S2 345mm X 32mm Upgrade

[Ryss]

Question : How does this conversion sound.
Caliper : Twin pot from a 1996 Audi A8
Disc : Merc 345mm X 32MM . weight 12Kgs

Thinking about an upgrade on my S2 and S2\V8 projects.

Here are the details on the S2:
Originally tried a Merc E500 W211 four pot caliper but the mounting lugs where too close to the original mounting points on the strut. Same Problem with A8 disc and calipers on the S2 strut.

Then hit on the idea of the Merc discs with the A8 calipers. Because of the larger dia. the caliper is moved away from the strut making it easy to make up an adapter.

Fits in a 17" wheel both in dia and offset. Only machining required on disc is to bore out the center of the disc by 1mm to fit the Audi hub.

Only thing that worries me is that this will be a big increase in unsprung weight.

Here are some pics.







Other thing is pads will have to be made as they are not available in South Africa other than from the agents and that's at a ridiculous price.

[macspring]

Would it not be possible for someone not in SA, but on here to post a set of pads to you ?

btw, what part number is the disc you have in mind ?

Kind regards.

[Ryss]

Hi David,

Yes I would source the pads in the UK and my sister could bring it back to SA when she comes back. But suspect it will still be cheaper to have them made in SA.
Merc disc is ATE 132.0114 or the set I bought where Febi # 21950.

[martinjs]

What about mounting brackets?

[Jamo]

Why use the merc disk instead of the A8 345mm disc?

[Ryss]

In Reply to Jamo : "Why use the merc disk instead of the A8 345mm disc?" Well I went hunting for a four pot caliper and I found these Merc calipers (Brembo).



As a result started with matching discs, but also becuse the Merc PCD is also 5 x 112. Disc height of the Merc disc is less that the Audi and just has enough clearance between the S2 strut and the inside surface of the disc. In this pic the center has not yet been turned to fit over the Audi hub, so it will still move towards the strut when properly fitted. As will be seen the clearance between the strut and the disc is about right taking this into account.



Also wanted a different height so that the mounting points of the caliper and strut where not on the same plane, as this will facilitate the making of the adapter. This was the problem with the A8 disc and calipers on the S2. The discs fit but everything is too close to make an adapter plate.

Paid BPS 300 for the caliper and BPS 150 for the discs, which was also a factor.

In reply to martinjs : "What about mounting brackets?" An adapter plate will be made up with two holes for the caliper and another two holes so that it can be mounted to the strut.

[Ruhmic]

Brake Upgrade

Why do not you use the A8/S8 with the 4 piston caliper in combination with the RS2 caliper bracket?

[Ryss]

Why do not you use the A8/S8 with the 4 piston caliper in combination with the RS2 caliper bracket?

Price and availability. And its been done before.

[Ryss]

Well took the brake conversion to the next stage and had the Merc discs bored out to fit the Audi Hub.
Had done while I waited and cost me R100. (+- BPS 9.00)

Split the A8 caliper into its component parts.



1. Used the center part, which mounts to the strut on its own to measure and fit.
2. Fit disc to strut and bolt in place.
3. Measure disc thickness (DT)
3. Measure the caliper aperture in which disc runs.(CA) Audi uses a 30 mm disc but has enough space to fit over a 32mm disc.
4. (DT-CA)/2 = the thickness of two spacers required to centralize the caliper on the disc. Thickness of an old CD did the trick.
6. Centralize Caliper on disc and in the position required. Ensure clearance between outer edge on disc and caliper. Outer edge of pad should be inline with edge of disc or 1mm in from edge of disc. Dia of OE Audi disc and Merc disc are not the same so edge of pad does not follow edge of disc.


7. A small amount of material was removed from the strut to allow the caliper to sit low enough on the disc.
8. In this case there is enough space to fit the adapter between the strut and the disc, which will allow the caliper to be bolted to the adapter. However this will require the threaded hole in the strut to be bored out and a thread cut in the adapter.

Alternatively the adapter can be fitted on the opposite side so that the caliper is bolted to the adapter and the adapter to the strut. Both caliper and strut remain standard and the old brakes can be refitted if required.
5. Fit all mounting bolts with nuts and spacers as required.
7. Cut pieces of metal and tack weld the nuts and spacers together, so that they are in the correct position relative to each other.


8. Make a cardboard cut outs of shape required for the adapter.


Now need to send the cardboard cut out to a profile cutter and specify the material thickness and then send the profile to and engineering works to mill the correct heights, bore and tap threads mounting holes.

However first thing is to find some pads for the A8 caliper. If very pricey will see what it will cost to have specially made. Suppose I should have done this first.

[s2driveruk]

Why use the merc disk instead of the A8 345mm disc?

the 345 audi disc is only 30mm i seem to remember too

[Ryss]

Ok.. I finally decided to finish the upgrade and pleased to report that the Merc 345 x 32 mm discs mixed with the Audi A8 twin pot calipers work like an absolute dream.

No noticeable difference in ride despite increase in unsprung weight.
Breaking is perfectly balanced with infinite control, for smooth and progressive braking.
High speed stops still pending as brakes get bedded in.

Here are some pics.

Adapter


Old disc vs New


Finished look with 17" rims

[rs200]

exelent ..
well done hero !!!!

I must do the same on friends A6.. he bought A8 calipers , and now we need a disc.. but not 314mm.. we need 345..

[tajgreidotu]

Which model of mercedes are this discs from??

Thanks for the threat, its going to be usefull for me in a few days!

[Ryss]

The disc are from a Merc E500 W211.

Just one thing, make sure Your ABS brakes are 100% operational as with this set up, an emergency crash stop, results an immediate lock up of the wheels.

[rs200]

thanks for advice..