The GTM Supercar Build Log

Archive for the ‘Brakes’ Category

A Quick Lesson in Brake Bias

Sunday, September 5th, 2010

I haven’t remarked about the braking much until now because I wasn’t that thrilled with it. I wanted to make sure there wasn’t something I had overlooked in the braking system that was causing its sub-par performance before I started whining about it.

That being said, last night I was browsing through the Wilwood pedal documentation and realized the brake pedal has a balance bias bar that I had left at its default setting which puts even pressure on the front and rear cylinders at the same time. In this car, like many sports cars, the front brakes are larger, so naturally we would want a bias up front. We want those fronts to actually work harder.

The balance bar is located at the the top of the brake pedal and connects the two clevises that screw onto the cylinder push-rods. If you turn it clockwise (like tightening a bolt) it will move the pressure bias to the left, or the front braking cylinder if you have the brake lines ran that way. ‘Loosening’ the bar will move the bias to the rear. Wilwood claims in their documentation that maxing out the bias bar to the left (front) will put twice as much braking pressure on the front cylinder in comparison to the rear.

Once I realized this I cranked the balance bar so it was maxed out to give the front brakes as much bias as possible. Test driving so far shows  much, much improved braking performance. If at any point I determine the GTM will need MORE front braking bias then I will have to change master cylinders to get more pressure.

Clutch and Brakes Bled, Oil Pump Lines, Oil Cooler Bracket Fab, Steering Wheel, Underbody Panels, Misc Wiring

Wednesday, April 15th, 2009

Things are starting to fall into place. The AN lines were ran for the oil pump and cooler. Once the final bracket is fabbed up to mount the cooler I will mount it and connect it all up, assuming the last piece arrives. I am still waiting on the inline oil filter for the pump. The inline oil temp switch arrived today so that the oil pump will only turn on when the oil temp is at 180-degrees. I am also wiring a sensor that will trigger an in-dash LED in-case the pump fails, so I had to run that wire from front to rear.

The clutch and brakes are bled – mostly. The brakes are done, but the clutch will not fully bleed. Some further research on the forum afterwards shows that I will have to remove the slave to bleed it fully, then reinstall it.

An engine ground strap was installed, connecting the engine block to the frame, and more work was done in moving wiring away from the headers. The steering wheel was installed, and the fuel tank underbody panels were riveted in place, also.

The first start is coming soon.

Clutch Pedal Modification and Rear Brake Lines Tightened

Thursday, March 19th, 2009

I removed the clutch pedal tonight for modification. Josh will be cutting off the right side of the pedal and welding it on the left side of the pedal so I have more room between the brake and clutch pedals. I will then repaint the pedal and reinstall.

I also finally tightened up the rear brake line fittings. The braided lines I am using have made it tricky to get a spacer in between the fittings to hold them flush and secure against the aluminum panels they pass through so I took the Dremel and notched out the fitting lips a bit so I can slide some spacers in between the aluminum panel and the fittings. Worked great.

Brake Lines Completed

Saturday, December 13th, 2008

Tonight Josh came over and tackled the brake lines. He did an incredible job and created some really nice lines. Since the ss braided lines I use are the same size as the brake lines Josh did a bubble flare to mate the lines properly without using the metric adapter Factory Five supplies. The brackets that are mounted to the rear upper control arms for the front brake lines are very short and require a very tight (too tight) bend to get them to work. As a result, I will be using longer bolts for the rear upper control arms and will mount the brackets with additional lock nuts to the longer bolts after securing the control arms with the supplied nuts. This allows a nicer bend in the line when meeting the bracket. The rear brake line was routed down the driver side of the tunnel, then T’d off at the corner of the frame and ran across and up to the passenger rear brake.

While Josh was running the brake lines I took on the ambitious task of installing the bulb seal on the front wheel wells. You might notice I removed the AC blower motor. More on that next week!

Radiator mounting bracket fabrication, brake lines

Saturday, December 6th, 2008

Tonight Josh came over with the radiator mounting bracket he fabbed up that connects to the frame’s radiator mounting bracket. To mount his bracket he had to cut the mounting tab on the frame, and then drill out the original frame ‘tab’ and bolt the new mount to it.  Afterwards we laid in the radiator, pounded down the radiator mounting tabs on the frame to match the angle of the tabs on the radiator, and test fit it. Good to go! I painted the mounting bracket Josh made up and that has to dry, so tomorrow I will install everything.  I will post pics of all this later when I do the radiator install so it is all nice and organized in one post.

Next we planned on plumbing the clutch and brake lines, but Josh forgot his bender so we just got the brackets mounted for the rear stainless steel brake lines and attached the front and rear stainless brake lines. The clips that come with the stainless lines to hold the lines to the brackets are not ’snug enough’ so I have to track down some better ones. We will run the lines this weekend.

Rear suspension installed, Fuel cover panels riveted

Friday, November 28th, 2008

After getting the steering setup the rear suspension was installed. This was a real bear, as the brackets on the frame are very tight. After much pounding, swearing, and prying, the arms went in and were bolted. Th e-brake cables were then connected to the main e-brake bracket.

The fuel tank aluminum panels were also riveted into place as well.

E-Brake and Coil-over mounts Installed

Friday, November 21st, 2008

The e-brake is now installed, and it required no rivnuts. I also fitted the coil-over mounts to the rear suspension arms.

Brake Assembly

Tuesday, October 28th, 2008

Assembled the brakes today, excluding the last front caliper (waiting on the anti-rattle spring). Once I get the last brake assembled I will put together all the suspension arms.

Starting Brake Assembly

Tuesday, October 28th, 2008

I didn’t do much today, but I did get brake knuckles mounted to the wheel hubs. Cleaned up all the clips and anti-rattle springs for the calipers and got those clipped into the calipers. I am missing one for the front caliper, so I will have to wait for another to come from FParts. Tomorrow I will get the rotors and calipers all mounted.

In other news, I think I have picked out the color for the car and wheels. I was originally planning black/black like always, but I think this color will really look better. I’ll wait until later to post what it is.

Paint Prep Complete!

Sunday, October 26th, 2008

After five cans of primer and paint all of the suspension and brake components are repainted and ready for reassembly.