more 305 brake confusion - my car is a freak!

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nametooshort
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more 305 brake confusion - my car is a freak!

Post by nametooshort »

Ok, now I am really really confused, anybody know what going on?

While trying to convert my 305 to vented rotors (see my other recent thread), I stumbled on a real big weird problem that don't make no sense.

I had a look on the Brembo page, they call those brakes 247mm, and according to that page, NO 305 ever had 247mm brakes, they all (even the first gen ones etc) had bigger, mostly 266?! brakes.

So how comes mine has 247mm x 10mm brakes? It def for sure has 247mm x 10mm solid rotors! I measured.

I never knew this before.

So, it looks like 309s and 205s and c15s got rotors like mine, so whats going on there? Mr/miss previous owner fitted calipers/rotors/pads from a junker c15/309/205 at some point maybe?

But even weirder, how comes the calipers and pads for a 305 still fit? Back when I still hadn't given up on the horrible Bendix brakes and tried to just replace the whole system and hope it works, I ordered new calipers and new pads for a 305, and they were exactly the same as the old ones and fitted/worked OK.

So, if every 305 II had 266 rotors, than if I order calipers and pads for a 305II, I will receive the ones from the 266mm system, right? Cause the 305 II only used the 266mm system.

But my 305 has 247mm rotors, yet the new calipers and pads still worked.

Isn't that kinda impossible? 266mm calipers and pads cannot possibly fit and work on a 247mm rotor, right?

Whaaa?!

Unless the calipers and pads are somehow interchangeable between the two rotor sizes, but that can't be possible, since calipers are made to a exact rotor size?

I think?

Help I have no idea whats going on jajajaja.
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BX
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Re: more 305 brake confusion - my car is a freak!

Post by BX »

It is quite possible that the calipers and pads will work especially with a smaller disc. Does the pad overhang the outer circumference of the disc? Often the full diameter of the disc is not used. with a smaller disc the pad may overhang a little. No way can the discs off a mk1 305 be used as these cars had only 3 wheel studs and the Mk2 had 4.
it appears that both solid and vented discs are available. http://www.mister-auto.ie/en/front-brak ... 00007.html
The calipers http://www.mister-auto.ie/en/caliper/pe ... 5_g78.html
And what type of pad have youhttp://www.mister-auto.ie/en/front-brak ... 00005.html
As you say that parts site lists 247mm discs for the 306
20th Century Pug
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Re: more 305 brake confusion - my car is a freak!

Post by 20th Century Pug »

Too late for the OP, but others reading this may find it useful.

Only the 305 GTX had vented discs, and of course wider calipers. All the other models had solid. Not sure if the vented ones were a different diameter, but I believe they are the same as fitted to 405 models. The standard 305 wheels (both steel & alloy) will not fit a vented disc set up. The first GTX models in 1985 had solid discs, and when Peugeot introduced the vented discs, new alloy wheels were needed, referred to as 'Cromadora' alloys. Back then it created a strong sporty image. Now cars are heavier and vented discs standard.

The sliding calipers can suffer if the rubber seal splits. The slider & pin gets worn and binds. So the pads wear unevenly or drag. Make sure that the caliper can slide smoothly with the pads removed.

Vented discs don't stop you any quicker. What they do is dissipate heat more effectively, so you can brake heavier and more frequently without overheating & fade. Just what you need on a race track or descending an Alpine pass with a heavy trailer. For the majority of UK road driving there is unlikely to be any benefit in retrofitting an 80's classic.
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Re: more 305 brake confusion - my car is a freak!

Post by GiveMeABreak »

Discs with grooves or vented with holes will also wear out the pads more quickly.
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