Suspension Upgrade - Anti-roll bars

[11Budlite]

I have a 2019 Caterham 310S with the stock road suspension.  I've been doing some track days with this car, first with the stock 14" Avon ZT7 tires, and then switching to 185/60-13 Toyo R888R's.  I'm running 2 deg camber in the front and whatever the stock ears are setup for in the rear.  Since switching to the Toyo's I seem to be getting a fair bit more roll.  The stock road suspension has a 1/2" front anti-roll bar (orange) with no rear bar.  Would it be a worthwhile upgrade to go to the 5/8" front bar (red) and the adjustable rear bar?  How about the adjustable damper platforms and getting it corner balanced, would that be worth it?  If I had known I was going to enjoy track days as much as I do, I probably would have ordered my car with a more track focused setup.  I've attached the best photo I have showing the roll from the rear.  

[bball7754]

I had only the orange front bar originally, and decided I needed an upgrade when someone told me they were enjoying seeing my inside front wheel in the air on some corners.

 

I think in 1998 the orange bar may have been thinner, but not sure.  It’s been a long time, but went up a step in front, added a rear, as well as added a limited slip diff.  All were excellent upgrades in my mind.

 

Having said all that, I think I still have more roll than many/most of the newer and track oriented Caterham’s.  

[MV8]

I'd go with the slightly larger front bar only and no other changes.

[KnifeySpoony]

8 hours ago, bball7754 said:

I had only the orange front bar originally, and decided I needed an upgrade when someone told me they were enjoying seeing my inside front wheel in the air on some corners.

Putting a stiffer front bar would only increase the likelihood of lifting your inside wheel...

 

For the OP - Stiffer bars will mitigate roll, but the question is why do you want less roll? Contrary to popular belief, increased body roll doesn't really mean you have more weight transfer. Adding a stiffer bar at the front only might induce crippling understeer. If you like the balance you have now, you will need to be careful to maintain that as you increase the roll stiffness. There are 2 longstanding camps on how to control roll on a car. Soft springs/stiff bars vs stiff springs/soft bars. There are always compromises, and light dual-use cars such as ours can be hard to set up I think. Typically I would recommend going to stiffer springs. The standard suspension is softly sprung and good on-road (from what I hear). If you are tracking a lot, I would recommend more track-appropriate spring rates.

[MV8]

The lifted wheel is the result of roll. While the bar is trying to lift the inside wheel, it is not a 1:1 ratio even if there were no twist to the bar (infinitely thick bar) . The net result is less roll to net a lower inside wheel.

 

The primary downside is "push". How much from a bar that increases roll stiffness by 75 lbs at most is anybody's guess, but this is a fairly cheap part, much easier to change than springs and is worth a try.   

[11Budlite]

Thanks for the input guys.  The main reason I was contemplating a suspension 'upgrade' is my intended use for my car has changed since I purchased the kit back in 2019.  If I had known I was going to be using it for track days as much as I have, I probably would have gotten the 'R' pack and possibly with one of the Duratec models. I was looking at the difference between 'S' and 'R' suspension and the main difference was wide track, adjustable platforms, and the rear ARB.  The least expensive 'upgrades' would be the ARB and adjustable platforms so I thought I would look into that first. I still haven't determined if the 'R' pack uses the 1/2" front ARB or if it's the 5/8" ARB.

[ashyers]

On my SV I found removing the rear bar was a benefit on local roads (very bumpy) and autocrossing (bumpy too, more controlable oversteer). It made the car easier to drive and put the power down better. This may not apply on a smooth track with super sticky tires, but it's a data point. I think the platforms are a good idea so you can adjust the ride height, rake and corner weights to help dial in the car.

 

Andy

[11Budlite]

Thanks for your input Andy.

[Croc]

The problem with roll is your seat of the pants feel for it could be off.   Clearly, you are getting faster because the tires have given you more confidence to carry more speed with the more predictable grip so that is a good thing.

 

I definitely would corner weight the car with your weight loaded up in the driver seat.  The adjustable platforms may aid that - not sure which ones you are looking at?  On track there is noticeable difference to a car corner weighted with 1 person or with 2 people.  Getting that right makes a world of difference to handling feel and your confidence in the car, especially in the high speed corners.  It does not matter on the road as you are never on the limit (or should not be!).  

 

I would then try the car on track and assess it before going any further.   One step at a time in making suspension changes.

 

Personally I don't think your roll looks extreme given where you are in the S corner.   My US car rolls a lot at the rear but it handles very well so I have not tried to change it.  Flat handling is not always a sign of a good handling car - it is a result of the set up.  

 

I searched a bunch of photos to compare rear roll angles with the S suspension versus the R suspension - Donington Circuit for these.  My silver car is a 2017 420R and the charcoal car is a 2017 620S.  Speed through chicane on National configuration is identical so power is not a factor.  Tires are same.   Mine is an SV versus the S3 620S so optically the SV roll will look flatter than the S3.

 

 

 

 

The R pack option does make the car corner slightly flatter at the rear than the S Pack.  

 

If you do think a change is needed after trying the corner weighting, then I would go springs as the next change.  Always fix the primary cause first as the secondary factor can be used to tune the results. Caterham have a tendency to under-spec springs in their cars.  Uprating to something stiffer all round maybe what you need?   If the car feels good then I would not change just because you think it looks weird in a photo.

 

 

[11Budlite]

3 hours ago, Croc said:

The adjustable platforms may aid that - not sure which ones you are looking at? 

 

 

 

 

Thanks for your input Croc, very helpful. I was looking at the Caterham kit to go with the stock Bilsteins: https://caterhamparts.co.uk/dampers/41-damper-adjuster-kit-for-bilsteins-set-of-four.html?search_query=ADJUSTABLE+DAMPER&results=58

 

 

[11Budlite]

Interesting reading here: https://meteormotorsport.com/wp-content/uploads/2021/12/Caterham-Suspension-Recommendations-Jan-22.pdf.pdf

[11Budlite]

See my updated thread.

Edited September 10, 2023 by 11Budlite