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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Tue Sep 05, 2017 1:52 pm    Post subject: Floating Spline Drive Brakes - Next Upgrade Reply with quote

I'd like to go to floating discs on my car but everything out there in the aftermarket is a bit "meh", mainly because it's all based on off the shelf motorsport discs and the float is via bobbins which work great on a race car where the brakes are always hot but are mostly annoying on a road car because they are noisy and rattle when you pull up at junctions. The Brembo Track day discs are pretty good but are still £1500 odd which is a hell of a lot for two front discs. Alcon do a kit at £1350 but that uses their 360mm disc (as they don't do a 350 in the right thickness) so you need to ***** around spacing the caliper to use them (and there is no real performance benefit from that small an increase in disc size), plus replacement discs are £450 each.

OEMs like BMW and Merc get around it by having pin drive floating discs where the disc sits on multiple pins arrange vertically from the bell which is great but they are single use i.e. the bells can't be reused so it's an expensive way to do it and not viable for small production. Here's an OEM floating pin drive disc:


So I've decided to make my own, using a system with a compliant amount of float in it but with an anti-vibration element to stop clacky arrivals at the traffic lights. As always I've looked to F1 for inspiration where for the past few years a spline drive has been used in place of bobbins. Here's Mercs brakes for example:



This provides the float required but with less deflection, greater wear resistance, lower weight and reduced failure points. Here's the first draft CAD:



It's a 20 fixing system which captures the disc spline within the rotor spline. The inner retaining ring provides an amount of compliance to allow for float without it being noisy. The disc is used in a GT3 application currently so is well proven. Even better is that replacement discs are around £300 each, so 40 - 50% less than Brembo/Alcon replacement discs and although the bell is a complex piece on tight tolerances as there is no requirement for bobbins the cost is not too different to using bobbins.

I should have them made in a couple of weeks Smile
 
  
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coullstar
Nürburgring


Joined: 15 Sep 2015
Posts: 492
Location: Aberdeen/Torphins


PostPosted: Tue Sep 05, 2017 2:14 pm    Post subject: Reply with quote

What calipers are these to work with?
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2000 B5 RS4
1995 Corrado Storm.
 
  
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wasz
Albert Park


Joined: 28 Dec 2012
Posts: 1707


1999 Porsche 996 Carrera 2

PostPosted: Tue Sep 05, 2017 2:37 pm    Post subject: Reply with quote

Brilliant Cool

I'm sure you have it in hand, but I just imagined this conversation:

Insurance company: any mods?
popopbangbang: yes, I made my own brake discs
Insurance company: computer says no
 
  
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moorhouse
Nürburgring


Joined: 15 Apr 2013
Posts: 419
Location: Northumberland


PostPosted: Tue Sep 05, 2017 2:54 pm    Post subject: Reply with quote

Now that's what I call tinkering!! Hat's off to you. Just installed new front discs, pads etc and thought I was doing OK - now firmly back in my lowly place on the tinkerers ladder.
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HSC911
Sepang


Joined: 23 Jul 2014
Posts: 2862
Location: Bedford


PostPosted: Tue Sep 05, 2017 3:02 pm    Post subject: Reply with quote

worship

Pop Corn
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Tue Sep 05, 2017 3:10 pm    Post subject: Reply with quote

coullstar wrote:
What calipers are these to work with?


I run modified Cayenne 6 pots on mine but the discs are standad 997 Turbo size so this setup will work on 997 Turbo, 996 Turbo & 996 C4S (as a 350mm upgrade), 996 C2/C4 with Cayenne or aftermarket calipers - basically any of the 996/997 which use Turbo size 350mm X 34MM discs.
 
  
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coullstar
Nürburgring


Joined: 15 Sep 2015
Posts: 492
Location: Aberdeen/Torphins


PostPosted: Tue Sep 05, 2017 3:13 pm    Post subject: Reply with quote

Cool. Thumb
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coullstar
Nürburgring


Joined: 15 Sep 2015
Posts: 492
Location: Aberdeen/Torphins


PostPosted: Tue Sep 05, 2017 3:23 pm    Post subject: Reply with quote

Cool. Thumb
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Tue Sep 05, 2017 3:36 pm    Post subject: Reply with quote

wasz wrote:
Brilliant Cool

I'm sure you have it in hand, but I just imagined this conversation:

Insurance company: any mods?
popopbangbang: yes, I made my own brake discs
Insurance company: computer says no


Yes I think as the front uprights are laminated with carbon fibre to increase stiffness and there is an extra 30L of fuel where the spare wheel was most normal insurance companies would be a little concerned by it.

As it is the same company who covers our business operations covers it - I suppose on the basis that if they're covering the public liability of us running F1 cars down the beach front in Spain etc. then a Porsche built by the same people can't be any more risk Very Happy





The brake design I'm producing here is a modification of an 18 bolt application for GT4 (we design a lot of brake components etc. for motorsport). I've gone up on fasteners to allow for some loss of strengh due to aging and corrosion. The bells are way over spec'd for what they are doing and the loads they will see but it's always easier to over engineer and reduce than start on a small strengh multiplier and then have to find ways to increase it!
 
  
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ragpicker
Paul Ricard


Joined: 14 Apr 2013
Posts: 3049
Location: North East England


PostPosted: Tue Sep 05, 2017 7:34 pm    Post subject: Reply with quote

Oh my....

....he's at it again.....

what
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986 S - usually in pieces: http://911uk.com/viewtopic.php?t=112626
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Tue Sep 05, 2017 7:57 pm    Post subject: Reply with quote

ragpicker wrote:
Oh my....

....he's at it again.....

what


I never really stop - designing new bits for the car is a nice way to spend time when on long flights or waiting around at circuit. It's also had an unplanned break recently as a front wheel bearing failed early so I've refurbed a few bits to avoid it coming off the road in 15K to do them.

Laminated the front uprights with carbon fibre across the high stress areas and replaced the uprights for lower mileage ones with fresh bearings:


Laminated the rear most floor panel as I keep loosing these:


Rethreaded the floor retaining studs to M5 and riv nutted the two push fitting mountings to make it nut and bolt on:


Rebuilt all the Lobros:


Converted the caliper mounting brackets to Ti studs:


(Temp) Changed steering wheels as the airbag kept tripping the SRS light in the old one:


It's never ending - also fresh front brakes, new front TREs, changed the gearbox bush for the upspeced Powerflex one.... not bad going really as it only came off the road on Friday last week Very Happy
 
  
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MNC911
Österreich


Joined: 10 Feb 2016
Posts: 916
Location: Prestbury


PostPosted: Tue Sep 05, 2017 8:06 pm    Post subject: Reply with quote

I'm liking the adjustable suspension and the calipers. Have you a close up photos of them? The caliper looks very machined flat similar to AP Racing in silver finish. What's the story behind them?
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Tue Sep 05, 2017 8:36 pm    Post subject: Reply with quote

MNC911 wrote:
I'm liking the adjustable suspension and the calipers. Have you a close up photos of them? The caliper looks very machined flat similar to AP Racing in silver finish. What's the story behind them?




They are Brembo 18Z Calipers from the Cayenne Turbo S that have been converted to radial mount from lug mount by machining the mounting side of the caliper body down and drilling radial mounts into the body. These then mount to a hard annodised 7075 T6 mounting bracket which adapts the caliper boss spacing and offset of the standard C4 upright caliper mount to suit the modified Cayenne caliper. The flexi - caliper hard line is specific to this setup as there is no standard option that can be used and the flexis are off the shelf HEL.

They are designed to work with the standard (or any disc of the same size and offset) 997 Turbo 350mm X 34mm brake disc.

The original C4 front calipers are now on the rear of the car with 996 GT3 Mk1 330mm discs.

The master cylinder has also been swapped for one of GT3 dimensions but I have retained the standard C4 servo which gives a good balance of minimal travel in the brake pedal vs pedal effort.

It's a very effective setup.
 
  
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Guywilko
Newbie


Joined: 04 Jul 2017
Posts: 9



PostPosted: Thu Sep 07, 2017 7:24 am    Post subject: Reply with quote

Really fascinating, thanks.

My C4 ( a measly 101k miles) has a clonky front CV. Is it a regrease (on or off car) or is it a replacement job?

Cheers Guy
 
  
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EGTE
Nürburgring


Joined: 06 Jul 2015
Posts: 459



PostPosted: Thu Sep 07, 2017 8:31 am    Post subject: Reply with quote

Damn, your face must come off when you brake with that set-up Very Happy.

I put Cayenne brembos on a (1600Kg) RS4 and they would almost swap the car around if you braked in a turn.... on a 1300Kg 911; wow.
 
  
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1059



PostPosted: Thu Sep 07, 2017 9:04 am    Post subject: Reply with quote

What's the spec on that Lobro grease your using PPBB, looks very trick and much nicer than the usual horrid stuff.
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Thu Sep 07, 2017 6:57 pm    Post subject: Reply with quote

Guywilko wrote:
Really fascinating, thanks.

My C4 ( a measly 101k miles) has a clonky front CV. Is it a regrease (on or off car) or is it a replacement job?

Cheers Guy


Replacement I'm afraid, if it's clonking then it's worn (the excess clearance between the cage and balls or balls and body is what is causing it to clonk). The idea behind stripping and inspecting them is to monitor them for wear so you can make a good guess at when they will need replacing but I've always run a much better than standard grease in them which seems to be keeping any significant wear at bay.
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Thu Sep 07, 2017 7:01 pm    Post subject: Reply with quote

EGTE wrote:
Damn, your face must come off when you brake with that set-up Very Happy.

I put Cayenne brembos on a (1600Kg) RS4 and they would almost swap the car around if you braked in a turn.... on a 1300Kg 911; wow.


Yes they're quite good. The plan was to essentially transplant the brake system from a 2.3 Tonne car to a 1.3 Tonne car with the idea that if the standard bits in that worked well enough to stop 2.3 Tonnes from 170mph then on the lighter car they would offer good performance, low wear rate and cheap bits! The pads I use are £50 a set for example Smile

The rear is using the original front calipers with a 330mm GT3 disc so brake bias is still pretty much as it was, you can trail brake without unsetting it but as always with a 996 the engine position helps with that!
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 480



PostPosted: Thu Sep 07, 2017 7:02 pm    Post subject: Reply with quote

Harv wrote:
What's the spec on that Lobro grease your using PPBB, looks very trick and much nicer than the usual horrid stuff.


It's Redline CV2 - https://www.redlineoil.com/product.aspx?pid=82

We use it in a lot of the race cars including some of the F1s. Unlike most F1 lubricants it's actually quite cheap and a vast improvement on the usual stuff that gets used in road cars as standard.
 
  
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Guywilko
Newbie


Joined: 04 Jul 2017
Posts: 9



PostPosted: Thu Sep 07, 2017 7:25 pm    Post subject: Reply with quote

Replacement I'm afraid, if it's clonking then it's worn (the excess clearance between the cage and balls or balls and body is what is causing it to clonk). The idea behind stripping and inspecting them is to monitor them for wear so you can make a good guess at when they will need replacing but I've always run a much better than standard grease in them which seems to be keeping any significant wear at bay.[/quote]

Thanks. Is there a GKN part no for the inners and outers? can only find a full driveshaft in porsche catalogue.
 
  
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