How To: Convert your AWD 996 to RWD
 

I've seen the topic come up several times around here, so I figured I should make a How-To thread for everyone. :thumbup:

AWD removal is really easy. It literally can be done in your driveway in a few hours with just hand tools. Having the car on a lift is helpful, but not required; I had my car on jack stands. Unfortunately, I didn't take any pictures while I was doing it.

The gist of the process is:

1. Put the car up in the air, I recommend at least 12" between the bottom of the car and the ground, more is better though.

2. Remove the under trays (all three of them)

3. Remove the front wheels

4. Remove the retention nut from the front axles (32mm IIRC) (this is probably the hardest part of the whole deal, that sucker is on there good!)

5. Remove the 6 bolts on the inboard side of each axle

6. Move to the back of the car and drop the front support for the transmission near the output flange for the driveshaft (you might need to support the transmission with a jack)

7. Remove the three bolts that hold the driveshaft to the output flange

8. Loosen the center support for the driveshaft (4 bolts) and remove the two bolts that attach the differential to the front support

9. Support the differential and remove the center support (careful not to break the plastic clips that hold the coolant lines in place)

10. Tilt the differential down and slide the driveshaft out, set aside

11. Support the differential up again and remove the studs that go through the front mount for it

12. Once the studs are removed, you should be able to tilt the diff down and wiggle it out, be careful not to bash the aluminum coolant lines on the way out

13. Remove the axles

14. Disassemble the outer CV joint to get the axle stub separated (this is a little tricky, but there are a couple threads on here about how to do it)

15. Clean the axle stub and remove all grease

16. At this point, I painted the CV part of the axle stub with several coats of Plasti-Dip to protect it from corrosion should I ever want to convert the car back to AWD. I should just be able to remove the coating with some paint thinner and not have to worry about surface rust

17. Reinstall the axle stubs and torque them back down (130 ft pounds or something like that?)

18. I put the center diff support back in my car, not sure if it's needed or not. It wasn't very heavy and it seemed to support/protect the coolant lines as well as possibly provide a little bit of chassis bracing

19. Reinstall the under trays and go drive your car

I'm sure I missed a thing or two, but once you're under the car looking at stuff, it's not particularly complicated. If you can do something like a water pump replacement on one of these, you can do this.

Reversal is pretty much the same process backwards.

Attachment 1236924

Everything out:
Attachment 1236925

I love the car with the AWD removed! My butt dyno can definitely feel the missing weight and reduced parasitic drivetrain loss. The front wants to understeer a bit now under hard cornering, but I think I can remedy most of that with different alignment settings. ABS works fine, as does PSM. Since the whole AWD system is mechanical with no sensors involved, the car has no idea anything is missing.

Attachment 1236926

Here is an arguably subjective question. Was your fuel economy improved or did you spend too much time with your foot in it to notice?

Jason

Awesome write up Darrick. Thanks for posting.

Once the initial novelty wore off of being able to spin rear tires again, I have noticed a 1-2mpg increase in fuel economy. I used to average around 18-20 with it and lately I've been getting 20-21mpg (city driving).

Very interesting... I get ~18MPG on a Ballard to Redmond commute across 520. Maybe this is in the cards for me this summer.

Ugh, you couldn't pay me enough to do that commute. My Renton to Redmond commute via 405 is bad enough.

Haha well I have driven from SeaTac to Redmond on 405 after flying home early morning and ended up right in rush hour. The difference is MARKED. 405 is stop and go the whole way, whereas 520 is rolling slow the entire way. The only diff is that I have to pay that damn toll.

The freeway part isn't too bad, it's the winding down into Ballard that would make me want to stab people. I'm amazed how many people live in an area that is about as far from freeway access as you can possibly get.

You sir have hit the nail on the head as to why I live here. You have to mean to go to Ballard. There is no driving through.

Darrick, any idea how much weight your Pcar lost with this conversion?

Commute
 

Point of reference for C4/C2 comparison. My Ballard to Bellevue commute averages 23.2 mpg in a 2001 C2 Cab. 5 mi of city street and 8 mi of fwy/520 each direction. Travel east at 6 AM and west at 8:30 PM.

Redmond to Kirkland, 6 miles each way in a 2002 C2 6 speed. Sub 14 mpg in the city, 23 if it's all freeway.

I didn't put everything on a scale, but according to other threads about it in the Turbo forum, the removed components weigh about 80 pounds.

The AWD system is quite impressive in how compact it is.

Could shed a few more if the transmission is wapped out.

A C4S is 276 lbs heavier that a base C2 for the same year. So essentially what has been done is to make a slower C2, i.e. one that is still ~200 lbs heavier than a C2. The whole of a C4S is to make a car that looks like a Turbo, but doesn't perform like a Turbo. Really it is just pretty much a poser car: Turbo looks without Turbo price. While owners don't call them "poser" cars, they all say they bought the C4S due to styling. It basically has about that same weight with a lot less power as a Turbo. If you want the better performing lightweight 2WD version, you just get the C2.

I am very confused and not really understanding the point to this thread. From my reading I am guessing this is a thread about gas mileage? For gas mileage, I would get 8 mpg on the track, 16 mpg in the city and 27 mpg straight cruise @ 75 on the highway when I had my 02' X51 C2. It had Euro GT3 front seats, no rear seats, Techequipe rollbar and Fabspeed mufflers. Weight on the scales with the 18x9/18x11 CCW race wheels was 3060 lbs. Swapping the seats from high-backs to fiberglass Recaros and mufflers from the OEM chunks of lead to Fabspeeds dropped almost 100 lbs, giving an idea of how heavy those components are.