The moderately informational brake thread....

Rainbird

Registered User
You need to double up on the stock figure (or half that for the other calipers) to get a comparable figure - piston area may be 150%/etc more than stock but the way the caliper actuates is also different on the single piston sliding caliper. Effectively needs to push a piston twice as far to have the same result as it's only moving from one side.

Terrible description as I'm about to head into a client meeting at work, but in essence a single piston caliper needs to move "each" (there's only one) piston 2mm to bring both pads 1mm in, where as an opposing piston caliper only needs to move each piston 1mm.

Net result brings you right back to where you started in the original post, really.
 

Sam_

Down under
Double up on the stock figure (or half that for the other calipers) to get a comparable figure - piston area may be 150%/etc more than stock but the way the caliper actuates is also different on the single piston sliding caliper. Effectively needs to push a piston twice as far to have the same result as it's only moving from one side.

Terrible description as I'm about to head into a client meeting at work, but in essence a single piston caliper needs to move "each" (there's only one) piston 2mm to bring both pads 1mm in, where as an opposing piston caliper only needs to move each piston 1mm.

Makes total sense. I knew there was something amiss with my maths somewhere. I'll recalculate again!
 

Sam_

Down under
OK here's the correct numbers...

# Stock S3 ATE - 1 pot
54mm x 1 = 2290.22mm²
Total 4580.44mm²

# 18Z Cayenne/Touareg/Q7 - 6 pots
30/34/38mm
706.86mm² * 2 = 1413.726mm²
907.92mm² * 2 = 1815.84mm²
1134.11mm² * 2 = 2268.22mm²
Total 5497.78mm²
20.02733% larger than stock

# TTRS/RS3 - 4 pots
40/44mm
1256.64mm² * 2 = 2513.28mm²
1520.53mm² * 2 = 3041.06mm²
Total 5554.34mm²
1.028779% larger than 18Z
21.26215% larger than stock

# C5 RS6 - 8 pots
28/32mm
615.75mm² * 4 = 2463mm²
804.25mm² * 4 = 3217mm²
5680mm²
2.262375% larger than TTRS/RS3
3.31443% larger than 18Z
24.00555% larger than stock

# 17Z Cayenne/Touareg/Q7 - 6 pots
34/36/38mm
907.92mm² * 2 = 1815.84mm²
1017.88mm² * 2 = 2035.76mm²
1134.11mm² * 2 = 2268.22mm²
Total 6119.82mm²
7.74331% larger than RS6
10.18087% larger than TTRS/RS3
11.31439% larger than 18Z
33.6077% larger than stock
 

Prawn

My other car is a MINI!!!!
Your first lot of numbers months ago were actually correct @Sam_ :laugh: your latest update is also correct. The one earlier today wasn't.

Generally when comparing calipers you only look at one side of the caliper, as whether it's a fixed multi piston caliper, or a single pot sliding caliper, physics dictates that the opposing pad will. Exert and equal and opposite force so you only need consider 1 side.

My AP CP9660 Pistons are 27/31.8/38.1mm pistons giving an area of 5010mm^2 making them 9% larger than stock.
 

Tj 0785

Well-Known Member
VCDS Map User
So what’s best being closer to the original calipers or larger. And is there a point where its to large it won’t work with the original master cylinder
 

Sam_

Down under
Your first lot of numbers months ago were actually correct @Sam_ :laugh: your latest update is also correct. The one earlier today wasn't.

Generally when comparing calipers you only look at one side of the caliper, as whether it's a fixed multi piston caliper, or a single pot sliding caliper, physics dictates that the opposing pad will. Exert and equal and opposite force so you only need consider 1 side.

My AP CP9660 Pistons are 27/31.8/38.1mm pistons giving an area of 5010mm^2 making them 9% larger than stock.

Yeah I knew something was up with the first revision. Comparing two sides (and doubling the stock area) rather than one does result in different maths though - e.g. ~20% vs ~18% for the 18z. Either way, I was expecting the RS6/RS4 calipers to be wildly larger.
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
So what’s best being closer to the original calipers or larger. And is there a point where its to large it won’t work with the original master cylinder
Go too far with calipers like the 17Z and you get more pedal travel and what feels like a softer pedal. I have the 4 pot TTRS/RS3 calipers on my TT and find these really good with reasonable pedal travel and feel.
 

Prawn

My other car is a MINI!!!!
Comparing two sides (and doubling the stock area) rather than one does result in different maths though - e.g. ~20% vs ~18% for the 18z.


That's just a rounding error somewhere mate if you think about it.

Compare 1 and 2, one is 50% of the other.

Double them both to 2 and 4 and one number is still 50% of the other. Percentages don't change because you've doubled the numbers.
 

Sam_

Down under
I've let the computer do the hard work - maths at 1am is not my strong point :laugh:

upload_2018-8-9_16-13-29.png
 

vanilla_ice

Registered User
Yes it needs machining off the red lines, you also need to sleeve the actual bolt holes in the caliper with 1mm walled aluminium tube as the renault uses a larger diameter bolt.

I can't quite remember but I think the LCR caliper has 12mm holes?? And the Renault has 14mm?? The Renault is definitely one size up.

I'm sorry I cannot remember how long the bolts I ordered were but they are high tensile cap head bolts (many suppliers on ebay).

Once you have the caliper brackets and the calipers you can easily work out the length required, be sure to allow for the thickness of a suitable washer on the bolt (see my pics further up the page).

Hey @ben4866

I haven't given up on this idea. Can I pick your brains some more? How has this setup been working for you?

Is there enough meat on the creation brackets to be re-threaded to take the larger Renault bolts? I'm not sure I like the idea of sleeving with ali tube.
Are different lines needed? If so do you know the spec? Can you use the Renault lines??
LCR discs and pads 100% work with these calipers?

Many thanks.
 

ben4866

Registered User
Hey dude yes I still run this setup with zero issues at all.

My brakes get some serious heavy use so I can assure you the route I went is 100% reliable.

I went the sleeved route not because its the simplest way, its because its the strongest way, an aluminium sleeve in an aluminium caliper represents no risk/compromise. Whereas for me I didn't fancy weakening the brackets, although there is probably enough meat on them to survive being drilled and tapped larger.

I don't know if the renault brake lines would work or not, I seem to remember them being quite long on the renault. I just measured the length I needed and ordered some from HEL and made sure they had banjo ends as these brembo calipers are different to some other brembo setups.

Standard LCR discs with renault pads is what you need and this gives 100% perfect pad sweep.

This setup works fantastically well, I suppose the easy option would be use the whole LCR setup but they were quite expensive back when I built my car, I don't regret the route I went as its a better caliper and incredibly light weight. The new Alpine uses the same caliper.

Sent from my H8416 using Tapatalk
 

vanilla_ice

Registered User
Thank you for the feedback @ben4866, they do sound like a great upgrade.

I have found someone who supplies custom carriers and bolts specifically for the Renault Brembo calipers to fit MK1 TT's and S3's. They claim the standard lines work with them but a new banjo bolt is required. My own research suggests the banjo needs to be M10 X 1.0. Can you confirm please?

They make 312mm and 323mm disc options. I'm leaning towards 312mm as my discs have had little use and they'll be cheaper to replace in the future. Can you imagine there being any pad sweep issues? He claims there are none.

I don't doubt the 323mm would perform better, but I do doubt I'd notice the difference!

Finally, do the Renault pads have a wear indicator and is it compatible with our cars?

Thanks
 

Pedrosousa

Registered User
Hey dude yes I still run this setup with zero issues at all.

My brakes get some serious heavy use so I can assure you the route I went is 100% reliable.

I went the sleeved route not because its the simplest way, its because its the strongest way, an aluminium sleeve in an aluminium caliper represents no risk/compromise. Whereas for me I didn't fancy weakening the brackets, although there is probably enough meat on them to survive being drilled and tapped larger.

I don't know if the renault brake lines would work or not, I seem to remember them being quite long on the renault. I just measured the length I needed and ordered some from HEL and made sure they had banjo ends as these brembo calipers are different to some other brembo setups.

Standard LCR discs with renault pads is what you need and this gives 100% perfect pad sweep.

This setup works fantastically well, I suppose the easy option would be use the whole LCR setup but they were quite expensive back when I built my car, I don't regret the route I went as its a better caliper and incredibly light weight. The new Alpine uses the same caliper.

Sent from my H8416 using Tapatalk

Does this setup with the Renault’s fit under 17 inch avus without spacer?


Enviado do meu iPhone usando o Tapatalk
 
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