You have already done what i want to do to my 4.0 xk8 .. I want to swap my differential. I have found a 3.58 from a xj6 . Can u tell me what front plate i need to get and what flange also.Man i really need some help thanks in advance . I am still doing the camshaft swap also will let u know how that turns out after i dyno test it with both changes......... r

 

For u guys that have xkrs i spoke to phil at euro tek the cost of reflashing this unit is $2500.00

 

I'll call John and ask him for you if you want. He explained the swap to me over the phone, but I don't remember details.

And remember, you WONT change anything on the dyno as far as peak hp & torque numbers. What you will do is MOVE them practically.

Aka you trade top speed for acceleration... not gain hp. The car feels a lot faster off the line though.

Take care,

George

 

This is true for the rear axle ratio change, not the cam upgrade. In fact, the rear axle change probably decreases the hp delevered to the road brcause the resistances increases some, especially ig you also install an LSD.

rsigue, do I understand correctly that you can upgrade the cam on an XK8 without tuning to ecm but the XKR requires ecm tuning at a cost of $2500?

Mark

 

Its the tcm on the xkr not the ecme the ecu will not net any flashing what it needs when the camshaft is changed then i will disconnect the battery and then idle it for 10 minutes so that it can get used to whats new in fuel and air. Yes the rear axle ratio will not give new horsepower it will move the power band lower. But when the new cams are put in that will increase horsepower to that motor its a nobrainer . factory cams or small in nature to pass emissions. so this change will def bring new power.and yes its 2500 to reflash the tcm on the xkr spoke to phil twice to make sure i heard him correctly

 

Interesting, why does the tcm need to be reprogrammed for a cam upgrade?

Mark

 

Are you sure the TCM needs a reflash with the XKR? It's not with the cam swap but with the axle ratio change. Cams don't affect the trans.

I know the regular pre 03 Xk8's with the aj-16 (4.0) and the 5 speed MB sourced ZF trans doesn't. I'm not 100% on what trans is in the pre 4.2 XKR.

The zf6hp26 used in the newer cars is the roadblock to swapping rear ends on those cars. There is no way to reflash the trans for the new axle ratio, so the trans thinks it's slipping internally. (input shaft speed v/s output shaft speed ratio), and throws the trans into limp mode. So far I don't think there is a way around it.

Take care,

George

 

Input and output shaft remains the same so how can it throw codes?
Also the transmission is from mercedes not a zf sourced mercedes tranny

 

Only needs to be reflashed on xkr when rear gear ratio is changed. Just in case i didnt make my self clear. I spoke to phil and eurotek and this is the info he has given me.. He sends the tcm to germany to be reflashed thats why its so high.

 

If you don't reflash the TCM you will get incorrect gear ratio codes. I know this first hand.

 

Jxkar i still need your help

 

Glad to see your around..... I would like to ask u what flange u used and if i would need to do anything else........ Please it would help me to have everything before i get started..... My differential came in today can wait to put it on Richard

 

Ok, this makes sense. I changed the rear axle ratio in my 2002 XKR and had to have a new tcm program. So, just to summarize: tcm re-flash for rear axle ratio change, no ecm or tcm re-flash for cam upgrade. Thanks,

Mark

 

I still don't know what you will do about the rear propshaft connection.
The JURID flange will not bolt to the 4 bolt U-Joint flange.

The X308 is different in that it already uses the JURID flange but the X100 has the flat flange.

I guess a custom propshaft is in your future???

bob gauff