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I agree with the tyres, although many users like to go off-road where they will need different rubber (although why not have a second set of wheels?).

As for the toe-in, it is a compromise that involves steering feel, tyre wear and braking stability. It also affects fuel efficiency, as extra scrub wastes energy but you can't have everything.
 
Discussion starter · #23 ·
Sorry, not sure what this means...
You have no control over TC lockup - it's in the software and comes on and off....
Hi there. I'm not expert at all. I was told by one who said the TC won't lock up properly (is it fully, I have no idea) until 3k rpm and a certain load. If you just drive around town you often won't ever reach that.

What I find is it'll sit it higher revs and just be a bit strange until it's actually locked. It just feels a bit spongy I guess, to me at least. I might be completely wrong of course, I'm not a mechanic. It just gets on my tits being a bit strange and a slight disconnected feeling.
Somebody said something about a solenoid trigger point. I wouldn't know what one was if it landed on my head, moreover something I might go and see the doctor about!:wink2:
 
It is way more complex than that. The gearbox takes the throttle input, the rate of throttle change, the engine load, the acceleration, the road speed, the angle of the car (uphill or downhill), the gerabox oil temperature and then works out which gear it thinks you should be in and whether to lock the torque converster or not. It is pretty hard to work out what is going on, but it seems to work fine most of the time.

The only way you can get an idea if the TC has locked up is if you take your foot off the throttle, if the revs drop straightaway, it isn't locked. If they stay about the same it is locked. All the variabilities above mean that sometimes it is locked up at 15 mph, other times it isn't locked up at 45 mph.

I guess that is the point of an automatic transmission, it does all the thinking so all you have to do is press the throttle and turn the steering wheel!
 
One interesting thing however to achieve that, the toe I understand (being a non-technical computer guy) is 7-degrees factory-spec (or something) and at that, you'll get maybe 31mpg, as per the book stats. However, I noted that I started getting more and more MPG up to 37PMG on the way to Scotland (400 miles without stopping).
To cut to the quick, I had the tracking re-done and they said it was at either zero degrees or toeing out slightly hence the super-mileage. I had it reset to 7-degrees and MPG dropped again. I asked the guy to set it to 5 degrees and it made a difference. It is the biggest relationship (outside of actually breaking the engine in). Somebody far more knowlegeable than I could have a play and see if it is a true observaation or coincidence.
Re: Wheel alignment.
I used to 'track' over 40 vehicles a day for about 20 years.
7 degrees is waaaaay to much, we are talking in terms of 15-30 minutes of tracking (60 minutes in 1 degree), 7 degrees would give a toe in of about 40-45 mm!
It has been estimated that 12 mm's of excess toe in/out is the same as dragging the front wheels sideways 30 mts for every mile the vehicle travels forward.
A vehicles front wheels are never set up dead parallel, the whole theory behind it is to set the tracking either toe in or toe out when the vehicle is stationary, once in motion the wheels will be 'pulled' into or 'drop' into place and then run parallel (worn components allowing).
A front wheel drive vehicle is generally set up to toe out, usually around 1-1.5mm, once in motion the front wheels apply a motive force pulling the car body forward against friction caused by the rear wheels, brakes, resistance caused by moving through the air, applied load from passengers, goods and fuel etc, therefore as the front wheels pull against this lot they move forwards slightly in a horizontal arc due to play in front suspension components and the compliance in rubber suspension mountings, so once in motion the front wheels should end up parallel to each other.
Exactly the reverse is the case for a rear wheel drive vehicle, the body in this case being pushed forwards by the rear wheels, the front wheels here are usually set up to toe in by a similar amount, as the vehicle enters forward motion, friction on the front wheel bearings, brakes, air resistance against the tyres, and in the case of a Navara drag from the front drive shafts all serve to pull the front wheels rearwards, play and compliance in the front suspension then allow the front wheels to drop rearwards in an arc settling them in a parallel position.
Navara's and other 4X4's are interesting here, although having the option of front wheel drive, I doubt if this is used 99% of the time, even then it should only be used on loose surfaces, so the best option here is to set the truck up as rear wheel drive i.e. toeing in by about 1-2 mm.
A vehicle with excess toe in should show feathering wear on the near side front tyre, the reason being, when in motion on an ordinary road the camber of the road usually dictates that a small amount of right hand steering force is applied to stop drifting into the kerb, this then decreases the toe in on the O/S/F wheel and increases the toe in on the N/S/F wheel.
The opposite applies on a vehicle with excess toe out, in this case the right hand steering force decreases the toe out of the N/S/F wheel but increases the toe out on the O/S/F wheel.
Any vehicle with a major mis alignment will show wear on both wheels.
Manufacturers don't always get it right, Mk4 Cortina's (rear wheel drive) were specified to have a toe in of 6.5 mm, far far too much, front N/S/F tyres wore out at an alarming rate on all the local taxi's, I used to reset them against the manual to 1.5 mm this stopped the excess wear I never had to look for work once word got round.
Most racing car drivers I set up for had their own preferred specs, but generally they liked a slight toe out set up, on a rear wheel drive this gave a little more under steer on the track.
Excess toe in generally promotes over steering and a feeling of disconnected lightness.
 
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