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ST205 brakes on a ST165 with Infinity Q45 disc

Wed May 17, 2017 3:59 am

I’ve been running front and rear st205 brakes on my st165 for some time now and finally found some time to type up a how to and upload some pictures.

The rear 205 disc and caliper are bolt on minus having to bend the rear dust shield back so it clears the disc and making a small spacer to fit the center bore of the 205 disc to that of the 165 hub. I found that a stainless steel ruler from Westcott and some tin snips did a great job. The ruler was exactly the thickness I needed. Great thing was after doing the math to find the length/circumference the ruler had markings already on it.

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As we all know, the front is where the work is at.

I have researched people using or talking about using actual ST205 disc with custom caliper bracket (re-clocks caliper), IS300 disc, variety of Subaru disc BRZ and STI front disc, different generations of Supra disc, and even did some reading on Nissan R32 and R34 discs being options.

In all of the write ups, I found that everyone had to either do one or more of the following; use a spacer between the hub and disc, shave the disc down to the right size, or shave a great deal off the calipers mounting ears and/or the mounting ears off the knuckle.

With all of these builds the problems being fought were the ball joint clearance with the disc, disc offset and over all diameter.

My goal was to find a disc that did not need a spacer between the hub and disc, mainly because I was already running 25mm spacers front and rear. Second I wanted to shave the least amount of material off the caliper. Some of the builds I’ve seen had the calipers ears shaved down by quite a bit and I wanted to avoid this.  I decided to go on a long search of a disc with the best dimensions. First I bought a set of 205 calipers and got a spare front knuckle to take measurements on.

I looked at all of the disc that had been used on other builds as well as many others. I used Ebay to search Centric discs due to the fact that the picture had the dimensions of the disc. While most of the dimensions were there, I found one was missing.

I discovered that different car manufactures have different thickness of the top part of the “hat” the part of the disc that gets sandwiched between the hub and rim/wheel spacer. This dimension is important when calculating the distance the disc sits when mounted compared to the overall height of the disc. Most manufactures have a thickness of between 5 to 12 mm.

Other things to keep into consideration is the disc thickness as the stock 205 disc is 32mm. At first I wanted to keep a 30-32mm disc but found that if one even existed the amount needed to be shaved off the caliper ears to get the caliper to center was way too much. I also found that this thicker disc would not help with ball joint clearance. Some disc are two thin at 26mm (brz iirc). When using a thinner disc you have to take into consideration POT travel if pad spacers are not used. I found that a 28mm disc would be still usable without pad spacers.

After crunching numbers and testing a few different disc real world, I finalized with a 97-01 Infinity Q45 front disc.

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Measurements:
Distance from hub face to ears on knuckle 68mm
Distance from hub face to ball joint 50mm
Distance from pad side mounting face of caliper ears to caliper center 33mm
Thickness of caliper ears 17mm
Thickness of Q45 top hat 7.7mm
Theoretical ball joint clearance 4mm

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This disc has a thickness of 28mm which is like having 205 pads that are 2mm warn on each side. It weighs only 15.78 lbs., a lot lighter than the other options. Best of all it only required to shave 3mm off the caliper ears to center the caliper on the disc and gave me more than enough ball joint clearance.

Looking at some disc options that required the disc to be turned down to the right diameter i found that this many times left the insides of the pad area not contacting the disc surface. With the Q45 disc the pad makes full contact minis a 2mm overhang on the outside.

The disc also was re-drilled to 5x100, my friend was in the middle of a 5x114 conversion on his 6gc so these worked even better for him. The 165 front dust cover was taken off the knuckle.

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Mounting Solutions:

The 205 have the threads for the bolt to hold the caliper on to the knuckle on the knuckles vs the 165 having the threads on the caliper. I have seen other builds which thread the knuckle with a larger bolt but this requires you to also drill out/make the holes in the caliper larger too. I have also seen people use a bolt and nut which puts the nut in a very difficult are to hold back up while tightening. Ive also seen a bracket with threaded holes in place of the nuts, but still difficult to position and hold while lining the caliper and bolts up. These options did not seem optimal to me.

I ended up using a product called Time-Sert which threads a threaded sleeve in to the knuckle. This allowed me to use the same thread and size bolt which was originally used. Usually you have to drill out the hole but I found that the hole in the knuckle was already the right size and only needed to be cleaned up before being threaded for the sleeve. A M12 x 1.25 x 11mm Time-Sert was used and the kit was only 100 bucks which I split with a friend who is doing the modification to a 6gc.

10mm length sleeves would have worked but the 11mm gave me some over hang so I could use the supplied countersink on the caliper ears, giving me a small shoulder. This makes lining up the caliper to the knuckle a little bit easier.

Some of the knuckle casting had to be dremeled down to clear the caliper ears. I actually replaced the knuckles when I did wheel bearings later and cleaned up a new set of knuckles. I swapped knuckles primarily to get rid of the factory camber thing and to put new bearings in.

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The shoulder from the 11mm sleeves
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Shaving down the Caliper ears:

Shaving the 3mm off was done with a drill press and a Magnate 2704 Surface Planing Router bit 1.25” diameter. I used spacers from bearing puller kit to allow the caliper to sit flat on the drill press table and clamps and bolts to hold it down to the table as I took material off with the drill press and router bit. I made sure to measure before, during, and after with a caliper to ensure only 3mm was removed

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Centering the disc:

The Q45 disc had a center bore of 68.03mm so a hub centric ring for 68.1mm to 54.1 mm was used. It was thicker than the thickness of the top hat of the disc so it needed to be shaved down. I marked the ring and used an angle grinder to shave down the ring to the right height. This was done so it would not interfere with my wheel spacer.

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Before
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After
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4mm of Ball joint clearance
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Daylight pix
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2mm of pad over hang.
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Forgot to mention the specs for the rim I'm running. It's a 16x6.5" with 42mm offset. It's a factory Chrysler 15 spoke from a 04-06 Sebring with a 25mm spacer.
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Last edited by urbandork on Thu May 18, 2017 8:40 am, edited 17 times in total.

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Wed May 17, 2017 5:51 am

Wow Wow Wow. Very nicely done!

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Wed May 17, 2017 1:58 pm

Nice work!

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Wed May 17, 2017 7:59 pm

Great writeup!

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Sun May 21, 2017 4:20 pm

I'm glad this was posted up.

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Fri Jun 30, 2017 3:28 pm

The Time-sert thread repair is a nice touch. A much stronger helicoil-type solution.
I assume you had no issues torquing down the caliper bolts?

I'm doing the the ST205 front brake conversion currently (very slowly) and was going to have retaining nuts welded to the knuckle mount points but I do like your solution better as the welded nuts sit only a couple mm away from the disc and also mean I have to use non-standard bolts.

Nice install! 8)

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Sun Jul 02, 2017 10:27 pm

Nope no problem torquing the bolts down

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Tue Jul 04, 2017 3:36 pm

I love the write-up. Very detailed. Great job!!

Here are some questions I have for you. Maybe they'll help me with my conversions. I'm going to do the conversion and BBK in both my ST165s and my ST185. I am doing 5x114.3 lug conversions on all 3 as well, which adds another layer of work, but well worth it (greater wheel selection). I'll post and take pics, when it's my turn.

So far my collection of brake parts:
Lexus LS430 calipers
Lexus LS430 rotors (315mm) same size as ST205 rotors (F/R) No need to file the caliper to fit STi rotors (320mm)
+
5x114.3 hubs.

I just noticed the Infiniti rotors are 295.8 mm. I was wondering if you considered going with LS430 front rotors since they're the same size as ST205s (315 mm), since you were going to get them re-drilled anyways/. Maybe they won't fit well on your set up. However, the Q45 rotors seem to work well for you. I'm asking because I also considered the ST205 calipers for my ST185, and I have a good lead on a set for cheap. (I have ST205 rears for it, but will eventually test LS430 315mm front rotors or redrilled ST205 rear rotors, since I'm converting 5x114.3).

Have you considered the 5x114.3 conversion for it?

What are your plans for the rears? ST205?

With everything installed is your wheel offset the same?

Great work. And thanks for sharing.

Re: ST205 brakes on a ST165 with Infinity Q45 disc

Sun Jul 09, 2017 2:08 am

GT4times2 wrote:I love the write-up. Very detailed. Great job!!

Here are some questions I have for you. Maybe they'll help me with my conversions. I'm going to do the conversion and BBK in both my ST165s and my ST185. I am doing 5x114.3 lug conversions on all 3 as well, which adds another layer of work, but well worth it (greater wheel selection). I'll post and take pics, when it's my turn.

So far my collection of brake parts:
Lexus LS430 calipers
Lexus LS430 rotors (315mm) same size as ST205 rotors (F/R) No need to file the caliper to fit STi rotors (320mm)
+
5x114.3 hubs.

I just noticed the Infiniti rotors are 295.8 mm. I was wondering if you considered going with LS430 front rotors since they're the same size as ST205s (315 mm), since you were going to get them re-drilled anyways/. Maybe they won't fit well on your set up. However, the Q45 rotors seem to work well for you. I'm asking because I also considered the ST205 calipers for my ST185, and I have a good lead on a set for cheap. (I have ST205 rears for it, but will eventually test LS430 315mm front rotors or redrilled ST205 rear rotors, since I'm converting 5x114.3).

Have you considered the 5x114.3 conversion for it?

What are your plans for the rears? ST205?

With everything installed is your wheel offset the same?

Great work. And thanks for sharing.


With the 205 calipers mounted to the 165 knuckles a 315mm disc would have to be shaved down.

If you get the top hat thickness you could do the math and find out how centered the disc will sit. This assumes the 114 hub places the disc in the same place, it may not.

Either way I wanted to not have to shave down the disc outer dia. As I found with some of the 315mm subi disc it left the inside area of the pad not contacting a brake surface.

I wanted to keep it 5x100, I like my rims

Running 205 rears as outlined in the how to

Wheel offset is almost the same the Infiniti disc top had is 2.2mm thicker iirc 5.5 toyota thickness vs 7.7 Infiniti thickness
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