Strange caliper problem

Ronnie Beck

One of the 4 pins/bolts are different on the front calipers. Three are a brassy coloured bolt and one is a silver slider pin. Anyone come across this before or has some fitted a wrong part?

car is a polo 6N2 1 litre.



The odd one is like this


Other three look like these only they take a 6mm allen bit rather than a socket.

sebastianlieken

my golf mk5's calipers on the front use the top silvery one. (so that's the OEM one... EDIT; this may not be the OEM one lol)

They take a 7mm Hex bit and can be a bit of a pig to remove. Perhaps the previous mechanic who changed the brake pads damaged the OEM pins upon removal, or maybe they had corroded hindering the calipers lateral sliding ability.

as long as the bolt geometry is the same between all 4 bolts, you should be alright.
(make sure thread diameter is the same, the thread length from one end to the other, and make sure the shank lengths and diameters are the same)

I assume the brass ones are like the bottom one pictured, i.e. the tapered one?

It's not ideal as youre getting a tapered edge pressing against the carrier of the caliper rather than a flat edge. Now i'm just thinking.... is the silver one the bastard part....

when you put the slider pin (or bolt, whatever you wanna call it) through the caliper and into the carrier, does the mid section of the bolt meet a flat edge that would suit the silver slider pin, or does it meet a heavily chamfered hole edge that would suit the brass bolts?

sebastianlieken

actually, this might explain it.

the silvery slider pin is indeed the original part. fairly sure three of the original pins were destroyed in a previous brake job and they were replaced with those brass ones.

CJhaughey

They aren't brass, The finish is called Zinc Chromate.
Brass wouldn't be strong enough for brake parts.

Ronnie Beck

Just after looking here. It looks they are all zinc chromate bolts. They pass through a silver insert (I know it's not silver charlie;)). Maybe someone wrecked the bolt and replaced the bolt and sleeve with a pin .

Ronnie Beck

sebastianlieken wrote: »

actually, this might explain it.

the silvery slider pin is indeed the original part. fairly sure three of the original pins were destroyed in a previous brake job and they were replaced with those brass ones.

That doesn't look right at all. Probably a different caliper.

Kencollins

I had the same issue with those bolts.

When changing the pads it is really easy to damage the inside of the silver colour bolts. The female hex (or whatever it is) is hard to see from the outside, and using the wrong size allen key type thing will round the inside very easily.

I replaced them all round with the shear type bolts pictured under the original, never had any problems!

Ronnie Beck

Kencollins wrote: »

I had the same issue with those bolts.

When changing the pads it is really easy to damage the inside of the silver colour bolts. The female hex (or whatever it is) is hard to see from the outside, and using the wrong size allen key type thing will round the inside very easily.

I replaced them all round with the shear type bolts pictured under the original, never had any problems!

You reckon the silver are original too. Was that on a bora? My transporter has them silver pins too. I'll go out now for a look, take actual pics and get the brake code.

Kencollins

No, the car was a 98 polo. Stupidly designed really, bolt beats Allen key any day!

Merch

CJhaughey wrote: »

They aren't brass, The finish is called Zinc Chromate.
Brass wouldn't be strong enough for brake parts.

That looks very similar to cadmium plating. Zinc chromate is a primer also and more paint like in its application, where it chemically adheres to the metal surface.
I didnt realise that was zinc chromate plating until I looked it up and saw they plated the stuff too.