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re: More rear grip

You should give us more info i.e. tire sizes alignment, sway bars, ride height.

Looking at video, you throw the car into the turn and drift it. Be smoother, try to go slower, you will go faster!!! Lotus is not a rally car like Subis and Lancers.

Is the rear tire bigger/taller than stock? It looks like the car is jacking up due to wrong roll center....

Based on what I see, you need larger front sway bar. This in itself is not the best solution. Things to try :

0. Are you running the right tire pressure.
1. Wider rim and tire in the back.
2. Stickier tires in the back.
3. Torsen or LSD.
4. More rear aero i.e. wing.
5. Less rear camber.

Just some thoughts.

Anton

P.S. What are you running in this car, now? engine/tranny?
 

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Do you have temperatures across the tyre?
Is it common to understand the complete system...
Tyre tyre brand and compound?
Rear geometry?
Chassis heights?
And all the same for the front...

Data with G-force and slip would give a better picture of where it is at.
 

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Discussion Starter #4
Sure Gents!
here is present set up:
Jrz 3 way
F 550
HS 8
LS 6
R22

R600
HS6
LS4
R20

wheel alignment
F

L-2,37 R-2,35
L-1,5mm R-1,5mm


R

L-1,59 R -2.02
L+0,7mm R+0,7mm


Cusco lsd

Wheels

8x16 with Yoko 210/580r16 1,65 bar hot soft
10x17 with dunlop 265/630r17 1,9 bar hot mid

Difference in tire temperatures was 5-10 degrees between sections out/mid/in


Its N/A as i will race this month in polish national championships, the car is build according to Fia regulations and unfortunately min weight is 900kilos with engine up to 2000cc
 

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Could the rear tires have a hard compound and the fronts a soft? Tough to make a call with different brands of tires on each axle...

Use aluminum tape on your shims to even out your rear cambers...2 is better than 1.6

I'd try to reduce the toe out on the front too...that seems like an awful lot of toe out.
 

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A good starting point for suspension setup would be 3.8 camber in the front and ONLY 0.1mm toe out. For the rear, 2.0 camber and 1.2mm toe in.
 

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Sure Gents!
here is present set up:
Jrz 3 way
F 550
HS 8
LS 6
R22

R600
HS6
LS4
R20

wheel alignment
F

L-2,37 R-2,35
L-1,5mm R-1,5mm


R

L-1,59 R -2.02
L+0,7mm R+0,7mm


Cusco lsd

Wheels

8x16 with Yoko 210/580r16 1,65 bar hot soft
10x17 with dunlop 265/630r17 1,9 bar hot mid

Difference in tire temperatures was 5-10 degrees between sections out/mid/in


Its N/A as i will race this month in polish national championships, the car is build according to Fia regulations and unfortunately min weight is 900kilos with engine up to 2000cc
^FFS it is easier to read a core dump^

For each corner:
Weight
Shocks:
Rebound damping
Compression damping
Toe
Castor
Camber
Bumpsteer
Temps: inside middle outside
 

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re: Too little rear grip

I think, there is good advice about toe and camber, above. All of these depends on tires and driver and regulations... Always think that toe, camber and tire pressure work together. Make rear camber same, L and R.

Tire temps should be within 5C or 10F across. 10C or 22F delta is a little
too much.... Where are you seeing 10C delta. rear outer? (is my guess)

The Dunlops are not very popular here (hard to get). So I know least about them. Try bringing rear tire pressure down, if it is safe to 1.65 bar hot, as well. Alternatively, increase front hot pressure to 1.9. (safer, but less traction).

Somebody asked for tire temperature profile out/mid/inside. This would be useful to see not just for the delta but for the difference front to back. Hence, same slick manufacturer on all 4 wheels is more useful for this type of analysis.

You can try adjusting the shocks for more traction in the rear on corner exit.

More general thoughts below....

Wider tire takes less camber, but depends on the manufacturer, as well. I used to run 1.5 rear on 345's. Running a lot of camber on wide tire does not look right. It looks like the outside is off the ground. However, only temperature profile can tell.

A lot of my friends on faster tracks, after racing for many years, are adopting a 0 toe all around. Front toe out helps turn in. However, the srub on the tires creates an interesting temperature profile and behavior. Does a Lotus really need more turn-in? Rear toe-in is for high-speed stability as rear tires are forced to toe-out at speed. If the suspension is all solid, is this necessary in a modern race car? In cornering rear toe-in creates less traction.... again: only temperature profile can tell.

Anton
 

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Discussion Starter #11
As above
"Difference in tire temperatures was 5-10 degrees between sections out/mid/in"
So F 45/55/60 C
R 55/62/73 C


How about spring rates, no one commented? :(

guys, camber on the rear is nearly same, this is 3 minutes differenc!!!
 

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Discussion Starter #13
A good starting point for suspension setup would be 3.8 camber in the front and ONLY 0.1mm toe out. For the rear, 2.0 camber and 1.2mm toe in.
Sure but front is not a problem so why i should increase camber?
 

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Sure but front is not a problem so why i should increase camber?
Because it is for balance, front to rear.

Also, your tire temps tell me that you have too much toe or too much camber on the rear or both...as stated, wide tires will amplify the readings. That means that you will have a much smaller range...your settings will have to very accurate and close.

No one commented on your spring rates, because you're not even close on your suspension geometry settings... get that right first. Your spring rates are about right... they are NOT the cause of your handling problems.
 

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Discussion Starter #15
Jrz guy said i have to start with correct platform, which is springs rates as start point... :(
 

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Your springs are close enough...I have 550/700 on mine. The softer spring in the rear will get you more traction in the rear...which you don't have. At this point, going to stiffer springs in the back will just make your situation worse. Get the geometry right first...
 

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Discussion Starter #17
If your rebound is clicks from softest, then you have too much rebound damping. I know we talked about this before. Rebound damping should be much less than compression damping.
But how? Rebound is from 0 to 24 and for example low compression speed is from 0 to 6 clicks.
 

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Discussion Starter #18
Your springs are close enough...I have 550/700 on mine. The softer spring in the rear will get you more traction in the rear...which you don't have. At this point, going to stiffer springs in the back will just make your situation worse. Get the geometry right first...
Which car you are running and which shocks?
 

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Discussion Starter #19
Your springs are close enough...I have 550/700 on mine. The softer spring in the rear will get you more traction in the rear...which you don't have. At this point, going to stiffer springs in the back will just make your situation worse. Get the geometry right first...
My springs are close? At the front im at the limit of shocks regulation... Maybe I should use front 600 rear 650 and go lower with the clics?

Why you think my tire temp is too high? Dunlop guy told me 70c is minimum.
 

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My springs are close? At the front im at the limit of shocks regulation... Maybe I should use front 600 rear 650 and go lower with the clics?

Why you think my tire temp is too high? Dunlop guy told me 70c is minimum.
I never said your tire temperatures were too high...I just said that your tire temperatures are showing poor suspension setup.

Look...you are getting a lot of very good (free) advice here... Springs are NOT the cause of your handling problems. If you don't believe us, change them...then you will see that we were right.
 
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