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melmose

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  1. the ford focus year 2015 , has rear passive assisted steering. what effect does that have on the geometry of the car ?is it worth having or is it just another toy like the automatic handbrake which seems to be favoured by the car makers at the moment? thanks in advance , melmose .
  2. Thanks for the clarification Tony!
  3. Hi, i originally placed this query in one of the above pinned/sticky threads http://www.wheels-inmotion.co.uk/forum/ind...p?showtopic=165 and as i haven`t had an answer,thought it may be best doing a seperate post.Hope that`s ok? The dots on the sidewall typically denote unformity and weight. It's impossible to manufacture a tyre which is perfectly balanced and perfectly manufactured in the belts. As a result, all tyres have a point on the tread which is lighter than the rest of the tyre - a thin spot if you like. It's fractional - you'd never notice it unless you used tyre manufacturing equipment to find it, but its there. When the tyre is manufactured, this point is found and a coloured dot is put on the sidewall of the tyre corresponding to the light spot. Typically this is a yellow dot (although some manufacturers use different colours just to confuse us) and is known as the weight mark. Typically the yellow dot should end up aligned to the valve stem on your wheel and tyre combo. This is because you can help minimize the amount of weight needed to balance the tyre and wheel combo by mounting the tire so that its light point is matched up with the wheel's heavy balance point. Every wheel has a valve stem which cannot be moved so that is considered to be the heavy balance point for the wheel. As well as not being able to manufacture perfectly weighted tyres, it's also nearly impossible to make a tyre which is perfectly circular. By perfectly circular, I mean down to some nauseating number of decimal places. Again, you'd be hard pushed to actually be able to tell that a tyre wasn't round without specialist equipment. Every tyre has a high and a low spot, the difference of which is called radial runout. Using sophisticated computer analysis, tyre manufacturers spin each tyre and look for the 'wobble' in the tyre at certain RPMs. It's all about harmonic frequency (you know - the frequency at which something vibrates, like the Tacoma Narrows bridge collapse). Where the first harmonic curve from the tyre wobble hits its high point, that's where the tyre's high spot is. Manufacturers typically mark this point with a red dot on the tyre sidewall, although again, some tyres have no marks, and others use different colours. This is called the uniformity mark. Correspondingly, most wheel rims are also not 100% circular, and will have a notch or a dimple stamped into the wheel rim somewhere indicating their low point. It makes sense then, that the high point of the tyre should be matched with the low point of the wheel rim to balance out the radial runout. Very interesting and helpful,but as usual nothing is straight forward for me! On my new set of tyres,i have a red dot on 3 tyres and a yellow dot on one-which is the tyre that`s pulling,so may be able to do something about that one. However, i cannot find a notch on any of my steel wheel rims to match up to the red dots! In this situation what do you recommend? Also,if you can find all the dots,like in your illustration, when you line one of the dots up to either the valve or the rim notch,surely one is going to be lined up correctly and the other not? Do you compromise in this case and what is the best compromise? Cheers Mel
  4. The dots on the sidewall typically denote unformity and weight. It's impossible to manufacture a tyre which is perfectly balanced and perfectly manufactured in the belts. As a result, all tyres have a point on the tread which is lighter than the rest of the tyre - a thin spot if you like. It's fractional - you'd never notice it unless you used tyre manufacturing equipment to find it, but its there. When the tyre is manufactured, this point is found and a coloured dot is put on the sidewall of the tyre corresponding to the light spot. Typically this is a yellow dot (although some manufacturers use different colours just to confuse us) and is known as the weight mark. Typically the yellow dot should end up aligned to the valve stem on your wheel and tyre combo. This is because you can help minimize the amount of weight needed to balance the tyre and wheel combo by mounting the tire so that its light point is matched up with the wheel's heavy balance point. Every wheel has a valve stem which cannot be moved so that is considered to be the heavy balance point for the wheel. As well as not being able to manufacture perfectly weighted tyres, it's also nearly impossible to make a tyre which is perfectly circular. By perfectly circular, I mean down to some nauseating number of decimal places. Again, you'd be hard pushed to actually be able to tell that a tyre wasn't round without specialist equipment. Every tyre has a high and a low spot, the difference of which is called radial runout. Using sophisticated computer analysis, tyre manufacturers spin each tyre and look for the 'wobble' in the tyre at certain RPMs. It's all about harmonic frequency (you know - the frequency at which something vibrates, like the Tacoma Narrows bridge collapse). Where the first harmonic curve from the tyre wobble hits its high point, that's where the tyre's high spot is. Manufacturers typically mark this point with a red dot on the tyre sidewall, although again, some tyres have no marks, and others use different colours. This is called the uniformity mark. Correspondingly, most wheel rims are also not 100% circular, and will have a notch or a dimple stamped into the wheel rim somewhere indicating their low point. It makes sense then, that the high point of the tyre should be matched with the low point of the wheel rim to balance out the radial runout. Very interesting and helpful,but as usual nothing is straight forward for me! On my new set of tyres,i have a red dot on 3 tyres and a yellow dot on one-which is the tyre that`s pulling,so may be able to do something about that one. However, i cannot find a notch on any of my steel wheel rims to match up to the red dots! In this situation what do you recommend? Also,if you can find all the dots,like in your illustration, when you line one of the dots up to either the valve or the rim notch,surely one is going to be lined up correctly and the other not? Do you compromise in this case and what is the best compromise? Cheers Mel
  5. Can i put poly bushes on the wishbones and if so are they expensive? From what i`m seeing on here and WIM it `s pointing to the tyres isn`t it? Oh well,i`m playing about with the pressures and swopping around atm and there`s a marked change each time...i`ll really look into the wishbones again too.I`m an old codger on a small budget(well none actually after all this!) so have to be sure first:-) Very grateful for everyones imput
  6. I`ll go and try that now and keep tweeking for a day or so.i hope i can get it sorted as i can`t afford another set of new tyres! Thanks you so much for your input Tony and fellow members.I`m so glad i found this forum as it`s restored my faith somewhat,having had some seriously bad experiences recently within the motor industry. I`ll let you know how i get on,incase it helps someone else with a similar problem.
  7. Thanks for the link Tony. I swopped the tyres round on the front axle as you suggested (the tyres turned out to be asymetric and NOT unidirectional) and the red run out line is on the inside of all four tyres.I can send photo`s if you want me to. The handling has now changed to the following:- The car will now go in a straight line,but if you turn the steering wheel a degree or two to the left or right,the car will not correct itself.It will just drift to the left or right,almost as if the front wheels are aligning themselves to two opposing thrust angles-or is that impossible?! Hope this information will make things more clear for you. Thanks in advance Mel
  8. The tyres were put on before the geometry test though... When you say put the fronts side to side,i take that to mean swop them round? may sound daft,but i`m not a great expert and had better check with you 1st! It makes no difference, you can do a geo without the wheels being on! Yes swap the fronts over just to test if it drifts the other way, if it does it's the tyres. There's a sticky thread in the tyre forum explaining why it might be these. Thanks Tony. The tyres are unidirectional(?) so will try swopping front to back. My other half remembers that the red line on the each tyre was towards the outside edge,so that`s ok
  9. The tyres were put on before the geometry test though... When you say put the fronts side to side,i take that to mean swop them round? may sound daft,but i`m not a great expert and had better check with you 1st!
  10. Hello I have had my ford mondeo lx mk2 for a couple of years.it has always pulled to the left.As a result i have paid on a number of occasions for tracking,4 wheel alignment and this week for full geometric alignment.. Unfortuanetly it is still pilling to the left although i am experiencing some improvement. i have just had a brand new set of tyres prior to this and as far as i can ascertain the bushes are ok,the lower arms are not bent,so in my estimation it must be the thrust angle that is wrong. Here is the geometry readout done on a hunter machine-does this look ok to you? Cheers Mel
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