The GTM Supercar Build Log

Archive for the ‘Heat Barrier’ Category

Driving Notes, and Sticky Shifting Issue Update

Sunday, September 19th, 2010

The GTM has been seeing consistent usage whenever it has not been raining here. Odo is now at 311 fun-filled miles. Yesterday the wife and I went for its longest drive to date – 50 miles straight and it ran great. Today I took it out for another spirited 40. I’m starting to get into WOT usage in 1st and 2nd now and getting a feel for the car’s power more. Tons of power, and I’m glad I’m on DOT legal slicks. Street tires would be absolutely useless under a heavy right foot. A WOT 3-4 shift at 3rd-gear red line breaks the tires loose. A WOT romp through 1st and 2nd spins the tires most of the way. Braking is much, much better since messing with the bias balance bar. I have some tire rubbing issues with the rear tires rubbing the inside aluminum over dips in the road at speed (stiffer springs!), and the front left tire rubs the body on some turns at speed, or while going down/up an incline while turning (ie: driveways, ramps). Not sure how to address that one yet, but it is a common issue, apparently. I have been gradually filing away at the body where it rubs to see if that can give enough clearance. Raising the ride height a 1/4″ all around might do the trick as well. The ‘what is that noise’ radiator aluminum support mod I made recently is doing its job.

Getting back to the sticky shifting issue I reported previously in regards to the main shift cable getting too hot. I ordered some Earl’s Flame Guard which came recommended on the forums. I finally received it this week so I unhooked the shift cable, slipped it on, and called it good. No issues arose during the 50 mile drive yesterday (in low 50’s weather). Today was warmer (mid/upper 60’s) and I drove the shit out of the car. After 40 miles the shifter started getting sticky, but not as bad as it  had previously without protection, and it cooled down quite quickly. I never had any problems arise while using the temporary high temp reflective wire loom on the shifter cable so I ordered up a Thermotec heat sleeve that reflects 90% of radiant heat up to 2000 degrees, which I will slide over the Earl’s Flame Guard sleeve for even more protection. This winter I will have the exhaust coated as well to reduce temps, and probably come up with a heat shield to go between the exhaust and transmission/shifter cable surface.

“Is that a Lambo?” tally: 6

Sticky Shifting Dilemma and CAI Reinstalled

Sunday, September 5th, 2010

After each of my several longer drives in the GTM (20 min+) I noticed something that should not be happening – after 20 or so minutes of driving it became really difficult to shift the transmission into gear. I can only describe the feeling as ‘sticky’ or ‘sludgy’, as it would still shift fine, but it took considerable effort to move the shifter up and down into gears.

My first thought was it was because I did not have the trans oil cooler running. My second thought was that the clutch stopper was potentially stopping the pedal too soon and the clutch was never fully deactivating when shifting and when it heated up it was creating friction, and thus the sticky shifting. I activated the cooler pump, moved the clutch stopper back some more, and hit the road. Same problem after extended driving.

After numerous replies on the GTM forum I turned my attention to the thicker of the two shifter cables that run from the Brandwood shifter box to the trans shift rod. This cable controls the fore and aft motion of the shifting (ie: going into gear), and it also runs very close to the exhaust. The responses I received pointed to a potential overheating issue with the cable, causing the shifting issue. I ordered an Earl’s Flame Guard insulation sleeve for the cable, but in the mean time I used some extra 3/4″ corrugated high-temp resistant wire loom to wrap the shifter cable. I took the car out for the longest drive to date and when I pulled back in the garage the shifting was as smooth as it was when I first started the car. Problem solved 🙂

With the shifting issue taken care of, I set to reinstalling the cold-air intake. To create a buffer between the exhaust and the intake sleeves I actually just loosened the exhaust collars and rotated them so the bolts that run through the collars would support the intake. I then stuck some Thermotec heat barrier to the bottom of the sleeves where they rest on the collar bolts. I took an extended drive with this configuration and it worked great. Intake air temps dropped from 140+ degrees at speed when previous drives were logged, to 75 degrees. HUGE difference. Leaving the car at idle for several minutes after the 30+ minute drive had the IAT’s sitting at around 100 degrees. Previously the IAT’s would see 150+ degrees while idling. The CAI is pure win.

Rear Wall w/Window Completed

Saturday, May 22nd, 2010

Time to tackle the rear interior wall and window! With everything fit in place I removed the rear wall for the 30th time, covered it in suede and installed the rivnuts for the engine cover and fuel tank covers. The holes for mounting the wall to the body, upper cockpit sidewall mount, seat belt mounts, etc, were cut out with an exacto knife.

After letting the window sit a bit so the suede was stuck good I installed the interior window. If you browse the GTM forum you will find that this is typically a very rough process and takes a long time. With that in mind, I was mentally prepared to be patient for a few hours and I ended up finishing the entire window install in less than an hour. Nice!  It is actually pretty straight forward, and I spent more time figuring out how the weather stripping gasket closer tool worked than anything. I installed the weather stripping while having the wall turned ‘interior’ down, using a clamp to hold the gasket open as I slid it onto the aluminum. Once that was in place I slid the window into the window groove within the gasket by inserting one side first and sliding it to the end of the aluminum, then flipped the entire wall piece over and used a little flathead screwdriver to push the gasket over the window. This took about 10 minutes and the window popped right into the groove. With that done I flipped the window back over and squirted some Windex in the remaining groove that needed to be closed, figured out how the closing tool worked, and then went to work. If you are working to the left with the closing tool you just need to keep the prong of the tool pushed in and under (back towards you) the groove that receives the ‘tongue’ of the weather strip. It’s not easy to push the tool over the tongue and have it seal, so I kept spraying Windex on my finger and rubbing it on the strip ahead of the tool as I pushed.  After the window was done I covered the back of the window with the adhesive-backed heat barrier I used previously on the GTM.

With the window done, I pulled the contact paper off and saw only one scratch, which seemed to be there from the manufacturing process.  Before calling it a night I installed the rear wall again.

Thermotec Heat Barrier

Tuesday, February 17th, 2009

Today I applied Thermotec adhesive-backed heat barrier to the fuel tank cover panels, engine cover, and the entire interior of the tunnel. This will reduce radiant heat greatly and keep the interior of the car much cooler. The barrier is very easy to apply. I will most likely cover the interior of the dash console when it is ready for installation as well.