XK8 LSx - 6 Speed ( Manual Transmission ) Conversion

This has been a fun side project for us, working on and off for the last 2 years. Our XK8 LS conversion kits have been very popular and most customers are satisfied converting the car with an automatic transmission. But a few, including me, wanted to know what this car with an LS engine and a manual trans (as in, shift it yourself, with a clutch pedal and everything) would be like. The main goal was a finished product that would appear as if the manual transmission was a factory option. That objective took the most time, but the end result was worth it.

Starting in spring of last year the car has been on the road doing shakedown miles and it's just fantastic. Running up through the gears and listening to that LS engine rev is music to the ears. The clutch pedal has a feel very similar to any modern Camaro or Mustang- firm, but not overly heavy, and the shifter rows through the gears like it should. It is just a kick to drive. The engine has plenty of torque to pull the car around (even with the very lazy stock 3.08 XK8 differential), and the double overdrive is nice for the freeway (it pulls 1200 rpm at 70 mph in 6th with no trouble).

Note- only the manual transmission part of this conversion is really new. From the firewall forward, this installation is basically identical to the LS-automatic XK8 conversion we have offered for several years now. It really is just the transmission, shifter, and pedals that are new here, and the results to date are just great. Our CAN interface unit works perfectly in this application- just like in the automatic conversion, the car believes it is still original, and the new (LS) engine believes it is still running in the donor Camaro.

This is now a real option for these cars- anyone can have a manual transmission LS powered XK8 using our kit and parts.

Manual Transmission XK8 LS Kits are now available- for more info, please call or Email.

Here are some pics of the car as it is now- it's a clean, simple installation, and the black 19" wheels set off the white body very nicely. The build itself is fairly basic using a low mileage 2002 Camaro LS1 engine and T56 6speed transmission.

What were the obstacles for a manual transmission into the XK8 chassis?

The challenging areas of the manual trans XK8 conversion  have only been the shifter location and how to manage adding a clutch pedal to a car never designed for one. And remember, we are trying to do this in a way that looks like a factory installation, not a quick add-on.

• Shifter- Because we wanted the center console to remain essentially stock looking,  the T56 shifter had to come up in the original automatic shifter position. And we needed to be able to do it in a  reasonably simple and inexpensive way. There are several different shifter schemes GM used on the T56, some mounted to the transmission itself, some offset to the rear, and some even anchored to the body with levers reaching forward to the transmission.  Cutting to the chase, a combination of some OE GM T56 shifter components and a little tweaking worked perfectly. The actual hole required in the tunnel is reasonably small. Here's a pic of the shifter in the prototype, with the (basically stock) console around it. All that has been changed is the addition of a black leather boot to replace the original J-gate shifter base.

• Pedals- Because the car has ABS brakes (and we wanted to keep them) it was required to keep the stock master cylinder and brake booster. The challenge was how to re-engineer the XK8 brake pedal box to also accommodate a clutch pedal and hydraulic master cylinder. Unlike earlier XJS and XJ6 models that used a cast aluminum pedal box that could be modified/welded for a clutch pedal and clutch master mount, the XK8 uses an injection molded plastic pedal box that cannot be altered that way. And also, this project was to ultimately become a kit for customers to install on their own cars, so requiring sheetmetal modifications to the firewall would be outside the "friendly conversion package" goal. After much work, several prototypes, and  many tests, a final version of the pedal assembly was devised that met all of the requirements. The new clutch and brake pedal assembly fits nicely into the footwell with adequate spacing (even for my 10-1/2W feet), uses a common off-the-shelf clutch master cylinder, and it is even possible to install the entire new assembly without having to remove the brake master cylinder from the car (so no brake bleeding is required- very nice). Below are some pics of the new pedals in the footwell and a topside view of the installation with the new clutch master . The clutch master is the silver unit mounted vertically behind the brake booster with the blue hose leading to the remote reservoir, mounted inboard. You can also just see the braided steel high pressure clutch hydraulic line. Everything fits nicely under the plastic cowl cover and the hood closes normally.

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• Transmission mounting, etc.,.- A few small changes were required to the automatic transmission mounting hardware in the original XK8 kit to work with the manual trans. Once done, everything fits nicely with plenty of room for service. Due to the smaller size of the 6-speed transmission, it's easy to remove it from below the car to replace a clutch or do other work. That makes routing exhaust piping, etc.,. even easier here than on the automatic cars.

And some other interesting details on this particular build (not necessarily unique to the manual transmission aspect..)

• Intake- a cold air intake system is plumbed over the radiator and to the cool area ahead of the AC condenser. This actually is a standard K&N kit for the 1998-2002 Camaro LS1 cars and is also California emissions legal. If you look closely at the engine compartment pic,  you can make out the large K&N filter just ahead of the radiator.

• Exhaust- this car runs a true dual 2 1/2" mandrel bent exhaust system with twin GM cats (required for California emissions), a stamped X-pipe, twin turbo mufflers, and twin tailpipes (that go UNDER the differential, and not through the rear suspension). Interestingly this exhaust is nearly identical to the system on my 99 Vanden Plas- same piping, same mufflers, same cats, everything- but no x-pipe and the XK8 is half as load as the sedan. I believe the X-pipe has some noise/resonance canceling feature that comes into play here. Either of these systems were easily built at our shop using the Flowmaster mandrel bent 2 1/2" dual exhaust kit (you can find it at Amazon, Summit, and other suppliers)

(Note: the intake and exhaust schemes here could also be used on an automatic XK8-LS car)

Please get in touch via Email or phone for more info.