Some Observations on Using OEM Toyota 4 Piston Calipers Options

[Coomer]

I was at the junkyard today browsing for something new for one of my cars, and I came across some trucks, which got me thinking about some comments some members had made a while back about using some 4WD Toyota four-piston calipers on the front of a sixth gen. Celica.

Some interesting facts:

• The caliper bracket's two holes to mount it to the hub/spindle are much closer together than on our sixth gens. This means that the caliper bracket and caliper can't bolt to a stock sixth gen. Celica hub/spindle.
• The trucks I found these four piston calipers on use a [url=http://www.buybrakes.com/store/BR25508]vented rotor that's 18mm thick[\url]. The [url=http://www.buybrakes.com/store/BR25425]ST204's vented rotor[\url] is 26mm thick. ST185 rotors are 23mm thick, as are AT200 rotors, but I'm sure the the ST's rotor isn't a large enough diameter. That said, it looked as if 5mm thicker rotors could fit in the calipers, but that may be because the used rotors and pads were worn down on the calipers I saw.
• The trucks I found these calipers on also use a 289mm diameter rotor. This could mean that even a ST204 or ST185 rotor (275mm and 277mm, respectively) may not be a big enough diameter rotor. However, they might work, depending on how the four-piston caliper bracket was custom-mounted on a sixth gen.
• The four-piston calipers use a different sort of brake line. A small portion of it is rubber, from the body to the hub/spindle, and then from there, the brake line turns back into a hard line until it hits the caliper, with a 10mm connection similar to the ones found where the rubber brake line meets the hard line on our sixth gen. Celicas. One might be able to use the truck's brake lines and just bend the hard part of it to get it to work.

In the end, this conversion may be possible, but I'm not going to be the one to try it. You'd have to drill and tap at least one additional hole in your hub/spindle to get the caliper bracket to bolt up. At that point, you'd probably want to try a ST185 rotor or a similar large-diameter vented 5x100 rotor that's closer to 18mm thick, which may be too thick for the caliper, or too large/small of a diameter for the four-piston caliper.

Then there's the issue of the caliper being in the right place for the rotor to slide into place. While spacers could help and probably solve the problem if the caliper is out too far, if it's in too far, you'd be in for a lot of fabrication work. Then you'd have to figure out brake lines, though I have a feeling the truck's lines could be used if modified properly.

But if someone wants to try, it may be worth it in the end. You may be better off getting ST205 four-piston calipers, but those are much harder to come by and more expensive, and they require some modification as well I believe, though not as much.

Four-piston calipers can be found on several Toyota 4Runners and trucks with 4WD and V6 engines, and probably more Toyotas. I found four-piston calipers on a '95 truck with 4WD and a V6 and on a '88 4Runner with 4WD and a V6 also. The junkyard wanted $25.00 per caliper had I bought them.

Just figured you guys might want to know. Post up if you've got any more information or questions.

[Bitter]

coomer, an easy way to check this is to CC the stock caliper at rest and at fully extended (pull it out with something) and then find the difference, this is how much fluid the master cylinder will ever have to move to put it all the way out there. then do the same with the 4 pot. you can just do one side at a time tho or one pot at a time, just be careful with the math as it could get a little tricky keeping track of 4 displacements. if the displacement of the stock is close to the displacement of the 4 pot then it shouldnt be a problem. if its alot more then you'll get low pressure in the 4 pot calipers at max pedal stroke and probably be locking the rear brakes before the fronts can bite. to fix that you could try swapping a truck master on over....but then you have to do something about the rear brakes, what does the donor truck have out back? is that fluid displacement near what your stock rear brakes need?