Control Arm Theory: Issues when lowering?

[noone]

Hi,

I've had a few passing comments and I'm now hunting to find information about the control arm and possible issues with lowering.

I currently have a Polo GTI and have replaced the stock springs with H&R springs, which help the vehicle sit lower by about 25mm.

I'll be moving to Coilovers in the coming month.

When having a wheel alignment recently, the mechanic commented about my lowering and said something in passing about the control arm not being flat.

I'm assuming this relates to having the shorter springs installed.

Can someone help me understand:

1: What the issue is

2: How it can be resolved

3: Will this continue to be an issue when i put in Coilovers (I'm planning on dropping it as low as I can without damaging it).

Expertise wanted, but some experience or links to information would be appreciated.

[Shteifen]

the lower you go the higher your control arms will be pointin up, since they pivot from the subframe, the lower the subframe is the more of an angle they are going to be at. at stock height they are pointing little down i think.

if your looking for better handling, simply going lower isnt going to get you there... to an extent maybe a little, but better handling has to do with the shock/spring combo.
personally i have the hottuning coilovers. i got them for two reasons, they were cheap, and they go much lower than i need or want.
bad thing is, at the height they are which is rather low, they handle like ****. which is unfortunate really. and my girlfriend complains to no end that its too bumpy, and really it is, but i havent raised it cos i like the look and im lazy as hell.

ive read on VW Vortex there is a thread there about lowering for better handling where it says as a general rule of physics, that if the control arm is no longer pointing at a downward angle from the subframe then it will negatively impact handling.

so in answer to your question of if it will be made worse with coilovers, it just depends on how low you wanna go. if you go TOO much lower than stock, your handling characteristics are gonna start getting pretty lousy, but then again it depends on how low yo go and also what company made the coilovers. the more money you paid for them, i would suspect, the better ride they will give.
if you want the issue "resolved" and by resolved im guessing you mean no longer having the arms pointed up, then all you gotta do is raise it up to stock height, which wouldnt be advised by too many people on VW forums

my 2c. if i got anything completely wrong im sure someone will chime in, ive had a few beers so i imagine i got something wrong.

in my opinion, as a member of this forum i would suggest you dump the **** out of that thing and put some picture up of it


-steve

[schoona]

If there was a HOF for posts...lol

AFAIK, having your control arms level will yeild the best handling (as far as lowering and changing the geometry goes), then the better springs/shocks will give greater control and damping ability with possibilities for adjustabilities.

GET FSB/RSB and 3 wheel into car parks at snails pace

[noone]

Thanks for the input guys.

I'm not aiming to go lower for better handling, thinking about dropping it for style, so I'm happy with some compromise, but want to understand what options are out there.

Given there are many people lowering by huge amounts (maybe more so with non VAG's), I was surprised not to hit a goldmine on Google. Maybe I need to try refining and changing my wording.

I'm thinking there are a couple of ways this is dealt with:
Alterations to subframe
leave it as its not really that bad
different control arms.

I don't know, guess unless someone chimes in with some good info, I'll let you know what I find.

Here are some interesting articles I've hit so far:
Autozone
Chassis and suspension handbook

Cheers.

[schoona]

I dont think changing your control arms will make that much of a diference, considering its the angle at which they sit havingthe effect (in this regard anyway).

Jump on vortex and have a look at the US guys. I haven't looked personally, (only mk3 stuff for me) but anything you want to do, im sure it has been done over there.

[Mrk_Mickey]

In answer to your queries about this ^^^ post, you won't get out of worse handling without MASSIVE work to the structure of the car and the subframe.

Think about it like this. When your car sits at stock height, and goes around a corner (effectively shifting weight around), your control arms are going to become level or just pointing up while in heavy cornering. However once the car is lowered the control arms will be sitting in the same position as heavy cornering 100% of the time, and when you actually corner heavily the control arms will depress and turn upwards. I'm not 100% sure why this is bad for the handling but I know that once the control arm is pointing up you're losing potential handling ability.

To overcome this, you either need to raise the mounting points of the control arms so they sit higher into the subframe/body (which isn't very easy at all) or you need to pull your subframe up (probably much harder than that). Again I'm not 100% sure but I don't think aftermarket control arms can help as it's about the angle at which they sit.


The lower you go past the 'sweet spot' the worse your car is going to handle. I'm comfortable with the limits of my car, and my car tucks rears and JUST tucks front tyres. In an identical VR6 with higher suspension, you can feel the difference around a corner.

[GoLfMan]

well I've dropped my thing 75mm from standard and it still handles like a go kart

I havent noticed any real difference. In fact I'd say it handles heaps better than stock!

[Mrk_Mickey]

well I've dropped my thing 75mm from standard and it still handles like a go kart

I havent noticed any real difference. In fact I'd say it handles heaps better than stock!

Yeah that's mainly due to the spring and shock difference compared to stock. If you raised your car so that the control arms were JUST pointing down you'd notice a hell of a lot more

[noone]

Thanks Mickey, good input.

Well Goflman, I've got the AP Coils on the way. I'll keep you informed as to how it goes and try and get some progress pics when its happening in a few weeks.

I'm not looking to go show-car low, but if I can, it will be as lowest Polo GTI around...

[abreut]

You can get the control arms back to level on a lowered car by using ball-joint extenders. For example if your control arms arms are pointing upwards and are one inch higher at the hub end than at the pivot point end then a one inch ball-joint extender will get the arm back to level. However its useless doing this mod unless you also correct the tie-rods which will be pointing at roughly the same angle as the control arms were. That's when you flip the tie rod ends to the bottom of the steering arm - if that brings them down the same amount as the ball-joint extenders you should have level and parallel control arms and tie-rods, and be back to standard geometry. No more bump-steer!