turn in problems

[rsfruitbat]

Hi Guys

After some advice again if possible please

Did a fairly wet event at a venue called Llanbedr in west Wales at the weekend.

Struggled to get the car turning in as much as I would like alll day. Grip seemed fairly good in that we knacckered a pair of new wets in 6 stages (about 36 miles). Very little wear at the rear.
On the back we were running Yoky AO48's starting off at 22psi and ending up at 32psi with still no significant oversteer.
I have usually overcome the turn in problem by messing around with tyres and pressures at the back.

My questions are:
I am still running rubber top mounts with a coilover GAZ conversion with about 220lb springs. Should i go to solid top mounts (rose joints and if so whose)?
or
convert the back from the std setup to similar to BLS's tangerine rocket and go coilover bolt on unit at the back?

I await enlightenement

rsfruitbat

[Veesix75]

I can't really comment from the perspective of the events you do Ade, but is the rear axle set up with any rear camber and toe?

My standard 33 axles/hubs/stubs have been shimmed for neg camber and toe out to aid turn in.

I also run stiffer rear springs / shocks which I'm told helps promote a bit of over steer.

I know others ran different set ups, but I'm roughly on 450lb fronts and 650lb rears for springs. I also have the shocks set to almost as 'hard' as they can be, just slightl backed off from full hard setting.

The ao48 is quite a grippy tyre, perhaps a looser rear tyre will help you?

[rsfruitbat]

Hi Veesix.

rear axle is as std. Do you know how much neg and toe in you have on the rear of yours?
What tyre pressures would you normally run?
Rears were stone cold all day. perhaps i should have gone with mediums on the back or splashed out on some new Dmacks.
Its one of those where the conditions were that rough you didnt want to try anything too extreme.
The handling wasnt that bad. its just i felt like i was doing all the work and not the car?

rsfruitbat

[Veesix75]

I honestly can't remember what the rear toe etc is.

I did have a sheet with it on, I'll see if I can find it.

Also, I think I meant toe in on the rear, not toe out.....

[Spacenut]

I honestly can't remember what the rear toe etc is.

I did have a sheet with it on, I'll see if I can find it.

Also, I think I meant toe in on the rear, not toe out.....

Really? Toe-out would definitely promote oversteer - you usually toe-in at the rear to stabilise the handling. The cited example is the venerable Beetle, which is set up (from the factory) with toe-in on the front and toe-out at the rear. Oversteered badly with very little provocation!

But every car is different, and the forward-biased, FWD 'Sud (and 33) is about as different as you can get from a Beetle!

Tyre pressures are a fairly crude way of altering the ratio of grip from front to rear. Does the 33 use a longitudinal Watts linkage to locate the rear axle? If so, the beam should act like a massive ARB, increasing weight transfer at the rear. So the only way to make the chassis understeer less would be to remove the front ARB, if you have one. But I'm wondering if your rally car has upper and lower trailing arms to locate the rear axle? If so, a bigger rear ARB (or 'Sud type Watts linkage) might help...

Lauren

[rsfruitbat]

Hi Lauren.

although the rally car is a 33 its all Sud underneath.
We have run with and without the front ARB and currently run without.

The back is as per Sud with panhard rod and forward and rear facing watts linkage not the later 4 forward facing that was fitted to the S3? 33's.

I am thinking f trying some stiffer springs on the rear to see if I am going in the right direction.

rsfruitbat

[Spacenut]

OK, so it looks like your car has all of the bases covered already - no front ARB and mahoosive rear ARB courtesy of the longitudinal Watts linkage. So the only variables left are spring rates and suspension geometry, specifically toe-in/out and possibly camber and castor angles.

I know that the 'Sud castor angles are small anyway, but some cars actually use negative castor to encourage turn-in. Also 'Sud negative camber is the biggest in the business, hard to see how this could be improved. So I guess a twiddle with the toes and some stiffer rear springs are your best bet.

Lauren

[Veesix75]

It is toe out on the rear.......its been a long week.

[rsfruitbat]

Thanks for the advice.

what do the racers do for front strut top mounts?

Also thought about raising the ride height a little at the back?

Many thanks RSfruitbat

[Spacenut]

Yup, increasing the rear ride height will move the roll centre up a bit, which should help.

A lot of Mac strut moderns use adjustable top mounts, either with slots for camber adjustment, or those alloy plates with a ring of holes and an offset centre mount, that allow you to adjust camber and caster simultaneously. I don't know how easy they would be to adapt to an Alfasud suspension though, or even whether it would be worthwhile doing so. Alfasud stock camber and caster is probably as good as it gets for road use, although I have read that modern competition radials work well with up to 3 degrees negative camber...

Lauren

[Veesix75]

I use standard rubber to mounts currently. I've go some solid ones to try.