Suspension lowering, angles and set-up

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Attack2001
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Suspension lowering, angles and set-up

Post by Attack2001 » 14 Dec 2012 12:44 am

Hi all, as i'm moving away from the volvo scene i thought i'd share my idea's and experiences with regards to suspension set-up etc.

Now from what i've found with the front suspension, lowering it too much past 'centre' destroys the handling. Here's what i mean, this is arch gap of my car with 195/45/13's on 8j wheels.

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Now i think it looks awesome, however look underneath and it looks like this:

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Now as you can see the lower arms aren't exactly in the best shape or angle. This is the problem with lowering the car too much, now if you already know this, feel free to correct me/make it far more understandable etc etc this is purely because i always have people asking me how low my car was, and then ask why when i say, "looks cool, handles like crap". So the problem is when it comes to setting the suspension angles, and how they perform on the road.

To understand you have understand how with the lower arm in a fixed position on one end, and attached to the suspension at the other, when the strut moves up and down, because the lower arm is fixed at the other end, the suspension moves up and down in an arc. Now if the lower arm was parallel so the mounting points (one being the bolt in the subframe, and the other being the ball joint under the strut) if these two points were parallel and in line with each other along the horizontal axis, at this point the end of the lower arm, or the strut is at its furthest point in the arc, as soon the lower arm moves up or down (rotating around the pivot point where its attached to the subframe) it starts to move back on itself as such. This also works if you were to leave the suspension, and move the subframe up and down, from parallel, as the subframe moves down, the inner end of the lower arms would move down, and the lower arms would be point upwards towards the lower ball joints.

So now with that in mind, when it comes to set-up, forgetting the top mounts at the moment, if you wanted to incease the negative camber on the front wheels, you would simply make the lower arm longer, this would in turn 'push' the bottom of the strut outwards giving you the camber. This is where the problem revolves with regards to lowering your car too much, my car was lowered on coilovers (so i could litterally stick it on the deck) and as you can see in the pictures the lower arms are, when its sitting static, already in an angled position upwards. Now this is the reason, even with my camber top mounts set to max, i could still only achieve just under a degree of camber on the front wheels, not good!

Now if you think of this while driving along, tearing through those country roads, as you do :wink: come up to a tight corner, on the brakes, now even with the 400lbs front springs i had, the front of the car would still dive (to put it into perspective, our race car will be running at the class weight of 945kg, same as a volvo! and were looking upwards of 800lbs, nearly a 1000lbs front springs, because race car! haha it will be running some serious rubber on the front however). Now when the front dives, the subframe dives and moves towards the ground, this in turn pulls the inner pivot of the lower arms towards the ground. Now this is where the magic happens, to start off with, as my set-up was already badly angled, when the subframe dropped it pulled the bottom of the struts in even further, as the ball joints were effectively travelling even further round in the 'arc'. Because it was pulling the struts in, (in drastic terms) this pulled the wheels onto positive camber, which is definately not what you want under braking. So this means you have to brake sooner and lighter, to slow the car down gradually as the wheels will just lock up through lack of grip if you brake late. So time is lost there.

Now you've slowed the car down for the corner, you've got to go through it. More badness coming here. So the your going through a left hander, all the weight shifts to the right handside of the car. This transfer of weight, makes the car lean on the right side, the right side of the car lowers down on the suspension, the subframe once again moves down towards the floor, thus once again, it pulls the bottom of the strut intowards the car, here comes the positive camber! and the following understeer puts you on the otherside of the road... So you have to slow down so to not lock up on the way in, you cant corner as hard due to the understeer that will become of it. Its a set-up full of slowness. The car may look good slammed on the ground, but it wont corner!

So, this is what you want, ideally you want the car with the arms just above parallel. If you have them parallel the car will still pull them in under hard braking and cornering pulling off camber and moving towards positive camber. Now if you want them with the lower arms angled slightly, how much i dont know, you want the end at the subframe higher than the ball joint end. This will then cause the lower arms to "drop onto parallel" under hard braking and cornering. This in turn will push the bottom of the strut out for braking and cornering giving even more negative camber. This isnt ideal with regards to the braking as you are still not using all the width of the tread, however its better than positive camber under braking, and far better during cornering as you've got the camber for the car to 'lean onto' giving better cornering grip, thus better cornering speeds :) When it comes to running camber on a car, its always a compromise between braking grip and cornering grip so you have to find the inbetween :)

To get the lower arms in the correct position and still run the car low? Ideally you want to run the car lower to the ground for centre of gravity reasons and less force on the car trying to making it 'roll onto the outside wheel -the inside wheel still has grip too! So you can run 15s, so visually you'll have a smaller arch gap, you'll also be able to run wider rubber for better grip and you get better mpg. If you want to run 13's then you need to do some modifications. You can either lower the ball joint end of the lower arm down, however this will bring it lower to the ground and more likely to hit something if your as low as i was, or you can move the pivot point of the inner ends of the lower arms up, simply by re drilling the hole. Out of the two i'd choose the later. On our race car that Gartrac set-up back in 1990 odd, to sort this problem, they used rose joints on the lower arms (its a fiat 131 however the principle still applies) and then used a longer bolt, and a spacer to space the lower arm down to the correct angle. Being Gartrac and anyone that knows, knows Gartracs work is top shelf stuff, some of their work is awesome and they definitely know what there doing. However this moves the lower arm down making it more susceptible to damage as your running the car so low on the road. So i think the best way to do this is to raise the pivot point in the subframe. You do run into problems such as running out of room for the arms to move, or maybe not being able to move it up high enough, however it can be achieved by cutting 'the roof' as it were of the tunnel that the lower arms mount into, and welding in new sides the travel from the original 'tunnel' and up to the higher part of the subframe. Then re-drill the holes so the lower arms are positioned correctly.

Well its lengthy, but this is based on my experiences with the 300's and the racecars i've grown up around, thats my 2p, more like a few quid!, on how to set-up the front suspension for better braking and cornering ability. Just like you would if it was a race car :) The amount of times i've come up to a corner and you can hear the outside wheels fighting for all its worth and the understeer, its just appauling, oversteer i can handle, but understeer is my one big bug bear haha. Well, i hope this makes some sense and can be of help :) I was heading towards sorting it however things changed and i now own a lada, which is even harder to get this sorted with its double wishbones, as i've got two arms that need sorting now! haha but hey ho i'll sort it :)

Thanks, Thomas...............
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Chris_C
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Re: Suspension lowering, angles and set-up

Post by Chris_C » 14 Dec 2012 10:59 am

There is one extra thing, which is what I think was causing most of your problem, bump steer.

You are correct in saying when the car dives, the wheel effectively comes in relative to where it was before. However, as well as that, look at where the ball joints in the track rods are. They are designed from factory to not be parallel, i.e. to have some bump steer. This in the case of the 300 isn't a bad thing (normally you hear bad things about bump steer) as it is designed to modify the geometry to give you more turn in when it all compresses, whilst not causing huge scrub when you are driving in a straight line.

With you suspension starting so far from factory and having to be tracked at that point, it means that if the car lifts (when accelerating) the wheels go in completely different directions to expected. When braking, you don't have the movement for the extra turn in.

It's also why I'm so so paranoid about finding a "correct" quick rack and not just bolting up a Sunbeam rack as has been done before, or an Escort rack. A few friends have Escorts, I know they are wrong by about 3 inches.
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'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

Attack2001
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Re: Suspension lowering, angles and set-up

Post by Attack2001 » 14 Dec 2012 11:10 am

Ah yes, this also true :) With that in mind, running the same set-up with all arms just above parallel, under hard cornering braking and cornering, it will induce toe-out. Which is what you want for better turn in, and is what im currently setting on my kart :) I hadnt thought of that :)

Thanks, Thomas...............
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Re: Suspension lowering, angles and set-up

Post by Chris_C » 14 Dec 2012 03:58 pm

Depends which "side" (in a lefty righty sense, rather than a forward backy sense) the ball joint is relative to the wishbone pivot at rest, it can induce toe in as well (he says looking for the meccano to check he's right)

EDIT: Meccano says it can, therefore it must be true. Everything should be thought through then made in meccano, I'm sure this should be taught in schools!
'89(G) 340 GLE B172k
'03 S60 D5 SE, '91 (J) MX5, 1954 Cyclemaster
Ex:
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

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Re: Suspension lowering, angles and set-up

Post by Nimminz » 16 Dec 2012 12:32 am

Chris_C wrote:Everything should be thought through then made in meccano
This is truth!

Read it all and understand everything you've both said. I'm not 100% on how much room there is but i seem to think its about 2 inch between the arm mount and the chassis mounting area? So raising the pivots is very possible. I have a spare subframe which i was intending on cleaning up and strengthening before sticking it on the car So might give this a go. Bit i'm not too sure on is why have it a bit angled upwards when level? why not exactly horizontal? Moving the rack up is going to be a lot more difficult though. Tie rods / radius arms would then be sat at a greater angle so the mounts for them should be moved up? or, because it's just to stop the control arm tilting back/forwards it doesn't matter about it's angle, only its length - which would be easier to sort?
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Attack2001
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Re: Suspension lowering, angles and set-up

Post by Attack2001 » 16 Dec 2012 02:33 am

Matt, you want the lower arms angled upwards, so the ball joint end is lower than the subframe end. You want this so under braking and cornering, when the front end dives, the subframe mounting point moves down so the two points at each end then become parallel on the horizontal. This in turns literally, pushes camber on which as said, is much better for cornering.

However its a one or the other, no camber and good braking ability, the car will brake in a straight line much better as your using 100% of the tyres contact patch, as soon as you turn (in drastic terms) the car will start to lift the inside edge of the tyre and then you'll loose grip during turning. Then you could run camber, however you'll have to extend your braking distance due to less contact patch, however as soon as you start cornering and the car 'rolls onto' the outside tyre, hopefully using (this is the bit that takes shit loads of testing haha) all the tyre contact patch available. Now the reason you would really want the camber, is it increases cornering speeds, which means you come out of the corner with far more momentum to get you to the next corner :)

With regards to the steering rack, once again i forgot to mention, this was also addressed. With the picture below - This is the 131 i was talking about :)

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Now you can just about see the spherical bearing thats been put in the end of the lower arm. However look at the steering arm/track rod. Gartrac have fitted a rose joint, and swapped it, from mounting on top of the 'knuckle', and now it bolts up from underneath. You can do this on the volvo, and the ideal is to keep the lower arm and track rod at the same angle to each other. If simply by swapping it from on top to underneath puts it at a different angle, you can make a spacer and space it down till there at the same angle :)

Just looking through the facebook page, found a picture of the saloon with my wheels on. Its running cut front springs, which means its not as low as i was running as its not possible because the car just sits on the bump stops. However the point is, look at how bad his lower arm is, and he still wants to go lower! :shock:

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Thomas.............
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Re: Suspension lowering, angles and set-up

Post by Nimminz » 16 Dec 2012 01:04 pm

ahhh, just realised which way you meant, ball joint end lower than subframe end - i was thinking you meant the other way, thus my confusion.
'88 360 +T LSD - sold
'87 760 TDI (D24TIC) - sold
'04 V40 D sport (F9Q, decat, Remapped, launch control)
'89 740 SE (b230ft, 12psi, V-cam, headwork, 'remapped', banded steels)
'86 340 DL 1.4

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Re: Suspension lowering, angles and set-up

Post by Frits » 17 Dec 2012 09:18 am

Massive story, sorry for haven't read all. I've an idea for adjusting rollcenter, bumpsteer settings.

I can agree for bad handling on the lowered cars. The best handling 300 I drove, was actually my almost stock 340. I would kill some the get my 360 handle like anything that felt like the 340...

Well first i'm going to try to adjust my springrates and damping like how I set up the 340. And if I can get the feel'n right, I'll lower it again. And I want to adjust the inner suspensionarm hole. (Make a higher mount) and as I'm planning to shorten the ackerman arm, I'll also lower it to get bumpsteer to a minimum. This is the way as it isn't possible to raise the steering rack.

Well, I'll keep in touch, but first have to repair some panelish stuff.... As I pretty bad crashed it in Lydden Hill.

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Re: Suspension lowering, angles and set-up

Post by miniswift » 17 Dec 2012 10:33 am

Hi,

In a classic Mini racing series, they us similar setup to bring steering arm to near flat by using rose joint and high tensile bolts.

For my Mini, I have moved up bottom arm mounting hole by 1" but this will improve angle of bottom arms. I have spare bottom subframe from Matt.
I will be making it camber adjustable as well as increase height by 1" but I'm not sure if it has enough clearance or not.

Tom, Can you take a photo from side view with 6" ruler so that I can see what space I will have?

Cheers
Atchi

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Re: Suspension lowering, angles and set-up

Post by Chris_C » 17 Dec 2012 11:09 am

Frits wrote:As I pretty bad crashed it in Lydden Hill.
Just seen your Facebook page bud, sorry to hear this, but at least it was doing what you built the car for. Good luck with the rebuild.
'89(G) 340 GLE B172k
'03 S60 D5 SE, '91 (J) MX5, 1954 Cyclemaster
Ex:
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12; '91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

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Re: Suspension lowering, angles and set-up

Post by HenTio » 17 Dec 2012 03:49 pm

Great writings guys!

I have a question: what is the maximum lowering to keep those angles about right?

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Re: Suspension lowering, angles and set-up

Post by Attack2001 » 17 Dec 2012 04:07 pm

I think we need lower arm shots of all the different heights people are running, wheel size doesn't matter. I suspect the majority of you are running dais lowering springs too. I just had a look and measured it to be about a maximum of 60mm of room to move the lower arm mount up on the subframe. however there maybe other clearance issues that I haven't noticed.

Thomas........
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Re: Suspension lowering, angles and set-up

Post by miniswift » 17 Dec 2012 10:34 pm

Hi Tom,

So If I have 50mm(2" in old school), I should be able to do what I have said.
I can move a pivot point of bottom arm as well as fit an adjustable cam bolt for camber adjustment.
If I make one, I think Matt will be my tester like my LSD... :lol:

I think it will be easy one as I have all the tools and material just need more hrs in a day!

Cheers
Atchi

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Re: Suspension lowering, angles and set-up

Post by Attack2001 » 17 Dec 2012 10:47 pm

Sounds good to me Atchi :) If you lead the way and get it sorted, everyone else can copy you :) I would have done it, but as said, im moving into the Lada scene, cos im cool that like that? haha :lol:

Thomas..........
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Re: Suspension lowering, angles and set-up

Post by miniswift » 17 Dec 2012 10:54 pm

Eee....What Lada?
Lada Riva?
You can fit Suzuki Swift 1300 16v Gti engine with Jimmny(SJ10/13) 5 speed gearbox to make it std 110ps with 40mpg!
I heard you can buy LSD to go drifting, too 8) .

I think an estate will be fun one to play with.

Cheers
Atchi

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