morghen

i've tried to install the 928S4 (M030) rear calipers today on my 924.
I use late offset 944S2 rear assembly but with the early calipers...this worked just fine...but today while tightening the S4 calipers i've noticed that the hat of the rotor is too tall for these calipers.
This makes the rotor sit closer to the inside of the car by a few mm...making impossible the use of these calipers as they actually touch the disk.

So..there goes the question...what the hell? the non M030 rotors are not identical to the M030? or am i missing something?

i've tried PET but my current internet connection is VERY slow...so i just cant download the damn pdf

pkt1213

M030 are different front and rear if I remember correctly. Check a parts website like pelican or lr for part numbers. I think 928 motorsports just started carring a good deal on them.

ramius665

So let me get this straight. You've been running 944 S2 rear suspension but with the 924 brake calipers and now you tried to install 928S4 calipers? Per the PET, there is no difference between M030 and non-M030 rear calipers or rotors. And in the front, the M030 calipers just had a larger piston on each side (36mm/44mm vs the non-M030 36mm/40mm)

morghen

i've been using 944 NA calipers on the S2 rear assembly.
now i have M030 calipers and the disks are too far on the inside...3-4mm perhaps.
the disk hat is too tall....i can solve this with a spacer shim on each bolt as the seating area would be the same...but i'd rather buy the correct rotors.

i was thinking that maybe the rotors are the same and the factory also used some spacers for the calipers.

rlets

I ran into the same thing on my '87 n/a. I installed a set of turbo rear calipers with turbo rotors and had the same interference. My solution was a 2mm washer on each bolt between the hub and caliper at the mounting point. A bit of a hack. But 3 track days later I see no abnormal wear and the bolts are still tight.

Rich

morghen

yea, sure the washers are no prob if the screw is tighten with the right torque...but this is quite strange isnt it?

i also have the 928 S4 rear rotors and those appear to have a too short hat
i'll check it out tomorrow..perhaps the 928 rotors will work...if not...i'm going to fab two Al spacer washers and use my old rotors.

btw, i checked in PET and PET does not show any difference.
Perhaps there is a difference in 928 S4 rear calipers and 944/968 rear calipers.

951Saga

My PET version shows spacers, 999 025 131 02, to be used between the caliper and control arm along with spring washer, 900 028 014 02 for the bolt. This spacer is shown in the rear caliper illustration.

The rear hats changed in ’87 when ABS was added. New hat is 951 352 041 02, the old 944 and all later 928 hats from ’87 on simply finished with 01.

951Saga

M030 front has different spindles, hubs, calipers, rotors… etc. Look at PET for the ’88 model year,(Turbo and Turbo S), to see all the options for each part number.
M030 calipers attach through the topside to the spindle unlike all others who bolt through the backside.

MAGK944

My turbo rear calipers have factory spacers on the bolts. I thought they all had them, they are shown in PET.

MAGK944

....item 8: http://dcauto.gotdns.com/illustration/index/841355267

morghen

thanks a lot guys! going back to the garage to finish the job

today i'm going to do the fronts.

Mr.Rodgers

Thats what I thought

951Saga

Aaron (ramius665) is correct regarding the ‘87+ rear brakes... not so for M030 front bits.

morghen

lets get things straight....S2 trailing arms and hubs can be used with early calipers(1 cyl/piston per caliper)
thats what i was using until now. it worked quite nice...never had a problem even on the Nurburgring or goin down the Swiss Alps
i got a nice deal for a set of 924 S4 calipers so i upgraded to early calipers(NOT S2 calipers) to M030.
I had to add 2mm spacer washers on the rears so the calipers clear the rotors and center on the rotors.

potent951turbo

As already stated, your missing the factory spacers.