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BOF

Member Since 02 Nov 2012
Online Last Active Today, 09:07 AM
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Posts I've Made

In Topic: What Causes Uneven Tyre Wear?

17 April 2014 - 08:46 PM

To be honest, every car I've ever had has always seemed to have tracking issues that just won't go away - until I took it to this certain garage who managed to fix it.  Unfortunately I've now moved away and said garage is best part of 80 miles away.

 

Welll

  • I used to have tracking issues, 20 years ago. If you ask me, those cars had issues with the tracking going out. If you ask the cars, there were probably issues with my driving (although, I ought to mention that there was more 'kerb parking' in where I drove, back then).
  • I know you won't think much of this, but if you think that there is a garage which will sort it for you, it might be less hassle just to go there. or, maybe ask locals which companies they rate.

 

 

As for tyre pressures, I always do them from cold, with a digital pressure gauge, then double-check the same value shows on the compressor.  I *think* I'm on 33PSI all round (whatever info it says inside the fuel filler cap, as that's where I looked to find the right pressures).

 

So, the car is not a MkIV, then. Well, it might be old enough to have problems with bushes, then.

 

I doubt that 33 psi all round is what is recommended for 'normal' driving. There are different pressures for different conditions (depending on speed and load) but the pressures for 'normal speeds' (probably under 100 mph) and part loads (different five up and/or with a full load area) are probably lower than that at the rear, and that or a bit higher, at the front. Now, my personal preference is somewhere around the recommended for the fronts and about 2 psi lower for the rear for normal driving, with the fronts up a psi and the rears up closer to the fronts for combined high speed and high load situations (the recommends for the rears change too much, for my money, with load, but that's only my preference...but the rears changing from around 27 psi to around 41 psi is rather too wild for me; maybe if I was in Germany, I'd always go with the high speed recommends). 

 

I can't say that I really like the digital pressure gauges, because the resolution is usually not as good as you'd like. That said, it doesn't sound as if this problem is down to 1 psi measuring uncertainty. In fact, going out on a limb a bit, I'd say that it must be something more dramatic than that. The gauges on the compressors? Now, those can be really inaccurate. I've got a 'stand-alone' analogue gauge, a (Michelin) foot pump and a compressor. The compressor will tell you whether there is air in the tyre, or not, the foot pump gives you a pressure within a couple of psi (the gauge is too small, and any stiction in the mechanism amounts to 2 psi, or so...and Michelin is one of the better ones) and the stand-alone gauge is pretty much spot on when compared against a motorsport gauge, with a calibration certificate (not that I'm actually that bothered, provided that it is consistent and repeatable).

 

Have you tried doing anything about tyre temperatures? You might not have an optical pyrometer to hand, but it ought to be obvious if one edge of the tyre is running a lot hotter than the rest of the tread. And, you might even get an idea of whether it just happens going round corners, or whether high speeds and straight lines are implicated, too.

 

I did get a sheet when I had the alignment done, not that I pretend to understand anything that was written on it...

 

If you got both before and after numbers, one question is whether anything changed dramatically. The obvious things to look for are toe in and camber, but there are probably other important things too, that I haven't quite thought out yet.

 

I don't think that it can be anything at the back, unless it is way, way out and the front has been set up oddly to compensate. And I can't quite see that happening accidentally, so you'd be primarily looking for big changes at the front.


In Topic: What Causes Uneven Tyre Wear?

17 April 2014 - 09:30 AM

 It isn't the alignment, and it isn't the tyre pressure.

 

Well, something is wrong. And it seems, with what you've had done, to be that something is wrong that shouldn't be.

 

  Do worn shocks cause this? 

 

Worn shocks can make wear worse, but not usually in this plane. Out of balance wheels, plus worn shocks will tend to produce uneven wear around the wheel, but this isn't what you've got.

 

 

I had full 4-wheel alignment done less than six months ago, and two brand new Bridgestone tyres on the front.

 

The n/s is fine, but the o/s is totally mashed on the inside edge already.

 

 

Well, the alignment could have been done badly, or there could have been a fault with the tyre. Neither of those should have happened, but either could have.

 

Did you get a print out of the alignment details, once it had been done? The tracking could have been set up to the wrong values, or the sensors on the wheels could have been fitted incorrectly (easier, if there is a defect in the wheel itself, of course - if the wheel is bent, then the tracking that you get is dependant on where you mount the sensor on the wheel). The person doing the tracking should have checked for this, but maybe they didn't, or didn't look carefully. Ideally, spin the wheel and look for problems (while you are there, check the brakes aren't, eg, binding at some point in the revolution).

 

 Did you look at the failed tyre for any feathering on the edge of the tread pattern? Did the inside of the carcass look ok (there wasn't any evidence of broken plies leading to bulges inside the tyre?)

 

Check also that the bolts holding the strut mount have not come loose or that there are witness marks showing that the strut mount has moved over time. This is probably quite unlikely, but as you can check just by opening the bonnet and looking....

 

 

And I can't remember when prior to that but the only time they were lower than normal was when the weather was cold in January, and I put a couple of PSI in each...So something over the last six months has been destroying my n/s front. It isn't the alignment, and it isn't the tyre pressure.

 

What are you checking the tyre pressure against? How do you know that it is accurate?

 

The last time I had the alignment checked (when both tyres were worn on the inside edge)...

 

So, the 'progress' has been from both tyres wearing unduly rapidly (?) on the inside edge, to only one wearing on the inside edge? If I had to guess, I'd guess that the tracking on both sides was quite a way out, and it has been corrected but only on one side, for whatever reason. I've no idea what would constitute evidence to 'prove' that the alignment had been done badly, but I'd doubt that you'll now get it.

 

My feeling is that you'll have take it to someone to check the tracking (again!). Ensure that you have the tyre pressures set correctly and that the car is normally loaded (eg, if you have an estate and the rear is normally loaded with equipment, get the tracking done in that state). Check the wheels first, to ensure that that there aren't any bumps or bends on those. Check the wheels for play (if there is play, the alignment could be anything, depending on where the wheel is, at the time). Keep a close eye on the wear patterns once it has been done.

 

Check for broken springs. As it might be just the section close to the mount that is broken, you'll have to get 'up close and personal' to do that. (Maybe, you can take a photograph which shows it well enough, which would avoid the necessity to take the wheel off, of maybe you can see enough just by swinging the steering over to full lock. But, if you are taking the wheel off anyway...)

 

Bushes can be a bit controversial; it is difficult to get three people to agree whether bush condition is good, without getting four different opinions. It would be useful to know the age of the car (newer vehicles shouldn't have bushes in bad condition, unless the vehicle has had some kind of incident, even though that incident might not have to be big enough to cause other damage and be recorded. Is this a vehicle that you have had for long?) If you hit a pothole at speed, that can be enough to damage a bush or throw the tracking out. I know that's worrying, with the state of our roads, but it is the case.


In Topic: S-Max Battery

14 April 2014 - 09:17 AM

Hi everyone

I've just purchased a 60 plate s-max titanium with 30k on the clock ...

 Should a battery really only last that amount of miles and for its age?

 

While a battery should last longer than that, it is difficult to know at this point what went wrong.

 

it is possible that the dealer had the vehicle hanging around for a while (what did the brake disks look like?) and that the battery went flat, and that does vehicle batteries no good at all.

 

The car had been doing roughly 7.5 k miles per year, and that's on the low side. Now, if this was 'the aunt minnie cycle' (lots of short, shopping, journeys), the battery may never have been fully charged, and that does vehicle batteries no good at all. That part, the battery not charging fully, isn't really a problem if your usage is going to get it charged fully, but, if you reproduce the previous user's usage style, you'll probably find that the battery doesn't last that long, either.

 

The other possibility is that there is a fault, leading to unusual load on the battery, or that the battery isn't charging properly. At some point, I'd want to check that the 'on charge' voltage makes sense, just to ensure that there isn't an alternator fault behind this. Not the most likely thing, but, if it is the case, you'd want to be back for the alternator under warranty as soon as you can.

 

(Also, have a look round for any unusual wiring - a possibility is that someone has had some extra piece of equipment wired in to the vehicle, and the wiring has been removed fairly brutally, leaving uninsulated wire hanging around that could lead to intermittent shorts across the battery.) 


In Topic: Tyres For Focus

05 April 2014 - 07:16 PM

...so would i be ok the stick some 97H's on the front and leave the 93H's on the back (as currently) of should all four be the same

 

 

I don't see why 97s would be a problem - having too low a load rating would be a problem, but i don't see a problem with having too high a load rating. Given the the static load at the front of a front wheel drive car is higher than at the rear, I don't see the problem with this suggestion. (Although, if you frequently drive with the car loaded to the gunnels, that might change, biasing the load more to the rear.)

 

BTW, the easy way to have more of choice of tyres is to allow tyres of a higher speed rating: again, if you go to a lower speed rating, that is potentially problematic (might have to inform the insurance, for example, if the car can exceed the speed rating of the tyres). But there are more 'V' and 'W' rated tyres around in this size than 'H's.

 

...to be only around 4 different tyres for my current size (215/55 R16 93H), but, on one of the sites (black circles, i think) it didn't ask for the load index, just the speed rating...

I had a quick look on pneus-online, and there, with an open speed rating and any load index, there are 7 pages of about 50 tyres per page (some less than that really, because there a quite a few duplications and a few winter tyres, so say about two hundred distinct tyre types). 

 

Pneus-online usually have one of the widest selections, even if they aren't that often the cheapest. Well, except when some of the others don't have they tyre that you want.

 

(In passing, there doesn't seem to be a supplier which is always the cheapest - one supplier is cheap for some tyres and another is cheap for others.  Camskill, mentioned above by Hyrule, is often one of the cheaper ones, though. Also, some people just deliver tyres, and others have fitting partners, so fitting is in the price - its a matter of which you prefer.)


In Topic: Sort This Rust Out, Easy Or Not

02 April 2014 - 09:06 PM

After talking to a few people, am staying well away, and now looking at a  Xr31 convertible 

 

That's probably sensible (well, the 'staying away from this example' part, anyway), but sensible isn't always the most fun.

 

I'd guess that the area around the top of the hatch is do-able - stress concentration from the hinges, maybe. It would be work, certainly, but you can get at both sides and I'm not sure how much you'd have to cut away to get rid of all the rust (and, if you don't get rid of all the rust, it will be back).

 

The base of the windscreen would be harder. It is not so much that there is lots of welding, more that you'd have to disassemble the car into nuts and bolts to do it. Well, wings off, dashboard out to even get started. And, I bet when you did that, you find a few more currently hidden horror stories that you hadn't anticipated.

 

And it is stressed area and if you don't do it right the car will be dangerous (crumble in an impact) and might fail an MoT...but then, I guess that's a chance you have to take.