DIFF SWAP UPDATE 3.15 LSD to 3.38 LSD (TORSEN)
Well what a fun day!
Top down all the way from Kent to Basingstoke at the crack of dawn.
Lovely breakfast and then some whacky races around the Basingburgring with the VAG fan boys, (terrible dieseasel lovers to make things worse, had us choking in the Z3 with their fumes. Not naming any names but
@Rally knows what I mean
)
The Z returns after 4,5 yrs:
Car raised and the work begins (that work includes swearing, getting covered in amazing amounts of rust, having a laugh and a bit of pain - it’s takes some seriously clever manoeuvring to get the diff out when you don’t have a saggy subframe!):
Extension on extension on extension on extension...you get the idea!:
Gaz thinking ‘how the hell have I ended up back under this old shed?!’:
The now infamous Zedshed footwear standards have been maintained over the years however there is a new sock code to adhere too now
Okay now some technical stuff.
2.2 3.38 diff next to 2.8 3.15 diff (both confirmed to be torsen items)
Spot the difference?
Nope, neither did we, luckily BMW put a helpful little sticker on that is just about there after 20 years!
Turns out that a 2.2 diff is direct fit with the MK1 2.8 - no changing of propshafts or drive shafts or flanges (
@Lee gave a detailed explanation of what exactly went on and
@Rally took even more detailed notes so if you need more tech specs on this point
@Rally is the man to ask
)
In between work we did squeeze in some cultural education and Lee kindly let us have a play with a proper drill from the 50’s. Why don’t they make stuff like this anymore?
@Rally and I went to the same school of engineering - when in doubt
hammer it (turns out to be safer than using a grinding too
)
Not too much appreciation for my love of cable ties from the proper engineers but some of the VAG crew knew the benefits
. So much so we are apparently getting Carol Vordeman to do count of how many ties we have on each car
A good example: This tie reinforced exhaust mount looks as good as I ‘engineered’ it 4yrs ago
The pile of bits that that came off kept growing...
Comment on the BC and poly bushes after 4yrs - the springs are rusty and this year the coating has come off them but the shocks are still good and leak free which is more than I can say for other coil overs I’ve had, still very happy with the BC kit and will give the springs some attention.
The poly bushes are as good as the day they went in and despite worries / internet talk that they would cause the diff mount to fail that has not been the case I’m pleased to report.
The car is getting very crusty under there so needs some love under the bodywork this winter...
So mid afternoon and all back together again.
A couple of, ahem, test drives around the Basingburgring by Lee and Gaz to confirm all is well....
So the big question- what does it drive like???
Initial impression feels like it had a little turbo bolted on. It was just more urgent everywhere.
1st is still very usable and changing to 2nd will be interesting in the wet at full bore. 2nd to 3rd is superb, just pulls and pulls.
2nd is now particularly good at skids - the LSD part of this is confirmed as being healthy (although some wet weather testing will be needed just to be extra sure
)
I had to head back onto to busy M3/M25 to Kent so got to really test out 5th in the usual 70mph > 5mph > 70 >40> 70 type driving that is the British motorway on a weekend.
What can I say - 5th is epic - I no longer go for 4th when spotting a gap, just plant it in 5th and it goes at any rev.
It feel like it is a 4.5th gear now.
Cruising revs are higher and my calcs say it will do just over 130 before entering the red. So 10mph down - not that I’ll miss it given we don’t have any autobahn
Closer to home I got into familiar A roads and lanes and got use the gears more. The difference became very apparent on familiar roads where I could really compare. The easiest way to explain it is like having a small turbo- no lag and just more torque. If you’ve owned a VTEC you’ll recognise this analagy - it now just falls into VTEC after each gearchange, even if you didn’t redline it so it’s in its ide powerband more of the time.
Although the gears are shorter I can actually rev out a gear more as instead of taking 2nd, 3rd will do (which has always been a good year on the 2.8 but now even better). 4th is great for flowing A road work now, lovely torque and pulls strongly a bit like 3rd used to be..
I then tried ‘lugging’ it in 5th. The 2.8 party piece has always been how tractable it is even in 5th. Well now it’s even better and the shorter gear, funnily enough, make for a more relaxing drive as I can leave it in 5th and still have plenty of poke on a nice A road. It’s pulls cleanly from under 20mph and in no time up to 60 all in 5th. The only car I’ve driven that pulls like this is has 8 cylinders and 4.4l at its disposal. The little Z really feels more brawny now.
So initial impressions - love it more that I thought I would. I’ve hung on to my old diff in case I didn’t like this but I don’t see this 3.38 coming out of this car (unless a turbo ended up under the bonnet!).
If I did a lot of motorway work I’d want a 6th gear (and if we find a box that fits and is not off a unicorn M3 EVO it could well happen - currently the knowledge is that only the M3 EVO 6sp will fit with shortened prop shaft. However, maybe, just maybe there is another ZF box in the BMW parts bin that will work and is more freely available than a M3 box, here’s hoping). With a 6th gear it would be better than BMW intended and what they really should have done in the beginning...
For the way I use this car (for pleasure not commuting big miles) this mod is just perfect and I’m looking forward to re-learning driving it along familiar roads as the gear shift points have all changed!
Oh and a side effect of this is a positive change in exhaust note - it’s just sounds ‘more’ now given the revs it sits at / way the power is being delivered. After the remap, the track day and now this diff the car is sounding better than ever (apart from a rattle which is looking like the cat and not a bracket
- on the bright side it means that the sports cat I’ve wanted for years just has to be done. Is, along with a sneaky bypass valve - after hearing what it sound la like without a backbox on it just has to be done).
Reflecting back on the car with Gaz and Lee looking at all the changes it’s quite something that a car I was thinking of breaking 5yes ago was brought back to life in the Zedshed and has blossomed - just so much fun for so little £ cost and endless fun tweaking (the frustrations get forgotten!)
it’s a hard to beat formula and one of the many reasons for me anyway, a Z3 is a no brainer keeper!
Final shot of the day in its national habitat - it’s the second time in month I’ve filled up twice in a day
Thanks again to
@Lee @GazHyde @Rally for the hard graft and fun and to
@pgunter and
@Oldguysrule rule for coffee and moral support
Who knew that rolling around under a Z3 fighting with rust inaccessible bolts is actually fun with the right company (and tools and experienced supervisors!)