Wishbone Modification/Mount

[sambo82]

Hi All,
Just got back from my first track day at Combe. This is my spec and setup as we ran today.
http://www.cliosport.net/forum/showthread.php?687440-172-Cup-Track-Build

Cant really fault the road holding and handling but we were getting a fair bit of body roll out on track, which would in turn create scrub and eventually under steer.
When I got the car setup I was shown a diagram explaining that by lowering the front you shift the roll centres by decreasing the angle of the wish bone to ball joint, basically creating more leverage for the engine and body to exert on the damper. Hence by actually lowering the front its created extra body roll. This was noticeable on the corners requiring greater degrees of steering input.

Now I was told that by lifting the wishbone mounts on the subrame by around 40mm, to compensate for the 40mm drop, this would return the roll centres to standard. Now I'm sure I came across something similar on here a while back, and an associated modification, but after a fair bit of searching I still cant find the post/topic.

Can/Has anybody

A) Point me in the right direction
B) Done this mod
or
C) Remedied this issue differently

Cheers
Sam

 

[green]

Cup race cars have hub extender pins to bring the roll centres back. There are quite a few theads on it and I think I remember someone said they where testing a retro fit pin for standard cars.

 

[sambo82]

Found the thread I remember seeing cheers. They seem to be heading down the extended ball joint route. Would raising the mounting point on the subframe side work?

 

[NorthloopCup]

Found the thread I remember seeing cheers. They seem to be heading down the extended ball joint route. Would raising the mounting point on the subframe side work?

Yes it would work but it also needs to be fully braced to compensate for the extra leverage it'll add to the subframe. I'm the guy doing the hub mods btw.

 

[MG cup]

By doing it this way you are adjusting the Roll centre but not in the correct relation to the steering arm, you will then need to adjust the track rods with an adjustable spherical bearing. Too much work for me.

If your doing it yourself then take the easy option and have a pin made up and then buy cup racer uniball holders, that way everything can be bought off the shelf except the pin, this will come in handy if you bash it. You can also adjust it with different length pins as it suits you.

Either that or buy Northloop's setup when he starts selling it.

 

[NorthloopCup]

adjust the track rods with an adjustable spherical bearing.(1)

If your doing it yourself then take the easy option and have a pin made up and then buy cup racer uniball holders, that way everything can be bought off the shelf except the pin, this will come in handy if you bash it. You can also adjust it with different length pins as it suits you.(2)

Either that or buy Northloop's setup when he starts selling it.

(1) adjusting the steering arms is the easiest bit to do tbf. I'll have rosejointed steering along with spherical bottom ball joint bearings and wishbone bearings

(2) you can't just machine a pin up at different lengths to suit either unfortunately. It's all about how it acts on the bottom of the hub. The added leverage it puts on the hub is quite substantial, so there's a set length you can go to BUT the hub must be modified to suit otherwise it will elongate the hole that the pin sits in/is secured by. The other issue is the cup racer ball joints need re-drilling to sit further inboard.

For the record I'm not trying to 'big up' the way I'm going about doing it either. Everything has been calculated and simulated to see possible stress/failure points. I don't care if others are not interested in buying a kit off me for their car. The modifications I'm doing to mine are based purely on me wanting to get my car handling better, and if that's what some of the racers/trackday goers want also, then there is a solution without going to full cup racer suspension.

I looked at the modified subframe route as well and tbh, it just made my balls twitch. I wasn't at all comfortable with the leverage issues it would subject the subframe to, and neither was my machinist mate who's an aerospace engineer.

 

[MG cup]

(1) adjusting the steering arms is the easiest bit to do tbf. I'll have rosejointed steering along with spherical bottom ball joint bearings and wishbone bearings

(2) you can't just machine a pin up at different lengths to suit either unfortunately. It's all about how it acts on the bottom of the hub. The added leverage it puts on the hub is quite substantial, so there's a set length you can go to BUT the hub must be modified to suit otherwise it will elongate the hole that the pin sits in/is secured by. The other issue is the cup racer ball joints need re-drilling to sit further inboard.

For the record I'm not trying to 'big up' the way I'm going about doing it either. Everything has been calculated and simulated to see possible stress/failure points. I don't care if others are not interested in buying a kit off me for their car. The modifications I'm doing to mine are based purely on me wanting to get my car handling better, and if that's what some of the racers/trackday goers want also, then there is a solution without going to full cup racer suspension.

I looked at the modified subframe route as well and tbh, it just made my balls twitch. I wasn't at all comfortable with the leverage issues it would subject the subframe to, and neither was my machinist mate who's an aerospace engineer.

I wasn't slating your idea btw mate, what I was saying is I'm not keen on the subframe modification idea.

For easyness if I was doing it myself and nobody was making a kit like you I would buy cup racer uniball holders and have a pin machined to suit the 1*2 hubs. Depending on what you wanted you could then get longer shafts or drill the bottom arms to run the originals.

 

[sprintcup]

(1) adjusting the steering arms is the easiest bit to do tbf. I'll have rosejointed steering along with spherical bottom ball joint bearings and wishbone bearings

(2) you can't just machine a pin up at different lengths to suit either unfortunately. It's all about how it acts on the bottom of the hub. The added leverage it puts on the hub is quite substantial, so there's a set length you can go to BUT the hub must be modified to suit otherwise it will elongate the hole that the pin sits in/is secured by. The other issue is the cup racer ball joints need re-drilling to sit further inboard.

For the record I'm not trying to 'big up' the way I'm going about doing it either. Everything has been calculated and simulated to see possible stress/failure points. I don't care if others are not interested in buying a kit off me for their car. The modifications I'm doing to mine are based purely on me wanting to get my car handling better, and if that's what some of the racers/trackday goers want also, then there is a solution without going to full cup racer suspension.

I looked at the modified subframe route as well and tbh, it just made my balls twitch. I wasn't at all comfortable with the leverage issues it would subject the subframe to, and neither was my machinist mate who's an aerospace engineer.

Cough cough, guinea pig available when your ready lol just let me know when.Keep me at the top of your list for these as soon as a set are available none RJ'd as you know.

Regards Russ

 

[sambo82]

Cool, cheers Northloop. Sounds as tho I will be awaiting your kit then!! I thought the subframe would have to be braced to compensate, but didn't really think too much about the rest of the steering components needing to be modified to suit aswell. Without somebody holding my hand and physically walking me through and pointing the procedure out to me I kinda get a bit confused with it all!! I can grasp the theory side but translating that into the physical side gets a bit lost in translation.

Any ideas on when the kits will be available?

 

[NorthloopCup]

Cool, cheers Northloop. Sounds as tho I will be awaiting your kit then!! I thought the subframe would have to be braced to compensate, but didn't really think too much about the rest of the steering components needing to be modified to suit aswell. Without somebody holding my hand and physically walking me through and pointing the procedure out to me I kinda get a bit confused with it all!! I can grasp the theory side but translating that into the physical side gets a bit lost in translation.

Any ideas on when the kits will be available?

I'll drop you a pm mate over the weekend.

 

[NorthloopCup]

I wasn't slating your idea btw mate, what I was saying is I'm not keen on the subframe modification idea.

For easyness if I was doing it myself and nobody was making a kit like you I would buy cup racer uniball holders and have a pin machined to suit the 1*2 hubs. Depending on what you wanted you could then get longer shafts or drill the bottom arms to run the originals.

Sorry mate, only just seen your reply! I didn't take it as you were slating the idea mate at all. My reply was possibly a bit strongly worded, but I don't want people thinking I'm saying the subframe mod idea is not as good as my idea, just because its my idea if that makes any sense? I'm not out to make a quick buck.

 

[sambo82]

I'll drop you a pm mate over the weekend.

 

[len_beach]

Are these still being developed Northloop?