750i brakes

[Toby_Unna]

Having trawled through various threads about this brake conversion I thought I'd put one up with my experience.

I used standard 750i calipers (£30) and Audi TT 225bhp 312mm discs (£109 pair all in from GSF, for cross-drilled Zimmerman ones). I then paid £20 to have the necessary 1mm taken from the centre bore of the discs along with two extra holes drilled; very straightforward and 1 hour's work max. Mount brackets are currently fabbed from MDF to get the dimensions right (I haven't been able to get a template for the 300mm.de adapters and only started work on this today!); probably get these cut from 20mm steel as the 20mm ish MDF fits with plenty of clearance, and i'm not expecting them to be particularly expensive to make.

Clearance to my 17 inch wheels is plentiful, and I know some 16inch wheels will fit too. The most important thing is that the ofset of the discs is very close to the E30 ones, so no spacers etc required. Obviously no driving impressions yet (!) but I know Ant's tried a similar set up and got on well with it.

Overall seems to be very good value for 312mm brakes, especially as the price of consumables when they wear out will be much more reasonable than say for a Willwood kit.

I understand I'll be ok with the stock e30 M/C, but have the 750i one available if needed - will I need it? bearing in mind that I already have a fairly small brake servo?

Also will the car now be hoplessly underbraked at the rear?



new and old discs before machining



TT discs machined and fitted



caliper fitted on mock-up mount bracket







wheel rim clearance





EDIT: quick plug for Bilt Hamber de-rusting products. they're f**king brilliant!

[nickso]

nice.

i was thinking about going ahead and sorting this out myself after the group buy failed. the only thing that piut me off was i wasnt sure what material to make the adaptor out of. someone mentioned on the group thread that standard steel wasnt a good idea dont know why though.

[ed325i]

They use the e28 535 m/c on 300mm.de
I drilled 3 holes in mine the same as the 300mm.de ones.
You have to use the correct grade of steel what ever that is.
nice work toby

[Ant]

I used the stock e30 M/cylinder, great feel, not long travel and zero issue to date.

On Dimmys car the brakes were massivily OTT and locked up with slight provocation, once the ABS was sorted out( FUBBARRED) all works as well as could be

Nice Work Toby

[Turbo-Brown]

When you say the correct grade of steel?

The brackets holding my calipers are made of aluminium to around 8mm thick and haven't snapped off

[ed325i]

Its just when I ordered mine tino had to wait for the correct grade of steel to turn up as they sent him the wrong grade.

[funky-monkey]

I guess there's no chance of these fitting under 15"s?

[ed325i]

I guess there's no chance of these fitting under 15"s?

No.

[Andy335Touring]

Nice work Toby, now find me some thing similar for my 15's !

I guess there's no chance of these fitting under 15"s?

no chance

[Jhonno]

nice on.. yet again Toby!!

[Turbo-Brown]

Fair enough.

Think I'll be making mine out of good ol' mild (subject to calcs of course!) when I get around to it.

EDIT> Ooh! Toby, you couldn't tell me what the dim from the face of the disc that sits against the hub to the inner most face of the disc is could you? And (moon on a stick time) how much clearance there is to the steering knuckle?

Only ask as I got a set of 330Ci discs and have found that they'll fit in my Comp 42 wheels whilst retaining the Wilwood calipers but I've not been able to check that the discs will fit on the legs yet.

Sorry to go off topic dude!

[fuzzy]

will you be making up extra caliper mounting brackets to perhaps sell on to fellow zoners attempting this conversion?

[Toby_Unna]

Think I'll be making mine out of good ol' mild when I get around to it.

I was going to add that aluminium is commonly used to mount calipers. I'm going to use mild steel too, and i'm not expecting anything to snap off. as long as it's sensibly spec'd (i.e. nicely overspec) there isn't going to be a problem. the rest of the parts holding the caliper (carrier, strut base) aren't made out of fancy weird grade material, they're made to be cheap

I'll get some measuring sorted for you tomorrow Alex, no verniers though so it'll be basic ruler and eye stuff

Fuzzy, once I have my mounts made I'll know a price. At the very least I'll be able to supply dims/templates (as no-one has yet measured a 300mm.de bracket); they're a nice straightforward design and won't be hard to make/get made

Ed, I thought it looked like 300mm.de only added two holes? I tried to copy what they did anyway.

[d1mmy]

Excellent work Toby. My set up is very good. Highly recommend it (with ABS )

[Greeny]

I might have a go at this conversion myself, I have a lathe and milling machine in the garage so I could modify the disks and make the caliper mount spacer myself.

A cheap big brake conversion

Anybody know how easy the 750i calipers are to get hold of?

[Martinaston]

The audi A4 1.8 turbo (not quatro) 285mm discs fit under 15 inch wheels.

[lenny-d]

why is everyone using the 750i calipers, wots so special about them as 300mm.de use the calipers of an e36 328i and they're bound to be easier to get the hold of

[Turbo-Brown]

Ruler and eyecrometer's great dude

What I'm hoping for is "there's miles of clearance from the back of the disc to the knuckle"

[ed325i]

Ed, I thought it looked like 300mm.de only added two holes? I tried to copy what they did anyway.

They drill out that little screw hole. but yours look ok.
You can get hold of blank discs which have no holes in so you can just drill the 4 needed, which is now what Tino is doing.

[Toby_Unna]

Finally got the caliper brackets back for these this morning, the bloke making them decided to go on holiday!

anyway brackets cost £40 and should do fine. got them on this afternoon and went for a play, and they are very good indeed! no fade, loads of braking power, generally brilliant! being a bit careful while everything beds in and with the discs being new etc, but overall i'm very impressed, well under £200 total spend.

if anyone wants templates of the mount brackets, just ask

[ed325i]

Nice one just need to get some m3 calipers for the rear now.

[Demlotcrew]

I felt the pedal to be too soft/long travel with the stock E30 MC so fitted the 25mm one from the 750i.

Good work!

HTH

[Theo]

The bigger master cylinder is a good mod, greatly reduces the stroke of the pedal - well worth doing IMO.

[Toby_Unna]

cool thanks for that you two. it's available for nowt from the same place as the calipers, might have to stick it on i guess

[Turbo-Brown]

How much clearnace to the knuckle did you have in the end Toby?

Only ask as the 330Ci discs have about 1.5mm when mounted on the 4 stud hubs (just as a trial and they'd need moving out a tiny bit to get the track rod end in) They do give a lot of clearance for pistons on the outside of the disc though

[Toby_Unna]

never measured those dims for you did i Alex

knuckle clearance with these is similar to 325i discs, the offset is very similar.

i'll get the ruler out next time i have a front wheel off mate, sorry about that

[Templ8e30]

Any chance you could mail me the templates please Toby ?

Templ8 at hotmail.com

Cheers buddy,

Iain T

[Quaser]

What options do 15" BBS wheels have? 285mm discs with which calipers?

[toby]

^ good question!

[Martinaston]

E46 with brakets or possibly the E46 M3 set.

[toby]

E46 with brakets or possibly the E46 M3 set.

Thanks, have you done this or are you estimating?

[Martinaston]

I bought the bits and had the discs machined and just needed to get the brackets made, but then bought another car so its still sat on the back burner.
The 750 calipers don't fit under the 15' BBS wheels with the 285mm discs though, so i went for the E46 calipers but they don't cover the full face of the disc because they have the smaller pad.
I was hoping that Stuart could get hold of some E46 M3 calipers to have a measure up because they have the same size pads (60mm i think) as the 750i calipers but the body is slimmer, so they would cover the whole face of the disc and i hope fit under the wheels.
Have a search for a thread called "massive brakes" most of it is in there.

[Demlotcrew]

The E46 M3 calliper is not slimmer, its a bit bigger than the 750i/540i/M5 callipers.

I was going to use E46 M3 callipers also but found that they were too big to fit inside the 16" hartge wheels and used 540i calliper instead.

HTH

[Martinaston]

Is that with the 300mm discs ?

[Toby_Unna]

To all that have pm'd about brackets, and everyone else interested, I'll get a proper template drawn up (instead of the grubby drawing I gave the bloke in the machine shop!) as soon as I can and distribute it

these brakes are brilliant! and for the first time ever my car went though its mot without the tester moaning about the brakes being out of balance/sticking calipers/etc which has to be a good thing!