After putting on the smaller spare tire the car would not accelerate.
Amid all the confusion it took me a while to realize that I needed to deactivate the traction control (ACS).
I looked and could not find this instruction in any of the manuals.
Yes, I am sure I have read that in the manual somewhere.
I am guessing that the spacesaver has about half as much grip as a normal tyre as it is half as wide and that this confuses the ASC as the diff will not apply power evenly between the two wheels, so it will back of the engine revs. Did you see the ASC light come on?
You are supposed to do the same in the snow, but I normally leave mine on as I want the electronic LSD bit to help me. I would turn it off if I found the car was backing the power off when I didn't want it to though.
Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
After putting on the smaller spare tire the car would not accelerate.
Amid all the confusion it took me a while to realize that I needed to deactivate the traction control (ACS).
As I keep telling people - read the Owner's Handbook! At the top RH corner of page 75 it states clearly:
'If the spare wheel has been fitted, switch off the ASC+T'
I often think that people these days - particularly young males - are incapable of reading a greater amount of text than a classified advertisement, unless it is pressented to them on a screen!
The reduced width if this spare is only part of the story - it is also of smaller diameter than the 'real' wheels, so if fitted on the front the ABS will think that it is slipping, due to its higher speed, and reduce braking effort on that wheel. This is one of the reasons we are told to drive at a reduced speed when using the spare.
If fitted on the back, in addition to this problem the ASC will also think that it is slipping, reduce power (no effect) and then apply the brake to slow it down and feed more torque to the other wheel.
Apart from all this, the smaller diameter will mean that the differential gears are operating all the time, which does them no favours.
I put my primary protection in the use of Ulttraseal, which is a far better idea than the M Mobility Kit, use of which virtually wrecks en expensive tyre, and can place you in danger while you use it.
Last edited by Mike Fishwick on Sun 10 Jan, 2010 10:57, edited 1 time in total.
My manual is the 1998 issue - the info is probably somewhere else in the 1999 version, but it's so cumbersome to find in pdf form. You cannot beat a real book, as even when looking for something else, various other bits of information stick in your head.
It's like the craze in the MoD during the 'eighties for microfiches instead of real manuals, which was eventually scrubbed.
It's interesting that BMW are rather reticent about telling us what to do with the dead wheel, and never even refer to the shaped white plastic bag in the tool kit - never mind where to put it! That's what the passenger's knees are for . . .
Interestingly, on page 75 of my UK manual, it states, with a big /!\ just after the bit about rocking the car and snowchains:
If the spare wheel has been fitted, switch off the ASC+T. Otherwise, the smaller tyre diameter on the spare wheel will impair all functions of the ASC+T.
This paragraph is omitted from both the version bonbon has linked to, and the other US versions of the manual I have as PDFs.
So before you start preaching the gospel, Mike, you might like to check that it is in ALL versions of the manual.
Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
It seems there are a few versions of the manual. In mine the bit about turning off the ASC-T is on page 141 (Wheel Change) center paragraph half way down. Page 75 is Heating and Ventilation/air conditioning
As always Mike you deliver your message with the grace and tact of an elderly male trying do the splits whilst giving rhetoric on the meaning of imigration.
Oh dear - you just can't please all the people all the time, can you?
Perhaps our difference is based on age - at 18 going on 65 I was raised well before the idiocy of being PC, and worrying about 'What will people think etc' so no longer worry about the reactions of others very much!
Certain people seem to have left their sense of humour at home, or are of the 'Positive criticism' brigade - in other words looking for anything to whine about . . .
If people cannot see the humour in my comment regarding reading amounts of text, then that's their problem. Perhaps I have tings wrong, and should be thrown off the forum - if anyone thinks so, just contact the Forum Admin - help yourselves.
Mike Fishwick wrote:My manual is the 1998 issue...
...It's interesting that BMW are rather reticent about telling us what to do with the dead wheel, and never even refer to the shaped white plastic bag in the tool kit - never mind where to put it! That's what the passenger's knees are for . . .
Interesting; in my 1996 Owner's Handbook (pt no 01419789951) on p119 it states:
"Note that the defective road wheel cannot be carried in the spare wheel holder. Protect the defective road wheel in the plastic bag (supplied with the toolkit) and place it in the luggage compartment"
The handbook is for the 1.8 and 1.9 versions (I have a supplementary handbook for the 2.8 differences - there is no reference to wheel changing in there). Looks like some owners must have pointed out that the wheel doesn't fit in the boot. Seems that BMW realised the error of their ways and simply chose to omit references in all subsequent handbooks!
It's a good job that we've got a forum where we can help each other with our zeds if BMW are changing what's written in the manuals...
Current...1998 ///M Coupe
Previously...1997 Z3 2.8
My manual does not mention where to put the defective wheel, I found that one out for real!
It does not mention anything about turning the traction control off, it drove ok with the skinny on as long as I did not go over 20mph
My manual is 2002.
Don't lose the plot Mike, your wisdom is valuable to those of us who just want to run a non boring car at reasonable cost.
The world is too judgemental these days. But back on topic, my manual has no mention of asc off for skinny wheel.
The more I use my Z the better, more reliable and less costly it gets.
Slap my wrist
