Caterham Chassis Limitations
Discussion
Hi all,
I am relatively new to caterham ownership, 9 months about 5k miles fast road use on the mountain roads, and come from an S1 elise.
I adore the car, and all that goes with it and find it so much better suited to me than my 100% custom tuned nitroned, 180hp elise.
However i found the car k-series 1.6 superlight has limitations which i never experience during the 10 years of ownership of the elise.
The weakest point is the unstability/sensitivity of the rear axle over non perfectly flat road surfaces.
I always allow a generous margin allowing for the rear to cope with non flat surfaces so to avoid nasty non recoverable situations.
Something which was never needed to that extend with the elise since its suspension could cope with all kind of crap thrown at it despite how close you drove to the limit.
Second limitation is break efficiency which i found considerably lower than the elise on similar tires 048s despite the AP 4pot upgrade and RS14 on the caterham.
It has now happened twice to lock the front although i was expecting much more grip prior that.
Combining the above two how come the higher powered cars with +200 and +300hp cope and maintain a balanced experience?
You could easily have +300 and +400hp on the S1 elise without really feeling short of something else. (although much more boring to drive)
I guess the answer is it all comes together on track when conditions are more predictable and repetitive.
What do you think, what is your opinion regarding limitation of the caterham chassis when pushed hard?
I am relatively new to caterham ownership, 9 months about 5k miles fast road use on the mountain roads, and come from an S1 elise.
I adore the car, and all that goes with it and find it so much better suited to me than my 100% custom tuned nitroned, 180hp elise.
However i found the car k-series 1.6 superlight has limitations which i never experience during the 10 years of ownership of the elise.
The weakest point is the unstability/sensitivity of the rear axle over non perfectly flat road surfaces.
I always allow a generous margin allowing for the rear to cope with non flat surfaces so to avoid nasty non recoverable situations.
Something which was never needed to that extend with the elise since its suspension could cope with all kind of crap thrown at it despite how close you drove to the limit.
Second limitation is break efficiency which i found considerably lower than the elise on similar tires 048s despite the AP 4pot upgrade and RS14 on the caterham.
It has now happened twice to lock the front although i was expecting much more grip prior that.
Combining the above two how come the higher powered cars with +200 and +300hp cope and maintain a balanced experience?
You could easily have +300 and +400hp on the S1 elise without really feeling short of something else. (although much more boring to drive)
I guess the answer is it all comes together on track when conditions are more predictable and repetitive.
What do you think, what is your opinion regarding limitation of the caterham chassis when pushed hard?
V7SLR said:
You've answered your own questions ... your Elise was fitted with Nitrons. Speak to Simon at Meteor Motorsport and do the same to your Caterham, it'll transform it in all the areas you've mentioned.
Yes, thinking about it and the difference the Nitrons did, this could be a good reason to believeI can see all the points mentioned above and accept them.
First of all let me clarify once more i prefer the caterham to the elise but i can see some considerable limitations in the car's chassis and architecture as mentioned above.
Yes my car now has 048s (i am on the second set) which are past their best, yes i have a rear antiroll bar set to one before stiffest setting, it was corner weighted to 2kg front left and right 3 months ago, the geo was re-adjusted 2 weeks ago with the same accuracy i was doing my elise for almost 10 years (String method),
I have tried the green and orange front antiroll bar as well as all settings of the rear including not having one.
I understand this is very sensible to weight transfer and time needed for this to happen but cannot see how the caterham can generate the same g- forces during braking, as the elise as it feels it can not put enough weight in the front to make use of the full potential of the tires and 4 pot AP brakes.
Similarly, the rear always jumps around and unsettles when over not flat tarmac and close to the limit this is not inspiring confidence.
Yes over a perfectly flat road it is the greatest.
Ah, the car has no noticiable bump steer so all is well set up in the front
First of all let me clarify once more i prefer the caterham to the elise but i can see some considerable limitations in the car's chassis and architecture as mentioned above.
Yes my car now has 048s (i am on the second set) which are past their best, yes i have a rear antiroll bar set to one before stiffest setting, it was corner weighted to 2kg front left and right 3 months ago, the geo was re-adjusted 2 weeks ago with the same accuracy i was doing my elise for almost 10 years (String method),
I have tried the green and orange front antiroll bar as well as all settings of the rear including not having one.
I understand this is very sensible to weight transfer and time needed for this to happen but cannot see how the caterham can generate the same g- forces during braking, as the elise as it feels it can not put enough weight in the front to make use of the full potential of the tires and 4 pot AP brakes.
Similarly, the rear always jumps around and unsettles when over not flat tarmac and close to the limit this is not inspiring confidence.
Yes over a perfectly flat road it is the greatest.
Ah, the car has no noticiable bump steer so all is well set up in the front
Edited by analog_me on Thursday 10th August 09:20
Amris said:
Definitely worth getting it professionally flat floored. I couldn't believe the difference it made on my car and would most likely cure all of the issues you are seeing. Only decision you have to make in my eyes if whether to get some shiny new nitrons too before hand too ;-)
I am confident of my corner weighting and geo settings. However having experienced the before and after nitron on my elise i totally agree with you😁
Hi all,
Today I took the car into a garage with a perfectly flat floor and industrial finishing and did some measuring to test my geo.
I used 72kg ballast and my own bathroom scales and planks of wood of similar thickness.
I put the car on the planks of wood and rolled it until one wheel at the time was resting on the scales.
The results were better than perfect I think, and the figures were always coming up the same to the kilo :
LH RH
Front 132kg 131kg
Rear 187kg 145kg
Total 595kg full on fuel and liquids.
Clearance 67-68mm under the sump
Rake was 22mm with the bigger 205 tires at the rear.
Then i went home put my string lines around it and measured the geo;
Front toe 0.2mm toe out total or 0.02 degrees
Front camber -2.15 degrees.
Brakes are Rs14 all round, however tires are now in a BAD state 3years old and and very very close to the legal limit if not beyond.
I think so are the bilsteins...
So i think i only need some cash now to bring it to what i think is it's best state of tune.
Today I took the car into a garage with a perfectly flat floor and industrial finishing and did some measuring to test my geo.
I used 72kg ballast and my own bathroom scales and planks of wood of similar thickness.
I put the car on the planks of wood and rolled it until one wheel at the time was resting on the scales.
The results were better than perfect I think, and the figures were always coming up the same to the kilo :
LH RH
Front 132kg 131kg
Rear 187kg 145kg
Total 595kg full on fuel and liquids.
Clearance 67-68mm under the sump
Rake was 22mm with the bigger 205 tires at the rear.
Then i went home put my string lines around it and measured the geo;
Front toe 0.2mm toe out total or 0.02 degrees
Front camber -2.15 degrees.
Brakes are Rs14 all round, however tires are now in a BAD state 3years old and and very very close to the legal limit if not beyond.
I think so are the bilsteins...
So i think i only need some cash now to bring it to what i think is it's best state of tune.
HustleRussell said:
Improving your suspension may then be a case of ensuring that the springs are correct and your dampers are controlling them effectively.
Yes LHD car.I agree with you regarding the springs. Do you know what means the writing on the springs ?
Front: 06/03 Caterham 1.61 VA
Rear: 21/01 Caterham 1.61 HA
DCL said:
My 2p
You may want to put those weights in a corner weight calculator such as
https://robrobinette.com/corner_weight_calc.htm
Although having the fronts the same may seem like a good idea (and does have it's applications), it will give a cross weight of 53% and that will be noticeable for the general handling. You have a difference of 40+ KG between the front/rear balance from left side to right side, and across the rear axle for that matter too. That will give a balance different between left and right cornering, and stability will be reduced.
IMHO it is better to move nearer 50% although favoring the front slightly may help braking lock-ups (ie keeping them within 20 KG or so)
The argument that fronts should be equal is flawed as the driver side of the car is heavier and means braking effort required to stop evenly is not that straight forward.
Hi David and thanks for you input.You may want to put those weights in a corner weight calculator such as
https://robrobinette.com/corner_weight_calc.htm
Although having the fronts the same may seem like a good idea (and does have it's applications), it will give a cross weight of 53% and that will be noticeable for the general handling. You have a difference of 40+ KG between the front/rear balance from left side to right side, and across the rear axle for that matter too. That will give a balance different between left and right cornering, and stability will be reduced.
IMHO it is better to move nearer 50% although favoring the front slightly may help braking lock-ups (ie keeping them within 20 KG or so)
The argument that fronts should be equal is flawed as the driver side of the car is heavier and means braking effort required to stop evenly is not that straight forward.
Edited by DCL on Friday 18th August 14:41
I did have my elise set up with the diagonal weights equal but feel the same is not so beneficial with the dedion rear axle of the caterham. Having said that i am far from a race driver or with such experience. I just enjoy it when it all works to my standards of perfection and enjoy tuning it to reach this point. But have little experience in comparison to the UK caterham race team standards.
As you mentioned with the current setting i do feel the lighter right side and the wheel spins (or lifts) quite often on tight right hand side corners.
I just thought since i am not after best times breaking consistancy might be more important but now i tend to believe there is a compromise between the two.
Most probably it is not optimal to equalise the front to the last kilo and loose out on the diagonals.
How much difference would you allow the front to have so not to effect the breaking.
Are you suggesting than 50% on the diagonal with <20kg different left to right on the front is a better compromise?
Is there an "ideal" "perfect" weight distribution to try?
May be i should try Simon Roger's standard (no scales) setting and see what figures this gives so to get some more experience and feel on the car's handling.
Hi all,
I followed the senior members advise and readjusted my cornering weight by following Simon's advice.
Luckily enough all i had to do is take some turns off the rear driver side spring then put the car on the scales.
The figures i got where following.
Left Right
Front 138 121
Rear 163 142
The total weight is different to my previous but this time i used different scales.
I then put the figures in the website https://robrobinette.com/corner_weight_calc.htm and my figures coincided with the suggested "ideal" setup.
I cross checked my scales several times for consistency then decided to leave it as is for a while.
I havent driven the car yet and do not know which of the two settings i prefer yet.
I tend to like the idea of equal fronts as tested but need to test this setting for a while as well.
May be with a car like mine having a tired past it best suspension and a f**ked LSD this setting is more even.
I will need to check and reconsider when cash will allow me to fix the above two.
I followed the senior members advise and readjusted my cornering weight by following Simon's advice.
Luckily enough all i had to do is take some turns off the rear driver side spring then put the car on the scales.
The figures i got where following.
Left Right
Front 138 121
Rear 163 142
The total weight is different to my previous but this time i used different scales.
I then put the figures in the website https://robrobinette.com/corner_weight_calc.htm and my figures coincided with the suggested "ideal" setup.
I cross checked my scales several times for consistency then decided to leave it as is for a while.
I havent driven the car yet and do not know which of the two settings i prefer yet.
I tend to like the idea of equal fronts as tested but need to test this setting for a while as well.
May be with a car like mine having a tired past it best suspension and a f**ked LSD this setting is more even.
I will need to check and reconsider when cash will allow me to fix the above two.
Hi all
So a quick update,
I fitted some new tires 175/60r13 and tweeked the rake a tiny bit, i now have 12-14mm rake and the car handles so much better, it is much more adjustable and feels well balanced however i would prefer a lower level of grip at the front but still maintaining a quick, agressive turn in to "flick" it into the bends.
Is it better to raise the front a tiny bit 1-2 turns or reduce camber which is now set at 2.15?
Too much grip at the front makes it boring since it will always oversteer even if not pedalled well.
So a quick update,
I fitted some new tires 175/60r13 and tweeked the rake a tiny bit, i now have 12-14mm rake and the car handles so much better, it is much more adjustable and feels well balanced however i would prefer a lower level of grip at the front but still maintaining a quick, agressive turn in to "flick" it into the bends.
Is it better to raise the front a tiny bit 1-2 turns or reduce camber which is now set at 2.15?
Too much grip at the front makes it boring since it will always oversteer even if not pedalled well.
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