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modern rally cars
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- Subject: modern rally cars
- From: Dave Eaton <email@example.com>
- Date: Wed, 06 Aug 1997 10:32:08 +0012
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well for the rally geeks in the world, nz has just hosted it's round of the fia
world rally championship. as usual i did the rally-geek thing, although having
to get back to work from holiday meant that i missed 2 days of it. fwiw, subaru
1st (erickson), ford 2nd (sainz) and 3rd (juha kk) and mitsibushi 4th (burns).
i got talking with a chappie from the mitsibushi team who was a little
underemployed (due to tommi makkinen rolling out on the 1st day). he had some
interesting things to say on the modern rally cars.
1) weight distribution is as much a problem today as it was in the group 'b'
quattro. most of the modern wrc cars are about 50:40 f:r distribution which
isn't ideal. a lot of effort is undertaken to try and move the engine mass
back behind the front axle line, although with the regulations stating that the
crank can only be moved 20mm from original, most teams tip the mill backwards
(towards the firewall) to improve things. other thing is to try and get the
weight down low.
2) speed on the special stage (significantly faster now than the group 'b'
cars) is mostly due to improvements in suspensions and transmissions. remote
dampers (mostly bilstein) allows quick cooling of the shocks and very
sophisitcated valving and differing rebound rates etc account for the rest. no
rocket science because, although more science is becoming involved, it is still
a matter of extensive testing and trial and error.
3) transmissions are still developing rapidly. ford have debuted the 1st
sequential gearchange and toyota will follow bu the end of the month. these
units are being provided by xtrac and will allow clutchless gearchanges (engine
ignition is cut for the instant of the change) in about 1/500 of a second (yes
thats right) via either a paddle, joystick or convential fore 'n aft lever.
while f1 gearchanges happen in about 1/1000th of a second, thats still pretty
4) active diffs are getting more sophisticated all the time. surprisingly a
lot of centre diffs are still fixed ratios with active front and rear diffs
tied to acceleration sensors on each wheel. software control is becoming more
sophisiticated all the time. didn't get much information on this side of
things because of the intensive development all the teams are undertaking.
5) all the engines are much the same. anti-lag systems mean that their 300+hp
is more usable than the 450+hp of the group b cars. work going on with
scavenge systems and low friction, as well as ways of improving torque and
final coment. these cars are fast. picture a car on a rock hard road covered
with small gravel (aka marbles) going flat out on the straights in 6th gear at
200 kph! these guys are totally committed and are having to drive flat out on
every special stage. brings back fond memories of 1985-6 for me. the end
result after 3 days of special stages had subaru 13 sceonds in front of ford
with the other ford 6 seconds further back. that close.