Aw11 st205 GT4 Front Brake Upgrade

[safeforever]

Hey everyone, as per my title, this little write-up will be a brief recount of my experiences with the aw11 st205 front brake upgrade! Now hopefully i’ll be able to get pictures to work with this.
To start off with, MASSIVE thanks to nathan, who did pretty much all of the work involved with this and did an impeccable job! Also gotta give credit to this most useful page (http://www.mr2mk1club.com/Bigbrakes.html) as this served as a fairly accurate guide for this upgrade.

Now! Firstly, the brakes themselves. Here you can see the old aw11 brakes, looking quite tiny next to their replacements. The st205’s were taken down from 315mm diametre to 300mm, so that they would fit. They also had a 4x100 stud pattern drilled into them, and the centre was increased from 55mm to 58mm. (if you look closely you can see the 4mmm spacer ring, but more on that later)

Here you can see the different callipers, the larger ones obviously being the st205 fronts. The mounting holes for these needed to be drilled out to 14mm in order to match with the aw11 hub.

The first step was obviously to remove the current brakes, and boy was that a pain! All the bolts and clips were very easy to remove, but the discs did not want to move. So it was a matter of patiently heating them with a torch and hammering them off. Once this was done we were left with the hub. Now these required only a tiny amount of modification, and this was in the form of an m14 tap. This threaded the holes ready for the new bolts that would be holding these massive brakes on.

Now came the fun part, putting all of this together! And this is where we encountered our first major problem. The aw11 hub is supposed to have a centre 54mm in diametre, but on my car it was slightly different, measuring in at 54.1mm. get this checked if you’re thinking of doing this upgrade!! Once this problem was fixed, it was back on track. The discs slotted right onto the hub. (in this picture the centre rings are missing, but they’ll be back later)

So now it was time to mount the celica calliper, and this also returned a bit of a problem. In order for the callipers to sit far enough out on the aw11, you need to place a 2mm washer inbetween the calliper and hub on each mounting bolt. The problem we had here was that our washers were too large in diameter, and were catching on the hub. This was obviously something that needed fixing, and so with a bench grinder we made them so they could easily fit onto the hub.

Ok, so now these brakes were on the car, we ran into the problem that was the most annoying, as it took several days to get the parts necessary to bypass. That’s right, my wheels were too small! They are a set of 16x7’s, and although they were large enough vertically to fit everything underneath, they were far too small horizontally. After testing my other set of 16x7’s, i found that this problem could only be solved in one of two ways;
a) buy a new set of wheels , or
b) buy some spacers so the wheels will clear
As i had only just purchased these wheels, i didn’t like the idea of buying yet another set quite so much. In the future maybe, but not right now. So i decided to go with spacers, so i went on down to jax and they ordered me a set of 4x100 to 4x100 25mm bolt on spacers and rolled my guards so that the wheels could still fit underneath. After a few days waiting, the spacers turned up, and this was what i got!

Shiny yes? Well anyway, now that i had these, i could finally complete these brakes! So it was back to work. After reconnecting the brake lines (aw11 ones fit perfectly, and supposedly the stock gt4’s also work well) and topping up the fluid, we put the spacers and wheels on, and headed off to test these things out. We had a feeling that the master cylinder may not be able to push enough fluid for these brakes. However, after testing the new brakes, we saw that the little aw11 cylinder was more than capable, and was bringing my little car to a halt in much less time than before. The only drawback we could see was that the tyres i am currently using do no justice to the cars stopping power, locking up when there is still plenty more in the brakes.

So here’s the final product.

Once again, i must thank Nathan for the wonderful work he did, and if anyone in the ACT region wants similar done by someone who actually knows what he’s doing and is extremely good at it, then contact me and i can put you in touch with him.

So one last thing. If you are thinking of doing this for yourself, then i’d advise getting everything measured up properly and double checked. Trust me when i say that not doing this can end in annoying waits!
Hope everyone enjoyed this, and maybe even found it useful.
Cheers:
Adam.
([email protected])

[YLD-16L]

Nice work, it looks to have come together very well.

+rep for the write up and pics.

Is the Nathan you refer to a person in a business or someone working from home?

[MR22ZZ]

Nice work, it looks to have come together very well.

Just one Q. In the pic comparing the GT4 disc to the old MR2 disc it looks like an option may have been to utilise one of the wheel stud holes already in the disc and then redrilling the other 3 (4x100). That would have given you 1 shared hole and the other 3 would have been spaced a little away from the original 5 holes.

isn't that what was already done?

[YLD-16L]

isn't that what was already done?

Indeed it is, I need glasses more than I thought

I edited my post to remove my useless question.

[takai]

isn't that what was already done?

It is what has been done. The lower left hand hole is shared.
I had the same thing done for ST185 discs when i did my AE92 Superstrut conversion.

[safeforever]

Is the Nathan you refer to a person in a business or someone working from home?

kinda both, his job has a LOT of very precise metal-working involved, and he does things for people like this and turbo-ing vehicles and stuff like that. does a wonderful job, after having seen his xr6(he made all the manifolds etc) that he turboed and these brakes. great bloke too.

[wagonist]

A tip for newbies

You should never need to heat up & bash rotors to get them off.
If you look at the pic of your rotor, you'll see there are another 2 smaller holes opposite each other. These are threaded (can't remember the size & pitch ), so you simply screw it bolts to these & keep tightening.
The end of the bolt comes through & pushes against the hub, therefore moving the rotor outwards off the hub.

[Ben Wilson]

can't remember the size & pitch

M8 if I remember correctly, just don't use bolts you mean to use later...

While it looks like a nice conversion, I have to ask why? Does the extra breaking ability really compensate for the increase in unsprung weight?

[wagonist]

Considering that when it had all new suspension, tyres, etc, I could get my 1300kg <60kW ATW turbo diesel Caldina to keep up will a modded Corolla Sportivo along the Putty Rd because I'd close up any accleration gap under brakes, then in something with a much lighter weight & more grunt, then hell yes, they'd be worth it.

I would recommend a tyre upgrade. With the Falken Azenis or Bridgestone RE040s I've had on my car, getting the ABS to kick in required a real hamfisted stab at the brakes in a full emergency.

Also, dunno if you've started doing this or not, but I've gotten into the habit now of every time I start to brake, checking the rear view mirror, because you're pretty much guaranteed to be able to stop better than the car behind & you can moderate your braking to not hit the car in front.

[Ben Wilson]

Considering that when it had all new suspension, tyres, etc, I could get my 1300kg <60kW ATW turbo diesel Caldina to keep up will a modded Corolla Sportivo along the Putty Rd because I'd close up any accleration gap under brakes, then in something with a much lighter weight & more grunt, then hell yes, they'd be worth it.

I'd be willing to bet that the difference was far more down to driver than car....