Albi Blue 200 >> BMW E46 Track Car

Ordered myself a new diff. Didn't last long not touching it after Snetterton.

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Decided it was the end of the road for the quaife, it's been a great diff in the car which I've ran with a 3.38 and a 3.73 ratio. But I am finding the limit of it more and more with the car this past year.

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Removed the old diff with the 3.73 ratio and decided to sell it as a complete built unit, already sold and gone to a new home! It didn't make sense to strip down a perfectly working diff to make the new one.
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Bought another 3.38 ratio diff from an auto to use as a donor
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Started with disassembly of the donor, can confirm old diff oil still stinks. Ripped it open on an old towel and thrown them straight in the bin
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Obviously I couldn't leave the casing in the rusty old state so gave it a good jet wash, degrease and a wipe down with some thinners before giving it a coat of paint
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Put all the parts through the parts washer and laid everything out ready for building.
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Bearings and crown wheel fitted to the diff, getting some more use out of the press I bought many years ago on a bit on a bit of a whim, turns out I use it all the time.
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Started with setting up the bearings and the pinion drag and then set about putting the diff in the casing with the bearing on.
Got loads of photos but will keep the post short rather than a how to. In total about 6-7 hours worth of building, due to the size of the diff unit it doesn't fit inside the diff casing in one piece, so every time you want to take it out to adjust the shims you have to split the diff in two.

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Managed to get the bearing clearance to a spec I was happy with as well as getting the backlash to 0.1mm. Overall everything has gone together with the provided shims which come with the Kaaz diff but it's right on the tight end of the spec
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All reassembled with new seals. I have built this one with a 3.38 final drive and while the diff was apart to fit it inside the casing I have dropped the lock down to 65% as per the Kaaz Manual which they refer to as the "Medium Hard Setup"
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Back in the car it goes
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Bought a set of replacement discs for the rear while I was working on the rear end as well as a replacement ARB bracket, somehow managed to loose a bracket at Snetterton, I think I've forgot to torque the bolt up for the bracket when messing with fitting and removing the rear ARB and the bracket has left the chat
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Final job for the weekend was adjusting the splitter mounts, with the new bumper the splitter needed raising 15mm to bring it up snug under the bumper, adjusted the brackets and refitted.
Note- That isn't the placement for the reg plate... Just popped it on there for today as I didn't want to mark the new bumper

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Been a big job but it will hopefully be worth it, we'll see on the next track day!
 
So did the decision to move on from the Quaife come around the same time that you started running slicks?

Not from the slicks.
It’s something I’ve been putting a bandaid on for a year or two.
Unless the rear of the car is pretty flat coming out of corners with both wheels on the floor the quaife tends to slip the inside wheel still.

I’ve made improvements to keep the inside wheel on the ground.
Full rose jointed/uniball and solid mounted rear end
Running without ARB
Stiffer arb.
Experimented with spring rates
But still will never be as good as a plated diff but back in 2018 there wasn’t the choice of diffs and all the technical information which goes with it.
Interestingly this Kaaz diff isn’t actually listed as fitting my car and ratio anyway but did the research to check before buying.



The second corner at Snetterton is a perfect example of this.
I just put the inside right wheel onto the raised bit of the kerb and loose all drive coming out of the corner. I have to lift and wait for it to grip and then apply power again .

 
I went from the standard E46 M3 viscous diff to a plated drexler and the difference was night and day. I imagine this will be the same type of change. I don’t get any of that spinning up that you experience in your video when sending it over curbs etc
 
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I went from the standard E46 M3 viscous diff to a plated drexler and the difference was night and day. I imagine this will be the same type of change. I don’t get any of that spinning up that you experience in your video when sending it over curbs etc

Hopefully it’s worth it, lot of hours gone into putting this one together. I used to have a gripper in my clio box and it was fantastic. Driven a mini recently with a gripper and it just reminded me how good they are and the consistency every single time.

It’s gonna be an absolute savage with a proper diff

Hopefully! Just want to be able to get on the throttle through the corner without hanging to lift. RWD is amazing for corner exit but this should make a world of difference!

I’m also hoping by going back to a 3.38 final drive I can use the Rev range a little more. Peak torque hits about 4k and can Rev it to 7k at the moment and through that whole area it pulls really well. Hoping I can use less gears and stay on the throttle more. Lots of time I’m changing up to 5th for a few seconds to drop back down.

Will see if it’s any different. Will have to use second a little more I’d imagine for slower hairpins.
Going back to EFI tuning in August for a map check so will see if we can widen the power area a little more too.
 
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Summer Update.
Not as many updates as there used to be but will try and keep it updated when I can.
After finishing putting the car back together after stripping the rear end and fitting the new diff I started to do some prep for some dyno time.
Noticed the swirl pot pressure was playing up again so put a proper APS fuel put in the fuel pump holder and chucked this back into the tank. Way overkill for the needs of the engine as it's only filling the swirl pot but I I was given a brand new one and bought myself another one so I've got a spare in the track day box.

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Spent a few weeks messing around with a the V3 firmware for the ECU Master black which will be released at some point in the not too distant future. Got the car running an a fresh map, transferred everything over to the new software, found a lot of bugs and suggestions which have quickly been sorted by ECU master at this point.

Took the car down to EFI tuning to get Chris just to run through a few things mainly checking the VE table as the fuel model is different in the new ECU software

Have to do I am really happy with how the front end of the car looks now it's be freshened up with new bumper and some paint
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Since I was on the dyno I have set up the Exhaust Cam as it is fully variable on the M54. From previous mapping sessions and experimentations on the OEM ECU I know these engines do pick up some torque in the mid range when retarding the exhaust cam.
First job was to set up the PID for the Vanos controls for both Inlet and Exhaust.
Work through the VE table to some full load power runs.
Do a quick test on the cam angles just to make sure what I had put in the ECU was most efficient.

Few hours of start stop running and ironing out a few bugs with the V3 software I was really happy to see the engine making
267ftlbs and 271bhp.
but with a good chunk of additional torque in the mid range. Right where I'm going to need it with the new differential as I've moved from a 3.73 back to a 3.38 final drive
I was also happy to see it make the same power it made when the engine was first built!
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New laser cut design for the mounts for the wing
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Still keeping my hands on Clios too. Quite a few friends still are using them that I do track days with. This one had new suspension fitted. I had it in the garage for setting right heights and alignment before Anglesey.

Anglesey Trackday - This was the first track day of the week.
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Anglesey Summary
It was a bit of a mixed bag.
Turns out I am still having issues with the Michelin Slicks on the car despite the new geometry, when I get some videos up you'll be able to see the lack of grip on the rear right - Lots of sliding around when loading up that corner even when turning into corners made for some amusingly large drifts!
I used the day to run the car in a few different damper and ARB set ups from full soft to full hard to see how the car felt in different set ups.
The Kaaz differential is amazing! Really impressed - Spent a bit of time in the carpark in the morning doing figure of 8's to bed the diff in followed by an easy session clutching down around corners to let the plates bed in without any load - Following that I was straight into it. The drive out of corners is so much more consistent driving both wheels and the little bit of wheel slip and hop you get with the Quaife is gone!
I wasn't feeling 100% throughout the day either with the usual symptoms of food poisoning so was happy to get around 100 miles in all day after calling myself an early lunch break at 12:00 and having a rest till 1:30.

Cadwell Prep
After Anglesey I drive straight home as we had also booked Cadwell Park for the Wednesday of that week.
First job on the list was to replace the slicks for a new set. I had already planned for this and collected another set of slicks with a different compound which I was more interested to try.

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Quick wash of the wheels and an oil change, geometry ajustment and back onto the trailer

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Drove over to Cadwell Park Tuesday evening ready for Wednesday morning...

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Cadwell Park

Start of the day didn't go as planned... Sighting laps went off without a hitch but only managed about 5 laps in session one before loosing power steering through through hall bends, quick look at the dash and noticed battery light on... pulled off the circuit at the end of hall bends.
Popped the bonnet for a quick look while waiting for recovery. Aux belt had popped off and the Aux belt tensioner was stuck down at the bottom wedged between the PAS pulley, fan and engine block.

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Not the first time I've been pulled back by the tow truck from Hall bends and I'm sure it wont be the last. At least I managed to get off the circuit without causing a red flag

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Had a good look at it in the paddock and found the two bolts holding the tensioner on had sheered off causing the tensioner to fall off and down into the PAW pulley and damaged the PAS pulley.
Had to take the oil filter housing off and drill out the snapped bolts.

Damaged PAS Pulley
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Managed to find a replacement PAS pulley in Louth and pick up a new tensioner while it was in pieces and set about building it back up
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Managed to get it back together with new parts and some replacement bolts from the spares box and managed two sessions before lunch.
First one to shake the car down and check for leaks or anything else visible.
Followed that up with a good 20-25 minute session before lunch.

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First session back after lunchtime
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Not the cleanest of photos of the E46 but not looking too bad after back to back trackdays in the same week
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Managed a full afternoon of laps. Car felt fantastic on a different set of Michelin slicks and the Kaaz diff performed brilliantly around Cadwell Park. Finally managing the drive out of Mansfield without slipping the inside wheel. Spent a lot time trying to optimise the car set up but despite all of that it was just a plaster until I fitted a proper plated diff.

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Good updates as per!

Does your mate with the Cayman have a build thread for it by chance ?
Thanks. Try to keep the updates coming and interesting.

He doesn’t have one for the Porsche but eventually I think some of it will be posted on Instagram.

 
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