Montego Blue E86 is Long Gone - Z4MC 2025 Summer Prep
- Thread starter lucasxdiniz
- Start date
1536Z4 said:
I'm guessing that a lot of parts were 'discontinued' in 2019, 10yrs after the last Coupes were made. Since then the stocks have been drying up.
lucasxdiniz said:
I got the part from Quarry Motors. They have a reasonable return policy/warranty for a used part and the packaging was pretty good + pretty much delivered next day. Previously I said I probably caused the part to crack by cleaning it, but I no longer think I had anything to do with the part cracking. Once I removed the part from the car, I realised it was going to happen whether I touched it or not as the plastic is fairly thick and the crack had properly propagated.
I also ordered a new collar (mine was a bit rusty) and a new o-ring from BMW. Installing it was very straight forward; turns out I can drop the exhaust in less than half an hour and that's the hardest part of the job (if your tank is empty).
But such is my luck that I broke something else in the re-assembly process. Once I installed the filter in place and made all the connections up, I wanted to make sure there would be no leak, so I put 25ltrs of petrol into the tank. There was no leak, I was happy and proceeded to put most of the car together. Once the exhaust was in place, I started it up to bleed the cooling system and only at that point I noticed that my fuel gauge wasn't working... Many things went through my head in terms of what I could have damaged or installed incorrectly. I was most worried that while pushing the pipes/wiring/filter back into the tank I managed to damage the wiring inside the tank that relates to one of the fuel senders (best case scenario here would require taking the pump out of the tank to repair the wiring).
I could see on INPA that the instrument cluster was not getting any signal from the RHS fuel sender as the resistance read too high. Our fuel tanks have two fuel senders, the LHS is integrated into the tank and RHS into the fuel pump. At that point I knew I had a wiring problem somewhere but for the life of me I could not find the pin-outs for the connector that go into the tank, so I couldn't check if the resistance values made sense at the fuel filter (60Ω empty 350Ω full).
After two days of research/contemplating/dreading, I decided to just remove the filter again and check the wiring from the source. So I did that and, by far, the worst part was removing the fuel. You can't syphon more than maybe 5ltrs of fuel from the fuel tank even when following BMW's procedure (inserting 90cm of hose into the tank). I had to remove the fuel via the fuel filter opening which is possible as you can control how much fuel comes out by using the fuel filter as a bore seal.
Once I could see into the tank, I immediately saw what pinout corresponded to the RHS fuel level sender and with a multimeter I was able to check that the RHS fuel sender was working correctly by moving it by hand and seeing the resistance value change. For posteriority:
I traced the issue to be in the harness that connects to the connector above. However, it was the opposite end of the harness which I had not directly touched and as close to the connector as it could get - a bit odd!
Unsurprisingly, the 'adapter lead fuel pump' harness (#3) is no longer available from BMW and no one has stock. Since the wire break was so close to the connector, there was no way of repairing the wire on its own, and I didn't want to just solder two harnesses together and effectively delete the connectors, so I enlisted the help from one of the electrical graduates from work and he managed to change the connectors to DT connectors. Before and after:
As he de-pinned the original connectors, he found what happened. One of the crimp seals had failed and water got into the wire and corroded it; so minimal disturbing of the harness was enough to break the wire where it was corroded. You can see pin #3 still has the crimp inside of the connector and one can see what remains from the copper wire.
Definitely a lot of unexpected work on this one. But learnt a lot and didn't bodge the wiring, so an overall win.
Keeping my tradition of being terrible at posting stuff as I do them... here's a bit of a dump of what I've done to the car since the last post almost a year ago now.
April - August 2024
After I fixed the fuel level sender issue, I managed to have yet another fuel system issue (self-caused again). On my first trip to North Wales to test the car, not long after the last post, I ended up stranded there since my car suddenly cut-out and wouldn't start. I managed to diagnose the problem on the side of the road (fuel pump fuse had blow) and avoided needing to be towed back home. The root cause was a broken clip allowed the power supply harness for the fuel pump to drop and chafe on the prop-shaft, eventually shorting positive to ground. More details here. Thankfully that was the last issue I had, the car ran flawlessly thereafter; all the work I've done since are just small improvements.
September 2024
I never loved the brakes on my Z4M; I always found them too sharp, so very hard to modulate, and they juddered once they were warm. The juddering was a weird problem as it only ever happened when the brakes were warm and lightly pressed, on hard-braking they were fine and brake power was always very good. When I noticed the juddering, it was straight after the installation of wheel spacers, so I focused a lot of energy trying to ensure the spacers were concentric, flat etc etc. The discs didn't seem warped to me, and I was reluctant to spend £600+ on a new pair when my discs were only 5% worn (27.9mm thick). I spoke to a machinist at work and he agreed to clean them up on the CNC lathe we have. He removed 50microns of each side (making my discs 11% worn at 27.8mm thick) to clean them and confirm they were true.
A freshly turned disc:
When I was removing the discs, I also spotted the cause of my brake judder. The OE ATe brake pads had pretty much broken apart and every time the brakes were warm, they would deposit a lot of material unevenly across the disc faces and cause the issue. But even with this, I can't say I had ever got close to getting brake fade or just a bit of a spongy pedal - it was always too sharp and powerful.
Since I don't intend on tracking the car anytime soon and was happy with the performance of the OE brake pads, I decided to give EBC RedStuff pads a chance. I almost got YellowStuff pads because I loved them in the 3.0si, but I like the idea of less brake dust and if OE pads don't fade in fast road driving, the Reds should be sufficient. So I got them installed on all 4 corners.
They took absolutely forever to bed in, I was even thinking that they were absolutely crap, but they did eventually bed in and now the brakes feel amazing - so I am very happy with the RedStuff pads so far and no more judder. Brake dust is better than the OE pads, but nothing spectacular, however, the dust certainly washes off of the wheel much more easily than I remember the ATe dust doing.
When I got the discs turned, I also got some thicker hub spacers turned (5mm) to increase front camber. I chose to not have adjustable top mounts with my BCs, so I was limited in the slots to about -0.5° of camber, but the kit included hub spacers that brought camber down to -1.5°. I felt the car needed a bit more front camber, so I thought 5mm spacers would get me to -2.0° which should be the sweet spot.
Photo shows the spacers installed with longer bolts:
Now with the slots all the way in, I get as low as -2.8° of front camber. God the car felt pointy and straight line braking was noticeably worse with that much camber. Note that I did not re-set toe after that camber change, so take the handling comment with a pinch of salt.
And with the slots all the way out, I get -2.2°, which feels really good! So I have ~0.6° of camber adjustment via the slots - I think most people will have similar amounts depending on their ride height and offsets.
Brakes and camber upgrades were thoroughly tested in North Wales with other Z4 buddies and one of my best friends in his ported RX8:
A shot of the rear underside after a few months of enjoying the car after all the restoration work. I may have being doing the same to the front of the car this past winter... Will start posting about that soon hopefully.
April - August 2024
After I fixed the fuel level sender issue, I managed to have yet another fuel system issue (self-caused again). On my first trip to North Wales to test the car, not long after the last post, I ended up stranded there since my car suddenly cut-out and wouldn't start. I managed to diagnose the problem on the side of the road (fuel pump fuse had blow) and avoided needing to be towed back home. The root cause was a broken clip allowed the power supply harness for the fuel pump to drop and chafe on the prop-shaft, eventually shorting positive to ground. More details here. Thankfully that was the last issue I had, the car ran flawlessly thereafter; all the work I've done since are just small improvements.
September 2024
I never loved the brakes on my Z4M; I always found them too sharp, so very hard to modulate, and they juddered once they were warm. The juddering was a weird problem as it only ever happened when the brakes were warm and lightly pressed, on hard-braking they were fine and brake power was always very good. When I noticed the juddering, it was straight after the installation of wheel spacers, so I focused a lot of energy trying to ensure the spacers were concentric, flat etc etc. The discs didn't seem warped to me, and I was reluctant to spend £600+ on a new pair when my discs were only 5% worn (27.9mm thick). I spoke to a machinist at work and he agreed to clean them up on the CNC lathe we have. He removed 50microns of each side (making my discs 11% worn at 27.8mm thick) to clean them and confirm they were true.
A freshly turned disc:
When I was removing the discs, I also spotted the cause of my brake judder. The OE ATe brake pads had pretty much broken apart and every time the brakes were warm, they would deposit a lot of material unevenly across the disc faces and cause the issue. But even with this, I can't say I had ever got close to getting brake fade or just a bit of a spongy pedal - it was always too sharp and powerful.
Since I don't intend on tracking the car anytime soon and was happy with the performance of the OE brake pads, I decided to give EBC RedStuff pads a chance. I almost got YellowStuff pads because I loved them in the 3.0si, but I like the idea of less brake dust and if OE pads don't fade in fast road driving, the Reds should be sufficient. So I got them installed on all 4 corners.
They took absolutely forever to bed in, I was even thinking that they were absolutely crap, but they did eventually bed in and now the brakes feel amazing - so I am very happy with the RedStuff pads so far and no more judder. Brake dust is better than the OE pads, but nothing spectacular, however, the dust certainly washes off of the wheel much more easily than I remember the ATe dust doing.
When I got the discs turned, I also got some thicker hub spacers turned (5mm) to increase front camber. I chose to not have adjustable top mounts with my BCs, so I was limited in the slots to about -0.5° of camber, but the kit included hub spacers that brought camber down to -1.5°. I felt the car needed a bit more front camber, so I thought 5mm spacers would get me to -2.0° which should be the sweet spot.
Photo shows the spacers installed with longer bolts:
Now with the slots all the way in, I get as low as -2.8° of front camber. God the car felt pointy and straight line braking was noticeably worse with that much camber. Note that I did not re-set toe after that camber change, so take the handling comment with a pinch of salt.
And with the slots all the way out, I get -2.2°, which feels really good! So I have ~0.6° of camber adjustment via the slots - I think most people will have similar amounts depending on their ride height and offsets.
Brakes and camber upgrades were thoroughly tested in North Wales with other Z4 buddies and one of my best friends in his ported RX8:
A shot of the rear underside after a few months of enjoying the car after all the restoration work. I may have being doing the same to the front of the car this past winter... Will start posting about that soon hopefully.
Looking pretty tidy.
When you say the “judder” has gone, do you still get a bit of a rumble from the drilled discs?
Reason I ask is that I had this sound/feeling with brand new pads and discs, and just assumed it was an unavoidable trait of drilled discs. But since then I’ve been in and driven a few cars that have them and none of them have made the same noise under braking.
When you say the “judder” has gone, do you still get a bit of a rumble from the drilled discs?
Reason I ask is that I had this sound/feeling with brand new pads and discs, and just assumed it was an unavoidable trait of drilled discs. But since then I’ve been in and driven a few cars that have them and none of them have made the same noise under braking.
MrPT said:
I would say I do have the typical drilled disc sound, but I think the M discs aren't as bad for it as the cheap drilled discs I had in the 3.0si. If anything it may be the pad/disc combo you have making it more pronounced.
I will be doing a caliper upgrade next winter, so may need your help then on what to get as I want to do the rears as well. If I remember correctly you upgraded your rear calipers; many people don't seem to bother and rear kits are harder to find.
North West Surrey
Those pads look a right mess. 
Good to know you managed to save your discs though. I had new front calipers, discs and pads fitted to mine last June at RBM so I know what they cost! Maybe I have just been lucky but they worked fine straight away, and I haven't noticed any noise from them.
That's a great photo of the three blue Coupes!
Good to know you managed to save your discs though. I had new front calipers, discs and pads fitted to mine last June at RBM so I know what they cost! Maybe I have just been lucky but they worked fine straight away, and I haven't noticed any noise from them.
That's a great photo of the three blue Coupes!
andyrich1512
Member
I also have a montego blue Coupe - coming up to 4 years ownership and I bloody love it. Fantastic cars and yes they are so good looking.
Think I am going to take the plunge and do a few bits to it - a bit of tidying here and there, upgrade the hifi and maybe wheels and suspenion.
Mine has the nimbus grey interior - I've always fantasized about having a BMW with that lovely cream leather the same as yours actually but mine is still pretty nice -just need to restore the seats a bit like you have done. Yours look amazing now - good work!
Hope you enjoy the car as much as most folk on here - me included!
Think I am going to take the plunge and do a few bits to it - a bit of tidying here and there, upgrade the hifi and maybe wheels and suspenion.
Mine has the nimbus grey interior - I've always fantasized about having a BMW with that lovely cream leather the same as yours actually but mine is still pretty nice -just need to restore the seats a bit like you have done. Yours look amazing now - good work!
Hope you enjoy the car as much as most folk on here - me included!
andyrich1512 said:
Definitely upgrade the suspension if you can, it does transform the car. The OE set up is ok, but leaves much to be desired in the 3.0si.
Or better yet, do a diff upgrade!
It's almost the end of April and the car is still SORN, unfortunately. The part I've been prep'ing the front end for still hasn't arrived and I've decided to wait until it's installed to get the car out. However, come May 1st, the car will be out of the garage with or without it.
The front subframe is easy enough to remove and I have the space to drop it (just), but since all front end bushes are still all in great condition and the surface rust was only on the exposed lower parts, I decided to leave it in place for now and gave it the same treatment as the rear subframe got last year:
Now on the engine bay side, there isn't much I can improve on unless I take the engine out. The winter work plan was to refurb the throttle bodies, but I decided to delay that for now so I wouldn't be changing too many things in that area before getting a new intake and then not knowing if any problems are related to the work I would have done or intake related... But the slam panel was looking pretty rough and letting the engine bay down, and the washer tank looked dirty so I addressed those.
After doing the slam panel, I decided to do the bonnet latch and the cross-brace, but while trying to remove that, I ended up stripping one of the bolts, so ended up having to remove the front bumper to address that. So while there...
More to come soon, I hope.
The front subframe is easy enough to remove and I have the space to drop it (just), but since all front end bushes are still all in great condition and the surface rust was only on the exposed lower parts, I decided to leave it in place for now and gave it the same treatment as the rear subframe got last year:
- Surface rust wired brushed off;
- Rust converted
- Everything painted with POR15
- New OE bolts for pretty much anything rusty
- ARB completely stripped and powder coated
- All ally parts cleaned and polished
- Engine undertray repaired and reinforced with CFRP.
Now on the engine bay side, there isn't much I can improve on unless I take the engine out. The winter work plan was to refurb the throttle bodies, but I decided to delay that for now so I wouldn't be changing too many things in that area before getting a new intake and then not knowing if any problems are related to the work I would have done or intake related... But the slam panel was looking pretty rough and letting the engine bay down, and the washer tank looked dirty so I addressed those.
- Sanded all the accessible surfaces
- Flattened all corroded areas
- Several coatings of Zinc primer
- Two coats of satin black paint
- Trying out my M cover with a bit of a contrast which I ended up quite liking
After doing the slam panel, I decided to do the bonnet latch and the cross-brace, but while trying to remove that, I ended up stripping one of the bolts, so ended up having to remove the front bumper to address that. So while there...
- Cross-member stripped, primed then painted with POR15 to resist stone chips
- Latch sand blasted then painted with POR15
- Headlights professionally re-lacquered
- Cleaning... so much cleaning and then waxing/protecting.
More to come soon, I hope.
