Jump to content

BMW Geometry again.


Anees
 Share

Recommended Posts

  • Replies 75
  • Created
  • Last Reply

Top Posters In This Topic

If the wheels are visibly out, but the machine still thinks it's fine, is there not something weird going on?

 

Personally I'd want to get it on another machine to start with, just to see if it says the same thing.......

 

Offer a spirit level and a ruler to the wheel and see what you get.

Link to comment
Share on other sites

Other than the castors being low the report looks fine.

 

I did mention that, but they said its only really a concern if the car is pulling - which is isn't.

 

Good point Parthiban - but then who's machine do you trust? Drury insist their machine is accurate and correctly callibrated and say the machine itself has build in "safety" features to prevent innaccurate geometry readings and I know from past experience that Drury are good. Also with geometry I could put the car on someone else machine and because the measurements are so tiny and accurate it would read different again

Link to comment
Share on other sites

If the wheels are visibly out, but the machine still thinks it's fine, is there not something weird going on?

 

Personally I'd want to get it on another machine to start with, just to see if it says the same thing.......

 

Offer a spirit level and a ruler to the wheel and see what you get.

 

thats a good idea mate - might try that tomorrow if I can.

 

Anees :blink:

Link to comment
Share on other sites

Good point Parthiban - but then who's machine do you trust?

Yeah it's a tough one, but the only thing it could clear up is whether the drury machine is telling the truth or not........if another machine shows something up as being way out, then there would be something to look into..........the best option obviously it to bring it down to Tony to check it over :blink:

 

Good idea there though, a spirit level should show up any obvious difference - another would be to use a ruler to measure horizontally from the wheel to the arch to see if one wheel has more camber than the other.

Link to comment
Share on other sites

Another update after a few days of driving:

 

Firstly the good news - took the car to erm......70mph(++) and the rear now seems fine so the car is not wondering all over the place. So thats good.

The back end of the car now seems to be "perfect".

 

Bad points however are:

 

The car is still rolling too much considering its on Eibach Coilovers and has Eibach AntiRoll bars. Today I was at Charlesworth Motors in Glossop (Steve's place) and compared to Steves 320D Sport on standard suspension my car does have alot more roll. IT SHOULD BE LESS!! lol

 

The steering is still slow and appears to have a dead spot in the centre compared to Steves. Seems uncommunicative.

 

At the garage they drove the car really hard around some corners and bends and checked the tyres for marks that suggest the tyres were "too soft" (the side wall having marks where its gone over etc) but didn't find anything un toward.

 

Steve says he finds it very hard to believe its the tyres and also doesn't think its geometry since the wondering problem seems to be sorted. After having a good look at the car he is suggesting that the springs have just worn and become soft.

 

Simon (Steve's right hand man) thinks it could be tyre roll but no marks on the tyres appear to show this. The strange thing is that when the car is parked up and you try to bounce the car up and down its solid but its rolling a lot in the corners which leads us back to springs.

 

We have also noticed that the rear shock are wet at the top which they shouldn't be so my plan is to try and push and get the whole set of Eibach coilovers changed under warranty due to excessive roll (caused by the springs) and leak from the shocks.

 

I am so tempted to just get another set of tyres for the car to be honest - Verdestein since Steve has these on his 320D and raves about the grip and the responsiveness.

 

Overall its more questions then answers really................

Link to comment
Share on other sites

Pneumatic or tyre slip will not mark the tyre.... It's the travel between the bead point at the rim and the tyres contact patch. The whole idea of low profile tyres is to minimize this travel so that the communication between the tyre and rim is more defined.

 

Obviously if there's issues with the dampers leaking then this entire thread is blown away, but i still think the real issue is the slip-angle.

Link to comment
Share on other sites

I think before going any further I need to get the shocks and springs replaced (they are just about inside the 2 year warranty period) from Eibach.

 

Simon did mention that the front tyres do look abit "soft", Steve is not convinced but I keep thinking back to what Tony said:

 

 

I wouldn't recommend the asymmetric on any car now due to the complaints, these being..

 

* The steering feels like there's a delay between yaw and actual grip.

Link to comment
Share on other sites

  • 2 months later...

I have been busy with other things so not made much progress with this, but a a further update.

 

I emailed Eibach complaining about the excessive roll the car has at the front and after a delay they will not replace the front shocks, claiming that the reason the roll is so bad is because the obviously worn shocks on the rear are causing all the cars weight to transfer to the front when cornering which is why the car is rolling so much. They have accepted the rear shocks are faulty and have sent me a pair of rear shocks.

 

I am quoting the email they sent me. Does it should feasible?

 

Although the majority of roll control is determined by the springs and dampers, there is still a contribution from the damper. Given that the rear dampers are obviously defective and we can assume that they have experienced some damping force degradation, a greater sense of body roll is to be expected. It is important to remember that the car’s body is a very stiff structure and therefore capable of transferring load from rear to front very efficiently. Any reduction in roll stiffness experienced at the rear of the car will inevitably result in a greater roll moment being experienced at the front – the front is therefore experiencing a greater roll moment than usual and will therefore also display a greater roll angle.

 

1. Spring rate (stiffness) does not degrade with use.

2. ‘Stiff and Bouncy’, as a comment, also supports the theory that the springs are fine (Stiff) and that the damping force has degraded (Bouncy). Essentially, springs and ARB’s support the vehicles mass, provide compliance for sharp road inputs and determine the cars ultimate roll angle (i.e. when the compressed springs and wound up ARB forces equal the cars roll moment force). Damping will determine the rate or speed with which this roll angle is achieved. With this in mind, weak damping force will result in the ultimate roll angle being achieved more quickly than with firmer damping, thus resulting in a perceived ‘feeling’ of greater roll but in actual fact the ultimate roll angle is the

Link to comment
Share on other sites

  • 2 months later...

Bit of an update to this thread.

 

I had my original BMW suspension put back on the car about a month ago and to be honest it didn't really make a massive difference. Like Tony said straight away, I am convinced it is the tyres now causing the problems.

 

I was going to live with it, until the tyres wore down and replace them, but faith has forced my hand with a non repairable puncture on the rear tyres so I have bitten the bullet and gone for Verdestein Ultra Sessantas which I had on the Aristo before and were great and I also know Tony rates them and they are used by many happy BMW owners.

 

I can sell the three remaining Goodyears - 6mm thread left on the fronts to hopefully get some of my money back.

 

Hopefully when the Vredesteins are fitted I am finally happy :rolleyes: It also shows that Tony was correct from the start!!

 

Thanks,

Anees

Link to comment
Share on other sites

Permission to be smug granted! :D

 

Its not that I didn't believe your diagnosis from the start but I had Steve from Charlesworth, the mechanic I use normally from Auto-Serve and a few others said that they definetly didn't think it was the tyres at fault and I suppose I just went along with it.

 

Fingers crossed we have success now.........

Link to comment
Share on other sites

In wim we digest logic, chew it and spit it out. In the real world there's no real right or wrong, only what's expected, if you can in vision beyond this then there is a a totally new horizon. The manufacturers get it wrong more times than you would believe.

Link to comment
Share on other sites

In wim we digest logic, chew it and spit it out. In the real world there's no real right or wrong, only what's expected, if you can in vision beyond this then there is a a totally new horizon. The manufacturers get it wrong more times than you would believe.

Very unusual scenario - and great testament to how your vast experience picked it up almost straight away when logically it made no sense :sick01:

Link to comment
Share on other sites

Right, new tyres were fitted yesterday.

 

I can report: .....

 

- Much better turn in! Car feels less "mushy" if you know what I mean and sharper.

- Backend feels planted again - I pushed it to "some" miles an hour and backend was planted and not all over the place

- Seems to be less bodyroll too (but it was wet so not pushing it yet)

 

And this was in the wet!!

 

Overall, considering the tyres still probably have there coating on them and will need a few hundered miles to bed in properly they are in instant improvement! In short I am confident that once the tyres bed in, my car is BACK :smile_anim:

 

Much happier with the car now. The strange thing is my goodyears looks like new and the fronts (225/40/18) have only 7mm wear and the rears 6mm (255/35/18). Still hope to sell those. They are great tyres but just don't seem to suit my BMW.

Link to comment
Share on other sites

Excellent...... I deal with more and more cars nowadays that have handling issues related to tyres, old school fast-fit are letting people down with poor advice and fitting tyres to cars that need, nay must have specific compounds.

Link to comment
Share on other sites

Glad you got it sorted Anees :smile_anim:

 

 

I'm starting to get a little worried myself, since the weather got colder I've been having really bad traction problems (wheels are spinning up all over the shop, which in an IS200 is a rare thing) - tyres look fine and grip at speed is fine too, hope you'll be able to shed some light next week Tony :rolleyes:

Link to comment
Share on other sites

Glad you got it sorted Anees :rolleyes:

 

 

I'm starting to get a little worried myself, since the weather got colder I've been having really bad traction problems (wheels are spinning up all over the shop, which in an IS200 is a rare thing) - tyres look fine and grip at speed is fine too, hope you'll be able to shed some light next week Tony :huh:

 

Brick under the throttle should deal with that :smile_anim:

Link to comment
Share on other sites

  • 2 weeks later...

Further update....

 

FANTASTIC TYRES!!

 

I have had:

 

Dunlop Sport Maxx, Falken-FK452, Michelin Pilot Sport PS2, Goodyear Eagle F1 Asymmetrics and now these Vredesteins. I would rate them as the best tyres I've had so far. Just SO GRIPPY!!

 

;)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share


×
×
  • Create New...