Cat SX3 grip roll and high speed instability

[Gavin Collingwood]

I've been on here before trying to sort this out and I'm still struggling, I race at bury metro which is very very high bite astro and I can't seem to fully get rid of grip roll. Mostly at high speed and sweepers. I've been running schumacher yellow mini spikes with the outside row cut on the rear and the inside and outside TWO rows cut on the front. My oils are 40 on front and 32.5 on rear I'm running a 4.5lbs spring on the front and 2.5 spring on rear and running 3 hole rounded pistons with the rears drilled to 1.6mm. The front shocks are on the middle hole on the tower and outside on the arm and inside on the rear tower and outside on the rear arm. I'm maybe thinking using 2wd fronts to take away the grip but I'm not sure if its just the front causing it to roll or rear aswell? It's very frustrating as otherwise the car feels good
Any help would be appreciated
Gav

[mark christopher]

Ride height?
Do others suffer same?
Using too much lock?

[Gavin Collingwood]

Well yes others were struggling a little but less so. Was running 19 mm so it was low, now the steering rack I would like to shorten the links as the Ackerman on the inside wheel turns further than the outside wheel too much in my opinion and may cause it to get snatchy anyone know of a trishbits/rude bits type of steering rack that shortens the steering turnbuckles that may help this?

[Chrislong]

Gavin, you know if you lower and stiffen the car so much the car can just snatch grip roll rather than chassis roll, especially if you are limiting droop by using outer hole on wishbones. See if you can find a Cockerill or Moss setup for Southport/Stotfold (also high bite Astro) and try that.

[Gavin Collingwood]

But surely if you have more roll you'll produce more grip and then roll even more...?

[robstanway]

Gavin,

I've got an SX3 setup that i used at Southport... I'll send it to you when i have chance over the next couple of days - If you PM me your email i'll attach it.

You will defiantly benefit from un-cut staggers on the front, it just doesn't look the best.

Depending on the oil... I used 32.5 losi in the back with 4 hole pistons and 45 oil in the front with 3 hole pistons, black roll bar on the front and possibly run the shocks on the outer hole on the front wishbones, I also found a slightly slower servo with the expo reduced helped a lot.

try using the core 4 lb springs on the front they are less aggressive and compact at a slower rate. I also found running the car lower helped me with the grip roll situation.

Hope this helps....

Rob

[Gavin Collingwood]

Uncut staggers? So the old sytle stagger ribs then?
I was thinking maybe 2wd mini spikes as they're a lower profile and would roll less and give less grip than the 2wd lower profile mini spikes? Worth a try. Cheers for that I may try it, my email is [email protected]. Think ill try the cockrell set up from RHR first which was high bite

[Rickyktm]

Iv just been upto the track gav and run my cat for the first time on there and i see what u mean about the grip roll.i couldn't push the car as much i wanted due to grip roll.

[robstanway]

Gav,

It is the old type yes, they are a little more expensive but give you less initial bite. I tried Toms setup at Southport... The amount of steering was unbelievable.... I am defiantly not talented enough to run his setup!

I also added Trish's center weight between the battery to calm it down a bit over the bumps.

The setup defiantly works and stops the roll over but looks rubbish with the slim wheels/tyres.

I thought in the end i'd rather go home happy than p**ed off.

For my driving the 2WD spikes were too snatchy and as they wore down i ended up with under steer.

Obviously everybody's driving style is different and not everything will suit but i'm sure you will be happier than you are at the minute.

Try tightening the front diff as well, you defiantly want it tighter than the back one.

Rob

[Gavin Collingwood]

Yeah my front diff is tight but that's another side issue I can't stop the rear diff chirping too and holding the spur and rear wheel it still slips but the only way I can stop it slipping is to run the rear as tight as the front and that seems too tight? I may give it another re built and use X gear diff grease as this stuff is awesome with the RB6...

[Gavin Collingwood]

Also I'm running the rude bits lipo tray weight

[Gavin Collingwood]

Just had a thought, I'm running full rebound, would running less rebound help?

[Chrislong]

I never ran any rebound, ever.

Check chassis is brace properly and screws tight. When i drove an Academy SB-sport (shite), it was so flexible, when I went around the corner the chassis twist kind-of unloaded and flipped it in dramatic style - much like driving over a landmine.

Having more roll yes - can increase grip and cause more grip roll. Its the happy medium you need. As too stiff can make it fail to lean and just griproll instead.

if you can find a setup from Belgium GP, this track is insanely grippy and all astro, may help. I know I haven't ever driven the Bury new track but I have seen it (heck I work within 1/2mile of it as the crow flies).

[BradW]

Hi Gavin - I think we met at JE yesterday. I went down to the Bury track this morning with another couple of chaps, Rickyktm and Spennyyk2 and had much the same problem! It was my first drive in 18 years with that new K1 you saw yesterday. It went great but the big problem was definitely grip roll! I was, perhaps foolishly, running yellow mini pins but they're the only tyres I've got yet - just wanted to make sure everything worked, and it did!

Driving came back to me like second nature - really quick, but because of the grip I really had to be careful on the sticks! I had a go with Spenny's SX3 which was a little better for having part worn yellow mini spikes which could break loose a little. But I definitely can see what you're saying! If you get any good advice, let me know - sure I'll be down there at some stage for a club meet!

[mark christopher]

Originally Posted by Gavin Collingwood

But surely if you have more roll you'll produce more grip and then roll even more...?

softer lets the car roll more, stiffer will make the car load up and it has no more roll in the chassis and over she goes.

re your diff, your 100% undoing the lock bolt before you adjust the diff? had cougar. sx3 and k1 and the diffs were all faultless. my front are rear feel about the same, but that should not be your grip roll problem.

[spud31]

what about ballistic green spikes these are a different profile so grip roll less

[cryer-evo]

What camber are you running mate I had a lot of grip roll when I got my car then I put 2deg camber front and back so so much better also what inserts are you running you won't tubby med ones

[Gavin Collingwood]

I'm running 1 deg all round and I'm under the impression that adding more camber will increase grip as the car enters the turn as more of the tyre will be contacting the track? I'm using schumacher blue medium

[cryer-evo]

Give it a go I didn't believe it at first

[cryer-evo]

Ow and another thing that helped on my car was to put 2mm spacer on the front ball stud on the hub