while I am waiting on a Quaife LSD does a V8 LSD diff fit in a V6 premium? if so does anyone have a part number for me to look for? I don't mind the higher gear ratio as I run out of first anyways before I can shift right now and will be upgrading to more ponies with VAP as soon as I have something that keeps the rear planted. @Onca Engineering for your expertise.

 

You sure?
Coz the V8 diff is the e-diff, i.e. an electronically controlled LSD whilst the V6 LSD is a mechanical LSD (and the base model V6 diff isn't even an LSD it's an open diff).
I guess a V6 Premium has an LSD, but either way I can't see the e-diff being a straight swap for a V6 mechanical diff, not without some re-programming electronic wizardry which may not even be possible.

 

@Zen Beer Yes, you can consider an eDiff from a V8, but here are the challenges.

• The gear ratio is 2.56:1 which is about 25% less RPM at the same speed as your 3.31 (V6 LSD or MT), or 20% less RPM in a 3.15 (V6 AT Open)
• The donor eDiff would require a tear down to assess the condition of the clutch pack, and consider the moly ceramic replacement from Racing Diffs.
• The left side rear axle probably needs to be swapped as the eDiff clutch pack sticks out on that side… I have seen three different drive shaft lengths in F-TYps.
• The eDiff wire harness and control box is needed for your car, but I am not sure if the box will work by itself. It may require interface communications with the ABS unit or wheel speed sensors.
• The vehicle level controller may also need to be programmed due to the error messaging and disable function in the eDiff controller.
• I have a nice eDiff in stock from a XJL V8 with OEM carbon friction plates in good condition. E-mail if still interested.

I am working with Quaife on a new batch of 10 ATB units with an option for 10 more. These will be professionally installed in core rear diff units by Simply Performance in the UK. Simply Performance offers many part upgrades and rear diffs for classic Jaguars, and this is there entry into modern Jaguars.
Our order for ATBs is expected before the end of the year (small batch orders are often delayed by larger orders from key customers).

I really enjoy my V6 Manual with Quaife ATB and I just checked my diff oil after +10k miles and it was in very good conditions with a small amount of metal paste on the magnetized drain plug, and it had good color and consistency. So that indicates my ATB is properly worn in and operating well.

I will post an update video on YT #OncaEgnineering channel. In about a week’s time…. Also covering porting of the SuperCharger!

Drive well,
Herman

 

ok thanks any updated ETA on the 10 units. I was going this route until they became available. Mine with the open diff now that I am comfortable with the car it is becoming a bit harder on the tires or tire in my case I liked the idea of the reduced RPM's but didn't know about the Ediff. Guess I am back to the V6 option for now
thanks for the info

 

Thanks much Herman for the detailed answer!
But I thought you had to use SDD if you changed the rear axle ratio?
No programming is needed with a gear change?
.
.
.

 

@clubairth1
Experience:
So far, OncaEngineering has worked with 3 customers who have changed their rear diff ratios, two V6 F-Types, and one V6 XE.
These customers did not change any parameters in SDD, and I have not heard back about any error codes.
A few of the above cars were V6 Manuals, but at least one was a ZF Automatic. (I can check my records)

Note: these changes in rear diff gear ratio were applied to RWD cars only.
The rear diff ratio change would obviously not work on an AWD variant.

Speculation:
Changing the rear diff gear ratio would introduce a slightly different engine speed-to-rear wheel speed ratio.
But this ratio changes with each transmission gear selected, and I would think a transmission controller or diagnostic routine would rather use transmission output shaft speed rather than some external speed sensor at the wheels.

Evidence:
If you have any SDD codes or parameters that receives the need for the rear diff ratio, I would be very interested.
Perhaps Onca Engineering should invest in the SDD system and see what is possible.

 

Thanks for the detailed answer. Interesting as it appears there is nothing required in the programming. But I guess no speedometer errors either since the modern cars use the ABS for speed? So the rear end ratio does not matter.
.
.
.