GT4 Brakes on a 6th Gen Options

[Fastbird]

After consideration I've decided to start my own thread on adapting GT4 Calipers to the 6th Gen Celica. This is a working thread, if you want to know something you don't see mentioned please ask, I have no problem giving up the info that I know or have found.

FIRST AND FOREMOST, I want to offer thanks to Stevenson a.k.a. Culpable04 for the work he's done. Between him and Preludekid on NewCelica, we'd still most likely be stranded with nothing. That said........

I'm not going to rehash how to get the caliper to fit. Culp's thread covered that quite nicely. This thread is going to be about getting it all to work, finding out what does and doesn't, ect.

First up, with some searching we know that the 7th Gen uses an amazingly similar brake design to our own. A lot of teh information I've gathered came from there. What I know right now:

You can use a max diameter rotor of 300mm without having to use a custom caliper bracket. I was originally going to make a caliper bracket and use a larger rotor, but I though, hey, let's just use what Toyota gave us. So 300mm rotors is what I"m looking for.

Sourcing the calipers is hard. I am in the process of paying approx $325 (200 pounds) for a set delivered from England. I'd suggest hitting GT4OC as there's usually a couple of part out's going on. If the caliper needs a rebuild, don't worry. I have verified that the 93-98 Supra does indeed use the same hardware, pistons, seals, and pads as the ST205, and parts are readily available. Current pricing for a basic piston rebuild will run you about $120ish so factor that in if you go to buy a set of bare calipers (was a factor in my purchase, I could have gotten bare housings for 140 pounds shipped, and $100 less, but it wasn't worth it in the end).

So.........knowing we can use 7th Gen front brakes on our cars, I used that as a starting point. The 7th gen guys are using a Mercedes rotor, though the FEBI part number won't cross reference on the site. Not a big deal though. As soon as I have calipers in hand I'm going to start snagging rotors that look like they're going to work. How am I figuring this out?

Math and measurements. Right now the information I've got says that the stock Celica GT rotor is 275 (274.9) mm diameter, with a 55mm center bore and 14.4mm bolt holes. Thickness is 28 with a height of 49.1 giving a hat size or offset of 21.1mm.

Once I get the ST205 caliper in hand I can mount and take some comparing measurements as to the new offset of the rotor pad surface centerline location between the stock rotor/caliper setup and the new one. This is going to easily be accomplished by measuring the stock rotor centerline, then mounting the ST205 caliper and finding the new centerline. Then it's going to be a matter of finding a rotor with an offset that gets close enough to either center up or work with a spacer. I know it's going to change so I'm stuck at this point right now. *EDIT 1* The outer edge to centerline for the ST205 caliper is 54mm. Found a good depiction in an OLD thread on here. I'm going to measure the knuckle edge to centerline of the stock rotor tomorrow so that should give a good basis. I'm ALSO going to measure the knuckle thickness because I'm also open to backside mounting the caliper which would open up rotor options too.

*NOTE* The ST205 rotor is 32mm thick. Most of these aftermarket rotors I'm putting on my test list are 28mm thick. I can't find extrusion specs for the caliper pistons, so rather than take a chance I'm planning on using a 2mm pad spacer on each side to prevent possible over extrusion of the caliper pistons.

Right now based on my research, there are three veyr likely candidates for this:

CLK320 2003ish model year
CL55 AMG 00-03 model year
SL500 Mid-90's (97 is what I used) model year.

All are 300mm and have varying offsets.

Then there's the bolt pattern issue. The Benz's are a 5x4.5 (114.3mm) bolt pattern and are not dual pattern. How do we correct this?? I was doing some searching yesterday morning and came across the following website, and just though it was an ingenious way to accomplish the task. You essentially make a three hole jig. Two holes with the 114.3 spacing, the third offset in the proper location for a pilot hole for the 100 spacing. I'm going to grab some junkyard rotors to play with this one, probably next week I'll start working on my jig. Here's the link for those interested: clicky

That's all I've got right now. More to come!!!

This post has been edited by Fastbird: Jun 19, 2009 - 9:43 PM

[AnaXyd]

Great information in addition to Culp's thread. Is the ST brakes the same as the GT brakes?

[Fastbird]

Great information in addition to Culp's thread. Is the ST brakes the same as the GT brakes?

Same knuckle as the GT, different caliper and rotor size, but once everything's off the same stuff I'm getting geared up will go right on the ST.

[Batman722]

here's an option also
so to add this up

GT4 calipers $325
rebuild $120
new pads $80
shim/carrier kit $50
SS braided lines (GT lines too short) $80
5-10mm spacers $100
rotors...$100 ? (hopefully)

EEK ! all together is $855...if you can get the rotors that cheap but maybe your wheels have a great offset and won't need spacers...
but tough for many to swallow.

I would love to have GT-Four brakes on my car but for that much $ I would rather get a Willwood BBK for $750 or just go ahead and get the TRD Scion BBK for about 1K (which also fits on 7th gens no prob).

I'm glad you and Stevenson are doing this, it's great info for everyone.

[Fastbird]

here's an option also
so to add this up

GT4 calipers $325
rebuild $120
new pads $80
shim/carrier kit $50
SS braided lines (GT lines too short) $80
5-10mm spacers $100
rotors...$100 ? (hopefully)

EEK ! all together is $855...if you can get the rotors that cheap but maybe your wheels have a great offset and won't need spacers...
but tough for many to swallow.

I would love to have GT-Four brakes on my car but for that much $ I would rather get a Willwood BBK for $750 or just go ahead and get the TRD Scion BBK for about 1K (which also fits on 7th gens no prob).

I'm glad you and Stevenson are doing this, it's great info for everyone.

The caliper rebuild is only $100 if you need pistons. A simple seal kit is about $10 for both sides, and everything else (shim kit, clips, bars, ect) is only about $40 or so. Lines are going to run a tad obviously. It's not going to be cheap, but it's still half the cost of all but the cheapest of legit brake kits out there.

[AnaXyd]

Why do we need spacers after this rebuild? Im sorry if its explained already. Thank you for answering by the way.. This swap is exactly what I need to do to get my car legal with the 3S-GTE.

The knuckles/hus will hold the power, btw? Have anyone checked this?

[vincent_doggy]

Why do we need spacers after this rebuild? Im sorry if its explained already. Thank you for answering by the way.. This swap is exactly what I need to do to get my car legal with the 3S-GTE.

The knuckles/hus will hold the power, btw? Have anyone checked this?

If your rims have 35 offset or lower, say 32 or even 30, u can clear the thick thick caliper, other than those offsets sure u need spacer, that make you have more clearance.

This post has been edited by vincent_doggy: Jun 20, 2009 - 2:35 PM

[azian_advanced]

you may need the spacers (depending on you wheel width and offset) so that the rims clear the calipers.
i would be more concerned with the caliper mounts breaking before the knuckles. but i'm sure the metal won't break as the brakes are only as good as the tires. so one would lose traction before damaging the caliper or the knuckle.

[AnaXyd]

Ah, thanks! I got this now. So, I cant run these calipers and rotors with my 14's winterwheels anymore! I got some big 18's at summer, so I think they got enough offset to clear the calipers.

Just to be sure: Bigger offset = more clearance?

I really dont like the thought of the hub breaking, or the caliper mount at the hub.. A loose caliper is not what I want when I need to to a emergency break!

[azian_advanced]

bigger offset = less clearance

[Fastbird]

Quick update: Heading to the junkyard tomorrow to grab a kunckle/hub/stock brake setup off of a 6gc that's there. Word is they just got a fresh one in and I should be able to get to it. Hopefully I'll come home with something and be able to get rolling.

GT4 calipers should be here by weeks end also.

[Rusty]

hey azian_advanced nice helpful pic you have there

so any wheel bigger than 16" GT4 6-spoke rim will fit << with the correct offset


so with the front's pretty much set for going in with a few minor adjustments... what about the rear brakes? drum brake sizes for the handbrake and cable length etc?? I'm kind of worried about how well they will fit in?

And lastly should any work be done the the GT4 brakes when you get them?

[Batman722]

what about the rear brakes? drum brake sizes for the handbrake and cable length etc?? I'm kind of worried about how well they will fit in?

the rears bolt right up with the rear 205 rotors. You do need a 5.5mm spacer between the caliper and hub and the ebrake lines work fine.

Lubu did the 205 front and rears a while back here.

[Fastbird]

what about the rear brakes? drum brake sizes for the handbrake and cable length etc?? I'm kind of worried about how well they will fit in?

the rears bolt right up with the rear 205 rotors. You do need a 5.5mm spacer between the caliper and hub and the ebrake lines work fine.

Lubu did the 205 front and rears a while back here.

No sh*t??????? The rears just bolt up? Dang.......... I wasn't expecting that one.

This is going to take a slightly different turn. I've taken some initial measurements and my goal now is to make a caliper bracket and space the caliper out in order to fit in a 12.7" or 13" rotor (323mm or 330mm). More to come on this. I'm going to post some sketches about the offsets and spacing up later once I get them done.

I DID get a hub/knuckle today though. Junkyard had two new 96's in there, a GT and an ST. Sadly the Yota's were in the back of the yard and that knuckle loaded up is HEAVY when carrying it a half mile.

LOTS more to follow.

[Fastbird]

Ok, so my chicken scratch isn't really worth posting here. Here's the measurements I've got:

Knuckle thickness = 10mm
Frontside of knuckle to stock caliper centerline = 30mm
Backside of knuckle to stock caliper centerline = 40mm

GT4 Caliper mounting backside to centerline = 54mm

Knuckle thickness is important as the caliper can be mounted front or backside.

I plan to work up proper specs for a 300mm rotor AND a 323 or 330mm rotor with a custom cut spacer.

For the 300mm rotors, I need to see how thick the bolt flange on the caliper is first, but if it's what I'm anticipating it to be I may have found an array of rotors that would nearly be a direct bolt on once redrilled. More to come here, I'm kind of stuck without having the GT4 calipers in hand.

For the larger calipers with the bracket, I absolutely have to know the bolt flange thickness, so I'm REALLY stuck there.

More to come.

[Culpable04]

here is a hint

4runner has the same calipers, and they come in 2 versions.

standard = ~ 319 mm rotors ( with 16" wheels )
Sport ~ 338 mm rotors ( with 17" wheels )

I assume the calipers used with the 319mm rotors, have a bracket the same length as ST205s, the Sport ones are 9 mm taller ( on the bracket ) to so that means those bolted on a celica would accommodate a 320 mm rotor.

4runner 2003-2006 sport package (17 wheels with this brake set-up )

also when planning on bigger rotors for the front, don't forget about the back, the brake force has to remain at the same ratio ( or close enough ) to OEM or your tail may come and say hi in a event of hard breaking, so bigger rear brakes and maybe an adjustable proportioning valve may be needed. if using ST205 size rotors front and rear just swap to a ST205 brake proportioning valve if easy to find, but as far as I've found so far, the number ( ratio of braking force front : back ) seems to be the same even with our non performance brake systems.

[AnaXyd]

So what you are saying, is that the brake ratio is not perfect when we swap the both front and rear calipers to a ST/GT?

[Fastbird]

So what you are saying, is that the brake ratio is not perfect when we swap the both front and rear calipers to a ST/GT?

Both would most likely be fine. Just the fronts you may or may not be where you need to be.

Nothing new going on. Waiting on calipers to show up before I can get cracking. Using some numbers I've found in various places has given me enough to work off of but I want to get a caliper in hand and double check the measurements before really digging into it and modding rotors.

[Rusty]

when are your GT4 brakes arriving, mine should be with me early next week, and just slowly start gathering the parts.

[RavenAegis45]

Awesome Post my Friend

[Fastbird]

when are your GT4 brakes arriving, mine should be with me early next week, and just slowly start gathering the parts.

I will hopefully be getting mine sometime next week. I'm lining up some rotors that I need for testing already, but if I get lucky and the measurements I've taken hold up, it'll be a one shot mockup deal. I am quite positive that I'm going to be very close first shot with as much researching I've done. Just waiting on my calipers.......I've got the knuckle on the garage floor ready for everything.

HUGE thanks to Jimmykay.......he used a CAD program to plot out my bolt pattern charts so I can make my jigs for a 5 x XXX to 5x100 conversion on the rotors, and he also did a rendition of a bracket with my measurements for pushing the caliper out. Saved me an absolute TON of time. He's the man, nuff said.

[AnaXyd]

I got ABS on my current setup on my ST. Will the GT4 brakes work 100% with this ABS setup withouth any modification? If so, I dont see any way to wait any longer to buy some brakes and do the conversion!

[Fastbird]

I got ABS on my current setup on my ST. Will the GT4 brakes work 100% with this ABS setup withouth any modification? If so, I dont see any way to wait any longer to buy some brakes and do the conversion!

Yeah. The caliper doesn't have anything to do with the ABS. The ABS is controlled by the BPMV.

[yagamius]

what about using the GT4 ST185 calipers and rotors Front and rear to make the conversion into an ST, I heard that the rear rotor drum will fit into our regular drums, just need to clarify this

[Rusty]

right my brakes should be arriving in the next day or so... but I cant really do much at the moment, I might also get some knuckles just incase I screw up. then I need to get some flexi lines, 297mm front rotors (now with the front rotor sbeing smaller would it look really funny/odd with the back rotors bigger??)...oh and bigger rims so they'll actually fit, but I STILL cant decide lol

[Fastbird]

what about using the GT4 ST185 calipers and rotors Front and rear to make the conversion into an ST, I heard that the rear rotor drum will fit into our regular drums, just need to clarify this

Couldn't tell you there, haven't messed with any of the ST185 stuff.

right my brakes should be arriving in the next day or so... but I cant really do much at the moment, I might also get some knuckles just incase I screw up. then I need to get some flexi lines, 297mm front rotors (now with the front rotor sbeing smaller would it look really funny/odd with the back rotors bigger??)...oh and bigger rims so they'll actually fit, but I STILL cant decide lol

My calipers have been shipped (reportedly) and I'm getting one set of my test rotors this weekend (buddy has car with rotors I want to use and is conveniently doing a brake job on Friday).

Still stuck waiting for calipers though.

[Rusty]

you can drool over mine if you want





just picked them up tonight

[Fastbird]

Calipers showed up last night. Unboxed them, all are in great shape though quite dirty. Doesn't matter though because it's what I needed. I also have my set of test rotors that if I'm right once redrilled will be just about perfect for what I'm looking for. More to come if I can get some free time this week..........

[jeffrosie]

Any further progress on this??

[Rusty]

nothing much yet as far as I know

one thing though why are the front calipers not threaded is it due to SSS? then how do they bolt up etc

[jeffrosie]

The hub is threaded, and the calipers bolt on to it.

[Rusty]

any update on this anyone??

[Rusty]

question would you need a new brake master cylinder (or at least a GT4 one?), since you need to push more fluid through or will Braided Brakelines do the trick?

[Culpable04]

no

stock one will do

[BonzaiCelica]

Will a 16 x 7" wheel with the offset +38 on the front axles and +35 on the rear clear the gt-4 brake calipers on all 4 rotors?

[vincent_doggy]

Sorry to Hi-Jack thread:

I got 2 sets of ST205 Front Caliper + ST205 315mm Rotors here

A. One set the caliper had been clean and paint in red and the rotor had been slotted


B. Another set, stocked and not yet touch

Can help to trim down the 315mm rotor to 300mm, a shop locally offer cheap labour cost for doing that.

PM me with your offer, I will get u a shipping quote

Vince

This post has been edited by vincent_doggy: Mar 26, 2010 - 12:12 PM

[Batman722]

Will a 16 x 7" wheel with the offset +38 on the front axles and +35 on the rear clear the gt-4 brake calipers on all 4 rotors?

probably not.

[Culpable04]

with an offset of 35 is the lowest you can get the brakes to fit without using spacers, but it all depends on the spoke design of your wheels.

in any case, just get the right spacers and you can keep your wheels. mine are 16 x 7 +38, I'm using a 15 mm spacer on the fornt to clear the caliper, haven't had a problem since.

[BonzaiCelica]

i currently have motegi FF7 16 x 7 with +42 offset as of right now

culpable 04 where is your thread on how you fitted your calipers?


This post has been edited by BonzaiCelica: Sep 16, 2013 - 10:53 PM

[Culpable04]

i currently have motegi FF7 16 x 7 with +42 offset as of right now

I plan on getting SSR Type F 10 Spoke wheels, 16 X 7 with +38 offset, will the gt-4 calipers clear that?? or would i need a 10mm spacer in the front to get it to +28 offset??? culpable 04 where is your thread on how you fitted your calipers?

GT-4 and SS-III celicas are the only ones with dual front piston calipers, right? Oh and If I were somehow able to get my hands on Superstrut suspension, they would most likely come with these brakes right

AGAIN +35 is the mleast you need to clear, and even some +35 wheels won't clear due to their spoke desiign, the size of the spacer will depend on the spoke design, mine are +38 but my spoke go inward so I needed a 15 mm spacer to clear my wheels, in some cases you will just need a 5 mm spacer, it all depends on each individual design, but bottom line is +35 or lower is where you want to start,

[BonzaiCelica]

I currently have some stock ST celica front rotors laying in my garage. Would I be able to use rear gt-4 brake calipers and front st brake rotors for my rear brake setup??

[vincent_doggy]

I currently have some stock ST celica front rotors laying in my garage. Would I be able to use rear gt-4 brake calipers and front st brake rotors for my rear brake setup??

Don't be silly

[BonzaiCelica]

ha why not it seems to be the same size as the rear gt-4 brake rotor. or are the front and rear rotors on the gt-4 the same size?

[Rusty]

uhh handbrake??

[enderswift]

x2

you're forgetting that the rears have to double as drums for the e-brake. So the fronts wont work

[vincent_doggy]

The rear rotor of ST205 is also 315mm diameter, just a lot thinner than the front thou

[BonzaiCelica]

Looking at part numbers and it seems quite weird, SS-II Beams Twin Piston has different part number from SS-III Beams Twin Piston Superstrut Suspension:

7150 VALVE ASSY, PROPORTIONING
47150‑12060 ST202..CV, SS2 1 $238.65
47150‑12160 ST202..CV, SS2, ｱﾘ(ABS) (12/1994 - 11/1997) 1 $263.16
47150‑12210 ST202..CV, SS2 (12/1997 - ) 1 $262.53

47150 VALVE ASSY, PROPORTIONING
47150‑12050 ST202..SS3 1 $238.65
47150‑20280 ST202..SS3, ｱﾘ(ABS) 1 $275.30

47150 VALVE ASSY, PROPORTIONING
47150‑20240 ST20*..GT4, SS1, ｱﾘ(ABS) 1 $262.96

Why does the GT4 Part Number Refer to the SS1 Celica if the SS-I never came with ABS??

GT4 Front and Rear Brakes mean you should upgrade to GT4 Master Brake Cylinder??

This post has been edited by BonzaiCelica: Dec 22, 2011 - 5:02 AM

[BonzaiCelica]

just goes to show you how great the front and rear gt4 brakes are at heat dissipation) watch from 8:03 - 8:28

1998 Honda Civic Type R (EK9) weighs 2400 pounds
1998 Toyota Supra TT weighs 3400 pounds

http://www.youtube.com/watch?v=szBNLJlJePY...feature=related

This post has been edited by BonzaiCelica: Aug 28, 2023 - 5:56 PM