I had a go at replacing the rear brake discs/rotors and pads on my Volvo S40.
However the retaining bolt even after several applications of WD40, leaving it soak some and some gentle persuasion refused to budge.
I eventually stuck a 5mm torx on an extender, hammered it in and was able to free it.
I needed to do this on both rear discs, I've put it back in... tight enough that I think it will hold but not tight enough that I can't get it out again, i also gave it a very small spot of grease to ensure I wouldn't have to fight too hard again to get it out.

I've been looking everywhere for a replacement, I also plan to do the front discs too but can't seem to locate a suitable part for both front and rear discs.

I'm assuming it should be standard, does anyone know what I should be looking for in size/dimensions for front and rear as "Volvo S40 disc retaining bolt" doesn't through up anything that I would say looks right.

1: At present I don't drive the car very far, but once a month make a long trip to scotland.
2: As you can see it's getting on a bit, I do not plan to sell it on (but would replace the bolts if I was)

Any help would be greatly appreciated, I want to solve this before I do the front brakes and have the necessary bolts handy when I do.

 

Take a look at this diagram:

Rear wheel brake. Fits: 2003 Volvo S40 2.0l 4 cylinder Turbo | Volvo Parts Warehouse

You should be able to find the OEM part number to help your search - I assume you don't have a parts supplier local?

In terms of the other parts, are you concerned with finding the correct size for the rotors (discs) or just the odd bits like the retaining bolt should you have to replace? To find the correct disc, if there are more than one size for a given Volvo year/model (like the V70s had three different disc sizes one year for base, turbo and R), you may need to use the VIN code to find your suspension code. In North America, I believe all Gen 1 S40s have the same 281mm front disc size.

 

Thanks that's a big help.

I'm pretty sure the discs and pads I found for the front are correct.
I would just feel happier that this one part was right, my un-expert opinion is that the retaining screw provides more a way of stopping stuff coming between the disc and the hub and cuasing corrosion, rather than contributing anything towards releaving the stress of braking on the 4 studs.
Even so I'd rather not leave something important to safety to chance.
Looking at the same link, it appears that the front pair do not have a retaining screw, which is a relief.

 

Don't worry about the retaining screw/bolt. The wheel and thus the wheel nuts hold the disc on more than that glorified grub screw ever could.
Don't use grease on stuff like that, buy the correct anti seize and do it right. The same stuff is good to apply to the mating surface of the disc and hub too. Do NOT use on the wheel nuts though!!!!
Leaving them out will have zero adverse effects though, so I would not bother replacing them.
If it does bother you that much, you can remove them, and grind a flat cut into the head, allowing the use of a flat screwdriver to remove them in the future.
Over the years, and a different manufacturers, that retaining bolt has been omitted altogether, a torx screw, a philips screw, and spring washers. All do the same job as the first option, meaning nothing.

Martin

 

Thanks, that saves me wasting my time trying to source these things, they've been nothing but a pain.

I need to bleed the brakes, so will probably take them out when I'm doing that.