Floor Pan Replacement
Discussion
OK - there are several threads about this but bear with me. I would like to do it myself and I will write it up and take photos as I going along to put a walkthrough on Nobleparts and elsewhere. I should add that I am an accountant so if I can do it then most others should be able to although I do have the benefit of a garage lift.
Now I have started with the front panel as that looked the worst - there were some gaps at the front and it was clear that water had been sat on top of the floor pan with loads of other s
t.
So questions:
Are there any other essential jobs to do whilst the floor panels are off? The car is a late 2005 M400 and generally garaged since I bought it so not in bad condition.
I plan to rivet the floor back on as I believe this will give a better seal than screws which can be a bit hit and miss back into steel. Also quicker to drill them out than remove the screws again.
I have the Sikaflex and Hammerite ready to go.
Anyother comments, suggestions or tips?
Thanks....now back to the rugby
Now I have started with the front panel as that looked the worst - there were some gaps at the front and it was clear that water had been sat on top of the floor pan with loads of other s
t.So questions:
- I presume you can replace one section at a time and not have to do them all together - is it recommended to do them all at once?
- For the centre section - can it all be done from below the car or do you have to remove the seats and carpets (more tools required if I have to remove the seats). Does it damage the carpet?
- On the front section I have removed all the rivets and left with 6 hex bolts to remove. I learned from the other thread that there are held by nuts that can be accessed from under the front clam - I have looked but nothing obvious - do I need to remove anything else. Any photos of where they are to guide me.
Are there any other essential jobs to do whilst the floor panels are off? The car is a late 2005 M400 and generally garaged since I bought it so not in bad condition.
I plan to rivet the floor back on as I believe this will give a better seal than screws which can be a bit hit and miss back into steel. Also quicker to drill them out than remove the screws again.
I have the Sikaflex and Hammerite ready to go.
Anyother comments, suggestions or tips?
Thanks....now back to the rugby
To keep it all together for the time being - here is an email I received from Chris Parkin (which I am sure he won't mind me posting) 
"There is no reason you can not attack one section at a time.
You need to take off the front clam to get the the 6 bolts holding on the front section, there you can see the nuts going through a small area of box section, they can be difficult to get to so you may have to take off the power steering fluid cooler and oil cooler to get to them.
For the cabin floor pan i would take out the seats, 4 allen key fixings per seat, they used a air ratchet to fit them in the factory, so if they have not been out before be carefull as 3 out of 8 on mine were cross threaded and they can round off very easily, the floor will drop down with carpet attached although there are certain areas like the two chassis bras in front of the seats where there is insulation glued to the floor pan and then the carpet is glued to the insulation, this can cause damage to the carpet whilst unpealing, i think it is best to have a spatula ready to unstick the insulation from the floor pan and leave it stuck to the carpet, as this area of carpet on mine was stuck the the chassis and not the floor pan.
Use a 5.5 mm drill to take the heads off the rivets, any that get left suck in the hole drill them out with a 3.5mmm, or tap them into the chassis member with a punch. I can understand why you would want to re rivet but i think you will find 4mm S/S self tappers bite into the existing holes perfect, just in case you decide to go for that option, as imo rivets do not always give a good seal, they compress the panels togethers but the shanks do not always expand to fill the hole in the chassis member, allowing easier ingress of water, (if water gets under the rivet head).
Not sure if you have done the radiator before, but if not, some of the screws can be a bit tricky to get the fan housing out, and you have to take off the top fixings of the radiator then rotate the radiator to nearly vertical to get to the bottom fixings, and then release the side splash guards to gett it out, just give me a shout if you need any advice with this one.
Personally, seem as though you have full access to the tunnel i would recommend the tunnel cooling mod, very easy mod once you have the radiator and floor pans off and if you have not already done it, it is also the pefect opportunity to run new silicone coolant hoses, spray a little WD40 on the shifter, adjust the hand brake cable etc..
Other non essential mods, like the bits of padding that trim the tunnel are bolted through, this will be your best oppotunity to get the the nut heads, i took out the screws and refixed with velcro, for easy future removal in case of need for retrim just in case they ever get torn etc..it will also be your best opprtunity to add/change instrumentation on centre panel, change bulbs etc..although not an esay task you can modify the fixings holding the centre panel for easier removal (for future purposes), i.e instead of bolts and nuts, you can change for expanding plastic clips, (can get them from Halfords) glue to the back of the centre console with epoxy resin, if you ever need to take it off again you can pull it off from inside the cabin breaking the plastic clips get access to the bulbs wiring etc.. then replace the plastic clips again, then re-attach the centre console, i know you like your electrics so this mod may be ideal for you."
Some great advice there that is much appreciated
"There is no reason you can not attack one section at a time.
You need to take off the front clam to get the the 6 bolts holding on the front section, there you can see the nuts going through a small area of box section, they can be difficult to get to so you may have to take off the power steering fluid cooler and oil cooler to get to them.
For the cabin floor pan i would take out the seats, 4 allen key fixings per seat, they used a air ratchet to fit them in the factory, so if they have not been out before be carefull as 3 out of 8 on mine were cross threaded and they can round off very easily, the floor will drop down with carpet attached although there are certain areas like the two chassis bras in front of the seats where there is insulation glued to the floor pan and then the carpet is glued to the insulation, this can cause damage to the carpet whilst unpealing, i think it is best to have a spatula ready to unstick the insulation from the floor pan and leave it stuck to the carpet, as this area of carpet on mine was stuck the the chassis and not the floor pan.
Use a 5.5 mm drill to take the heads off the rivets, any that get left suck in the hole drill them out with a 3.5mmm, or tap them into the chassis member with a punch. I can understand why you would want to re rivet but i think you will find 4mm S/S self tappers bite into the existing holes perfect, just in case you decide to go for that option, as imo rivets do not always give a good seal, they compress the panels togethers but the shanks do not always expand to fill the hole in the chassis member, allowing easier ingress of water, (if water gets under the rivet head).
Not sure if you have done the radiator before, but if not, some of the screws can be a bit tricky to get the fan housing out, and you have to take off the top fixings of the radiator then rotate the radiator to nearly vertical to get to the bottom fixings, and then release the side splash guards to gett it out, just give me a shout if you need any advice with this one.
Personally, seem as though you have full access to the tunnel i would recommend the tunnel cooling mod, very easy mod once you have the radiator and floor pans off and if you have not already done it, it is also the pefect opportunity to run new silicone coolant hoses, spray a little WD40 on the shifter, adjust the hand brake cable etc..
Other non essential mods, like the bits of padding that trim the tunnel are bolted through, this will be your best oppotunity to get the the nut heads, i took out the screws and refixed with velcro, for easy future removal in case of need for retrim just in case they ever get torn etc..it will also be your best opprtunity to add/change instrumentation on centre panel, change bulbs etc..although not an esay task you can modify the fixings holding the centre panel for easier removal (for future purposes), i.e instead of bolts and nuts, you can change for expanding plastic clips, (can get them from Halfords) glue to the back of the centre console with epoxy resin, if you ever need to take it off again you can pull it off from inside the cabin breaking the plastic clips get access to the bulbs wiring etc.. then replace the plastic clips again, then re-attach the centre console, i know you like your electrics so this mod may be ideal for you."
Some great advice there that is much appreciated
Jim O. said:
david.mt said:
I plan to rivet the floor back on as I believe this will give a better seal than screws which can be a bit hit and miss back into steel.
If you decide to rivet the floor back on, use closed-end sealing rivets instead of the normal general purpose open-end rivets. Should make it a bit more water tight. 
S26VE P said:
Yep i would go stainless. Make sure they are the correct length for the thicknesses tho as stainless ones dont pull up as much as Alu ones.
Thanks - anyone know the thickness of the chassis. Also anyone considered stainless steel self drilling screws. I don't like SS tappers as they are often not threaded upto the head and just spin rather than grip or if the hole is just not wide enough can get stuck or snap.
I can also get self drilling screws that come with a hex head which would be fine for the aluminium sheet and could get some proper leverage on them using the electric drill to fit them
The devil said:
david.mt said:
OK...have bought some sealed rivets and various TEK self drilling screws so will have a play around and let you know which provide the best fastening and sizes etc.
Any more thoughts/suggestion or questions then shout away.
I used a TEK screw when I did my floor over christmas but I must admit the plan is to change them for a stainless self drilling screw when I can find some.Any more thoughts/suggestion or questions then shout away.
so if anyone knows where they can be purchased let me know.
I did try stainless self tappers from screwfix and they were useless, the heads were so soft they chewed up
You can get size 8 (4.2mm) and 10 (4.8mm) stainless steel self drilling screws from eBay and most fastner suppliers. I used a 4mm drill bit to remove the rivets and also have a 4.8mm drill (the sealed rivets that I could find were 4.8mm) so will be finding the best size of drilling screw to use in these holes and let you know in the write up. Also just bought 50ml of Loctite 243 to seal and lock for only £7.50
.There is someone on eBay (UKDrills) selling packs of 10 cobalt stub drills for £6 delivered which will be more than enough to drill out all the rivets on several floors.
Being an accountant I have to save the pennies
Ok....played around a bit earlier.
The rear floor panel is off:
The front has all the rivets drilled out:
And a close up of the bolts that also need to be removed - the nuts are under the front clam which needs to be removed to give full access.
Got bored so fitted some new wheels with wider tyres:
More tomorrow.
The rear floor panel is off:
The front has all the rivets drilled out:
And a close up of the bolts that also need to be removed - the nuts are under the front clam which needs to be removed to give full access.
Got bored so fitted some new wheels with wider tyres:
More tomorrow.
Andy - they are TrafficStar RTS alloys - I found them late last year at a bargain price so couldn't resist as they are supposed to be very strong. The valves are quite stange - like those used for split rims. Caused me a bit of grief for the pressure/temperature senders but managed to get them bonded in and work a treat.
Did a bit more work on the floor earlier. Most of the riviets in the final centre section are now out and managed to loosen all the bolts under the seats (Number 5 allen key head).
The bolts were M8 x 20 so order some stainless steel replacements. You can also see the hex head screw that I will probably used to replace the rivets.
I used a 4mm drill bit to remove all the rivets and then hex screws are 4.8mm and bite really well. With a bit of a flange on the head they should seal better than screws but will also use a bit of thread seal.
EDITED to include Jim O. instructions to remove front clam in case you want to replace the front panel too:
"Removing the front clam only takes a few minutes - flip it up, undo the two light connectors, pull the clips out of the pivot pins, undo the two leashes. Flip it down, pull the two pivot pins, wait for the other guy in the shop to finish welding and walk over, lift off the clam and put it somewhere safe. Put the pivot pins and clips somewhere where they won't get lost (like back in the chassis holes where they belong). Done."
And I can confirm he is spot on
Did a bit more work on the floor earlier. Most of the riviets in the final centre section are now out and managed to loosen all the bolts under the seats (Number 5 allen key head).
The bolts were M8 x 20 so order some stainless steel replacements. You can also see the hex head screw that I will probably used to replace the rivets.
I used a 4mm drill bit to remove all the rivets and then hex screws are 4.8mm and bite really well. With a bit of a flange on the head they should seal better than screws but will also use a bit of thread seal.
EDITED to include Jim O. instructions to remove front clam in case you want to replace the front panel too:
"Removing the front clam only takes a few minutes - flip it up, undo the two light connectors, pull the clips out of the pivot pins, undo the two leashes. Flip it down, pull the two pivot pins, wait for the other guy in the shop to finish welding and walk over, lift off the clam and put it somewhere safe. Put the pivot pins and clips somewhere where they won't get lost (like back in the chassis holes where they belong). Done."
And I can confirm he is spot on
Edited by david.mt on Sunday 21st February 14:58
OK - bought a few bits this week (exhaust wrap, ahdesive heat shield, heat tape, more screws and a horn!). Spent some time in the garage.
Both clams removed:
Got to the 6 nuts that were holding the front floor pan on and removed them:
Drop the front floor pan:
Dropped the rear:
Will hopefully remove the centre panels tomorrow so I can start cleaning up ready for resealing and replacing. Will also add some heat shield to the intercooler box, replace the radiator and some hoses, replace the horn, wrap the exhaust and do the tunnel/brake cooling mods - will add more photos as I go along.
EDIT - the rear chassis has some kind of grease sprayed on - is this required as a barrier between the chassis and the floor pan as this area is not sealed. If required what the suggested product?
Both clams removed:
Got to the 6 nuts that were holding the front floor pan on and removed them:
Drop the front floor pan:
Dropped the rear:
Will hopefully remove the centre panels tomorrow so I can start cleaning up ready for resealing and replacing. Will also add some heat shield to the intercooler box, replace the radiator and some hoses, replace the horn, wrap the exhaust and do the tunnel/brake cooling mods - will add more photos as I go along.
EDIT - the rear chassis has some kind of grease sprayed on - is this required as a barrier between the chassis and the floor pan as this area is not sealed. If required what the suggested product?
Edited by david.mt on Saturday 27th February 18:59
Stella Artois said:
Please can you put my mind at rest. Are they directional tyres, as if they are, isn't one on the wrong way? Its bugging me, Its the inner tread pattern on both, I'd expect them to be symmetrical to each other if directional. If not, its an optical illusion.
Thanks for your concern . They are Goodyear Eagle F1 Assymetrics 
.Bit more today (Sunday):
Removed the footwell section:
You can see where the sealant has failed and water can easily get in:
Then got bored of the dirty job so started to practice with the heat wrap:
Edited by david.mt on Sunday 28th February 15:01
Had a busy week and work and spent most of it in London so no real progress on the car. I did however read a few sites about galvanic corrosion particularly between steel and aluminium.
Now thinking about that and a recommendation to use some kind of gasket I am tempted to use some closed cell neoprene tape between the floor pan and the chassis rather than Sikaflex or any other sealant. This will surely be much easier to use and less mess - I also wouldn't have to work like an idiot to get it all fastened back before the sealant cured. I also have stainless steel fixing which I can add some neoprene washers to.
Neoprene is waterproof, so as long as the tape is thick enough to cover any minor undulations in the aluminium panels I can't see how it would not be effective. It would also stop any contact between the steel and aluminium and the washer would prevent the same on the exterior of the floor.
I could stick the neoprene to the panels and then just offer them up and fasten back the chassis - the resultant seal should easily be waterproof.
Any comments?
Now thinking about that and a recommendation to use some kind of gasket I am tempted to use some closed cell neoprene tape between the floor pan and the chassis rather than Sikaflex or any other sealant. This will surely be much easier to use and less mess - I also wouldn't have to work like an idiot to get it all fastened back before the sealant cured. I also have stainless steel fixing which I can add some neoprene washers to.
Neoprene is waterproof, so as long as the tape is thick enough to cover any minor undulations in the aluminium panels I can't see how it would not be effective. It would also stop any contact between the steel and aluminium and the washer would prevent the same on the exterior of the floor.
I could stick the neoprene to the panels and then just offer them up and fasten back the chassis - the resultant seal should easily be waterproof.
Any comments?
Ok - I can feel the divorce coming soon as after another day in the garage we made some more progress:
The floor is now completely off:
The front end dismantled and the radiator off:
The back end dismantled and the exhaust fully wrapped:
And all the panels piled up waiting to be taken for coating - I don't have time to clean them myself - just doing the chassis is going to take an age.
I just have on screw left to remove from the tunnel access plate and then I can start rebuilding - I just hope I can remember how it all goes back together again
The floor is now completely off:
The front end dismantled and the radiator off:
The back end dismantled and the exhaust fully wrapped:
And all the panels piled up waiting to be taken for coating - I don't have time to clean them myself - just doing the chassis is going to take an age.
I just have on screw left to remove from the tunnel access plate and then I can start rebuilding - I just hope I can remember how it all goes back together again
TuxMan said:
Looks good Dave !! Buy wife new pair of Louboutins ...... Works for me :-)
Mine is clearly much cheaper so dinner out usually works Not much progress this week as spent most of it working away. I did sneak a couple of hours today and now the tunnel plate has been removed (bought a right angled driver), with holes cut and one flange riveted in place. Now waiting for the second flange which is on back order
.
I also managed to remove the baffle plate from the air scoops so they are now ready to go back on the car - they have just been sprayed to clean them up.
Should get the floor panels etc back at the end of this week and with a clear weekend I am hoping to make some good progress.
For anyone still watching - I am almost ready to the put the floor back on.
I have all the aluminium panels back now with a marine black powder coat:
If you look closely you can see how badly corroded the metal is - this is on a 2005 model and it was suggested that if I had left it much longer then I would have had to replace the aluminium.
Rear splash guards now back in place:
Heatshields refreshed:
Chassis treated to a wire brush treatment and some rust primer on the more exposed areas (I will obviously paint them black):
And finally some neoprene washers to provide an additional gasket between the stainless steel fastenings and the aluminium sheet (I think I will use at least 400 when finished):
I have all the aluminium panels back now with a marine black powder coat:
If you look closely you can see how badly corroded the metal is - this is on a 2005 model and it was suggested that if I had left it much longer then I would have had to replace the aluminium.
Rear splash guards now back in place:
Heatshields refreshed:
Chassis treated to a wire brush treatment and some rust primer on the more exposed areas (I will obviously paint them black):
And finally some neoprene washers to provide an additional gasket between the stainless steel fastenings and the aluminium sheet (I think I will use at least 400 when finished
):TuxMan said:
Hi Dave ,very very nice mate going to look the dogs bks when its done !!!!! be a shame to get it dirty
Yes - bit pissed off as the weather has been great and would love to get it dirty but let down with the remaining flange - ordered on 1 March and told in stock but clearly not and second will not arrive until next Tuesday/Wednesday. Can't rebuild the front until the tunnel access plate is put back in place.ks when its done !!!!! be a shame to get it dirty Other than that I have everything ready to put it all back together. The rear end is now back so once the radiator is fitted it should start up (after a bit of a charge).
Will get most of the floor back this weekend so just need to refit the radiator sometime during the week and make sure everything is in order for next weekend.
TuxMan said:
Yep know what you mean , getting all the stuff together is a major feat !!!!! After 5 months I am still waiting for a few bits !!!!! Are you going next weekened be good to meetup for a chat ! Simon
I am planning to turn up - I would like to catch up and chat too - would like to bring my Nob but otherwise it will have to be some Pork.TuxMan said:
Sounds good , will be there in the Noble ,need to sort out what I need to do floor bring me a few of the fixings you are going to use if you have some spare . Need to do it next as my floor leaks like a sieve !!!
No problem - I can bring you a nice sample pack for you to play with - but there will be no BHP improvement 
worty said:
Picked mine up from Jetsream yesterday after a service and a few bits & bobs. The floor had some work last year but needed a couple of the panels replacing this time. Hopefully should now be watertight.
Got to say Dave & Matt do a great job down there. It always seems like a new car when its had a service
Hope to see you lot at Mikes
worty
I am hoping that I won't have to touch mine for a good few years once finished - otherwise I will have wasted hours and should have done the same as you and just thrown it at a garage who do such work every day.Got to say Dave & Matt do a great job down there. It always seems like a new car when its had a service
Hope to see you lot at Mikes
worty
worty said:
Was I dreaming or did you say you had a spitter for sale? I need a new one.
worty
Sent you a PM so shout if you didn't get it.worty
Had a good day and the rear clam is now back on - also rebuilt the front end including the new Pro Alloy radiator and new hoses/pipes. I have coolant ready to refill so should be able to start and move the car this week (see separate thread).
Have a bit more cleaning of the centre chassis area before fastening the floor pan back but most of the work now done so should be just a case of cleaning certain areas and then bolting the cleaned panels back.
Have ordered some more neoprene strip and another 300 stainless screws as I seem to have used far too many already. I will have plenty spare so will bring them next week (if I get the car back on the road so anyone interested can see what I have used).
Too dark for more photos now so will have to wait until tomorrow.
The devil said:
have you a link to where you bought the screws
http://www.shop4fasteners.co.uk/ I drilled out the rivets with a 4mm cobalt bit and then I am using the 4.8mm stainless steel self drilling screws (as below) to refix the floor. I am also using some neoprene washers to ensure there is not contact between the aluminium and the fasteners.
http://www.shop4fasteners.co.uk/acatalog/Self_Dril...
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