Hello All, I am newbe to cars.. i bought this second hand BMW 525i 1990 model. The problem with this car is it tends to sway to the left when i am driving straight and so i have to be very carefull when driving... when i went to a near by garage he changed tie rods and a couple of other things in the front... and gave me a bill of 2000$ and now when it still persists he says i have to change the control arm... can anyone please suggest me what could be really wrong. Thanks a ton in advance
Number one, most common problem with used cars that can cause this problem: mismatched tires. I've bought two used BMW's, from dealers, where the tires caused this exact problem.
Check out, are the tires all the same brand, size and approximate wear level? Even if so the tires could have been improperly rotated and so may be essentially ruined.
You can check out this problem by fitting a temporary set (if you can find one that fits), or just bite the bullet and put on new rubber. Don't waste more money on a mechanic guessing what might be wrong under your car. If something's worn, a decent mechanic will be able to see or feel it without guessing.
Another problem you can sometimes feel with badly matched tires is that the car will feel like it's pulling against something and then suddenly that thing lets go, then it starts pulling again, then lets go. This can set up an odd, somewhat subtle lurching feeling to the ride that a mechanic might not notice but which can drive you bananas.
If you're new to cars you probably don't know this, but it's really unbelievable what a difference a high quality, well-maintained set of tires does for your ride, and the number of dealers and mechanics who don't notice when this is the problem.
Bing! Give the man a cigar. I have seen this happen too with properly matched tires (all the same brand, model and even batch) but where one of the two fronts had less wear on it because it had been rotated out of the trunk!!
Apparently the PO had curbed the front off-side wheel and made some ugly modifications to the rim. Being the intelligent type he swapped it for the spare which was a matching alloy! Only problem was the other front tire was worn down about 3/32 more, so it pulled. Simple fix though, put the odd (newer) tire on the rear and voila! shes a runnin straight now.
Hmmm... not sure about that. I think they will wear back in given enough timne and tread depth. But I might be convinced otherwise since I have to admit I have never tried it.
With steel-belted radials -- basically all modern tires except (maybe?) some snow tires -- the internal belts pull on the rubber they're bonded to inside the tire, and sort of "bed" themselves in for whichever direction they're pulling.
If you rotate a belted radial from one side of the car to the other, the internal belt will then begin to pull against the rubber in the opposite direction, essentially un-bedding itself. Depending on the tire construction this can cause all sorts of different bad things to happen, the basic idea being that the integrity of the tire is ruined, and merely rotating it back to the original, "correct" side of the car, will not fix it.
And then, of course, there are some unidirectional tires where the tread itself will only work correctly on one side of the car. I'm sure, somewhere out there right this minute, somebody is misrotating a set of these and, given my track record, will one day try to sell that car to me.
I haven't kept up with tire technology in more than a decade, but this is how it used to work. If some Bridgestone engineer wants to tell me it doesn't work this way anymore, I'd be pleased to hear it, but I believe this is still very true and is the sort of thing that should be required knowledge for anybody who owns a car.
I ran my rear tires -- directional Khumo Estca 711, backwards for about 3 months unwittingly. They're about 3 years old now, probably be their last season. What damage do you think I might have done to them?
If that is the case (and I'm not yet prepared to accept that it is without further investigation) then why isn't there a safety
*requirement* to have directional indicators either embedded in all radial tires (like the unidirection tread ones that you mentioned) or added to the tire/wheel after they have been installed the first time?
Perhaps I'm wrong. Perhaps things have changed. I've checked the Yokahama, Michelin and Bridgestone sites and there's nothing to support me on incorrect tire rotation ruining tires. In fact, the Michelin site shows a recommended style of cross-rotation that I was taught would damage radial-designed tires, and which absolutely cannot work with directional tires, and they didn't include any caveats about directional tires being an exception, so I'm not sure they know what they're doing with that little demo.
So, okay, take what I said with a grain of salt. Just check for well matched tires. I'll continue to pay attention to rotation as I've always done until I hear something definitive from my BMW mechanic or tire manufacturer (and frankly I'm not sure I'd take my mechanic's word for it).
Oh no, I've just never gotten more than 2 years out of my own Kumho Ecsta
710s. Could be I drive too hard, or my pit crew isn't rotating properly.
On a serious note, Kumho provides virtually the same rotating advice as Michelin, except in a fancy video format. Plus they address the directional tire issue:
-"Regarding the time of tire rotation, exchanging the tire position should occur between 5,000-7,500 miles, or according to the advice of the vehicle manufacturer".
And the advice of the vehicle manufacturer? Don't rotate your tyres!
It's time alright... I have my stock basketweaves off and I'm planning to refinish them, then mount new rubber on them and retire the Kumhos and the temorary wheels I have them on.
I haven't done any really heavy rain driving this season which is where i would really notice the reduced tread depth, but in the dry, they are doing an excellent job. No tread grooves doesn't hurt dry traction. :-) Only they don't balance well, shakes from 85kph to 95kph, smooths out, and shakes again over 140kph. Did that last year too though. I'm hoping the new rubber will clear that up, I'm leaning towards Toyo Proxes this time.
I probably drove them about 5000 to 8000km backwards, I wasn't marking it especially though. Much of that at speeds of 100kph to 140kph -- my average speed as per the OBC these days is 64kph which includes in-town, idling, parking, drivethroughs, etc. Again, being dry, I didn't notice.... if it was wet those tires would have been channeling water in towards their center groove which I would imagine would cause hydroplaning or reduced grip.
Look up a few lines. You didn't say 710's or Victoracer, or anything about a particular tire model. You said: "The Kumho Ecsta's are racing tires, not street tires."
I replied that the majority of Kumhos labled Ecsta are street tires. This would infer that some (a minority) of the ecstas are racing tires.
The part I don't understand is the part where you didn't look back in the thread rather than the post. Earlier in the thread the 710s were specified, and in this post I short-handed it.
It looks like one or two have twigged the joke, but it is still very much an insider's one.
I did actually have a quick look at the Kumho website to see that rotation guide, but it would not enter my head to check out a specific model number to see if you were up to something.. Life's too short, especially if one has never heard of the brand and has Michelins, Pirellis, Bridgestones et al to choose from.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.