Suspension alterations before a geometric setup, advice welcome.

[MrRy]

Hi guys

Just want some input please from the geo gurus out there

I've got a DC5 with Tanabe Sustec Pro Coilovers. It bump steers / hops around quite a bit when cornering on un-smooth or gradient surfaces. I've put them onto the softest settings but suspect it's the height and suspension travel causing part of the issue, alongside the arms and the geo.

I'm going to inspect the car first before looking at some Eibach front camber bolts, a front rack rasier from Tegiwa and Eibach rear camber arms before installing them, getting the bushes checked over (and replace with OEM or Mugen bushes) and getting a full geometry setup.

Is there anything else worth doing to the suspension in peoples experiences that have also helped transform a cars handling that is a 95% daily / road compliant car ?

Thanks
Ry

 

[maxvr6]

If i understand correctly the main thing that causes bump steer on these cars is when you lower it past a certain point (35-40mm i beleive) the angle of the steering arms and lower control arms end up out of tolerance which results in bump steer. So along with the rack riser to correct the steering arms angle you will need some roll centre adjusters which are basically extended ball joints, these will correct the angle of the lower control arms.

Also are the coilovers you have fully adjustable? Do they not already have camber adjustment on the top mounts? If they do you shouldn't need the Eibach camber bolts.

You may also have too much toe out at the front from the last geo, which may emphasise the bump steer.

The bushes in the lower control arms should definately be checked, but you wont be able to get replacement OEM's without buying the complete lower control arm from Honda which will cost a fortune. Mugen bushes or Hardrace, Superpro etc are your best bet, but a PITA to install unless you have access to a hydraulic press.

If i am talking out of my ass can someone who knows better please correct me.

 

[MrRy]

Thanks for the input Max.

It sits very low, I've not looked at raising yet but that would be a requirement as it's a little too low for road use. I'll check to see if they do have camber adjustment in the top mount or not.

They have a slight amount of toe out, but it's more the camber that is noticeable.

I'll look at going down the Mugen bushes route if I need any. I fully re-bushed my DC2 Turbo with Hardrace bushes and on standard suspension it was too harsh for the road and sent the handling and body roll to the extreme. Mugen Gold suspension helped improve the feel as it had tighter dampening when needed, but never again will I use Hardrace. Their track rod ends are also a load of crap and fell apart after a few thousand miles. OEM / Mugen (and Spoon to a degree..) is the way forward with Honda bushes.

Cheers

 

[mike.williams]

Ive installed super pro caster increase bushes, extended ball joints and the rack riser bracket. Cars not on the road yet but mine used to bumpsteer a fair bit

Hoping it should be improved once back together.

Ride height an toe will affect it too. Im going to try 0 toe on the front and slight toe in on the rear. Car will be low but at an abuse-able height for b roads and track duty.

If your car isnt going to see the track, springs would be better for this chassis

 

[Wingnuttzz]

Are you sure about running 0 toe on the front Mike? Unit any type of power it's just going to start toeing in?

 

[mike.williams]

Are you sure about running 0 toe on the front Mike? Unit any type of power it's just going to start toeing in?

was going to use it as a starting point really, ill be running alot of camber. what are you running mate?

 

[Wingnuttzz]

was going to use it as a starting point really, ill be running alot of camber. what are you running mate?

I can only go by what i've read and been told rather than by experience but I generally thought 0 Toe or Toe in on the front was to be avoid as it was just meant to ruin the way the cars responded to steering input.

I think the "norm" for FRSU's was 1mm total toe out at the front, so 0.5mm either side. Its not much, but if you think about the way the suspension acts under any type of power (so the car squatting at the back) the car will naturally toe in again. But the touch of static toe out will really help steering response.

I believe the above is what i'm running but it was setup by TDi and I never got a print out with it.

 

[mike.williams]

Cheers. Makes sense.

 

[paul hughes]

Your all a bit right and your all a bit wrong at the same time :lol:

Camber is not a definitive setting on any car, so you cant say I am going to run 1 degree, or 4 degrees of camber. Camber should be set according to tyre temp across the belt. This changes from tyre to tyre and from spring to spring, due to the mechanical grip your tyres create and the compensatory camber you chose. Inner and outer belt temp should be as close as possible, 15%-20% spread is normal. Better than this is a pretty good set up.

If you just chose your camber off the top of your head then it will more than likely be the wrong compensation for the grip created and your tyres will wear on the inside or the outside. Its better to just go to a track day and set it yourself, all you need other than the normal allen keys and TRE spanners is a tyre temp probe which will cost less than a faulty laser set up, also a piece of 12ft string and a mate to do your toe. its more fun learning as well

Don't forget you need to re set the toe every time you move the camber on either side.

Happy Track days.....

 

[maxvr6]

Totally understand what you're saying which is why I have tested my geo settings at Bedford Autodrome last year, otherwise how do you know if you are making use of the entire contact patch without measuring it?

I progressively went faster throughout the day adjusting my tire pressure as I went, then took a temp reading across the width of the tires after a few hot laps. I found that I had roughly an even temp across the inside and middle of the tire with about 4 degrees less on the outside which as I understand it is roughly where you want to be since you spend the majority of the time in a straight line depending on the track. Does that sound about right Paul?

I am also planning on changing to Superpro caster increasing bushes for my front LCA's which increase positive caster by 1 degree, and if I understand correctly also results in an increase in dynamic camber, but by how much dynamic camber increases for each degree of caster seems to be a question that has no answer. So I was thinking since my settings already seem about right I could measure the increase in dynamic camber, then based on that I could reduce the overall camber settings accordingly to achieve the same overall camber (static + dynamic) to improve straight line stability, braking, tyre wear and general overall grip.

I am yet to discuss this with my geo guy so I could be totally wrong haha! Its just my own theory based on what I have learnt about geo settings, please educate me oh great Oracle of the Buddy club :xnworthy:

 

[MrRy]

Just to update this thread.

I've booked in to get my geo sorted with Brosport. I've got some rear camber arms and I've inspected the bushes and my front compliance bushes are split either side on both bushes. I've not checked the rear bushes on the front arm but will replace them also during the geo all being well.

I suspect the compliance bushes play a big part in my wheel hop. Ive got some poly inserts for my two torque mounts so if these also improve things, I'll bin them and get new mugen / OEM mounts.

Sent from my Nexus 4 using Tapatalk

 

[MrRy]

Your all a bit right and your all a bit wrong at the same time :lol:

Camber is not a definitive setting on any car, so you cant say I am going to run 1 degree, or 4 degrees of camber. Camber should be set according to tyre temp across the belt. This changes from tyre to tyre and from spring to spring, due to the mechanical grip your tyres create and the compensatory camber you chose. Inner and outer belt temp should be as close as possible, 15%-20% spread is normal. Better than this is a pretty good set up.

If you just chose your camber off the top of your head then it will more than likely be the wrong compensation for the grip created and your tyres will wear on the inside or the outside. Its better to just go to a track day and set it yourself, all you need other than the normal allen keys and TRE spanners is a tyre temp probe which will cost less than a faulty laser set up, also a piece of 12ft string and a mate to do your toe. its more fun learning as well

Don't forget you need to re set the toe every time you move the camber on either side.

Happy Track days.....

Quoted as that is some excellent information. I never knew it worked like that until now and what you said is so logical I dont know why I didn't see it like that before. Great stuff.

Sent from my Nexus 4 using Tapatalk

 

[paul hughes]

Well ,,to the relationship of camber to caster, I have not a bloody clue :lol:
But I think the caster bush kits that WE SELL ^_^ increase it by around 3 degrees. call us....you get forum discount.

We just used to set it all again with every change, But I will say that caster doesn't have as much affect as camber so I wouldn't worry about altering it once the bushes are fitted, but you can measure it. we use a longacre magnetic spirit level and a long piece of planed skirting board against the door(you will see why when you open the instructions), they have 3 adjustable spirit levels on them, they stick on your disc.
type CAMBER CASTER into google and make sure you have a few hours with nothing to do the top set of pictures will educate you.
P.S. you don't see Laser machines in pit garages because believe it or not they are very accurately wrong to 3 decimal places and take too long to set up. You are more likely to see spirit levels and bits of string and metal rulers. Also every time you come off track check tyre temp and re set your tyre pressure to 30-35 within seconds of stopping and before you start meddling with geo.