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unpleasant understeer
froggy - 24/12/06 at 03:19 PM

i knew this was coming as my mid mounted tl powered kitten has a go kart type axle but i was suprised how much it pushes straight on when you back off the power ! what do the the stock rod racers do in there suspension set up to try and help soften this out a bit any ideas ?(apart from use a normal diff)


Jon Ison - 24/12/06 at 03:38 PM

Are you using it on the road ?

You need more front end grip, too steer cars around corners with a solid back axle (locked or no diff) I find it best too unsettle the car going into the corner by monetarily turning the steering the opposite way as you let off the gas, then steer into the corner and make the back end stick out more by giving it large on the gas peddle, once the back end is out and the back wheels have broken traction steer it round on the throttle & opposite lock, not an ideal method on the road.......

Unless you can get the back wheels spinning (break traction) then it will always push on.

Softer front end, stiffer rear, higher pressure in rear tyres all helps.


omega 24 v6 - 24/12/06 at 03:53 PM

Normally we'd harden the rear shocks and/or soften the front. The fact you have a solid axle over a short length is not in your favour though.


Peteff - 24/12/06 at 04:21 PM

I'd try to get the inside rear wheel to lift so it doesn't grip as much. What kind of links have you got holding the axle in place?


Bob C - 24/12/06 at 05:22 PM

yeah - big antiroll bar on the back?
Bob


froggy - 24/12/06 at 05:31 PM

its a 4 link de dion rear end with panhard rod .ive pinched the shocks from my indy so its 350 up front and 200 on the back perhaps il swap them round first . its fine when you are spinning the wheels and to be honest i havent tried the car above 60mph yet, Rescued attachment bits 011.jpg
Rescued attachment bits 011.jpg


Minicooper - 26/12/06 at 05:11 PM

If it's a road car you need a diff, got to be easier than modifying a motorcycle rear wheel to act as a solid diff anyway.

If your careful you can get a complete Sierra LSD rear end with most things you need for £50 and modify that to take chain drive

Cheers
David


froggy - 27/12/06 at 08:00 PM

got a couple of 7" lsd,s for future builds but would like to stick with the go-kart drive for a bit just to see if i can live with it im going to swap the coilovers round tomorrow and mess with tyre pressures first


Jon Ison - 27/12/06 at 08:11 PM

Just be aware what you are doing is decreasing the rear end grip available too get it round corners, this will be lost in a straight line too both accelerating and braking, not ideal for the road.

If you have a car (with a operational diff) that understeers you would look too find more front end grip (safest way too do it) rather then decrease grip at the rear (not really recommended for road use)

Look on the bright side though, most car manufacturers build in understeer as it is considered safer then oversteer.


froggy - 28/12/06 at 09:53 AM

changed the coilover round and set the pressures up at 20 rear and 15 front ,much better
i put the car in my new brake rollers which has a weighing facility and it has 190kg on the front axle and 260kg on the rear .im going to curborough end of the month with some drift lads so il see what its like at full chat and if its too frisky butcher a 7" lsd to sort it out


les - 5/1/07 at 12:18 AM

hi,

I used to race 250cc karts- to get around this problem we used large castor angle on front- which causes inside rear to lift during cornering, so it can lose grip and allow the turn
if you experiment with it you can get very good handling- slight understeer which dissapears with just a touch of throttle and by doing this and running the rear dead square you dont suffer any traction or braking problems.

wet traction is superb with this set up.