Improving the ride quality Is250 F Sport

[McShmoopy]

Hi everyone

I was wanting to get some ideas and thoughts on how to improve the ride quality of my IS250, being an f sport the ride was quite firm but this was majorly improved with my Continental eco contact tyres, I recently have tried out a SE-L 250 and the ride quality was vastly superior, is it worth trying to get a hold of stock IS250 suspension used or getting after market coilovers, I have heard the springs used in the f sport suspension are very stiff so could changing those make a difference?

[Linas.P]

A lot of speculated about F-Sport vs. "Standard" suspension, but actually all the parts are identical. Apart of perhaps spring that is 10mm shorter and likely little bit stiffer. Was SE-L on standard 17" wheels? If anything - that will make 90% of the difference, spring making maybe last 10%. You have already addressed the tyres, which can make a huge difference. 

I have SE-L as a project car and if you interested you can come and swap out all the suspension components if you interested, I wouldn't mind F-Sport suspension upgrade 🙂 

Kind of side note - I have discovered by accident that stretched tyres are ridiculously comfortable, even if they look dumb in my opinion and I am not sure how safe they are. Basically I got 19" AM wheels with tyres and the tyres on them were rubber-bands basically. 215/35 in the front and 225/30 in the rear, I kind of wanted to get last breath of them (Falken Azenis FK510) and I thought the ride will be atrocious, not to mention based on load required I had to pump them to 40PSI to hold the weight of the car (max rating on the tyres is 50PSI). And the car rides extremely soft! My assumption that is because side wall is at angle. It probably isn't safe, it probably does not help handling, I do not recommend it, but it is unbelievably comfortable! 

Jokes aside - I don't believe there is that huge of a difference between F-Sport and SE-L, provided they are both on identical wheels and tyres. Seems like you have addressed the tyres, so perhaps next time consider downsizing to 17" wheels. 

[ColinBarber]

27 minutes ago, Linas.P said:

A lot of speculated about F-Sport vs. "Standard" suspension, but actually all the parts are identical.

Different springs, shocks, anti roll bars and anti roll bar bushes on the rear. Certainly the larger wheel size is a major contributor to the drop in ride quantity.

 

21 hours ago, McShmoopy said:

getting after market coilovers

you will find most are designed as performance upgrades and therefore will be stiffer than standard, so you need to be careful.

[Linas.P]

That is good point - aftermarket coilovers almost always going to be less comfortable "out of the box". What they call "comfortable" basically translates into - better road handling and less body roll with just 20% comfort penalty, so it is relative - they are comfortable compared to more aggressive coilovers, but they still less comfortable than stock . To really get them to be more comfortable you need ones custom build for you, basically choosing spring rates everything yourself, a lot of trial and error, it is pretty much rocket science at this point.

As well note - the less comfort may be somewhat related to age/wear, not necessarily F-Sport parts. For example when worn bushes start transmitting vibrations into the car body is not because they are too hard, but just because they worn out. So simply refreshing the rubber parts in particular can improve the ride. It won't be softer, but it will be less road noise and vibration. 

 

[J Henderson]

Rear dampers on my car are made by Tokico, with 48530-53280 part number. Fronts are Tokico too, but I don't know the part numbers of those.

As for coilovers, the only ones I've seen for an IS that supposedly retain a comfortable ride, are Hipermax III CLX by HKS.

[Linas.P]

3 hours ago, J Henderson said:

Hipermax III CLX by HKS.

Can't comment on ride, but the price seems to be above what average IS250 is going for!

[J Henderson]

The CLX are discontinued now I think. I regret not buying the new old stock set that was on eBay for absolutely ages.

They were about £900 or something.

[McShmoopy]

11 hours ago, Linas.P said:

A lot of speculated about F-Sport vs. "Standard" suspension, but actually all the parts are identical. Apart of perhaps spring that is 10mm shorter and likely little bit stiffer. Was SE-L on standard 17" wheels? If anything - that will make 90% of the difference, spring making maybe last 10%. You have already addressed the tyres, which can make a huge difference. 

I have SE-L as a project car and if you interested you can come and swap out all the suspension components if you interested, I wouldn't mind F-Sport suspension upgrade 🙂 

Kind of side note - I have discovered by accident that stretched tyres are ridiculously comfortable, even if they look dumb in my opinion and I am not sure how safe they are. Basically I got 19" AM wheels with tyres and the tyres on them were rubber-bands basically. 215/35 in the front and 225/30 in the rear, I kind of wanted to get last breath of them (Falken Azenis FK510) and I thought the ride will be atrocious, not to mention based on load required I had to pump them to 40PSI to hold the weight of the car (max rating on the tyres is 50PSI). And the car rides extremely soft! My assumption that is because side wall is at angle. It probably isn't safe, it probably does not help handling, I do not recommend it, but it is unbelievably comfortable! 

Jokes aside - I don't believe there is that huge of a difference between F-Sport and SE-L, provided they are both on identical wheels and tyres. Seems like you have addressed the tyres, so perhaps next time consider downsizing to 17" wheels. 

Thats good insight Linus! Interestingly enough its a 2011 IS250 SE-L with the 18" wheels, I borrowed it while my car exhaust was out of commission off my mum and have to say it was an incredibly smooth journey overall. The mileage was similar to my own car so I just assumed its down to the softer suspension, truth be told the ECO Contacts were put on for fuel efficiency primarily not necessarily comfort so maybe swapping the tyres again could be a good shout. If I recall I think my bushing did show some cracking so I would consider replacing those, I have seen Ahmed use LCA bushings from an RCF quite successfully to counteract inner tyre wear, would they be a comfier ride I wonder! I'd consider taking you up on your offer of swapped suspension thank you! Where about are you based? 

[Linas.P]

12 hours ago, McShmoopy said:

Where about are you based? 

In London 🙂 I quite honestly don't mind although car is close to 100k miles, so perhaps not a fair swap...   

I don't believe LCA bushings impacts ride quality at all, but surely they are better than worn out originals. So I doubt they would provide improvement in ride quality compared new to new, but neither they would make it worse and compared to old probably have slight chance of improving it a little bit. 

18 hours ago, J Henderson said:

The CLX are discontinued now I think. I regret not buying the new old stock set that was on eBay for absolutely ages.

They were about £900 or something.

I can only find references to the price of ~$4000-6000, £900 would be steal if the yare as good as you say, because that would be cheaper than OEM parts.

[H3XME]

Like @Linas.P said, tyres make the biggest difference generally speaking. @McShmoopy

I agree, stretched tyres are more comfy than regular tyres due to the angle of the sidewall, it flexes more. If your tyres aren't stretched, you'll find that the sidewall is pretty much straight, which is what makes it stiffer (that's why runflats are notoriously hard - reinforced sidewalls). It's not the best for absolute performance due to the sidewall flex but you will never notice this unless you're on the track. And yeah, if it's moderately stretched, say 225s on 9.5" wheels, or even similar to Linas's setup that I've seen in person, you want to run at least 44PSI (depending on how heavy the car, you might want more - like Linas) to avoid de-beading but this would occur when the tyre is extremely stressed - drifting, racing around. Normal use won't face this issue if you have say extra 8-10PSI more than what it says on the plaque in your door shut.

As for coilovers. I haven't had the pleasure of driving on HKS coilovers in a Lexus. I tried them on a JZX90 and some other cars but it doesn't matter - it's not comparable if it's a different car.

Look at technical specs of the coilovers you want to buy. TEIN Flex Z (damping adjustable and cost £804 new) I had on my black IS250 were very comfortable. The ride quality was better in every way than my tired stock suspension on IS250 SE after 130k miles. Comfort was retained, body roll was reduced (a little bit) and handling was improved massively. The standard spring rates of those coilovers are 8KG on front & rear. And that's what it all comes down to. Spring rates make the ride harsher. Dampers make a difference too, but it's mainly the spring. And it can't be one without the other. It works in harmony. For example my BC Racing coilovers I have now are 12kg & 14kg spring rates. It's not a massive difference in terms of comfort, but it's definitely noticeable. TEINs were A LOT nicer to drive on, perhaps not as stiff but for 98% of driving it's way better.

People make mistakes by buying lowering springs to get the car a little lower, but you're putting a shorter and therefore stiffer spring on a stock strut that works in a different pace than your new spring resulting in a harsh ride.

3 of my mates went for the Flex Zs and everyone is very happy. When I first gave them a ride in the car, they couldn't believe how soft and comfortable it was. And with adjustable damping, you can make the car softer than factory. Bear in mind, the stroke is shorter, so you can't be going over speed bumps at 30mph anymore because you will bottom out, but otherwise there are no drawbacks in my opinion.

 

[F.A.]

I echo what’s been said above really. 
 

We had a 2007 IS250 SE-L on standard 17” wheels and a 2011 IS250 SE-L on standard 18” wheels, at the same time for 8 years and the ride was much better on the 2007 model.