Dualing out oversteer in ITR DC2 - Page 2

tysonzane · 17th July 2007, 04:32 PM

Quote:

Originally Posted by beeker

Quote:

Originally Posted by tysonzane

Interesting you run quite a soft setup which i always reccomend for tarmac rallying. Upon seeing the video of your incident it instantly looked like you were running very heavy springs in the car and some over dampened bilsteins but as it turns out this isn't the case.

I'm running a slightly softer spring in the rear and alot softer spring in the front compared to you. I'm not sure if the effect of a large (IMO) gap between the weight of the front and rear has on the car. If it was my car i'd be running a softer spring in the front in general but i'm unsure if this will fix the over steering issue.

I'd start with camber kits front and rear and a decent allignment. I run .5 negative degree in the rear which has proven to work a treat on tarmac.

What tyre pressures where you running at the start of the stage where the incident occured? I check my tyres like a mad man at the start and finish of most stages and it is definately something to stay on top of. Also i think you've over tyred the car and i've found going to wider tyres actually had made cars more want to snap sideways on tarmac rally surfaces.

Remember Tarmac rallies are completely different to circuit racing you cant compare the two and you shouldn't spend lots of time and money testing on a circuit to build a suspension setup for rallying.

We had an alignment done 4 weeks prior to the event, and done by wairau alignment who i trust. But.... Now i think about it we did get the 4x wheels bearings proactivly replaced which may have been after teh alignment. Not sure what unbolting was needed here ?

Tyre pressure. 25psi cold front and rear which most the guys run. Some drop it 1psi in the back.

Tyre size. YEs i would prefer to run 215 or 205, but the 03G only come in 2x 16" sizes 225/45 and 205/55, and the 205's are too tall so 225 it was. or maybe i should accept that for a narrower tyre.

So what were the alignment specs if you dont mind me asking? We maybe able to help figure out what is going on.

So the 205 tyres have a larger profile? Perfect! The larger profile is great for tarmac rallies it makes the car to road contact more compliant as there is the flex in sidewalls. I can seriously tell the difference between a larger and lower profile tyre, the larger profile tyres tend to under and over steer alot less. Remember this is tarmac rallying not what some performance tyre place down the road reccomends that low profile tyres look cool and provide more go kart like handling because of the almost rock solid sideways. You just need to take a look at F1 cars to realise the above.

Give the 205 a go. Larger profile and a smaller foot print

.

Also dont be afraid to talk to the Dunlop Targa guys, they know their shit and are usually around at most "PITSTOP pitstop's". Once my car was behaving extremely badly and i had a few spins on the morning of Bambina and at lunch they said to drop all the tyres 1 psi each and boy it made a difference so dont under estimate pressures. I wouldn't run 25 on the front and 24 on the back but instead go for 24 alround but you'll have to experiment as to whats right for your car.

Have tyres been warm or overly hot when these spins have happened? The dunlops have a very particular operating temperature. When cold they're pretty average and they can also be shocking when you take them past their operating temperature and start to blister, they go soaky and just dont grip right. I can destroy a set of D01's at Pukekohe in about 5 laps from blistering and the tyres becoming hard and useless (mainly the front left for obvious reasons).

BigAl · 17th July 2007, 04:45 PM

Quote:

Originally Posted by beeker

Quote:

Originally Posted by BigAl

sudden lack of grip on the rear of a front drive car can often be caused by :

binding in the rear suspension . solution . remove rear springs and move suspension throught full travel . nolethane rear bushes are a big problem here

hitting rear bump stops . solution . run tie wraps on shock rods to ensure car is not running out of bump travel

rear alignment . solution check rear alignment and increase toe in by a small amount

insufficient rear camber .

weight transfer on power off. when trailing or dropping the throttle in turns weight is transferred to the outside front from the inside rear . this is often sufficient to reduce rear traction to a level where the rear will slide . it is often combined with an increase in understeer [loss of front grip ] and can be solved by a slight increase in spring rate all round and an increase in compression rate to the front

what are your current aligmnent settings ?

a day at the track with a tyre pressure gauge, pyrometer and alignment gear will give you plenty of info

you may also want to experiment with a slightly higher rear rates ..say 350

BigAl, have you looked at the in car video of the crash ? Tell me what you think.
http://www.youtube.com/watch?v=pU-tKU6Ye7k

I will also note that on targa last year we had some issues with bottoming out the suspension on the front. We were going to increase the bump rate in the front , but we didnt quite get to that. I read that increasing front bump rate increase understeer and reduces oversteet - maybe i should have!

On some other news, we have decided to reshell it. A repair was cheaper, but repairing a bent cage gives me the shits.

you have pm

beeker · 17th July 2007, 05:08 PM

Quote:

Originally Posted by tysonzane

So what were the alignment specs if you dont mind me asking? We maybe able to help figure out what is going on.

Have tyres been warm or overly hot when these spins have happened? The dunlops have a very particular operating temperature. When cold they're pretty average and they can also be shocking when you take them past their operating temperature and start to blister, they go soaky and just dont grip right. I can destroy a set of D01's at Pukekohe in about 5 laps from blistering and the tyres becoming hard and useless (mainly the front left for obvious reasons).

sorry dont have teh specs, but should have been back to factory spec as we asked. I might dig though my records just in case we have a copy though.

Tyres, they were good. No excessive use, or overheating. The did one wet'ish bent sprint a month earlier, and that was it.

tysonzane · 17th July 2007, 09:14 PM

Quote:

Originally Posted by beeker

Quote:

Originally Posted by tysonzane

So what were the alignment specs if you dont mind me asking? We maybe able to help figure out what is going on.

Have tyres been warm or overly hot when these spins have happened? The dunlops have a very particular operating temperature. When cold they're pretty average and they can also be shocking when you take them past their operating temperature and start to blister, they go soaky and just dont grip right. I can destroy a set of D01's at Pukekohe in about 5 laps from blistering and the tyres becoming hard and useless (mainly the front left for obvious reasons).

sorry dont have teh specs, but should have been back to factory spec as we asked. I might dig though my records just in case we have a copy though.

Tyres, they were good. No excessive use, or overheating. The did one wet'ish bent sprint a month earlier, and that was it.

At the moment and the more i've thought of it the higher profile 205 seems far superior to the 235 which IMO is just over kill for your car. There are so many people out there that think bigger and widder is better when it comes to tyres but this simply is not true, especially on front wheel drive hondas.

Bigelboe · 19th July 2007, 05:24 PM

If you listen carefully it sounds like you hit a patch of gravel just as it starts to go sideways, maybe that could have been a factor for the spin?

My only thought is maybe the rear swaybar is too heavy for the softer spring rate? When you gas off and turn in weight will go forwards and to the outside, if your springs are soft compared to your swaybar maybe its lifting the inside rear off the ground, slightly stiffer rear springs or a softer bar would mean the bar wouldn't be able to lift the inside rear as much.

Horny_Devil · 19th July 2007, 06:44 PM

http://www.turnfast.com/tech_handlin...ingtable.shtml

donno if that page will be any help

b18civic · 20th July 2007, 01:17 PM

I agree with Bigelboe when i seen footage i thought it was the new seal that would have put you sideways as there was alot in Waitomo rally

getting off the gas only makes things worse you need to get back on the gas asap and try and drive through and then lose the speed on the straight befor next corner

If you are having problem on normal tarmac as well then you will need to try playing with wheel alignment specs and spring rates as most guys have said
but i would tend to agree with the guy who said your tyres are too wide

also you should be changing specs from factory as factory specs are designed to drive around on normal roads at normal speeds not racing on back bumpy roads

b18civic · 20th July 2007, 01:20 PM

i would also recommend checking rear trailing arm bushes as they can corse this problem if sloppy if you still have factory ones i would suggest going to a
more solid bushed one

xsiv · 20th July 2007, 01:41 PM

yeah i think it a wise idea to get a new body, if a dammage role cage is repair, it will be could be weeker, dont want to take any risks :thumbsup:

Coupe-R · 20th July 2007, 01:58 PM

Quote:

Now i think about it we did get the 4x wheels bearings proactivly replaced which may have been after teh alignment. Not sure what unbolting was needed here ?

Id say most definatly the wheel alignment was out after this repair was done, by how much i dunno.

19th July 2007, 06:44 PM	#31 (permalink)
Horny_Devil Senior Member 18,000rpm+ Honda F1! Join Date: Jun 2002 Posts: 12,498 Location: Auckland	http://www.turnfast.com/tech_handlin...ingtable.shtml donno if that page will be any help __________________ D Series Guru My Profile - My Website - My Build Thread V2.0

20th July 2007, 01:41 PM	#34 (permalink)
xsiv Senior Member 6,000rpm (Max Torque) Join Date: Apr 2005 Posts: 2,391 Location: Hamilton	yeah i think it a wise idea to get a new body, if a dammage role cage is repair, it will be could be weeker, dont want to take any risks :thumbsup: __________________ xsiv da6 313kw b16a

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19th July 2007, 05:24 PM	#30 (permalink)
Bigelboe Senior Member 5,000rpm (VTEC Power!) Join Date: Nov 2006 Posts: 923 Location: Palmerston North	If you listen carefully it sounds like you hit a patch of gravel just as it starts to go sideways, maybe that could have been a factor for the spin? My only thought is maybe the rear swaybar is too heavy for the softer spring rate? When you gas off and turn in weight will go forwards and to the outside, if your springs are soft compared to your swaybar maybe its lifting the inside rear off the ground, slightly stiffer rear springs or a softer bar would mean the bar wouldn't be able to lift the inside rear as much.

20th July 2007, 01:17 PM	#32 (permalink)
b18civic Senior Member 3,000rpm (Grandma Drag) Join Date: Jan 2003 Posts: 322 Location: New Plymouth	I agree with Bigelboe when i seen footage i thought it was the new seal that would have put you sideways as there was alot in Waitomo rally getting off the gas only makes things worse you need to get back on the gas asap and try and drive through and then lose the speed on the straight befor next corner If you are having problem on normal tarmac as well then you will need to try playing with wheel alignment specs and spring rates as most guys have said but i would tend to agree with the guy who said your tyres are too wide also you should be changing specs from factory as factory specs are designed to drive around on normal roads at normal speeds not racing on back bumpy roads

20th July 2007, 01:20 PM	#33 (permalink)
b18civic Senior Member 3,000rpm (Grandma Drag) Join Date: Jan 2003 Posts: 322 Location: New Plymouth	i would also recommend checking rear trailing arm bushes as they can corse this problem if sloppy if you still have factory ones i would suggest going to a more solid bushed one