Joel K
Supporter
Continuing with the brake install, next up is mounting the parking brake calipers on the rear uprights. I have the RCR supplied optional Parking brake kit. The calipers look great with the SL-C logo and billet aluminum construction. Unfortunately, a number of builders have not been able to get them to grab well and replaced them with other options.
Since I already paid for them I figured let me give it a try and see if they will work out. The end design will probably incorporate a linear actuator vs. the supplied ratcheted handle. But before I get to the linear actuator install I focused on mounting the calipers
Video of the caliper install...
One issue I noticed is that the supplied brackets do not place the brake caliper close enough to the outside perimeter of the rotor. Just eye-balling it, a better location would be to bring the caliper about 1/4” closer to the rotor center. That would increase the contact patch of the brake pads. At this point I’m wondering if this is the reason some other builders have reported that these calipers don’t grab well enough. Here is a pic which shows the excess pad gap...
I milled down the bottom of the bracket to see if I could get the calipers better located. After trimming .2” off the bottom of the bracket, the pad coverage looked much better. I wound up using this as a template for the actual bracket...
Also, I was not looking forward to drilling two holes through the side of each upright to secure the brackets. The ideal bolt is 10mm and that leaves about 2.5 mm of material on each side of the upright so the drilling needs to be dead on. If I got it wrong and drilled through the upright webbing that would be really disappointing so decided to use a different approach.
I noticed some pics of PB caliper mount brackets in Rob Mesa’s and Kurt Hoffman’s build threads. These eliminate the need to drill into the side of the uprights. Rob’s mount to the inside face of the upright and Kurt’s mount to the outside face. Rob has version 1 of the uprights and Kurt has the latest. My uprights are different than either so got the cardboard and plywood out and started mocking up some brackets.
Here is a pic of the three designs I narrowed it down to...
Design #1 Rob Mesa Style - secures the bracket with the wheel hub bolts.
Design #2 Kurt Hoffman Style - bolts to the two threaded holes on the upright used by the GT-R, and are unused on the SL-C.
Design #3 was a hybrid approach, using one of the GT-R holes and the closest wheel hub bolt.
I think all three designs would work and decided to go with design #1 which is similar to many after market brake bracket kits which leverage the wheel hub bolts. I like the fact that this eliminates the need to drill holes in the side of the uprights and I can easily swap to another parking brake solution if this doesn’t work out.
Next step was to mock up a wood version of the bracket. This was a good excuse to purchase a set of transfer punches from Harbor Freight. Should have bought these in the beginning of the build. Saves you a bunch of time and adds accuracy to making brackets.
I used a transfer punch to locate the holes for the hub bolts and also the caliper mounting holes. Notice how much the stock bracket was trimmed to position the caliper closer to the rotor...
Here is a pic of the finished aluminum brackets. Milled the hub bolt hole areas of the bracket down 1/8” to keep the cap bolt heads away from interfering with the screws that thread through the stub axles...
Pic of the bracket mounted on the upright. This bracket places the caliper slightly higher than where most builders have mounted them and puts the caliper at the 3 o’clock position on the rotor...
Pic of mounted bracket with the cap bolts in place...
Pic of the caliper mounted on the aluminum bracket. Fabricated .89” thick spacers to replace the washer stacks...
Pic from above...
Caliper is nicely placed on the side of the rotor at the 3 o’clock position...
With the complete pad coverage on the rotor the calipers seem to grab quite well so fingers crossed they do the job and work out.
Moving on to securing the stub axles and main caliper install.
Since I already paid for them I figured let me give it a try and see if they will work out. The end design will probably incorporate a linear actuator vs. the supplied ratcheted handle. But before I get to the linear actuator install I focused on mounting the calipers
Video of the caliper install...
One issue I noticed is that the supplied brackets do not place the brake caliper close enough to the outside perimeter of the rotor. Just eye-balling it, a better location would be to bring the caliper about 1/4” closer to the rotor center. That would increase the contact patch of the brake pads. At this point I’m wondering if this is the reason some other builders have reported that these calipers don’t grab well enough. Here is a pic which shows the excess pad gap...
I milled down the bottom of the bracket to see if I could get the calipers better located. After trimming .2” off the bottom of the bracket, the pad coverage looked much better. I wound up using this as a template for the actual bracket...
Also, I was not looking forward to drilling two holes through the side of each upright to secure the brackets. The ideal bolt is 10mm and that leaves about 2.5 mm of material on each side of the upright so the drilling needs to be dead on. If I got it wrong and drilled through the upright webbing that would be really disappointing so decided to use a different approach.
I noticed some pics of PB caliper mount brackets in Rob Mesa’s and Kurt Hoffman’s build threads. These eliminate the need to drill into the side of the uprights. Rob’s mount to the inside face of the upright and Kurt’s mount to the outside face. Rob has version 1 of the uprights and Kurt has the latest. My uprights are different than either so got the cardboard and plywood out and started mocking up some brackets.
Here is a pic of the three designs I narrowed it down to...
Design #1 Rob Mesa Style - secures the bracket with the wheel hub bolts.
Design #2 Kurt Hoffman Style - bolts to the two threaded holes on the upright used by the GT-R, and are unused on the SL-C.
Design #3 was a hybrid approach, using one of the GT-R holes and the closest wheel hub bolt.
I think all three designs would work and decided to go with design #1 which is similar to many after market brake bracket kits which leverage the wheel hub bolts. I like the fact that this eliminates the need to drill holes in the side of the uprights and I can easily swap to another parking brake solution if this doesn’t work out.
Next step was to mock up a wood version of the bracket. This was a good excuse to purchase a set of transfer punches from Harbor Freight. Should have bought these in the beginning of the build. Saves you a bunch of time and adds accuracy to making brackets.
I used a transfer punch to locate the holes for the hub bolts and also the caliper mounting holes. Notice how much the stock bracket was trimmed to position the caliper closer to the rotor...
Here is a pic of the finished aluminum brackets. Milled the hub bolt hole areas of the bracket down 1/8” to keep the cap bolt heads away from interfering with the screws that thread through the stub axles...
Pic of the bracket mounted on the upright. This bracket places the caliper slightly higher than where most builders have mounted them and puts the caliper at the 3 o’clock position on the rotor...
Pic of mounted bracket with the cap bolts in place...
Pic of the caliper mounted on the aluminum bracket. Fabricated .89” thick spacers to replace the washer stacks...
Pic from above...
Caliper is nicely placed on the side of the rotor at the 3 o’clock position...
With the complete pad coverage on the rotor the calipers seem to grab quite well so fingers crossed they do the job and work out.
Moving on to securing the stub axles and main caliper install.
Last edited: