Suspension bottoming out

[Chris172!]

Hi,
I had standard shocks with Eibach Sportline springs on my 172. At Thruxton my n/ front suspension looked like this.....

So I changed all 4 shocks with new cup shocks from Renault Parts Direct.
At Castle Combe last weekend I had the same issue. It wasn’t quite as bad but was still bottoming out on right hand corners, which felt and sounded aweful.
I’m thinking it could be a faulty new shock, but any advice would be appreciated.
Cheers!

 

[STEVE.M]

Hi,
I had standard shocks with Eibach Sportline springs on my 172. At Thruxton my n/ front suspension looked like this.....
View attachment 1380337

So I changed all 4 shocks with new cup shocks from Renault Parts Direct.
At Castle Combe last weekend I had the same issue. It wasn’t quite as bad but was still bottoming out on right hand corners, which felt and sounded aweful.
I’m thinking it could be a faulty new shock, but any advice would be appreciated.
Cheers!

Remove what you have and sell them to someone that want`s a nice comfy road car.

GAZ GHA with 400/300 would be a minimum requirement if you are on a budget.

The front Eibachs are only about 240 lb.

PMS rear ARB might also be worth considering.

https://www.kamracing.co.uk/car-tun...2-gaz-height-adjustable-gha-coilover-kit.html

 

[Chris172!]

Remove what you have and sell them to someone that want`s a nice comfy road car.

GAZ GHA with 400/300 would be a minimum requirement if you are on a budget.

The front Eibachs are only about 240 lb.

PMS rear ARB might also be worth considering.

https://www.kamracing.co.uk/car-tun...2-gaz-height-adjustable-gha-coilover-kit.html

I have a Whiteline ARB fitted.
There is definitely something not right on the near side though as it’s fine cornering left but bottoms out cornering right.
It’s just a budget track toy so don’t want to throw lots of money at it.

 

[Brigsy]

Do you have the bumpstops fitted ? I think its fairly common to be on them under hard cornering on cup shocks & lowered springs.

 

[STEVE.M]

I have a Whiteline ARB fitted.
There is definitely something not right on the near side though as it’s fine cornering left but bottoms out cornering right.
It’s just a budget track toy so don’t want to throw lots of money at it.

Are there any real committed left handers at Thruxton?

 

[flebay]

Eibach Sportline springs

The H&R springs are stiffer, will be better on track and reduce body roll.

 

[flebay]

Also if your running spacers that will make the suspension softer.

 

[Chris172!]

Not running spacers.
There is definitely an issue with it, a track marshal even came over and mentioned that the near side looks like it’s collapsing when braking and cornering.

 

[flebay]

Not running spacers.
There is definitely an issue with it, a track marshal even came over and mentioned that the near side looks like it

It wouldn't take long to swap the struts left to right.

 

[Chris172!]

Good point!
Didn’t think of that, I will give it a try!
Cheers!!!

 

[Hyperhatch]

Also if your running spacers that will make the suspension softer.

I’ve never heard this before, what’s the reason for this?

OP - spring rates i’d go for

 

[STEVE.M]

I’ve never heard this before, what’s the reason for this?

Leverage.

 

[PhillipM]

It's wrong though, with a Mc strut your pivot against the spring is the bottom balljoint, not the wheel.
Spacers will generally reduce roll slightly from the wider track, but it's bugger all in the scheme of things.

Not removed the bumpstops have you? Should generally be sitting on them under heavy loads, they're basically a spring assister on modern cars rather than a stop.

 

[flebay]

It's wrong though, with a Mc strut your pivot against the spring is the bottom balljoint, not the wheel.

Wheel spacers made the ride softer on a mx5
https://forum.miata.net/vb/archive/index.php/t-611260.html

 

[STEVE.M]

It's wrong though, with a Mc strut your pivot against the spring is the bottom balljoint, not the wheel.

What a load of tripe.

Play with this to discover you`re an idiot.

Running spacers will increase the value of L.

https://www.engineersedge.com/calculators/levers/page_levers_1.htm

 

[PhillipM]

You've got your pivot points wrong there. Try a load of tripe yourself, if you're going to correct someone at least know where you should be applying the forces.

Your travel never changes, even if you put metre wide spacers on the car. All you're doing is changing the leverage trying to bend the upright.
I'd probably refrain from calling someone else an idiot if you have to revert to online calculator that's not relevant.

 

[PhillipM]

Wheel spacers made the ride softer on a mx5
https://forum.miata.net/vb/archive/index.php/t-611260.html

Wider track often means you miss a lot of the tramlines put into the road by other traffic, especially over speed pillows, etc.

Very easy thought experiment - say your bottom wishbone is 10 inches long, and your car sits 6 inches off the floor at ride height.
If you then put 10 inch spacers on the car - would your car would now sit 3 inches off the floor?

No.

If you didn't have a lower balljoint and a top mount, it would.

 

[flebay]

would your car would now sit 3 inches off the floor?

Unlikely but it could be lower.

 

[PhillipM]

Unlikely but it could be lower.

It's even worse on the MX-5 link you posted, as it's even easier to visualise on a double wishbone setup:

Now, if you have massive amounts of camber gain/loss built into your suspension, you can get a jacking effect there, but on a strut (and 99.9%) of setups, you'd have more variation from the friction in the strut/damper than the effect from that.

 

[STEVE.M]

I have more intelligent discourse with my dog.

If you fit longer wishbones, you increase the value of X.

No wonder that things always airbourne.

 

[PhillipM]

You're not fitting longer wishbones. You're fitting spacers, which aren't part of your pivot. They're outside of your pivot, the pivots are the bottom balljoint and the top mount. All the spacers do is increase the leverage the hub exerts laterally on the wishbone and strut, trying to bend it.


And that thing is always airborne because we hit things at 100mph that a Clio wouldn't even crawl over. I've built more suspension and dampers from scratch than you've probably had hot dinners.

You should probably try cutting out the silly insults when you think someone else is wrong and try having a discussion.

 

[PhillipM]

Here's a quick strut with the camber gain/loss taken out for simplicity:

And here's the same setup with 100mm(!) spacers in, note the motion ratio.

Now, of course, a real setup has camber loss and gain, which affects things a little from jacking against the wishbone and damper - but to put it into context, if you were running 20mm spacers...the effect is about a 0.5% change in the motion ratio - you'd have more spring rate variation than that from the temperature of the rubber wishbone bushes changing...and you're not seeing it in a photo on track...

 

[White16valver]

Suspension = magic.

Fact.

 

[flebay]

Here's a quick strut with the camber gain/loss taken out for simplicity:



View attachment 1380746

And here's the same setup with 100mm(!) spacers in, note the motion ratio.

View attachment 1380747

Now, of course, a real setup has camber loss and gain, which affects things a little from jacking against the wishbone and damper - but to put it into context, if you were running 20mm spacers...the effect is about a 0.5% change in the motion ratio - you'd have more spring rate variation than that from the temperature of the rubber wishbone bushes changing...and you're not seeing it in a photo on track...

'
@4:33
You can change the actual effective spring rate at the wheels. So not the spring rate itself that won't change but the effective spring rate at the wheels changes based on suspension geometry and by offsetting it your adding leverage to that wheel and so you're going to be reducing the overall effective spring rate of your suspension.

 

[Greeny.]

@Chris172! are you sure the bumpstops/dustfilters are fitted as mentioned above? I'm fairly sure replacement OE shocks don't actually come with them so you would had have to move them over from your old shocks. I only remember this as I had to order some myself when I changed a set on one of my old 172's.

 

[PhillipM]

'
@4:33
You can change the actual effective spring rate at the wheels. So not the spring rate itself that won't change but the effective spring rate at the wheels changes based on suspension geometry and by offsetting it your adding leverage to that wheel and so you're going to be reducing the overall effective spring rate of your suspension.

Yes, you can. If you have a solid beam axle, or a single link system, or something like the Triumph rear ends with insane camber change.
None of which is applicable to the front of a clio.

 

[Kev@KAM]

Really Phillip! what do you know lol

 

[STEVE.M]

Here's a quick strut with the camber gain/loss taken out for simplicity:



View attachment 1380746

And here's the same setup with 100mm(!) spacers in, note the motion ratio.

View attachment 1380747

Now, of course, a real setup has camber loss and gain, which affects things a little from jacking against the wishbone and damper - but to put it into context, if you were running 20mm spacers...the effect is about a 0.5% change in the motion ratio - you'd have more spring rate variation than that from the temperature of the rubber wishbone bushes changing...and you're not seeing it in a photo on track...

Well that`s jolly interesting and a tad over complicated for what was a simple question.

Anyway, if I have some nuts to crack, I will continue to pick a 48 inch breaker bar over a 36 incher.

 

[PhillipM]

Just don't use one with a balljoint in the middle and you'll be fine.

 

[STEVE.M]

Hi,
I had standard shocks with Eibach Sportline springs on my 172. At Thruxton my n/ front suspension looked like this.....
View attachment 1380337

So I changed all 4 shocks with new cup shocks from Renault Parts Direct.
At Castle Combe last weekend I had the same issue. It wasn’t quite as bad but was still bottoming out on right hand corners, which felt and sounded aweful.
I’m thinking it could be a faulty new shock, but any advice would be appreciated.
Cheers!

Looking at your picture again, I`ve noticed you are running a much lower profile LHF tyre than the one on the rear ?

 

[Chris172!]

Thank you for your replies.
I’m going to start with replacing bump stops to see if that makes any difference.
If it’s still crap I will replace the suspension with Coilovers. Am thinking BC BR’s after a bit of research.

 

[JamesBryan]

If you're planning on doing lots of track days, just get coilovers anyway it'll be worth it in the long run.

 

[Kev@KAM]

Thank you for your replies.
I’m going to start with replacing bump stops to see if that makes any difference.
If it’s still crap I will replace the suspension with Coilovers. Am thinking BC BR’s after a bit of research.

DS series will be the one to get.
https://www.kamracing.co.uk/car-tun...ilovers-172-182-renaultsport-inc-172-cup.html

 

[Tomotek]

Well this made for interesting reading [emoji23] .. I love how these threads asking for advice always go off on a tangent and the poor bloke asking the question is normally none the wiser..