Lancia delta suspension setup

[Testament]

took my delta HF to a trackday yesterday. Had a great time but there were two issues with the handling.

One: The old yokohama road tyres had no grip so the car was sliding everywhere in the corners, both under and oversteer, and not putting the power down coming out of the corners either. ok task one get new sticky tyres before next time.

Two: The car was lifting the inside rear wheel off the ground in many of the corners according to onlookers, I'm thinking this would explain the onset of oversteer mid corner. Does anyone have experience with FWD delta's or possibly offer some advice on how to cure this? Maybe some of it is just me being over enthusiastic and turning in too agressively?

The car is a standard Lancia Delta HF turbo, Front wheel drive, Mcpherson strut suspension all around. Any suggestions appreciated.

Thanks
Tom

[Julian]

The first problem is easy to fix - get some new tyres!

The second one is more complex. The FWD setup on the Delta is designed to lift a wheel so you may have trouble countering it.

The first problem is that you probably have the rear set quite hard with a stiff anti-rollbar. In relation to this the front should be relatively soft (in terms of actual behaviour in proportion to the extra weight at the front compared with the rear). If you have both set stiff you tend to find the body just rolls and you get nasty understeer.

In normal circumstances you want the wheel to lift, it cancels out the inherent understeer from the frontwheel drive setup. The normal tactic is to turn in harder than strictly necessary and force the wheel to lift early providing you with ample opportunity to get the steering balanced, at the same time you need to keep the power on so the rear is not trying to overtake the front from engine braking.

I suspect your problem with the oversteer appearing mid corner is that you are actually hitting the bumpstops on the rear suspension which creates a sudden change in behaviour. The cure for this is slightly higher spring and damper rates at the rear. You don't want it too stiff otherwise the oversteer become very sharp to the point where you need to be superhuman to catch it. Make sure you have proper progressive bumpstops fitted, if they are missing altogether you can find the handling very unpredicitable, especially over uneven surfaces.

If you want to stop the wheel lifting at all you need to look at the geometry of the suspension and you are going to have a hard time as the design is not favourable (this is partially a guess from what I know of the period designs from the Fiat/Lancia camp). Thankfully you don't have the rear beam setup that appeared on smaller cars so it isn't the end of the world.

If the car is lowered you will likely have moved the rollcentre at the rear of the car to a point where the leverage on the body cannot be controlled by the suspension. This will be down to the lower arm angles, normally they point upwards towards the inside of the car but as the car is lowered the angle reduces and you can end up with the rollcentre very low which levers the car upwards on the inside around a corner.

I'm no authority on this matter but you can learn an awful lot from a few good books on the subject. The likes of "competition car preparation" and "prepare to win" spring to mind. I wouldn't take any of them as the last word in suspension preparation but they do get the principles across in an understandable manner.

[sumplug]

Hi Tom,
Besides what Julian has quite rightly said, i think you will find your chassis is flexing also, One of the reasons is the old design and age especially. A front and rear strut brace will tighten the suspension towers. You also really need the chassis seam welding to stiffen and make fresh again. I bet the rear shockers have gone soft and are allowing to much movement. So a good upgraded full suspension kit will transform the car.

Andy.

[Testament]

If its supposed to lift that wheel it's not such a big deal then, it certainly makes for a fun drive. I will still have to look into new springs+shocks though, to go along with new tyres and possibly a power increase.

I dont under the chassis flexing though? I would have thought that would keep the wheel on the ground rather than lift it.

[Julian]

Any chassis twist would not be enough to keep the wheel on the ground but it might be enough to disturb the steering enough to cause some unexpected behaviour. Track usage does tend to cause flexure and I'm told that the original level of rigidity from the factory is only good for a few hundred miles. After the best part of 30 years your car is going to be nowhere near the original spec in that respect.

You would tend to find that the twist, if any, is in proportion to how aggressive you are in the corner. Keep it smooth and the car responds smoothly, turn in sharply off throttle and it will push everything beyond the limits of performance envelope. In general if the tyres are howling you are pushing the car too hard.

I believe you are right about the suspension though. Start with getting all of the joint and bushes sorted. Either fresh rubber of polyurethane for the bushes and new ball joints where appropriate. Irrespective of whether you use new dampers or not you should make sure you fit trackday quality (or better) bumpstops.

If you are going to do serious trackday driving I would also suggest you get the car corner weighted too.

[SteveNZ]

I suggest you fit new tyres, wheel align and try again.

My Uno turbo was exactly the same. under, over, understeer through a corner. I really thought there was something wrong. New tyres transformed the car. The car was very well balanced as soon as good tyres were fitted. It would lift the inside wheel easily and I had no idea until someone told me.

[Testament]

Someone did get a picture of it after all.

[SirYun]

a little inside rear wheel lift is pretty normal for a fwd.

I have heard about people tying to get rid of it on mini's by sticking in great big anti-roll bars ( twice the size normaly available.. i'm going to this get car as flat as a pancake come inappropriate or highwater!!). It did "cure'' the problem as now four wheels where firmly planted, but lap times increased by quite a margin.

after the usual suspects (tires, dampers, bushings) do check the rear tracking.. it can can do all kinds of weird stuff to your handling as well..

oh and a lot of my handling problems are in the actual handling (by me) i have found out

[Infectus-Guy]

Hi Tom,
Besides what Julian has quite rightly said, I think you will find your chassis is flexing also, One of the reasons is the old design and age especially. A front and rear strut brace will tighten the suspension towers. You also really need the chassis seam welding to stiffen and make fresh again. I bet the rear shockers have gone soft and are allowing to much movement. So a good upgraded full suspension kit will transform the car.

Andy.

I can definitely vouch for that, if you are going to be using it on the track i would highly recommend fitting a rear strut brace. In fact even if you're not using it on the track, i'd still get braces for the front and back as they're not super expensive. Its not so bad on the FWD cars admittedly but my evo has suffered severely front not having a rear strut brace coupled with "the usual" rust around the rear inner arch seams. It was so bad infact that when my Dad leaned on the arch once i saw the top of the rear strut tower deflect by about 1/4"!!! I always wondered why it didn't feel so tight at the back end!
I know yours is a minter, but still you can never always trust a 15 year old italian body shell to hold itself together.
Guy

[sumplug]

A good indication of chassis flex, is to jack the car up at the front Sill area on one side, and open the door. Bet its hard to close!!

Andy.