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#1 Front seat mounts
Posted: Mon Nov 10, 2025 9:00 am
by Knightrider
I have just started to put the interior of my series 1 2+2 back together, and hit a snag. The outside front mounting point for the front seat has come free from the chassis - I presume that there was a washer inside that has corroded away?
So I am now left with a 15mm hole that I cannot access the back of. What are the options? I thought about rivnuts, but an M8 or similar size rivnut would only fit a smaller 11mm hole.
#2 Re: Front seat mounts
Posted: Mon Nov 10, 2025 12:11 pm
by Gfhug
Simon, I’m happy to be corrected but I think you will need to weld in a new nut to the floor pan. If you look at your other seat fixings that you can see from underneath that will show you how they are. If the floor pan has rusted away at the seat attachment I should check all around for any other rust before progressing further.
Geoff
#3 Re: Front seat mounts
Posted: Mon Nov 10, 2025 12:26 pm
by Knightrider
Floor pan is solid - problem is that you can't get to the back without cutting a hole in the sill. Was wondering about using a jack nut which would fill a larger hole than a rivnut?
#4 Re: Front seat mounts
Posted: Mon Nov 10, 2025 12:46 pm
by mgcjag
Do you weld?....weld a nut to a small plate.....weld the plate to the floor/seat mount channel.....Steve
#5 Re: Front seat mounts
Posted: Mon Nov 10, 2025 2:34 pm
by Knightrider
Unfortunately not! If I can't find another solution I'll have to find someone to do it for me...
#6 Re: Front seat mounts
Posted: Mon Nov 10, 2025 7:55 pm
by abowie
An excellent time to go and buy yourself a MIG welder
Relatively inexpensive and easy to learn to use.
#7 Re: Front seat mounts
Posted: Tue Nov 11, 2025 3:25 pm
by Geoff Allam
3M and many other companies produce a 2 part adhesive labelled as structural panel bond or similar. Attach your preferred size rivnut to a small panel (should be an imperial size to match the original fastener). Then clean thoroughly the panel and the floor and bond the panel to the floor with a few small steel structural pop rivets for good measure.
#8 Re: Front seat mounts
Posted: Tue Nov 11, 2025 4:17 pm
by Knightrider
Not a bad idea! I'm not sure I want to experiment with MIG welding at this stage...
I think I might be able to achieve it with an M8 jack nut - should fit a 15mm hole. I might need a reducing sleeve to take the M8 down to M6 for a bolt to fit - just waiting for new seat mounting parts to arrive to test it...
#9 Re: Front seat mounts
Posted: Fri Nov 14, 2025 8:08 pm
by Knightrider
Quick update. Solved this by getting a bit creative - M8 Jack nut secured into the existing hole, inserted a M8-M6 reducing sleeve, allowing me to securely screw in the seat hardware with an M6 bolt.
Perhaps not pretty, but nice and secure without needing to resort to welding.
One step closer!