NS Dev
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| posted on 9/2/06 at 07:41 PM |
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quote:
Originally posted by David Jenkins
If you want a car that will hang its tail out nicely on demand, without scaring you excessively, go for 13" wheels that aren't too wide.
I have 13" x 5.5 wheels with 185/70 R 13 tyres (very old-fashioned!) and it's a pussycat in the corners.
I can hang the tail out when I want, I always have a fair idea when it's going to let go, and it's easy to recover when it does - see my
post on greasy roads elsewhere.
I don't have the ultimate grip that wider, low-profile wheels & tyres may have, but I get far fewer 'ring-twitching moments'!
In other words - I'm with Syd on this one... 
David
[Edited on 9/2/06 by David Jenkins]
As you will have guessed from my posts too, I'm with you as well!
You'll find you've got just as much grip as the "big tyre" boys anyway, it's just your more flexible tyre sidewalls will
give more progression to any loss of grip!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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JB
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| posted on 9/2/06 at 07:58 PM |
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LSD Causes Understeer
I actully think that LSD`s cause UNDERSTEER.
I have run my Minor with and without the Sierra viscous LSD.
With the LSD I was suffering a lot from power on understeer. My driving style was slow in and fast out (very safe way of doing it when learning a car
and track). But when trying to power around a corner I suffered understeer. If I tuned out the understeer, by softening the front bar it then caused
oversteer in high speed corners (not very good!!)
With my open diff I could power around the bends with a better balanced car at all speeds.
If I really provoked the power and steering I could get oversteer with both diffs, it was generally more controlable with the LSD.
As I got better at driving and carried more speed into the bends, the LSD became the preferred diff. I was going fast into the apex then powering out
and releasing the car from the bend. In other words I would be taking the lock off as I was under power.
So in my experience the LSD was good as long as I did not put power with steering lock applied. I had to bring the power in and unwind the lock.
In general though the LSD will be more oversteery under large provocative applications of power, because both wheels are spinning. However if the car
is set up and driven correctly the LSD will cause understeer when braking and when power is applied.
If anybody has difficulty with the LSD causing understeer then take it to extremes and think of a locked diff. With a locked diff the car always wants
to go straight on because it is so difficult to turn the wheels at different speeds when they are connected.
John
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smart51
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| posted on 9/2/06 at 08:43 PM |
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LSDs do cause understeer, but a sierra viscous coupling LSD in normaly deactivated. That is, if neither wheel has lost grip then it acts like an open
diff. Only if one wheel goes much faster than the other does the viscous coupling start to lock. It then tries to make both rear wheels turn at the
same speed, more or less. This makes it harder to turn, provoking understeer. I guess in this sense, it turns oversteer into something more like a 4
wheel drift.
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NS Dev
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| posted on 9/2/06 at 10:22 PM |
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quote:
Originally posted by JB
I actully think that LSD`s cause UNDERSTEER.
I have run my Minor with and without the Sierra viscous LSD.
With the LSD I was suffering a lot from power on understeer. My driving style was slow in and fast out (very safe way of doing it when learning a car
and track). But when trying to power around a corner I suffered understeer. If I tuned out the understeer, by softening the front bar it then caused
oversteer in high speed corners (not very good!!)
With my open diff I could power around the bends with a better balanced car at all speeds.
If I really provoked the power and steering I could get oversteer with both diffs, it was generally more controlable with the LSD.
As I got better at driving and carried more speed into the bends, the LSD became the preferred diff. I was going fast into the apex then powering out
and releasing the car from the bend. In other words I would be taking the lock off as I was under power.
So in my experience the LSD was good as long as I did not put power with steering lock applied. I had to bring the power in and unwind the lock.
In general though the LSD will be more oversteery under large provocative applications of power, because both wheels are spinning. However if the car
is set up and driven correctly the LSD will cause understeer when braking and when power is applied.
If anybody has difficulty with the LSD causing understeer then take it to extremes and think of a locked diff. With a locked diff the car always wants
to go straight on because it is so difficult to turn the wheels at different speeds when they are connected.
John
Totally agree with all this as well John, but again there is an issue! The problem with the open diff is spinning the inside wheel up out of tight
corners.
I know you have taken your minor round Curborough a few times, presumably with the open diff at some point, so you will know the feeling of time
ticking by as the inside wheel loses grip accelerating out of the corner before the finish straight!
With the LSD, although you may get (provoked) oversteer, it means you can hold the power on and use it to accelerate the car, even though it is
drifting.
Re. the locked diff, the grasser has this and I have driven it around a tarmac Kart Track, and yes, it understeers like crazy, but when you get used
to the corner entry technique required to make it work it's actually pretty quick!!
You have to brake very late into the corner, to take all the load off the rear wheels, then immediately apply power to steer into the bend. If you had
the car pointing in the right direction first you don't really even turn in much, the power sweeps the car into the bend, then you hold it there
with your right foot and just unwind lock (let it "pull on opposite" until you can straighten up again.
The big danger (which put me in the tyres on the Kart track twice!) is that if you are the slightest bit tender with the brake on the way into the
corner, the back won't unload enough, won't unstick enough and you will go straight on under power at some speed into the barrier!
On dirt this doesn't really happen!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Browser
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| posted on 10/2/06 at 09:06 AM |
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From my observations of comments made on here by various folks about the 'lively' handling of their newly-completed Locosts and of drivers
in general I have drawn the two following conclusions:
1) Sometimes not enough attention is paid to getting a car set up properly. THis applies to all walks of life, motorsport included. A well set up car
will always be easier to drive than a badly set up one. Junior Johnson, the notorious NASCAR driver come moonshine runner was quoted in an interview
as saying he never ever user brute force to drive his cars as he set them up so they didn't need it, and he wwas a big chap who could have
easily muscled cars around.
2) An awful lot of drivers (me included) really do not recognise where the limits of their abilities & talents are, and put themselves and their
car into an unrecoverable situation all too easily. Testosterone is a pain in the arse sometimes!
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Syd Bridge
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| posted on 10/2/06 at 09:27 AM |
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Geez fellas, don't too many agree with me and make me think I got something right for once. The smaller and narrower tyres are, indeed, more
foregiving and progressive leading to better 'feel'. 'Nuff said.
The diff thing is interesting. In particular, viscous diffs can be a big pia if made to work constantly. They don't get a chance to go open, and
end up acting permanently solid. Locked for all intents and purposes.
Plate diffs can be set up to give near to no slip, or be near open, and anything in between. I like the genuine Torsen type diffs, because of the
constant and very predictable behaviour, or so I'm told by those who I work with who use them.
Setup is THE most important thing.
I've got a few anecdotes, but the best was a Mustang in the 'states. I made a cfrp intake for it, 5.5lbs total. The original ali item
near 65lbs! The driver said the car had more grunt, but was undriveable in the corners. When I asked about corner weight setup and springs, I got a
blank reply. ( We'd taken 60lbs off the front axle.) Quick trip and some maths on the springs, and the car was constantly in the top 3. The
manifold was then banned in the class, so back to the heavy ali thing. More maths, new springs and arb's, and no change in placings. Top 3
consistently. Previous to all this his best was a 5th.
So, it shows just how important setup is.
Syd.
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britishtrident
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| posted on 10/2/06 at 11:24 AM |
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The Torsen diff is the best in therory --- my only actual experience with it has been FWD as used by Rover on the turboed 820 and 620 :-).
However have you noticed a lot of the cars that have made a oneway trip into the boonies recently have't been Locosts.
Tyres also play a big part --- fitting over wide tyres on a light car for road use has big disadvantages -- bigger isn't always best.
Unlike a racer where tread compound gives break away progression on a road car particularly in cold weather it is to a large part l down to tread, the
tyres available to Locoster were all designed for much heavier cars as a result the tread area of the tyre is not loaded to its design
parameters.
[Edited on 10/2/06 by britishtrident]
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