Floor board seals

Could anyone tell me what seal material and its thickness that goes between the floorboards and chassis. Do the floorboards sit down flush with the metal bodywork or stand proud?
Thanks in advance

Depends on what model and body style, and if you have plywood or steel floors.

Oops: XK150 FHC 1960 Plywood floors

Hi Mike…i have new floorboards ready to go into my 1960 150 fhc…there is no seal mentioned in the parts catalogue where the wood sits on the steel floor and body and no sign of sealant on the floors i took out…however there is the thick felt(available from usual suppliers) that sits on top of the chassis under the floorboard. …im replaceing the felt with thick neoprean. …Steve

Steve, my ‘original’ has signs of mastic and some cloth-like seal. This seems like an easy route for water to get in (although most of our cars are dry weather only, but I may chose to do a rally to two). I tried 3/8 this sealed-cell neoprene but then the boards stood proud of the metal surrounding the metal bodywork. I am still working the problem including the relative positioning of the gearbox tunnel and if that has seals. Once again the forward face of the tunnel looks as if it needs a seal. Like you I have not found and reference in the books.
Thanks for your response.

It wouldnt be difficult to fit thin aluminium sheet from underneath to fully cover the wood floor and lip it over the body metalwork that the floorboard fixes to with a neoprean seal around its perimeter…Steve

My 120 had 1" wide felt strips.

Edit: 120 and 140 have the felt strips, but I did not find them listed in the 150 SPC.

Hi Rob is that on a 150…Steve

I used automotive butylcord accordingly. It does not get hard and is especially convenient to seal between two flat surfaces e.g. chassis and floorboard.

Best Regards


Thanks to all for the help, with your advice and a bit of common sense I now have the floorboards in. Which leads to the next problem. With the boards in place and the gearbox tunnel in position I notice that the forward face of the gearbox tunnel ( a sort of hood or flange) fits on either side but has a 7/8 inch gap around the top. Very strange!
My car is LHD but the bulkhead has a cutaway on the RHS which is I presume for clearance for the throttle pedal and foot. I guess American feet did not need extra room. Or has someone been cutting and welding? Nothing suspicious on teardown.

I also have the large gap around the top of the tunnel…not sure why…photo of your cutout would help…Steve

Here are some pics. Pic 2 & 3 are taken from the side - where you can only get the camera, not your head. Note: gearbox is Tremec. Dynamat heat shield covering of most metal parts. My question is: has this car been modified or not. No other indications of rework during body repair.


My tunnel is the same as yours…1960 Rhd xk150 …flatter shape on the right hand side…and the gap at the top of the tunnel…Steve

Bizarre, how did you attach the tunnel ‘bonnet’ section to the bulkhead extension. Screws with spacers, foam packing. Do you get fumes from the engine bay?

Hi…only recently dismantled mine…so not reassembled it yet…it did need some work as it had been butchered by a previous owner i assume to remove the gearbox and overdrive without removeing engine…under the carpet mine was all paded out with under felt. …if you google xk150 gearbox tunnel you can find photos showing layers of felt bring used…Steve…example below

Thanks Steve
I saw the google site and feel better that the tunnel is correct on my car. I’m still baffled about how the flange is attached to the bulkhead. Can you see that on your car?

Hi Mike…my tunnel was only fixed at the sides. …there are top fixing holes in the tunnel but no idea how it was fixed originally to deal with the gap…Steve