Autocross

[KWM338R]

I was back in action flying the Dolly flag Stateside this weekend competing in an autocross. Thanks to Top Gear the Dolly is suddenly a lot more well known over here, although for all the wrong reasons. there are numbskulls around who genuinlyt believe bits just fall off cars for no reason!

Anyway the car ran very well and I posted some respectable times, I'll try and post a link once they are posted online. The problem is TRACTION, I have a real problem in this department and its slowing me down. I took an instructor out with me and he said that my line through the course is very good, the car just cannot respond quick enough. My question is how can I get the grip I need to send me hurtling out of the tight twisties of an autocross course. I have 180lb springs on the back lowered as low as they will go on spax dampers. This gives the car a flat stance front to back, so I think I need to get a shorter set of springs, should I go softer at the back? I think the fronts are 250lb. I had the dampers set to hard front and back, maybe I could soften those a bit too. It was also suggested I go with a stiffer anti roll bar on the front, will that help stop the inside rear tyre from lifting as much?

Your input would be much appreciated, I know most of you do track stuff but if I can get a bit of info on what does what I can then dial in the rear end over the course of the season. The car has a lot more in it, I reckon I can embarrass a few drivers in fancy machinery with the right setup.

Cheers
Mark

PS I know an LSD would help tremendously, but at the moment that's out of budget.

[Nick C]

IF it's grip you're lacking, the choice of tyre will probably make a lot of difference - is Autocross over there the same as it is here (grass track) or are you on a sealed surface?

[KWM338R]

Good point about tyres Nick, I forgot to mention I run Yoko A048 185/60, 32PSI front, 28PSI rear (cold). There is not a lot of movement in the tyre, i.e. they do not roll much so I feel the pressure is about right.

Here is a video of a typical run at Devens where I run, its longer and faster than a lot of autocrosses.

http://www.youtube.com/watch?v=7a_R-z7b_Eo

Cheers
Mark

[mbellinger]

Mark,

An interesting "track".

My 2p worth:

Stiffen the front further. You can go stiffer anti roll bar and springs - up to 400lbs is good. Trackerjack on this board runs a Sierra roll bar conversion which is very effective.

Then I would soften the rear a bit - I have exactly the same issues with my Toledo and that has even less weight of rear bodywork to keep the back tied down because of the shorter tail. I am going to soften my rear springs as I really believe it will help.

Finally my tyres are the same as you. I think you will see a startling difference if you try 26psi all round. Let us know how you get on.

[KWM338R]

Thanks for the input. I'm going to measure up a few small cars in the car park here to find what antil roll bar I can adapt to the Dolly, not too many sierras over here, the XR4 was sold for a few years but they are a very rare sight. I'm thinking the Mk1 Golf outside my window might yield something suitable.

I'll try your tyre pressure recomendation and set the dampers to soft next time out. The next event is not until the 25th of May so I have a bit of tinkering time.

Here's another video from trackside. http://uk.youtube.com/watch?v=OSKunnWaUXE

Cheers
Mark

[Neil907]

Unfortunatly i think the only way to get more grip will be with softer tyres and an lsd. Both my brother and myself do autotesting over here onb the isle of wight very similar to your vids but on a smaller scale. Steve Uses his sprint and I use either my rx7 or my Jensen healey untill I get the dolly finished. When he fitted his lsd the extra tracion he had out of the corners was very impressive. He runs yokohama Ao21r's which are very sticky. I stiffened the suspenion up on my rx7 last year and whilst its made it much better for trackdays its had the oposite efect for the auto tests and slides to much now.

[KWM338R]

Neil, I can't see A021r's listed on the yokohama website, are they a current tyre? Another problem running a Sprint here with 13" wheels is the availability of good performance tyres. How do A021's compare with A048?

Cheers
Mark

[zombeh]

Yokohama's website is, and always has been, a bit useless.

They're still listed everywhere in the UK, so I wouldn't have thought you'd have any problems getting them elsewhere.
http://www2.yokohama-online.com/gb/tyre ... yreID=1018

No idea how they compare to the A048s (my dry summery tyres are toyos), they're very soft as they're intended to be used when it's a bit wet (not that great when it's properly wet though as I found out at colerne)

[Mad Mart]

Once you've sorted your TRACKtion out, change to a 4.1:1 final ratio, that will really help you out of the twisties.

[KWM338R]

Yokohama's website is, and always has been, a bit useless.

They're still listed everywhere in the UK, so I wouldn't have thought you'd have any problems getting them elsewhere.
http://www2.yokohama-online.com/gb/tyre ... yreID=1018

Unfortunately that is not the case, especially over here. 13" tyres are not easy to come by and if they don't show up in their books it might as well not exist.

The general consensus seems to be go softer on the rear, I'm going to order a set of 150lb springs from AVO for my dad to bring over, oddly enough even with the shitty exchange rate its cheaper for me to buy springs in the UK than here. I have Spax adjustable dampers at the moment and they have 2.75" springs on them, there is a spacer to make up the difference between the spring and the seat. Whats the scoop on the top mount if I put 2.25" springs on, will I have to modify the top mount to stop the sprint moving around?(never thought to inspect it when I had the dampers off last week).

Cheers for all your input, I'm sure it will prove most valuable in the coming season.

Mark

PS Mart, If I go the Alfa route for the LSD rear axle it will have a 4.11 ratio.