Email sent to CA International about my thoughts! Looking forward to the response in the New Year. My current thinking is that if i sort out this car then, should the worst happen and then engine blows up, I can either transfer most of the kit to a new one or i just put a new engine in my shell that i know is sorted. All of the shells are the same age so I'm not losing anything, especially if I've overhauled all of the bits that wear. And i know that my shell is straight and hasn't been crashed and so is a good place to start from.
Good morning,
I am after a little advise and then to book my car into your partner garage in Erith Kent please.
Background.
I bought myself an e85 Z4 3.0Si roadster 6 months ago as a present to myself for a fun daily driver and occasional track day car. The car is high mileage, 170,000, but was one owner from new and has a complete service history. It also suffers from a bad respray done to cover a key scratch. The car has been inspected and has never had any crash damage and is very straight and in good nick underneath. I am currently adding about 2,000 miles a month but that should lessen in the New Year. It will still be my primary car though and will need to cope with everyday British roads with all of the implications that brings about potholes, poor road surfaces and speed humps.
Concerns.
I’ve just had a full Inspection 2 done and had the gearbox oil changed as well as the rocker cover gasket and oil cooler gasket done as there was a little leakage around these areas. The Air Flow Mass Meter was also changed as the temperature sensor had stopped working. This was supposed to stop the emissions light coming on as the cause was supposed to be the ECU not recognising the air temperature and hence not altering fuelling to match. Unfortunately the emissions light has come back on so that is clearly another problem! The front ball joint need replacing and the Rear Trailing Arm Bushes also need replacing. I have records of new front suspension arms and rear springs in the history but no record of the shocks ever being replaced. I suspect that the shocks are totally shot although they are not showing any signs of leakage and it passes and MOT. However it is not riding as well as I think it should and tends to “bang and crash” rather than soak up any of the irregularities in the road. I have also felt it hit the bump stops on occasion when driving through sudden dips in the road.
Brief.
I would like a fun fast road car that handles well, puts a smile on my face every time I drive it and can withstand the abuse of a few track days every year. I am more of a fan of driving rather than looking at my cars so the mechanical components come first and the cosmetic things later. I spent £3,500 buying the car and have a total budget of no more than £8,500 to complete it. I have already spent £900 on a hardtop and £930 on a Brembo 6 pot front brake conversion,
viewtopic.php?f=7&t=110609. That leaves about £3,000 in the budget, I do not count servicing or normal running costs as part of that budget just additional extras! That means there is a little flexibility if required. I am sure that as I get more track days under my belt then I will be looking to improve specific aspects of the car but I would just like it to be as good as it can be without spending a significant amount or running the drivability / comfort on a daily basis. After all it will spend the vast majority of its time running me to and from work not on a track.
My thoughts.
1. Replace / upgrade springs and shocks. I think that the car needs new shocks regardless of any other work. I think that it would benefit from a new set of springs as well. However I cannot decide between the Bilstein B4 and B6 shocks and the Eibach or standard M-Sport springs. The B4s are supposed to be a direct replacement for the OEM shocks but I have read that the B6s are better in terms of control. I have also heard that the Eibach springs, being progressive, are better than the standard M-Sport as they stiffen up through the corners allowing the benefits of normal(ish) spring rates over potholes but stiffer spring rates when cornering fast. Bearing in mind that I have the standard springs already fitted, albeit with a large number of miles on them, I could go back to standard. Also the standard springs do not seem to be overly expensive so swapping those wouldn’t be the end of the world.
2. Replace and upgrade the suspension bushes throughout the rear suspension. I was looking at the Rogue Engineering Uprated RTAB with the Reinforcements, if required, the Rogue Engineering Rear Shock Mounts and the Turner Motorsport Upper Monoball Sub-frame Control Arm Bushing. The other bushes would be replaced with standard Powerflex Polybush ones. I notice that there are a number of replacement Rear control Arms but I am not sure if they would be necessary on a mainly road car. I think that this should completely refresh the rear suspension and provide a subtle upgrade without ruining the ride.
3. Replace and upgrade the suspension bushes throughout the front suspension. I cannot see any uprated “lollypop” bushes on your site so I am thinking that replacing the standard items with standard Powerflex Polybush ones. Also I have been told that there is an uprated Ball Joint from Meyle that could be fitted, but you don’t appear to stock it. I would need the ball joint replacing regardless on any other work.
4. Replace the gear shift bush with a standard Powerflex Polybush one. This has never been changed and so will be worn. Replacing this can only improve the shift.
5. Fit the Brembo Front Callipers and CSL disks. Fit the front braided brake lines.
6. Refresh the rear brakes, replacing handbrake shoes and adjusting handbrake.
7. Preventative maintenance and engine management. When the new brakes and shoes / pads are being fitted it would be worth flushing the old brake fluid out and replacing with higher spec fluid. I am not sure which parts are likely to give problems during a track day but I am happy to do any preventative maintenance that is suggested to negate the risk of failure.
8. A full 4 wheel alignment and reset to fast road settings.
Looking at all of this I think that I am looking at about £1,500 in parts and another £5-600 in labour to fit. That leaves a little room in the budget if there are other things that you would suggest getting done / fitting at this point.
Questions.
1. What is your experience of these two suspension setups? Does the increased harshness of the B6/Eibach outweigh the benefits of increased road holding? Also is there anything that can be done with a combination of stiffer anti-roll bars and softer springs to allow for good road manners / comfortable ride at low speed and good track manners / fast road handling at higher speeds?
2. Would it be worth fitting strut tower reinforcement plates to the suspension towers front and rear when replacing the springs and struts?
3. Would it be worth replacing the Rear Control arms at the same time as the rest of the rear suspension, or is it an expense that I can leave as it wouldn’t provide a significant improvement and can be done later if necessary?
4. Would it be worth fitting strut tower reinforcement plates to the suspension towers front and rear when replacing the springs and struts?
5. Is there an uprated “lollypop bush” and Ball Joint that you would recommend using when refreshing the front suspension? Also should I be looking at any other items at the same time, possibly the track rods?
6. Is it worth replacing the front mounts with either Camber Adjustable or Camber and Caster adjustable items or is this an expense that I can leave as it wouldn’t provide a significant improvement and can be done later if necessary?
7. Is it worth looking at uprated anti-roll bars and drop links? Would it be possible to combine uprated / stiffer anti-roll bars with the new springs and shocks to give a suspension setup that can cope with my requirement of comfort on normal road and track day fun?
8. Are there any other components of the gear shift that could / should be changed to improve the gear change? It is not too bad at the moment but any improvement would be welcome.
9. With the Brembo front brake kit fitted is it worth upgrading the rear brakes more than changing the pads? Which pads would you recommend? Is it worth fitting a braided brake line for the rear at the same time?
10. Is there any preventative maintenance that you would suggest doing prior to a track day in early February. I have just had the oil / filter and gearbox oil changed as part of the recent Inspection 1.
11. Would you recommend strut braces and if so which ones?
12. Would you recommend and structural reinforcement or replacement of engine / gearbox mounts?
13. What is the earliest in the New Year that I could be booked into the Erith garage and how long would you anticipate the work taking?
I hope that this makes sense and look forward to hearing from you early in the New Year.
Many thanks,
Jon Leeper
Logistic Operations Manager | LCY8 | ATS | UK
Monday - Friday
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Look forward to seeing how this progresses, and for what it's worth I'd consider getting shot of the "summer" 108's and getting some 224's. Better offsets and less corrosion issues (split rims are unfortunately more susceptible). Got a spare set myself, if you're interested and sure a deal can be done 
https://powerflexstore.co.uk/bmw/z4-e85-e86-2003-2009/
I think being a bit more consise and cutting out the waffle would be a good start 