The servittonic steering module in the x308 is a relay that alters the level of assistance with vehicle speed. I've may have found a way to change this level assistance with speed. (For me the stock x308 offers too much assistance with speed). Where is this relay/module located on the x308 and how do I get to it. I've checked all the tech and workshop manuals and they're rather vague. They talk about it being located behind a "kick plate" on the left hand side.

thanks

 

Off-hand the only "kick plate" I've come across when reviewing the Jag manual is the one under the rear seat.

 

The Electrical Guide has a FRONT MATTERS section that shows the location of modules, relays etc.

The module location you want is behind the left front footwell trim panel below the A pillar.

bob

 

Thanks dude, I'll give it a go tonight.


I want this cars ride/handling compromise to be more like a contemporary BMW. I cant do much with the steering in terms of 'feel' but assistance can be reduced and I could increase the castor with shims

 

I did the mod when I rebuilt the car back in 2011 - the module is behind the outer footwell cover panel, there's a single fir tree clip in the center. It's easily identified once you pop the panel off - being LHD I'm not certain which side yours will be but mine was on the LHS.
It's a bellwire mod, 2 wires and done.
I fitted 2 switches to my dash center, one for shutting off the pas the other a 'garage door remote'...ehem
It's immediately noticeable the difference at speed is far better, just remember to switch it back on when going slowly as it can feel too heavy, but nowhere near as bad as when you loose the crank pulley and full pas, that's hairy on 19"s.
Maybe lighter brake calipers and rotors, along with the supersport springs could certainly improve front end matters, it did with mine. The Bilstein green cats dampers are spot on.

 

Thanks Sean.
I may actually modify the relay itself, I work with electrical bods.


To get more feel- I may look into increasing caster. The stock recommended is 4.5 degs (with a range quoted at 3-6 degs). BMWs commonly use 7 degrees or more- so I may adjust it to that with shims.
That should increase the steering tendency to 'self centre'

 

If you get some shims made - let me know. Has your car got the later version of lower steering column fitted? I think there's a centering adjustment on the rack. After a good alignment checkup mine centers ok but not BMW positive. I've poly bushed wishbones and kept shock mounts and AR bushes stock as they're specific rubber compounds.

 

Probably not, I'll look it up on the parts thing, but mine is a 2000.


I like the speed of the rack, just wish there was more feedback. Its not as 'light' as my 71 XJ6. My 70 Challenger is probably the worst.


My E24 M635 is surprisingly wooly in its steering, probably worn as its very un-BMW. The Aston has a nice fast crisp, responsive rack, but not the feedback I was expecting.
I've bought a quicker rack from a 4.7 N430 for that car. I think my 911 Turbo (993) spoiled me- by far the best steering I've come across.

 

I changed the assistance level to 'R sport' specs- as per green curve in the diagram below. It made sod all difference. No where near a BMW. I then obtained assistance values from various other applications. Its suprising to see BMWs, Audis and even a Ferrari giving higher assistance levels. The chart shows vehicle speed in km/h vs steering assistance current allowed or mapped into the eeprom of the Steering module. All of the non Jag applications give more assistance at higher speeds and yet most of them feel more positive on centre and firmer. This obviously means there are other factors of steering and suspension geometry that effect feel and steering effort. The Jaguar at about 2.8 turns lock to lock is a very fast rack- so its not this. I like how quick the Jaguar rack is. The BMW has more castor. I will try to mess around with castor- aiming for 7-8 degs, which is typical BMW.


When I fit my Brembo brakes, I'll also fit spacers on my asteroids- which will increase the offset (I don't particularly like the look of Milan, Montreal etc wheels- they look too much like BMWs ;-)). This increase in offset along with castor and tailoring of the assistance level should help. I was surprised to find that the old XJR-6 offers less assistance at sped than the X308 and other applications. I THINK the X306 steering rack is slower geared though. That will be the setting I will try next. I have one listed as ?69- (darker blue line)- that would be nice to try but I don't know what that is out of. I need to do some digging

 

I reckon with the 69 loaded you should feel a noticeable difference. But for now how about unplugging it and trying the steering without the module assistance. Have you refurbed all the front end bushes?

 

That's on my to do list, although I assumed they were worn, and went under the car and they look in really good nick. Struct top mounts need doing I think. I need to find out what the 69 is from