Jump to content
SAU Community

Recommended Posts

Hello!

I want to correct the roll center on my 1998 ER34.

When looking online, all I can find is roll center corrected parts for GT-R only.

 

I know extended ball joints are a thing, would this work?

The problem here is, I can find them for the front side only.

 

Also, I know there are adjustable lower control arms available that correct the roll center but they are a bit expensive and also only for the front side I believe?

 

Can someone help me please? I can't be the only one that wants/has corrected roll center on a non-gtr R34.

Thanks

Thanks for your reply.

I cannot access the car right now to measure unfortunately. But my guess is that it dropped 5-8 cm from stock. I want to correct the roll center because I think even the slightest correction will help making the car handle better, since I want to do more track events with the car.

If not please correct me.

Suspension wise it's got coilovers, hicas delete, adjustable camber arms, adjustable pillowball tension rods, tension rod bar, sway bars, drop links, roll center corrected tie rod ends. Aero is still untouched.

My intention is to build a good handling track inspired street car. Not too much power, just really good and precise handling. So yes, it is street driven but I will do the occasional trackday.

OK, so, the question again. "What leads you to want to correct roll centre on your car?"

Have you drawn a diagram that shows that it (the roll centre) is currently too low? You do know that this is not a crappy Mac strut car and that you generally have to lower the car excessively to cause this problem, right?

If you are sure you have a problem, what you need to do is cut and reweld the inner arm mounts (upper and lower) on the subframe to be higher by the desired amount (eg 10 or 20mm, or adjustable). I guess there would be weld on kits these days or you could do it custom.

If you are running the car low enough to have a roll centre problem on a street/track car, you are running the car way too low for practical use. I guess it could be a problem if you have a dedicated superlap car or similar 

Best place to start for handling is to post up your ride heights and alignment settings. The factory geometry is pretty reasonable for most use.

  • Like 2
6 hours ago, r34.bryan said:

Suspension wise it's got coilovers, hicas delete, adjustable camber arms, adjustable pillowball tension rods, tension rod bar, sway bars, drop links, roll center corrected tie rod ends. Aero is still untouched.

My intention is to build a good handling track inspired street car. Not too much power, just really good and precise handling. So yes, it is street driven but I will do the occasional trackday.

Sounds good. As everyone else is saying, if you haven't created a roll centre problem for yourself (by over lowering the car) then I think you are imagining a problem that isn't really there. 

Why do you think there is currently an issue with the cars roll centre? 

Back to some more practical advice, you say you want a 'precise' handling car, to achieve this you delete all the rubber bushes and hard mount/rose joint everything. Strong chance you'll then hate the car on the road so I don't recommend you do this. You'll also be creating a tonne of extra work for yourself as the rose joints are high maintenance.  

I'd say at this point your biggest win is going to be by putting some real tyres on the car. 

I'm guessing you do open track days and don't race in a class that restricts your tyre size or compound. So grab yourself a second set of wheels, the widest you can fit under your current guards and pop on a set of serious tyres such as - 

https://samotorsporttyres.com.au/product/hankook-ventus-z214/

or if you want to spend a bit more

https://samotorsporttyres.com.au/product/hankook-ventus-f200/

And if your Mr money bags, there are plenty of other manufacturers eg Michelin, Pirelli or Yokohama, who make slicks that would love for you to make a donation to them. 

Your current setup on a real tyre will be much quicker round the track then whatever setup your imagining on a street tyre will ever be. 

Plus you get to keep your nice handling street car/street tyre combo for daily duties. 

  • Like 1

So if I understand your comments correctly, there is no need to correct the roll center. Thanks for letting me know. Also thank you for the extra tips!

as for my tyre setup, I already run as much tire as I can fit in the stock guards. Yokohama Advan A052. 😏

It's not my daily car so I run them on the street as well. Works perfectly good for me!

  • Like 2
1 hour ago, r34.bryan said:

So if I understand your comments correctly, there is no need to correct the roll center. Thanks for letting me know. Also thank you for the extra tips!

as for my tyre setup, I already run as much tire as I can fit in the stock guards. Yokohama Advan A052. 😏

It's not my daily car so I run them on the street as well. Works perfectly good for me!

Sounds like a pretty well setup car. 

If you remember what it was like going from street tyres to A052, you've got about that much performance again to be gained from going from A052 to a race slick. 

Edited by Murray_Calavera
17 hours ago, Murray_Calavera said:

Sounds like a pretty well setup car.

Yes that's what I'm going for. I thought maybe correcting the roll center would make it even better, but I guess I was wrong.

17 hours ago, Murray_Calavera said:

If you remember what it was like going from street tyres to A052, you've got about that much performance again to be gained from going from A052 to a race slick.

That is crazy!

2 hours ago, GTSBoy said:

Keeping in mind that a full race slick really requires completely different spring rates to extract the best from them.

True, if you want to extract everything from the slick, the suspension needs to be setup with that in mind. 

However only changing the tyres and nothing else, the slicks offer another crazy step up in performance. 

This is a nice video showing that - 

Funnily enough, the video shows exactly what I said above. The step from street to R comp is the same again going from R comp to slick. 

 

 

16 hours ago, blind_elk said:

What size?

F:235 R:255

I had R888R before in F:245 R:265. I kid you not, the Advans are wider than the Toyos. I think a 275 R888R would be about the same width as a 255 A052...

 

5 hours ago, r34.bryan said:

F:235 R:255

I had R888R before in F:245 R:265. I kid you not, the Advans are wider than the Toyos. I think a 275 R888R would be about the same width as a 255 A052...

 

Diameter? Aspect Ratio?

On 1/18/2023 at 6:10 AM, GTSBoy said:

OK, so, the question again. "What leads you to want to correct roll centre on your car?"

 

Actually, I don't think this question has been answered. What exactly is the car doing - handling-wise - that makes you think it needs any adjustments to the suspension setup?

Okay so first off I don't have a lot of experience driving a lot of different cars fast. My car handles great, there is nothing weird going on handling wise (maybe a bit of bump steer). All I'm trying to do is make it handle as good as it could. The problem is I don't have anything to compare it to. So since my experience is lacking I'm reading online about other peoples (track)builds. And so my thought was "oh when you lower a car the roll center is off, so it needs to be corrected in order to make it handle better." Then I saw the kits are only available for R32-33-34 GT-R. Confirming these cars might need it. Hence my question how to correct it on a non-gtr Skyline.

Perhaps my question should've been: Does my car need a roll center correction to make it handle better?

Or: How to make an ER34 coupe faster around the track? (handling wise)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yes to both! Yes to standard ECU and tune, but exhaust is aftermarket. Unsure on brand. Actually have it sitting in at my desk haha! I have to set it up on my laptop but this is a great next step, will do. So I generally try to shift before 4.5K RPM most times. I largely don't do a lot of high-rev driving, but I will take it up to red 1-2x a week max, as I know the occasional "Italian tune-up" is good for these cars.  Oh wow, is this way better than what I'm getting. Does this mean there's a good chance I have an issue?   Thanks for all the info so far guys.
    • Old Son, did you re-use the Holden ABS in the new shell or try a different module?
    • Yeah, nah. I had the actuator rod off it today. The arm will not move at all. Neither out, nor in. Yeah, you'd think so, but I've been thinking about that. Even when the actuator rod fell all the way off at the beginning of this saga, it would build more boost and faster in lower gears than it would in higher gears, and you'd think that that was the opposite of what should happen. But I strongly suspect that there is a thing with the gearing getting the revs to rise faster, that there must be some transient effect with the gas flow rate rising quickly, that you don't get with the more steady state case of the higher gears. Keep in mind - the gate is not shut in either of my weirdnesses. So things are not "normal". We normally think about a turbo spooling up (below the wastegate target) with the gate shut. I have all sorts of mental models running now where the gate is a little bit open, and having it stuck open allowing gas out while it should be going through the turbine has all sorts of weird effects (in these mental models). I'm thinking in the higher gears, the ex mani pressure builds to the point where enough gases spill out the wastegate to just prevent the pressure rising much more at all, or just creeping up, all the whole the revs are increasing and getting closer to the point where a gear shift becomes necessary.
    • Is it possibly wastegate actuator itself is sticking, or even the rod to flapper? Otherwise I reckon things are getting a bit rusty/worn   Also odd it won't boost in 3rd to 5th, but will in 1st, I'd expect the other way around with it slightly open as there's more time on your way to redline for it to spin up
    • Does anyone know ow what these two plugs are for and if they should be unplugged? Just put the dash back together and can't remember if these were plugged in before or unplugged! (Blue and white plugs) 🤦🏽‍♂️
×
×
  • Create New...