20v vented rear brakes on 90q B2 - Page 2

maartenmoerman · 21-09-21, 10:21 PM

Quote:

Originally Posted by jogi730

Keep us up to date which route you go down

Will sure do.

Quote:

Originally Posted by msh

In case the car is being built for heavy track use, then, surely, go for vented discs.

This car is definitely not needing it now, turbo motor is being built at the moment, but I needed new brakes on the thing, so I will upgrade fronts to 280mm. Now I always see just the fronts being done, and never the rears. I don't like that sight. Both the front and rear brakes needed new discs and calipers, so, while i'm at it anway, i will upgrade it all. Basically make it look good / balanced

And yes, i probably won't need it, but it's also a fun exercise

20vcqdriver · 22-09-21, 07:49 AM

On my Cq I have A4 288mm up front and 256mm rear and never had rear lock up issues.
I have the Audi Driver/VWAUDI car issues that I wrote for the rears.
The 256mm discs are solid discs from the front of a Mk3 Golf TDi and have the correct offset and just need the holes changing to suit. Fortunately we have a good workshop at work that allows me to do the necessary alterations. On the mounting side I filled the original holes and re-drilled and tapped the mounts 5.5mm further out and used the original calipers. No issues in the 19 years since

Hanuman · 29-09-21, 04:39 PM

Quote:

Originally Posted by maartenmoerman

I'm also upgrading the front to 280mm with boxster calipers, golf 1 adapter kit, and redrilled/bored 280mm rotors for a Golf.

Not sure if my math is right, but i was thinking this:

- original 90q is 256mm front and 245mm rear. 256/245 = 1.04 ratio
- new setup is 280mm front and 269mm rear. 280/269 = also 1.04

Anybody can chime in, if my thinking here is correct, or do brake dynamics work in a COMPLETELY different way?

Did some more googling and searching 5x112 swap information (you'd be surprised what kind of info you find there). And some person pointed out somewhere that 200 20v brake might fit. Hat height of stock discs is almost 40mm, and the 200 20v brake (part number 447615601A ) is 46mm, but the disc is also 2 mm wider. This might fit with a spacer on the bracket? I noticed, i can get a set on ebay for 31 euro, so might be worth a shot...

Out of interest, what is the basis for going to 280mm fronts?

What wheel size are you going with?
How much machining work are you willing to undertake or have done on the discs? If it's not important, and having something off the shelf to fit straight away is a low priority, then the only real limitation may be the height of the disc. And even that can be overcome.
What's the thickness of the front disc?

Other than the Q7, unless I'm mistaken, Audi have a 68mm front bore. I'm toying with the idea of Mercedes disks which are 67mm, but in my case I'd rather not be doing any machining work on the service items. I want to be able to buy disks and pads, and fit them. Machining work being only necessary on the hardware to get a brake conversion done in the first place.

In your case, normal PCD is 108mm. But if you're willing to drill the disks as needed, then this is a small issue.

jogi730 · 29-09-21, 05:59 PM

One other option is to speak to Alex at Ultraperformance.
No idea of cost for your application, but he will make discs for you to your specification.

https://www.ultraperformance.co.uk/audi-s2rs2?page=1

I have no connection to them other than the fact I am using their dual brake booster conversion kit, one of the best mods I have made to my car.

maartenmoerman · 06-10-21, 08:51 AM

Quote:

Originally Posted by Hanuman

Out of interest, what is the basis for going to 280mm fronts?

What wheel size are you going with?
How much machining work are you willing to undertake or have done on the discs? If it's not important, and having something off the shelf to fit straight away is a low priority, then the only real limitation may be the height of the disc. And even that can be overcome.
What's the thickness of the front disc?

280mm would be best considering i wanted to use the largest possible disc under a 15" wheel. I am running ronal R8 15" ET42 at the moment. This does have a problem with fitment, and would require running 1.8mm spacers , which i don't want. I do have now also sourced a set of 280x22 mm AP racing discs, and with custom bells for the discs and custom adapters for the calipers I should be able to get away with a 0.8mm spacer between the discs & wheels.

I have no problem doing some work, as i just like to have a very nice solution

*edit* Ow, and one other thing that let me to 280mm discs is, i wanted to run nice shiny red porsche calipers, and i didn't want to upgrade the B2 front struts to the (different mounting for calipers) B3 front struts.

20vcqdriver · 06-10-21, 11:51 AM

Quote:

Originally Posted by maartenmoerman

280mm would be best considering i wanted to use the largest possible disc under a 15" wheel. I am running ronal R8 15" ET42 at the moment. This does have a problem with fitment, and would require running 1.8mm spacers , which i don't want. I do have now also sourced a set of 280x22 mm AP racing discs, and with custom bells for the discs and custom adapters for the calipers I should be able to get away with a 0.8mm spacer between the discs & wheels.

I have no problem doing some work, as i just like to have a very nice solution

*edit* Ow, and one other thing that let me to 280mm discs is, i wanted to run nice shiny red porsche calipers, and i didn't want to upgrade the B2 front struts to the (different mounting for calipers) B3 front struts.

Got the A4 288mm to fit behind the 15" wheel using the A4 carriers and calipers and yes converted to the early Series 3 struts that are identical apart from the carrier mount locations. With new pads had to take 0.5mm off the back of the spokes to stop catching but minor issue and avoids spacers.

maartenmoerman · 06-10-21, 01:17 PM

Quote:

Originally Posted by 20vcqdriver

Got the A4 288mm to fit behind the 15" wheel using the A4 carriers and calipers and yes converted to the early Series 3 struts that are identical apart from the carrier mount locations. With new pads had to take 0.5mm off the back of the spokes to stop catching but minor issue and avoids spacers.

That does look very nice! I might switch to that too if this endeavor of mine becomes too costly or difficult. I did read you have a pdf on your installation about it, would you mind sending me that?

20vcqdriver · 06-10-21, 01:22 PM

Quote:

Originally Posted by maartenmoerman

That does look very nice! I might switch to that too if this endeavor of mine becomes too costly or difficult. I did read you have a pdf on your installation about it, would you mind sending me that?

Have both the original 280mm and the latest 288mm install details, PM me your email address

22-09-21, 07:49 AM	#12
20vcqdriver 4 ring whore! Classic Audi Club Member Join Date: Dec 2007 Location: Wirral Posts: 3,910	On my Cq I have A4 288mm up front and 256mm rear and never had rear lock up issues. I have the Audi Driver/VWAUDI car issues that I wrote for the rears. The 256mm discs are solid discs from the front of a Mk3 Golf TDi and have the correct offset and just need the holes changing to suit. Fortunately we have a good workshop at work that allows me to do the necessary alterations. On the mounting side I filled the original holes and re-drilled and tapped the mounts 5.5mm further out and used the original calipers. No issues in the 19 years since __________________ Coupe quattro 1986:-~450bhp + loooong list of mods! Audi A7 Bi-TDI SLine Black edition 2015 mapped to produce 600lb/ft torque! Audi S4 4.2 V8 cabriolet 2004:- Last edited by 20vcqdriver; 22-09-21 at 07:54 AM.

29-09-21, 05:59 PM	#14
jogi730 jogi Classic Audi Club Member Join Date: Dec 2007 Location: Luton, Bedfordshire Posts: 1,689	One other option is to speak to Alex at Ultraperformance. No idea of cost for your application, but he will make discs for you to your specification. https://www.ultraperformance.co.uk/audi-s2rs2?page=1 I have no connection to them other than the fact I am using their dual brake booster conversion kit, one of the best mods I have made to my car. __________________ 1985 Audi 90 quattro 20v turbo with some tweaks