The GTM Supercar Build Log

Archive for the ‘Pedals’ 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.

Diffuser Install Complete, Pedal Box Cover Installed

Tuesday, July 27th, 2010

Tonight I finished attaching the diffuser to the frame. I slid the jack in under the diffuser and jacked the bottom of the diffuser up against the frame so I could drill a few holes and rivet it into place. The diffuser I have was quite a bit off in its design so the bottom of the diffuser does not sit flush to the frame. Not a big deal though, as I used the jack to push the end of it against the frame and sunk a handful of heavy duty 3/4″ long rivets into it to hold it into place. I pulled on it pretty hard to ensure it would hold up.

With the diffuser in place I installed the pedal box cover. This piece is not mentioned in the manual at all – it was just buried in within the aluminum parts. I don’t believe it was labeled in the parts list, either. This piece is meant to prevent water/air from getting into the driver footbox, but rather than silicone it in place I placed some double-sided tape under the panel edges to ’seal’ it in case I ever need to remove it in the future.

Clutch Stopper

Sunday, June 6th, 2010

A common problem with the supplied master cylinder supplied by FFR for the clutch is that it is too strong. If you depress the clutch fully it will often break the shift fork in the trans rather quickly. As a result many builder’s implement something to stop the clutch travel short so that this cannot happen. I have a heavy foot so I had Josh fabricate up a heavy duty stopper that was then fastened to the pedal box wall. Nice piece and it is adjustable as well.

Fuel Filter connected to rail, Transmission Cooler and Pump Install Completed, Fluids Filled, Fuel Gauge Tested, Clutch Bled

Sunday, April 19th, 2009

The other night the fuel filter output was finally connected to the fuel rail, and the transmission cooler was installed. With the cooler in place the AN lines were made and connected. I am using an inline oil temperature sensor that will activate the oil pump when the oil reaches 180 degrees. This connects to the cooler inlet and wires to the oil pump (wiring needs to be done yet). 

With the transmission and fuel lines completed the transmission was filled with Swepco 210 gear oil, the fuel system got 5 gallons of gas, and some coolant was added. When the engine runs the coolant fill procedure will be followed.

With some fuel in the tank I wanted to test out the fuel gauge. The gauge takes a switched 12v, ground, and the fuel sender wire in the painless harness. The first time I hooked it up it pegged at way past full, which was obviously not the case. After some research I realized I did not have to wire the fuel harness sensor ground to the PCM, so I cut the wire and ground it to the chassis and the fuel gauge worked. It reads at around 1/8th tank with 5 gallons, so it is reading low, but that is better than reading high!

I also replaced the oil-fill cap with a screw in K&N breather, and finished bleeding the clutch slave. To finish the clutch slave bleed the slave had to be removed from the transmission and held high with the bleeder at the highest point. This got the rest of the air out of the system and the clutch is extremely firm now. The pedal only needs to travel half its full range-of-motion to engage the clutch.

Carpeting, Suede, Footbox Aluminum, Clutch Pedal Reinstall

Monday, April 6th, 2009

Tonight was productive. I started out by installing the front footbox aluminum panel into place. Afterwards I moved on to tackling the thing I probably have been dreading more than anything this entire build – the driver’s side suede installation. I wanted to do the suede now so I could then in-turn install the footbox carpeting, which would then allow me to install the clutch pedal (otherwise it would just get in the way of the carpet install).

The suede is just one big piece and it is a pain to work with. My main advice is to just be patient with the process. I had to place, lineup, mark, remove, and cut frequently before I was satisfied with how the suede fit. Once I had it taped in place and cut to allow the fabric to be pushed flat without bubbling or wrinkling I got to work. I started gluing in the footbox, working from the floor up, and then outwards down the tunnel. The driver’s side is a pain due to the concave aluminum panels, so I glued the concave portion first then smoothed outwards towards the top and bottom, avoiding any wrinkling and extending my cut lines as necessary. Once everything was glued I trimmed the excess at the top and glued it to the frame.

With the suede in place I them moved on to the footbox carpeting. This was a pain due to the pedals being in the way, and having to fit, mark, and cut constantly, but patience prevailed. After the carpeting was done I reinstalled the clutch pedal. As you can see, the modified pedal allows for more foot space and freedom between the pedals.

After doing all this I realized I forgot to open up the duct outlet for the heater/ac. I slit the fabric above the vent and trimmed it a bit, then rolled it back down the edges of the Dynaliner to the mesh so it looks nice and clean.

Driver-side Axle, Water Pump Hoses, Clutch Pedal Mod, Other Stuff

Saturday, March 28th, 2009

Earlier today I finished the clutch pedal mod by placing some good grip tape on it. It looks pretty ‘factory’ now.

Tonight I started out by cutting the water pump hoses to length and then connecting them to the 45-degree fittings. Much nicer. I also started reconnecting the water pump corrugated lines – I decided to use better hose clamps for these connections.

After that I moved on to installing the driver-side axle. This was pretty straight forward. The passenger side will go in after I install the starter. I also noticed the trans/engine was off-center by a good amount, but after I slid in the rear frame member/transmission mount it centered up pretty good.

Lastly, the fuel crossover hose was installed on the fuel rails.

Water Pump Fittings, Axles, Clutch Pedal Mod, Carpeting

Friday, March 27th, 2009

Tonight I installed the 45-degree fittings into the water pump outlets and re-installed the pump. The hoses will now be able to run freely without being kinked by the frame.

Josh finished the clutch pedal already so I primed and painted it – just need some good grip tape and it will look good as new. This mod will free up a bit of foot space in the footbox.

The axles are assembled and ready to go.

I decided to install the remaining footbox carpeting on the passenger side. I wasn’t looking forward to doing these pieces, but I found the Super 77 spray adhesive stays very tacky for a very long time, so you have plenty of time to work with the carpeting – just be patient and keep your fingers clean. I find that spraying small areas of the carpet at a time works best so that you don’t have to try to fit in the entire piece of carpeting in at once.

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.

Gas Pedal Installed

Friday, November 21st, 2008

First thing today was the gas pedal. My crappy rivnut tool finally bit the dust while trying to do the first of two rivnuts to mount the pedal. I was pretty discouraged so I decided to move on to the e-brake install. While looking for the e-brake mounting bolts in one of the many boxes that came with the kit I found another unlabeled brown box. I had to open it to see what it was and lo and behold it was a Marson Thread Setter rivnut tool. The same one I was planning on buying online tonight. It was not even on my inventory sheet, so I had no idea it came with the kit. Needless to say it did the job quickly and I no longer dread rivnuts.

Pedal box and Cylinders Installed

Thursday, November 20th, 2008

Busy day today so I didn’t get much done, but I did shorten the master cylinder bolts and installed them. Attached them to the pedals (they are still very adjustable despite the shortening), and tightened everything up.