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TR6 Seat diaphragm failure on 2nd seat!


Freshman Member
Pardon - I'm learning here - this is my first post other than an intro!

I rebuilt the driver's seat about 4 yrs ago with foam/parts from Moss. The project's been idle until the last two months but I don't remember any problems with the first seat. I installed the seat diaphragm on the 2nd seat. All clips installed successfully but I went out this morning and there was a failure on 3 of the locations that pulled the small rod through the rubber. The garage and parts were not cold (Don't judge... I live in Texas and the garage was about 68F.) I ordered a single replacement diaphragm but after searching the forums and not finding any with this specific failure, I'm wondering if this is an installation issue (it's me, not you...) or a defective diaphragm. Any thoughts?


Country flag
Welcome to the British Car Forum!
It's been a long time since I replaced the diaphragms on my TR6. I can't say that you've done anything wrong looking at the pics.
I guess its possible that the quality of the rubber parts have deteriorated over the years due to inferior products being supplied to the vendors we buy from.
Have you contacted the supplier of the diaphragms?


Freshman Member
In fairness to Moss, I did inquire through their online system but there has not been sufficient time for a response. Since the first one did not seem to have the problem, I'm tempted to pull the other seat back out of the car and flip it over! I'll give Moss a few days to see how they respond.


Country flag
I’ve always found Moss to be customer service friendly. With the covid they might be operating remotely and it could take longer to reply. I’m sure they will find a solution for you.


Jedi Hopeful
Country flag
I had a pair of these fail in the same way after a few months. Dont remember where i got them, but there are some bad ones out there.


Freshman Member
Country flag
Not that this is necessarily what you did, but the last diaphragm I tore was from kneeling on the seat while trying to fix something. I felt a pop and sure enough, 3 of the clips had torn completely off.

It's possible, with a little extra grunt, to install doubled diaphragms if you want a little extra security (and possibly a little higher sitting position).


Country flag
I had the problem too, I don't remember where I got them, but drivers side failed a few years after redoing my TR250, I redid the seat properly with new seat foams (I had just recovered before) and has held up fine, I am not huge but not time at about 215 these days, sure that doesn't help. I think the new foams probably help spread the load better.


Jedi Knight
Country flag
It is most likely not you but it does not have to be pulled tight the foam does the work and the rubber keeps you off the carpet so use longer clips. Madflyer


Freshman Member
Country flag
I kneeled on my seat with a TRF diaphragm and it parted at the metal tabs as described in an earlier post; their part was very thin around the edges. The Moss replacement was much beefier and should last longer, but even with new foam a misplaced knee may wreck them.
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