FWD Alignment... Loads of tourqe steer

Hello everybody

Somewhat of a noob here when it comes to suspension and alignment. I have a FWD car I've tracked for 10 years and every year with some upgrades. It weighs 1050kg with a 3.2L supercharged v6 so I've always struggled a bit with tourqe steer, but for this season I've changed a lot of things. New Gaz gold coilovers with adjustable top mounts, Rallycorsa adjustable suspension arms getting rid of every "soft" bushing in the front and then probably the main reason for my struggles I've gone to 245/40-15 on a 9" wide wheel with higher offset to clear suspension. Now I'm not just struggling a bit to say the least, I'm getting tons of tourqe steer.

So I have a couple of questions

1: What's the easiest way to measure/calculate scrub radius and how much does changes in scrub radius affect tourqe steer?

2: Is there anything I can do to counteract tourqe steer with wheel alignment?

3: What else could cause tourqe steer? Is it just something you learn to live with and be a better driver?

4: Does anybody here who drives high power fwd cars struggle with the same?

My 5 cents worth, and more discussion points that cures.

1/ easiest way to get an approximation is to drive the vehicle onto a chalked, or clean surface, then work the steering left and right a few times, this should mark the surface as the tyre scuffs. You should see the contact patch formed a pattern that will be centred on the point the steering axis meets the ground. You can then check out how far from the tread middle the point of rotation is for the scrub radius.

The further out the tread middle is from the axis, the more positive it will be, and the greater the torque steer.

2/ possibly more -ve camber and caster, but that will introduce other potential issues. Reducing body/chassis role may help.

3/ one big issue that should be addressed, if possible, is to replace the long driveshaft with a similar length as tthe short one, with an intermediate shaft. Unequal length shafts are a notorious cause of torque steer, usually to the left or right, depending on the side the long one is fitted - you don't mention if it's worst in one direction, or roughly the same in either direction? I don't recognise the car, but there may be an option from another version that has the 2 piece drive shaft - like some of the single and twin cam' Vauxhalls, or a turbo'd version?

4/ I expect they mitigate it as much as possible, and live with what's left - and they will almost always be running power steering.

You didn't mention what differential you are using. A spool will be extremely difficult to work with, a tight plate type LSD will also be heavy on the steering as you're figting the torque loadings. If you can afford it, a Torsen/Quaife torque biasing diff' "should" be much easier to drive, but not perfect.

There isn’t a OEM solution to the driveshafts that I’m aware of. It doesn’t steer towards any specific side.

It has a quaiffe lsd already and powersteering with short ratio rack.

more negative camber and also negative caster?

Mas,

Putting more tire on the car can transition things from both tires spinning which allows it to go straight, to the back and forth of each side gripping/spinning as torque moves between axles, so your new wider tires with more grip are likely the biggest factor in the behavior change. You can go back to having less grip and let both tires spin which is more easily managed, or press on with improvements.

From the info you've mentioned so far, and Gord already brought it up, unequal length axles are the huge stand out. Unequal torque distribution to the tires is the common primary cause of torque steer.

I don't expect alignment to fully resolve this, but please give us a bit more info and we'll see what we can do.

What vehicle and what style front suspension does it have?

Just to be safe, can you please explain the torque steer condition(s) you're hoping to resolve?

I ask because I've found "torque steer" doesn't mean the same to all people and I just want to make sure we work on your specific concern(s).

For example are you trying to go straight and the car doesn't go straight?

Are you trying to put power down coming out of corners and the car is understeering, or ?

The car is a Opel kadett e gsi with mcphearson front suspension.

when I accelerate the car is all over it doesn’t seek towards any specific direction. Not being a pro driver by any means I feel that it handles well going into corners and also mid corner but once I straighten out the wheels and accelerate that’s when I struggle to keep it straight. Like I said it weighs 1050kg and puts down 330hp and 411nm. I’m trying to align it now actually and here’s a pic of what I’ve got it at for now. Which actually seems to have helped a bit

I would verify if the car toes in or out when the front ends lifts up during acceleration. I'm used to macpherson strut cars going toe out when they lift up, but definitely double check on your application.

If that's the case, limiting pitch helps reduce dynamic alignment changes, and some static toe in would help reduce dynamic toe out.

I'd just keep in mind that alignment changes which reduce torque steer may detract from performance in other areas, so compromises have to be made.

Was the alignment way off when you arrived today? I wasn't clear if you hadn't yet aligned the car at all since you swapped arms.

Camber was -1 deg toe in 0.05 total and the caster was +3.1 on one side and +5.3 on the other side, I don’t know why it was so different. But now it ended up

how would one go about limiting pitch?

Jacking the front axle up on the alignment rack while watching the values would should you whether the camber and toe curves are concerning or not. Then you know if keeping the front axle within a smaller range of travel is critical to forward grip or not.

Increasing damping via adjustments on your shocks or higher spring rate would both make the vehicle more resistant to pitch as well as roll. Before making any changes like that, I'd see what your alignment does dynamically, and consider how those changes would impact cornering and braking if this car isn't a drag car.

Ah, that it's an Opel/Vauxhall/Holden Astra is probably good news, especially if you're using the F20 gearbox. Exactly what is the engine and gearbox being used, and can you confirm the shafts are OEM?

I assume this was originally a single cam' engine, as they had the uneven length shafts, the twin cam XE (not sure about the ECOTEC) had the two piece shaft, with the centre bearing bolting to the block, IIRC. The V6 may also have the mounting points on the side, something you'd need to check, or possibly manufacture from scratch - I know it was available in the Calibra, with an auto', but i would expect it to still use a 2 piece.

Been a while, but as I recall, most V6 conversions used the F20 (or F28 if rich), with the gearbox in the OEM position, and the V6 mounted to suit - it looks like that's what you did?

Ah, just checked, the V6 DOES have the provision for equal length 'shafts, as fitted to the V6 Calibra - it used the 2.5 litre engine, though, and while the 3 litre is a straight swap and would also have the mount, I don't know about the later V6 variants - or the gearboxes, comes to that.

Many years ago I was on migweb.co.uk It seems to still be going, and you should fing some useful information with a search there.

I do have a '90 Calibra XE shell, with the equal length/intermediate shaft setup, that I need to strip and get rid of, which you could have - the shafts, I mean - but post/freight would be horrendous. You may be able to source them from the UK, or Germany, which would be a LOT cheaper, if it is, indeed, an option.

Well the engine is a y32se out of an Omega and the transmission is an F18CR. It is originally a 16v (c20xe) and it is the original shafts. But I'll look in to that, see I can find that.

Might be some confusion there, as I understand, the XE should have come with the F20*, the F18CR was normally for the single cam'.

Been doing a bit of checking - I'm not familiar with the different Astra models - but there may be some drive-shaft length variations between the different Mk's, so some may be a straight swap, but not others. There may also be a difference between the V6 and the XE middle bearing carrier. In principle, though, it's been done many times, and those who have done the mod' certainly seem to have a lot less torque steer. Your english is excellent, so I'd suggest checking out the UK Astra and Vauxhall forums and, if your German is reasonable, the Opel forums for more accurate information in the process.

*I've three, maybe four, to clear out, cheap - but NZ...

[edit] Very nice looking car!

Yeah the F18 I've got on now is from a mk3 diesel, I've trashed 3 F20's and this F18 has lasted the longest so far. I've already found the parts that I need, I've found that the bearing carrier is different between the c20xe and the c25xe but I'm hoping that the one from the c25xe which is a v6 also fits my v6. Only thing I'm unsure of is if the new shaft will fit my existing hub and if it's the right length.

But thank you all you've been very helpful.

IIRC, it's usually 3rd gear that strips? It may be worth building up a spare/broken g/box with a SCCR gearkit from Quaife, or one of the other gearbox specialists, ready for when the F18 fails, or you decide to go for a more track oriented set of ratios. From what I recall, they have both dog box and syncro' versions?

Yes 3rd gear twice and 5th once due to oil starvation.

I have looked at a gearkit from Quaife they are a bit pricy though, I've also looked at a Polish company who makes a VW transmission kit

https://racingcustomparts.com/produkt/c20let-02m-gum-vw-gearbox-conversion-set/

I've build an E46 330i that we 8HP swapped and that works amazing so naturally I thought that could taste a bit like that with a VW transmission on mine :)

But then again a F18 replacement is about 150eur here and the one I have on now has held up for 3 seasons now.

Awesome, the equal length shafts should help!