Roll bar and welded nuts on CP3/4
 

Hi,

I always had problem fitting my roll-bar, due to the distortion of the main hood after having fully welded the plates, cross bar and rear stays (I made a thread about that a long time ago).

It is always very hard to fit, and the bolts never want to go straight into the welded nuts. Lately, as I have used stainless steel bolts, some of the bolts that I forced a bit too much in the welded nuts have damaged their threads. Not completely, but I can see some of the threads have suffered, and now, it is even harder to fit the bolts correctly.

As I secure the bolts with nylock nuts below the welded nuts anyway (to stop the bolts to move because of vibrations), I was thinking about drilling the thread of the welded nuts to the same OD as the bolts (10mm in my case), to be able to fit the bolts easily. So they will be secured to the chassis only with the nylock nuts.

Do you think this would be a problem? I'm not talking about approval by our IVA (SFRO) or MOT, as I doubt they will check so far, but my concern is more if it will be OK to hold the roll-bar and keep it in place solidly? What could be the consequences of this set-up, and when it comes to solidity, what would be the difference with just the welded nuts as the book's design?

Thank you.

I can't see a problem with that at all. You have 4 M10 nuts holding the roll bar mount plate that is 3mm or 5mm plate to a 3mm thick CP3/4 the weak link will be where the back stays mount to.

Drill straight through and use 10mm 12.9 domed plated cap screws with washers and lock nuts.

Stainless is brittle and I would not use them them for anything of safety or stress,just my personal opinion.

Thank you very much for the replies and explanations. That is reassuring, so that is what I'm going to do: drilling these bloody welded nuts.

And thank you for the tip about the stainless steel bolts. I hadn't thought of that, so yes, I will try to fond 12.9 grade dome head bolts. But of I can't, I can use Allen or hex heads as here in Sweden, we don't have the radius issues you have with your IVA. And the 12.9 grade bolts I can source are black, so it is even better for the look :)

Thanks a lot.

If the bolts are black 'self colour' 12.9 or 10.9 they WILL rust. You need plated ones so they don't.

Its hard to believe that in the land of one of the best steel makers in the world they don't do plated cap screw's but these days anything goes.:rolleyes:

I will post you some if you are stuck.;)


When I made the plates for my roll bar I cut a hole in them to put the tube through and welded it on both sides,wasn't keen on just welding to plate to be extra strong.

Hummm, not sure about the plating thing. At the hardware store store where I buy my bolts and nuts, the 8.8 are plated (silver colour) and d 12.9 are black.

Actually, the idea of using stainless steel bolts was to avoid them to rust, so SeriesLandy is right to point out that the bolts I bought might rust, and I don't want that.

What do you think about this one? 12.9, allen head?


IMG_8120 par Voucht71, sur Flickr


IMG_8119 par Voucht71, sur Flickr

They are actually come covered with oil, they are very fat and oily, so I guess it for protecting them from rusting while stored, and that means that they are not plated and will rust on the car. Am I right?

So, I'll try to find plated 12.9 somewhere else, if you confirm that this one will rust. And if I can't, yes Paul, perhaps I'll accept your offer to post some to me :) Thank you very much for that, we'll see if it is necessary..., that is very nice. I'll keep you updated.

The car is now stripped off, the chassis is bare again. Water and salt from the road when I drove to the inspection last week made terrible damages (rust everywhere :mad: ), and I'm now grinding the welds before I take the chassis to the sandblast and powder coating company, hopefully this week...

It looks possible that they will rust.

rub the oil off with a cloth (on the head), get it wet and leave it outside for a day or two. That should be long enough to see if it will rust or not.

I have used those bolts before on my car trailer and they have been fine. They will be good for years & as they are for the roll bar, they won't be directly exposed to the elements anyway. If in a few years they look a bit rough, just replace them, as they don't cost that much anyway. ;)

Quick thought, why don't you permanently weld the roll bar in ? If it gets rolled, cut the bar off, dress it up & re weld. Even cheaper & even more strength than using bolts. :D