Front Inner Wheel patch repair...

[Chooch84]

Hi,

I'm going to have to do a patch repair on the RHF inner wheel arch panel, it looks as if the Stud which holds the wheel arch liner has caused a small bit of corrosion. Basically, it's caused a 50p sized hole where the stud used to be.

Does anyone know what thickness the wheel arch panel is? I've got some sheet metal but I think it might be a tad too thick. Not that it's going to make a great difference. I just want to make sure it's not too thin!

Thanks in advance,


T

[Jebus]

I have a similar hole on the n/s on mine and 2 holes below that on both sides back of battery box area/ under airbox, id assume 1.5mm would do fine when I last poked around by it.

[Laird Scooby]

Having done a similar repair (but closer to where the screenwash bottle is) i'm pretty certain it's 0.9mm. I'd suggest using 1.2mm Zintec for your repair though.

While you're doing it, any chance of some measurements and/or pics of the exact location of the stud please? I have a pair of 940 arch liners i want to fit to my 760 but no studs exist (or existed!) on that so i need to work out where they should go, thread size would be useful too please!

Despite being in the wheelarch, you should be able to do the repair from inside the engine bay - saves crawling around on the deck in this horrible wet weather!

[Ian21401]

I had a similar problem on the FNS of mine. The uppermost stud holding the arch liner was very badly corroded and whilst attempting to loosen the plastic nut to enable removal of the arch liner the stud broke away from the steel inner wing bringing a 10 pence piece sized piece of the steel wing with it. Working from within the engine compartment I opened the hole a little by removing it’s corroded edges back to good metal. I fabricated a patch, larger than the hole, from a section of new steel cut from a left over piece of sill repair panel. ( I have a box of various metal offcuts which I have collected over the years. ) intending to fix the patch from the engine compartment side of the inner steel wing. Cleaned the inner wing contact area back to bare metal. Managed to bend the patch slightly to follow the profile of the inner wing. Glued patch onto inner wing with Araldite as it doesn’t take any load. By the time that I was ready to refit the arch liner the patch was well cured. I coated the liner side of the patch with Waxoyl. I selected a suitably sized new self tapping screw to fit the original plastic nut. Installed the arch liner then, working from below, drilled the patch via the already existing hole in the arch liner with a hole suitable for the selected screw. Screwed the self tapper through the patch from the engine compartment then screwed on the plastic nut.
Finally painted and rust proofed the patch and surrounding area within the engine compartment.

[TonyS9]

I'd agree its 0.9ish sheet

For alignment just push the push arch up and settle it in place with the wing on and drill through the middle of the slot after you have repaired the hole. Then use a nut and bolt and/or weld it in too. I used stainless nut and bolt.

[Chooch84]

I've ordered a selection of mild steel plus some more Zintec, I've got 0.7mm or 2mm Zintec/zinc coated mild steel at hand which is too thin and too thick.

I believe it's around 0.9mm as I attempted to take a measurement of the panel. It came close to ~1mm, taking paint thickness into account it would have rounded closer to 0.9mm.

The existing stud sizes look to be M5 x ~16mm. I've ordered both M5 & M6 Zinc coated "Self-Clinching" studs, which I'll press into the repair panel prior to welding it in place. I was looking to get hold of a CD stud welder, but that's a lot of money to make the finish look OEM, but it would have been a nice toy.

As the slot sizes on the liner accept M6, I've ordered an assortment of some flanged Nylon nuts used on other OEM's which will do the job, as I have a feeling this isn't going to be the last of this issue.

The rusted area... Looks like the LHS is going to suffer the same issue Looks more like a 5p size now I've looked at it again.


Once repaired I'll go over it with etch primer and UPOL gravi-tex.

[ukvolvo]

Remember when using plate thicker than oe heat dissipation is different so its easier to blow holes

Mick

[Laird Scooby]

Originally Posted by ukvolvo

Remember when using plate thicker than oe heat dissipation is different so its easier to blow holes

Mick

That's true but the trick i've found to make it work is you put more heat onto the new piece which then helps "heatsink" the original metal which also helps reduce the shrinkage of the previously bent original metal. I've had some horrendous shrinkage on metal that was stamped out/formed and learned that trick as a result. Also playing the "Join the dots" game where you tack it in say all 4 corners working diagonally to start then do a small tack in the middle of each side, again going opposite sides and letting each weld cool before the next and just build up the welds like that works well.

Once there are enough welds, then it's join the dots time.

[Chooch84]

Hopefully, I should get through this without popping any holes, as long as I've got some clean metal to work with and I do the prep work correctly all should be well.

As you've stated Dave, I just need to get enough tacks in place initially to dissipate the heat the rest should ease up once enough material has been put down without putting too much heat into the area.

Failing that I could resort to duct tape repair... lol