Understanding and correcting understeer/oversteer - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

LoneWolfK16 · 03-02-2015, 09:46 PM

Can anyone mention anything that might or will cause understeer/ oversteer.
I am trying to rule out a bunch of things that are on my mind.
I'm sure there is more out there than just adjusting dampening (for basic suspension).
Maybe you can throw in something few people tend to think about as well.
I'm sure this can help a bunch of people if they're wondering the same.

Here's a link that helped me understand a little more and taught me something i didn't know about. (trailbraking)
http://winhpde.com/understeer-overst...removing-grip/
If there is a post about this already i apologize but I've looked and found nothing. Just found stuff about tire sizes and what kinds of tires to use/not use for drifting.

Croustibat · 03-03-2015, 08:52 AM

1/ there are so many different understeer/oversteer that you can't just be general on this. When ? side to side transition under/oversteer ? turn in ? power over ? Brake on ?
What you want first is a predictable suspension, not something that will "snap". This is achievable by using GOOD dampers/springs, GWO bushes or ball/heim joints everywhere (no PU on mcPherson / multilink, PU is somewhat acceptable on double triangles), and either using standard height or running modded knuckles that will correct the height change. Degrading handling to prevent under/oversteer is really not the way to go.

2/ this is zilvia. Most people don't/can't understand the previous statement, nor care. But if you want to learn about suspension, there is a stickied thread that you want to read.
http://zilvia.net/f/showthread.php?t=296725

LoneWolfK16 · 03-03-2015, 12:35 PM

Quote:

Originally Posted by Croustibat

1/ there are so many different understeer/oversteer that you can't just be general on this. When ? side to side transition under/oversteer ? turn in ? power over ? Brake on ?
What you want first is a predictable suspension, not something that will "snap". This is achievable by using GOOD dampers/springs, GWO bushes or ball/heim joints everywhere (no PU on mcPherson / multilink, PU is somewhat acceptable on double triangles), and either using standard height or running modded knuckles that will correct the height change. Degrading handling to prevent under/oversteer is really not the way to go.

2/ this is zilvia. Most people don't/can't understand the previous statement, nor care. But if you want to learn about suspension, there is a stickied thread that you want to read.
http://zilvia.net/f/showthread.php?t=296725

Thanks man. My issue was dealing with side to side movement (manji). I understeer quite a bit during the phase. After reading a couple pages i found my tire pressure might have been to high and my dampening on the front to high as well. If you have anything else you could throw at me I'd appreciate it a lot. I'm going to check out the link you sent me now.

Croustibat · 03-04-2015, 03:16 AM

Front engine rear wheel drive have a natural tendency to understeer, but this is not the problem you are facing here.

You misunderstood something from your link; when it says "soften your suspension" it does not mean open hydraulics; it means use softer springs, and adjust hydraulics accordingly. Same goes with "stiffer suspension"; it means stiffer springs. One of your problem is maybe your hydraulics are not setup properly, but chances are it comes from another: they CANNOT be set properly.

The biggest problem i see with entry level coilovers is their damping / rebound ratio is bad, meaning you cannot set them up properly. Either damping or rebound is correctly set, at best.
The cheapest coilovers i found with a somewhat correct ratio are the fortune auto 500 (there could be others, but megans/ apex/ gsp / bc and all these white branded coilovers are not ok).
The second problem is the lack of high speed/ low speed shock setup and adjustment (also called digressive valving. FA has found a way to get a somewhat similar effect for cheap, it is better than nothing but not the real deal - not the same price either)

First thing first, please describe all your suspension mods ( with brand and models when they exist ), what you are allowed to do in the class you are racing in (if you do), and your budget for parts / labor. I have nothing to sell you and i live on the other side of the planet so don't worry about hidden motives

03-02-2015, 09:46 PM	#1
LoneWolfK16 Zilvia Member Join Date: Dec 2012 Location: Japan Posts: 229 Trader Rating: (7) Feedback Score: 7 reviews	Understanding and correcting understeer/oversteer Can anyone mention anything that might or will cause understeer/ oversteer. I am trying to rule out a bunch of things that are on my mind. I'm sure there is more out there than just adjusting dampening (for basic suspension). Maybe you can throw in something few people tend to think about as well. I'm sure this can help a bunch of people if they're wondering the same. Here's a link that helped me understand a little more and taught me something i didn't know about. (trailbraking) http://winhpde.com/understeer-overst...removing-grip/ If there is a post about this already i apologize but I've looked and found nothing. Just found stuff about tire sizes and what kinds of tires to use/not use for drifting.

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03-03-2015, 08:52 AM	#2
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 41 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	1/ there are so many different understeer/oversteer that you can't just be general on this. When ? side to side transition under/oversteer ? turn in ? power over ? Brake on ? What you want first is a predictable suspension, not something that will "snap". This is achievable by using GOOD dampers/springs, GWO bushes or ball/heim joints everywhere (no PU on mcPherson / multilink, PU is somewhat acceptable on double triangles), and either using standard height or running modded knuckles that will correct the height change. Degrading handling to prevent under/oversteer is really not the way to go. 2/ this is zilvia. Most people don't/can't understand the previous statement, nor care. But if you want to learn about suspension, there is a stickied thread that you want to read. http://zilvia.net/f/showthread.php?t=296725

03-04-2015, 03:16 AM	#4
Croustibat Nissanaholic! Join Date: Aug 2011 Location: France - Toulouse Age: 41 Posts: 1,851 Trader Rating: (0) Feedback Score: 0 reviews	Front engine rear wheel drive have a natural tendency to understeer, but this is not the problem you are facing here. You misunderstood something from your link; when it says "soften your suspension" it does not mean open hydraulics; it means use softer springs, and adjust hydraulics accordingly. Same goes with "stiffer suspension"; it means stiffer springs. One of your problem is maybe your hydraulics are not setup properly, but chances are it comes from another: they CANNOT be set properly. The biggest problem i see with entry level coilovers is their damping / rebound ratio is bad, meaning you cannot set them up properly. Either damping or rebound is correctly set, at best. The cheapest coilovers i found with a somewhat correct ratio are the fortune auto 500 (there could be others, but megans/ apex/ gsp / bc and all these white branded coilovers are not ok). The second problem is the lack of high speed/ low speed shock setup and adjustment (also called digressive valving. FA has found a way to get a somewhat similar effect for cheap, it is better than nothing but not the real deal - not the same price either) First thing first, please describe all your suspension mods ( with brand and models when they exist ), what you are allowed to do in the class you are racing in (if you do), and your budget for parts / labor. I have nothing to sell you and i live on the other side of the planet so don't worry about hidden motives