Vented discs on rear and M/C sizes

[Sophia_Bush]

Right had a cheap idea for vented discs on the rear use normal 247mmx20mm discs but use the carrier/yoke thing from a xsi same design etc just wider for the disc you keep the handbrake mech normal side of the actual oe caliper

also M/C size from smallest to biggest what do we have? need to sort a new m/c out but 23mm one will be bit to big, current one on my quiksilver works fine with the 4 pots pedal is good feel but couild be better

[3cott]

The two port is a 23mm an the four port is 23.8mm

I don't no if there is any bigger ones

[swampy]

You wouldnt need a bigger mc as the fluid moved wouldnt increase.
The yokes are what are used to mount the caliper to the hub. Fitting a different one of them wouldnt make it so you could fit thicker disks.
Cituning used to do a kit for the standerd calipers that enabld it to use a 306 s16 266mm vented disks.
Thus retaining the standerd caliper, cables and hoses etc

[Mikol]

Gav you're full of bright ideas.

Can't see why it wouldn't work. The Bendix calipers are such a gay design the actual carrier is just two metal cylinders that the bolts mount through.

Doubt you'll get any noticeable gains but still worth a shot, just for the rep of having vented rears. :D

EDIT: Was going to mention about unsprung weight on the rear because of the vented discs but I realise the wider caliper is actually alloy so you'll save a bit there to compensate.

Keep us updated! :)

[tay56]

I think you can go all the way down to about a 16mm m/c depending on the amount of ports required. I know there's also 19mm, 23mm, and 23.8mm

[Sophia_Bush]

well my shitsilver has a 19mm m/c atm looking for something between that and the 23.8mm one

mikolus of 3 stud thats what I was thinking change carrier keep the oe handbrake caliper bosh normal disc on voila vented discs

[jeffchiz]

this is my house mates 23mm m/c which is a 4 port, wouldnt it say 23.8mm if it was 23.8 lol
http://img.photobucket.com/albums/v633/Stealth106/saturdays%20work/IMG00435-20100415-1757.jpg

[Mikol]

No.

All 23mm ones are essentiall 23.8mm

Likewise, a 20mm one is actually 20.6mm

And a 22mm one is 22.2mm

Gav you *can* get 22mm ones on a lot of PSA cars - IIRC 306 2.0's/S16's/XSi's without ABS have a 22.2mm cylinder listed (I assume it'll be a 4 port - its very unclear from the picture) and a few 405's may be the only cars to have it with the correct alignment to fit OE brake lines. If you have braided lines under the bay then you can use a much newer one from a 206 etc.

You can buy the 22mm one brand new for about £50 on brakesint.com, from a 405 and from the picture looks to be OE 106/Sax fitting.

Just thinking about the rear disc idea, you may have one or two issues is the offsets aren't completely compatible... Other than that I can't think of many other real pitfalls...

[Ashleyp]

I beleive standard saxo VTR/S MC is 22mm?

if so, get a non ABS vtr MC and your sorted?

[Mikol]

Aye, I've heard and I think I've seen one or two that are, but then again I've also seen some that aren't.

I bought a MC from a VTS from Sparco_Tom and it's got '20' stamped on it. So think it might be a PSA 'chuck-in-whatever-one-you-can-find' thing.

Good shout though, I'd forgotten about that!

[Sophia_Bush]

Good idea ash I should be able to sort VTR one easy then :D

But Mikolus that is cheap for brand new! Just have standard lines mate nothing fancy, the 19mm m.c I have is ok pedal travel is fine and braking is good but even though everything is bled up nicely pedal is I feel to soft.

Aye rear vented discs will have a play around with that idea over summer

[Mikol]

Yeah, my 266's are on a 20mm MC atm and I feel similarly - still need to bed them in to get a proper feel of them though so might stick it out for a bit and see if I need the upgrade... I get where you're coming from though. Although on the other hand I've played in a AX with 266mm Lucas brakes and a 23mm MC and the pedal was horrible - completely solid, no graduation IMO. Didn't like it at all.

Ha, yes it will have to be a race between you doing that and me making a 3 stud disc beam - something I never actually agreed to do I'll have you know! :p

Not sure it'll even work. CBA to fuck around with the GTi handbrake when drums are so much simpler.

[JoshB]

I've just removed my 2 port MC from my VTS and its 22mm.

Let me know if you want it Sophia_Bush, shouldnt cost much to post.

[axsaxoman]

what is wanted and has been for last ten years is a 26mm master cylinder to get rid of the quishy +long travel on the pedal .
I offered to get them made --If Icould get at least 10 sold to start with --but as they were going to be about £80 no one took me up on it .
bigger m/c is what is wanted --on any saxo/106
other alternative is to fit a double m/c unit to the servo ,then you can also have proper bias control

[Mikol]

Ah, Mr. Bush, I have some bad news.

I've been mining on the interwebs and have found

The stock rear discs have a centre bore of 71mm, front discs are 66mm, so that will need machining. That's the easy bit.

Let's have some numbers

247mm rear
Centre bore 71mm
Disc thickness 8mm
Overall height 25.3mm

247mm front
Centre bore 66mm
Disc thickness 10mm
Overall height 34.3mm

The problem should be really obvious by now :/ The actual friction edge of the disc is a wayyy different offset on the rear. This is mega gay.

If we assume the actual mounting face is the same thickness the rears are offset by 7mm less than the front. I.e. They're 7mm closer to the hub, or in real terms, the outside of the car

Let me get on the brembo website just to make sure they're the same thickness...

[jeffchiz]

I beleive standard saxo VTR/S MC is 22mm?

if so, get a non ABS vtr MC and your sorted?

no way, my vtr m/c is 19mm im sure they are the same as 1.4's but like mikol said looks like some came with 20mm

[PhillipM]

Tom Fenton on 205 drivers has done it to his 205, just because he could.

Pretty pointless though, the standard discs don't get hot enough to worry about even on track, nothing that some uprated pads wouldn't cope with.

[jeffchiz]

Ah, Mr. Bush, I have some bad news.

I've been mining on the interwebs and have found

The stock rear discs have a centre bore of 71mm, front discs are 66mm, so that will need machining. That's the easy bit.

Let's have some numbers

247mm rear
Centre bore 71mm
Disc thickness 8mm
Overall height 25.3mm

247mm front
Centre bore 66mm
Disc thickness 10mm
Overall height 34.3mm

The problem should be really obvious by now :/ The actual friction edge of the disc is a wayyy different offset on the rear. This is mega gay.

If we assume the actual mounting face is the same thickness the rears are offset by 7mm less than the front. I.e. They're 7mm closer to the hub, or in real terms, the outside of the car

Let me get on the brembo website just to make sure they're the same thickness...

are you talking about solid discs there? as vented front discs are 20.4mm wide

[Mikol]

Yeah mate, I used solids for the comparison as they're the most similar. The vented ones are actually the same height so the inside friction face has the same offset as the solid ones.

If that makes sense lol...

[jeffchiz]

Yeah mate, I used solids for the comparison as they're the most similar. The vented ones are actually the same height so the inside friction face has the same offset as the solid ones.

If that makes sense lol...

hardly none of this is making sense to me lol i just follow the crowd with brake modifications so i don't need to mess around with these calculations lol

[Mikol]

Probably a wise move haha :D

[Sophia_Bush]

now at least we have near all info required to do this won't be that hard either

[yr51ocw]

what is wanted and has been for last ten years is a 26mm master cylinder to get rid of the quishy +long travel on the pedal .
I offered to get them made --If Icould get at least 10 sold to start with --but as they were going to be about £80 no one took me up on it .
bigger m/c is what is wanted --on any saxo/106


26mm master cylinder on a saxo? What diameter caliper piston size do you plan on using with that? 70mm?

Im not surprised no one took you up on the offer, I dont know anyone who is serious about their car who would like a brake pedal that requires about 50kg foot force with very little pedal travel. Essentially leaving the driver with a 'digital' brake pedal, either nothing or full brakes with little movement of the pedal. Most people in motorsport tend to favour a longer pedal travel meaning it is easier to modulate the brake pressure to hold the braking force just off wheel locking point without crossing it.

[yr51ocw]

gav - I would suggest that it is a bit of a waste of money/time if your after a performance increase. How are your 4 pots holding up?

If you want to increase performance, I would look into the rear 2 pot set up, which would save on unsprung weight and performance pads would be alot cheaper.

[Sophia_Bush]

gav - I would suggest that it is a bit of a waste of money/time if your after a performance increase. How are your 4 pots holding up?

If you want to increase performance, I would look into the rear 2 pot set up, which would save on unsprung weight and performance pads would be alot cheaper.

My 4 pots are bloody amazing mate now they are properly beded in! even from cold the ds2500 are good :D

2 pots good idea now make me some :p

[yr51ocw]

need some time to get the capital cost together. My daily driver is costing me £1000 this month with mot failure/tax/insurance.

It will be something I will be looking into in the future, but for now I am completing a fuel tank and beginning on tubular wishbones. Keep reminding me though dude and in the summer I should find the time to have a look.

[Sophia_Bush]

ouch the 406 failed that bad?

aye will do mate all is well here

[yr51ocw]

yeah big bad fail, a full sheet of major fail points. But better the devil you know so im trying to fix it up at minimal cost

[Sophia_Bush]

aye knowing you spending out haha btw your capri wheels what was thje deal fitting them work wise

[yr51ocw]

centrebore needs taking out to 66.1mm. And then you need to find suitable nuts/bolts.

I used the std capri nuts but are a 12x1.5 thread. So the studs I have are M12x1.25 one end and M12x1.5 the other end. Then the nuts are closed ends which I had to open out.