Sorry should have clarified that as to many people don't use the BMC filters as K&N is the norm in the states.

I just decided to go with BMC as I have heard a lot of good things about them from some friends.

 

Albert,

I was talking to Matt at Spires last night and he mentioned a way to preload the rear sway bar with shims. I dont have my car with me at the moment but I think I'm going to give this a shot before my next track day.

If someone could find a diagram of the rear XKR suspension, I'll send it over to him and get the exact details.

 

Okay, I'll try to find it. Somewhere I read somebody's tune included changing the variable power assisted steering rate to give more road feedback.

 

I would love that as I feel the steering ratio is to slow

 

Thanks for sharing, Max. Interesting concept, I'm trying to get my head wrapped around to. Would pre-loading act equally in both right and left turns? I suspects that they would do that by changing the length of the side links on one side only, thereby twisting the bar when the car is in a neutral body position. Also, would it effectively change the bar rate, like compared to a progressive spring rate that gets higher with more compression?

An other thing to be aware; increasing just the sway bar stiffness MAY produce too much oversteer. I did say before that increased sway bar rate must be in tandem with decreased spring rates.

I would like to hear Spires's rational on using stiffer rear springs vs. the fronts.

 

Hes mentioned starting with 1mm shims on both sides which takes the slack out of the bar and tightens it up. Now if the bar is progressive it will add a bit more tension, but how much I'm not sure just yet.

 

Max

That does not make any sense. If you add an equal length shim to both sides the bar tension should be still equalized. As I visualize the bar setup, you can add the shims under the two bushing brackets or to the length of the side links and none of it should make a difference, as long as it is equally added on both ends of the bar.

If you are sitting on level surface, a properly setup bar should have no tension to it. If both wheels are raised or lowered exactly one inch, there should still be no tension on the bar. So, shims on both sides, simultaneously should have zero effect.

You are only going to take the "slack" out if you put shims on one side only. But, the more I think about the more I am convinced that such setup would effect the tension differently in a left vs. right turn.

What am I missing here? I am now wondering about the degree of expertise at Spires.

 

Well, the power steering is a ZF Servotronic 2 rack, with the level of assistance being determined by software running in the instrument cluster. That level is based on road speed and a steering map which is specific to the model and tyre size (selected from the car configuration file).

So I guess you could change the map and change the steering characteristics.

By the way, something interesting I noticed while looking into this: the 5.0 power steering system has a cooling circuit!

 

max,


not to pressure you.... but are you still going to run the quarter mile and post results? again, no pressure..... but the sooner the better ...LOL...

 

No pressure at all!

Its going to be next Friday at the earliest. My car is on the shop getting the rear diffuser and Alcon 6 piston front calipers installed. It should be ready Thursday next week so I'll hit the track on Friday.

Believe me I want to see what it runs as much as anyone

 

Holy crap! Considering the price from Jaguar for calipers and rotors you should have just bought a RS-GT

Did you get a killer deal?

 

Just posted this in the XF forums for someone else.

Jaguar Parts - Jaguar Parts Center - Call (800) 510-1401 for Genuine Jaguar Parts and Accessories

2011 Parts - Direct JPLV Porsche Parts.com


Just to give you an idea for the XF.

The front rotors are $180 each ($300 at the dealer)
Front wear sensors $35 each ($80)
Front pads $145 for the set ($200)

 

I got the factory Alcon calipers, hoses and brackets for 3k and paid 2k for custom Spires 2 piece Rotors with Pagid R29 pads.

For the rear I'm running stock calipers with EBC Yellow pads and custom fixed AP rotors.

That should take care of any braking issues.

Yeah i could have bought the GT but there wasn't one available at the time, and the dealers wanted 250k for them

 

Also one other trick is that the XKR has the metal shields behind the rotors and the XKR-S and GT do not. That kills airflow to the rotor so those are going in my stack of old parts...

 

$3K total incl labor? That's not bad, the retail on the calipers is $1700 each, plus $690 each for rotors, plus whatever misc hardware is required.

Did you have to modify anything to fit the calipers?

 

No they bolt right on and I got the calipers for 1500 but they literally the last set in the world and all the parts were source from three locations. THANK YOU SNG BARRETT!

This is what you need

C2P 16232 caliper
C2P 16231 caliper
C2P 13388 Bracket
C2P 13387 Bracket
C2P 16209 Hose
C2P 16208 Hose

These are the AP rotors that Spires made for the calipers

 

Labor won't be much its just a caliper and rotor swap which was going to happen anyway as my stock rotors are toast.

 

Max:

Since you went to the Alcon 6 Piston calipers........will your wheels have proper fitment over the oversized Alcon calipers?

 

Well, how does that help me?

Rotors look really nice! How quickly did you get them?

 

Rotors and caliper will be here next week. They are working on the rear Diffuser and a few paint chips this week.