Header Clearance Issues / T5 Installation

Header Clearance Issues / T5 Installation

A Study in Header Clearance Issues

Tuesday night I spent several hours finishing up the drive train installation by installing the T5 stick-shift.  At the end of the night as I routed the clutch cable down to the bell housing, my heart sank when I realized I had issues with header clearance.  I’m not upset about it, in fact I don’t know of anyone who’s installed headers who hasn’t had to make SOME changes to get them to fit without burning something up, but I’m a little miffed.  Why?  Because the instructions for the cable clutch setup clearly state on page 1 that, “The following exhaust systems are known to work with this kit…Doug Thorley Tri-ys” (emphasis mine).

cable clutch instructions - modern driveline
MDL cable clutch instructions

The clutch cable package is a pretty nifty setup that includes all the hardware necessary and detailed installation instructions.  I can’t fault the Modern Driveline guys on that front – they’ve spent a lot of time making the kit straight-forward and simple, and if you’re running a stock exhaust system it should work beautifully for you.  Headers, though, not so much.  The cable comes with an insulation sleeve to help mitigate the possibility of heat damage, but if the cable has less than an inch of clearance between the sleeve and the headers, the inside of the cable can become damaged.  How bad is my header clearance issue?  Bad!  It’s touching.  And there’s no way to avoid it.  The cable needs to be as straight as possible; pulling it out-of-the-way and bending the cable slightly will result in greatly increased wear.

I called Bruce at Modern Driveline directly and spoke to him about it, and he was helpful but thought the instructions said Doug Thorley Tri-ys didn’t work.  I’ll made sure to let him know, he was apologetic, and I can’t really fault him for something someone else made.  In any case, the solution is to go to the hydraulic clutch setup, which completely eliminates the risk of header clearance issues.  Had I decided to go with the hydraulic setup from the get-go, it would’ve been an extra $250 or so over the cost of the cable clutch setup, but since I’ve already got the cable setup and I’ve installed it (so there are “tooling marks” on the hardware), they can’t take it back, and I’m going to be out $460 to get things set up correctly.  Again, it’s just a little frustrating because I’d researched the setup before buying the headers and the transmission installation kit, and with the statement that these headers were, “known to work,” I’d settled on the cable setup.  Hopefully I’ll be able to resell the cable kit once I pull it back out, but it’s gonna be a huge hassle since removing the cable setup also means pulling the master cylinder and farting around with the pedal setup again.

The silver lining in all of this, though, is that the hydraulic setup gives smoother pedal feel with less effort, and after pushing the pedal down once I finished the installation, that’s probably a good thing.  The cable clutch is, in fact, pretty heavy, and I’m not nuts about how the pedal feels.  It’s hard to imagine I’d enjoy driving the car with a pedal that heavy.

Lesson learned: Doug Thorley Tri-ys do not work with the Modern Driveline cable clutch setup, but you’ll probably want to go with the hydraulic setup anyway if you plan on regularly driving your car.