Help me understand suspension geometry.

[Novablue454]

I'm reading this, and I'm still not getting it.
http://ismasupers.com/downloads/tech...ations%204.pdf

I have the SLR Ultra angle kit. At lock, I have a ton of positive camber gain. I go from negative camber straight to the outer sidewall at lock. What is causing this and how can it be remedied?

[s50b30]

Caster does that.
Why would you remove it?
What issues are you having?

[protomor]

At lock, ackerman and caster make the biggest difference. Some roll over is unavoidable but really you want to adjust caster. I doubt you will have much adjustment in it though. Slam it max neg and call it a day. Def under 9*

[Mikestokman]

I think the only real way to mess with that is wisefab where the knuckle has large geometry changes, and I've heard a few people say that it ruins the steering feel of BMWs. I believe Chelsea has a fair bit of camber gain in his setup aswell, what are you trying to change it for anyways?

[Novablue454]

This was at 9*. I think its at 7* now and pretty similar. It really doesn't cause any issues, just looks sort of funky. The reason I ask is because they just introduced these
https://www.instagram.com/p/BNvp8O9j...slrspeed&hl=en

and I was trying to figure out if they would have any effect on that flop.

[protomor]

To be fair, you shouldn't be hanging at that portion of lock anyway. It slows you down like a mofo. As long as your leading wheel is flat at ~45*, you're fine.

[Novablue454]

At lock, ackerman and caster make the biggest difference. Some roll over is unavoidable but really you want to adjust caster. I doubt you will have much adjustment in it though. Slam it max neg and call it a day. Def under 9*

The SLR lollipops give me some adjustment, not sure how much those. Max + is 7* with them (I gained the 2* by rotating top hats), no idea what max negative is. Surely you wouldn't want to go below 5.5* (oem) though?

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To be fair, you shouldn't be hanging at that portion of lock anyway. It slows you down like a mofo. As long as your leading wheel is flat at ~45*, you're fine.

I think really I just wan't to buy Sean's shiny new parts and am trying to justify it, haha

[Mikestokman]

Looks about the same, you're probably overthinking It haha

[s50b30]

I friend of mine has wf, where the strut is located in front of the center bore. Hes wheels where flat on lock, but the feel was so terrible that he swapped the strut tops for some generic ones. So now its just like yours.
I dont think its a good idea to change steering geometry bco looks.

[Press22]

I will trade you a setup that doesn't look weird for the SLR.

[Novablue454]

Don't get me wrong, I love my SLR. It works great and I am more then happy with it.

SLR just announced their new strut tops, and mostly I am just trying to figure what they are correcting. I end up at -5* camber with the Ultra kit. Are people really changing tophats just to take that number to -2* or -3*?

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Looks about the same, you're probably overthinking It haha

Touche!

[protomor]

5 is way too much. I really want like 3. even 2.

[welchct]

The real issue with the BMW is the off set between the ball joint and the centerline of the strut. When you add camper to the car it causes the tire to lay out at lock when running large amounts of steering angle. Wisefab tries to correct this by using lower control arms that relocate the knuckle forward and then the knuckle spacer moves the knuckle back in the center of the wheel well while moving the ball joint pick up point more in line with the strut.

This is why people say they don't like the dead feeling of the Wisefab kit. But it does solve the geometry issue these cars have. That steering input you have to force into the steering wheel is what makes BMW's "the ultimate driving machine". But it does not play well with large amounts of steering angle.

You can either remove the offset and have "dead steering" or leave the offset and deal with wonky geometry at full lock.

[s50b30]

Don't get me wrong, I love my SLR. It works great and I am more then happy with it.

SLR just announced their new strut tops, and mostly I am just trying to figure what they are correcting. I end up at -5* camber with the Ultra kit. Are people really changing tophats just to take that number to -2* or -3*?

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Touche!

Im guessing its to correct the massive amount of camber the ultra kit gives. Which is not achieved with standard strut tops.
I got the early style tops from slr, that in combination qith the hsd top mounts get the negativ camber down on my adjustable arms.
But this seems like a better solution if you dont have either already.

[Piner]

Its sorta funny reading this because realistically it isn't a problem. Its not something that needs to be fixed. It looks wonky sure but from a performance standpoint you actually want the tire to achieve less and less contact patch as you add lock. Aside from keeping the proper feel that others have mentioned when you are at big lock an over abundance of grip in the front will reduce the slip angle on the front tires. Think about it even with all the lock a wisefab or SLR kit gives you nothing will give you more than about 75*. You want the front tires to give when you go past that as people throwing in hard often do. Never mind backwards entries even just throwing the car in at 90* requires a good amount of slip angle on the front tires. With too much grip this will make the car more prone to spinning out around the axis of the front due to the braking effect this gives.

If you have ever driven a car with a shit ton of front grip and crappy rear tires vs a car with more even or less front grip you can't help but notice the car with less front grip is a good bit harder to spin. The front tires give up and slide past lock making the car feel like it has more steering lock than it may actually have. The jacking effect which is also a result of the suspension geometry that causes the tire to lean over helps shift more weight to the rear at big lock (The jacking force actually raises the front end of the car). This aides in gaining rear traction which can be the difference in recovering or spinning out. This Jacking force is also partially responsible for the self centering effect on the wheel (Along with ackerman and caster). Wisefab eliminates most of the jacking effect in their effort to have the tire flat at lock which is really just for cosmetic reasons and does nothing to aid performance in drifting and you also end up with a dead wheel in your hands.

[Novablue454]

5 is way too much. I really want like 3. even 2.

I feel like I could easily achieve that with a few minutes and a dremel.

- - - Updated - - -

Its sorta funny reading this because realistically it isn't a problem. Its not something that needs to be fixed. It looks wonky sure but from a performance standpoint you actually want the tire to achieve less and less contact patch as you add lock. Aside from keeping the proper feel that others have mentioned when you are at big lock an over abundance of grip in the front will reduce the slip angle on the front tires. Think about it even with all the lock a wisefab or SLR kit gives you nothing will give you more than about 75*. You want the front tires to give when you go past that as people throwing in hard often do. Never mind backwards entries even just throwing the car in at 90* requires a good amount of slip angle on the front tires. With too much grip this will make the car more prone to spinning out around the axis of the front due to the braking effect this gives.

If you have ever driven a car with a shit ton of front grip and crappy rear tires vs a car with more even or less front grip you can't help but notice the car with less front grip is a good bit harder to spin. The front tires give up and slide past lock making the car feel like it has more steering lock than it may actually have. The jacking effect which is also a result of the suspension geometry that causes the tire to lean over helps shift more weight to the rear at big lock (The jacking force actually raises the front end of the car). This aides in gaining rear traction which can be the difference in recovering or spinning out. This Jacking force is also partially responsible for the self centering effect on the wheel (Along with ackerman and caster). Wisefab eliminates most of the jacking effect in their effort to have the tire flat at lock which is really just for cosmetic reasons and does nothing to aid performance in drifting and you also end up with a dead wheel in your hands.

Thanks for the excellent info!

[SLR]

There's a lot to go into here, but Piner covered it pretty much, thanks Paul!

The only way to really alter this is to reduce caster massively like some other companies do, but then you lose the self-steering effect.

OR

Alter the kingpin inclination relative to the wheel inclination (not easily achieved with E46 knuckles).

If you can change to E36 knuckles you can actually shim the knuckle for more camber with the same KPI, (yes more) and then max out positive camber at the top mount which will translate to a flatter contact patch at full lock.

The E36 non-M knuckles actually get their self-steering from a balance with more trail than E46's and E30's. This is why E30 and E46's run more caster from the factory,and are more prone to losing their self-steer feel at big lock with low offsets.

As mentioned by others you really don't drive the car long at these steering angles, generally just entries, and once on throttle the steering stays under 45⁰ or so.

Of course like Paul mentioned, when you're doing a massive reverse entry, FRONT grip is the last thing you're looking for, and would actually make the car much morelikely to spin. This is the way Chels is able to do the insane entries and something Mike Essa did also before switching to the blue stuff. It's also why we always recommend front bars.

Also the jacking force created by caster helps immensely with snappy transitions which you rarely see the blue guys able to do. Talking to Chels after final round this year he said the whole reason he crashed Odi's car was he couldn't feel the front end at all.

Also a macpherson strut is always going to be a compromise in suspension design. Funny that it works decent in situations with very little travel and steering (road-race), but while great for drifting due to simplicity & clearance, the fact that KPI and steering axis are inseparable makes struts very frustrating to try and find the perfect compromise in drifting with tons of steering angle and compression+droop.

Here'ssome good info: http://www.technickslide.com/2014/08...es-tested.html

Also Stewy Bryant's feeling's are here (and I'm pretty sure he re-wrote this to be much less harsh on the WF stuff): http://www.inertia-ms.com/blog/?p=857

Stew and I spent many hours talking suspension theory last year at Driftland & the'ring and pretty much agree on our whole front-end philosophy

[tptrsn]

Wow, this is a good thread!

[Novablue454]

There's a lot to go into here, but Piner covered it pretty much, thanks Paul!

The only way to really alter this is to reduce caster massively like some other companies do, but then you lose the self-steering effect.

OR

Alter the kingpin inclination relative to the wheel inclination (not easily achieved with E46 knuckles).

If you can change to E36 knuckles you can actually shim the knuckle for more camber with the same KPI, (yes more) and then max out positive camber at the top mount which will translate to a flatter contact patch at full lock.

The E36 non-M knuckles actually get their self-steering from a balance with more trail than E46's and E30's. This is why E30 and E46's run more caster from the factory,and are more prone to losing their self-steer feel at big lock with low offsets.

As mentioned by others you really don't drive the car long at these steering angles, generally just entries, and once on throttle the steering stays under 45⁰ or so.

Of course like Paul mentioned, when you're doing a massive reverse entry, FRONT grip is the last thing you're looking for, and would actually make the car much morelikely to spin. This is the way Chels is able to do the insane entries and something Mike Essa did also before switching to the blue stuff. It's also why we always recommend front bars.

Also the jacking force created by caster helps immensely with snappy transitions which you rarely see the blue guys able to do. Talking to Chels after final round this year he said the whole reason he crashed Odi's car was he couldn't feel the front end at all.

Also a macpherson strut is always going to be a compromise in suspension design. Funny that it works decent in situations with very little travel and steering (road-race), but while great for drifting due to simplicity & clearance, the fact that KPI and steering axis are inseparable makes struts very frustrating to try and find the perfect compromise in drifting with tons of steering angle and compression+droop.

Here'ssome good info: http://www.technickslide.com/2014/08...es-tested.html

Also Stewy Bryant's feeling's are here (and I'm pretty sure he re-wrote this to be much less harsh on the WF stuff): http://www.inertia-ms.com/blog/?p=857

Stew and I spent many hours talking suspension theory last year at Driftland & the'ring and pretty much agree on our whole front-end philosophy

Awesome! So what do the new tophats you just released do then, simply remove some negative camber? Or is there more to them then that?

[SLR]

Well for the last 2years we've sold an offset top plate for E36 which bolted above whatever camber plate you already ran, and just moved the whole stack outboard to help dial out camber.

But it was designed for E36 only, mostly because the E46 has an extra 60mm between the strut towers, so they don't get the super-super camber when running an ultra kit if you run most camber plates max positive.

But there are so many variations in camber plates out there, and we still had no perfect solution for E30's that wnated to run an Ultra Kit since the E30 has one of the original bolts right in the way of where we'd like to put the strut bearing if maxing out the legal position.

So yes, the new plate lets you move the top bearing right up to the legal limit (on the bolt circle), both reducing camber, & also providing a range of positions you can use to set your caster how you like it. They are designed to work with the majority of coilovers (the slot dimensions are pretty much an industry standard), and use your existing slider, just replace the upper plate with the SLR piece and you're ready to rock.

As with most of our other products, it's designed so you can swap between platforms without buying a new part from us (less sales for SLR, but more savings for customer, haha!)

[protomor]

So you can swap it from an E30 to like an E46? Right now, I have WAY too much front camber on the E30 but eventually, it's all going on the E46 anyway.

[SLR]

Yessir!

[protomor]

details? I want. Looks like it'll add ride height too.

[jakeE36325]

Well I had placed an order for the first version of the top mount adapters. Got an email from SLR asking if I wanted to upgrade and sent me a link to the new adapters they just put up today. Of course I wanted to. They said they'll ship out tomorrow. Also asked about the thickness. The V1 plates are 9.5mm and the V2's are 19mm. Excited to get them in and dial out some camber.

[jeepster]

Paul and Sean covered this perfectly. I came from road racing to drifting. I had a lot of frustrations with suspension design because road racing geometry doesn't apply to traveling sideways and big angle. I have since spent a lot of time playing with settings in a scientific manner to get what I feel is the best compromise between, angle, grip, and feel.

On a side note, I need those top plates Sean!!!