85euro928

I'm looking for some advice on rear brake upgrades for my '85 ROW.* I need to install new rear rotors, rear wheel bearings, and a rear control arm (don't ask) and was considering upgrading to the S4 calipers and rotors while I'm at it.*
My questions are: Should I even bother?* Will these fit under my 16" phone dials? And should I use the stock S4 rotor or is there another rotor I should use?* Thanks in advance.

danglerb

Rear brakes do little to stop, why bother.

JHowell37

To put S4 brakes on the rear of your car:
1. You need S4 rotors. (I'm using cheap Sebro S4 rotors without issue on my '85.)
2. You need S4 calipers. (I've got a set if you're interested)
3. You need some thick washers to serve as a spacer between the caliper mounts on the hub carrier and the caliper itself.
4. If you want to retain your pad wear sensors, you'll need to replace them with sensors from a '86.5+.

The rears will fit under the manhole covers.

85euro928

Dan, I need to do it anyway so if the rotors & calipers fit the phone dials why not? It can't be that much more than the S setup? FYI, my rotors are shot and my calipers can't be that far behind.

JH, PM sent.

Thanks

tv

I think I remember reading that to upgrade to the Big Reds on a Euro the spindles would need to be changed. Sounds like a hassle, when I upgrade the brakes it will be to the F50 style 335 I think that has already been done by one here.

If you're gonna do it do it right.

danglerb

Manhole = flat disc, not phone dial.

85euro928

OK, just to clarify... right now I'm only doing the rear brakes so no spindle issues. I didn't want to open this can of worms but the front brake upgrade and new wheels will be my winter project (unless some other more critical item breaks).

Dan,
I said "phone dials" you said "manhole", does that mean that you believe the rear S4 brakes won't fit under the "phone dials". BTW, "Manhole" just sounds wrong

danglerb

I don't know on the fit, just that flats and phonedials are not the same. I suspect the flats have a lot more room inside, but don't know it.

85euro928

OK, thanks.

John Speake

What tire and rim size on your exisitng rims ?

Fabio421

Upgrading just the rears to S4 will result in the car stopping "flatter" but it will also tend to slide the rear a little when hard braking while going into a turn.

Shane

The rears will fit under 16" PDs, and you probably have with the stock brakes a 33bar bias valve, where S4s have a 19bar. With the 33 and four piston rear brakes you will be quite happy with the way it stops. As Fabio mentions just don't stab the brakes on wet corners and expect it to hold. With my '86.5 brakes I removed the 19 bar valve and put in a 55bar valve and my rears really do add to the stopping of my car, but will swap ends in a heartbeat if I'm not careful.

85euro928

John,
The tires are 225 50 16's, they're the original phone dials that came with the car.

Fabio & Shane,
Thanks for the heads up. My plan is to buy some not-too-grippy pads and use the car for the rest of the summer. When I garage it this fall I'll upgrade the front brakes and rotors and buy some appropriate rims.