The existing seats have the rubber diaphragms. Thanks for the info. / I'm getting closer to a decision. I have two MGB's, both '74 but completely different interiors, seems one is early 74 and the other later.

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purdysmg Avatar
John Harrison
Gjettum, oslo, Norway   nor
1978 MG MGB "Topless Go Go Girl"
I did my original seats in the 75 this summer and they had diaphragms from the factory. Have used both style of seat supports and find the diaphragms easer to install. Use an old hand held paint roller with the roller removed. Place the 4 metal hooks over one end of the seat near the back frame and use the paint roller tool to pull up on the oposite side hooks one at a time. I can install a diaphragm in under 4 minutes this way. I find little if any difference in comfort using the webbing.

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