Floor Pan Replacement

[david.mt]

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 st.

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.

I am also planning to replace the radiator so will take the front clam off and remove the old radiator. If I need to do this first it would be good to know.

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

[Jim O.]

david.mt said:

• 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?

Yes, you can do them one panel at a time, but it may be easier to get a good seal at the seam between the panels if you do them all at once.

david.mt said:

• 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.

If I remember correctly, they (along with a bunch of screws) hold the side panels/radiator supports in place. Remove the front clam, and reach in below the radiator - two of the bolts go through the outer bracket for the power steering cooler, the third one is on the same line but further back, and the other three are in the same locations but on the other side.

It's not very much labor to remove the front clam and these six bolts, so combining this with your radiator replacement job doesn't save a whole lot of time. But, you will have to do the exact same steps during the radiator job, so if you absolutely abhor redundant labor, you can combine the two tasks...

[art411y]

most definetly replace all the hoses under there with silicone 3ply items.you will need a complete length of 4mtrs for front to back rad to engine.not convinced that rivets are better than stainless self tap screws though.the carpet will come away complete with the floor.also do not use the ordinary type of hose clip to fasten the silicone hoses .full stainless clamps from a plumbers merchants are ideal

Edited by art411y on Saturday 6th February 20:02

[TuxMan]

Go for it Dave !!! Getting the rad out is a bit of a pain but while mine was out I did the tunnel mod and also changed the front water hoses , the new ones are not expensive and it makes sense while it's all in bits !!! I used :
SFS Performance
01582509250

They are also doing me all the hoses for my pro-alloy intercooler in red as I thought the STD black ones were naff !!!

[mgbond]

Nice one Dave, exactly what I need. Should be doing mine later in the year and your post will help.

Cheers


Bondy

[AMG Merc]

mgbond said:

Nice one Dave, exactly what I need. Should be doing mine later in the year and your post will help.

Cheers


Bondy

+1 here.

[david.mt]

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

[mgbond]

Indeed that is good. not sure why the rad needs to move but I like the idea regarding the center console.

Bondy

[Jim O.]

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.

[david.mt]

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.

Any metalurgist want to suggest the best material for the rivets - there is a choice of aluminium/steel/stainless steel/copper

[Gadgeroonie]

stainless steel would be best i think

[S26VE P]

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.

[david.mt]

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

[S26VE P]

There is also the option of rivnut's in the chassis so bolts/screws could be used.

[daddysumo]

david.mt said:

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

I used aluminium self drilling screws that were coated in a non anodising layer. They have a posi drive low and wide head and when used with a cordless drill went up very tight indeed.I used rivets in the seat rails incase of the screws being too long and fouling on the slide mechanism.....Oh and no leaks now !!!

[Gadgeroonie]

Daddy,

sounds like a good solution where did you get them

is it safe to use aluminium and steel together ?

[daddysumo]

Gadgeroonie said:

Daddy,

sounds like a good solution where did you get them

is it safe to use aluminium and steel together ?

I got them from my local fastner company.Will dig out the details from the box.

Well the standard set up is aluminium rivets into a steel box section. At least this way there should not be any oxidisation etc due to the coating.

[david.mt]

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.

[Jim O.]

Whether you use screws or rivets, it wouldn't hurt to put a bit of thread sealant on the fastener before installing...

[The devil]

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.

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