Front Droop travel - KW CS vs. TC Kline Racing Smart Design Coilover

[Master Apex]

The front droop travel on KW CS is ~1.5".

Does anyone know the front droop travel on TC Kline Racing Smart Design Coilover?
http://www.tcklineracing.com/suspension.htm

I am experiencing inside wheel lifting on the front wheels (at extreme lateral-g with R-compound), I think it has to do with the limited droop travel but want to know whether TC Kline Coilover has more droop travel than my current KW CS.

Thanks.

[Master Apex]

Droop travel is the difference between static height and the jack-up height so it tells us how much the suspension can travel down / droop.
1) measure "A" , distance (ride height) between the bottom wheel to fender line.
2) Jack up the front side until the tire is in the air, measure "B", new distance (ride height) between the bottom wheel to fender line
"B" - "A" = Droop travel.

This link shows the idea, but he does the distance from center wheel to fender line.
http://www.fromsteve.net/tech/Determ...-Travel-Damper

[mfanatic325]

I can measure this for you sometime soon, since I have TCK D/A's installed (just got back from a track day with them). But doesn't the static height depend on each person's height adjustment?

i.e. if you're comparing "static" vs. the jack-up to find the delta
But since each person's static is different, wouldn't that not be a very good comparison?

[Master Apex]

On my car (with KW CS and stock sway bar):
-lifting one side or both side, does not alter the measured front droop travel
-changing the ride height +0 , -0.5" from stock height (via moving the perch), does not alter the measured front droop travel.

I don't have experience with other coilover, that was the reason I asked for comparison.
Thanks

[mfanatic325]

Oh you know what, you're right. Now that I think about it, my TCK D/A's don't have twisting body for height-adjustment. Therefore, there's no bottom perch in question. Meaning the height that I'm adjusted to should not make any difference whatsoever in terms of droop-measuring differences/variations.
I will check on this sometime soon. My friend is currently borrowing my floor jack, so I will have to get that back from him. Otherwise I'd have to go into my shop. We'll see. Will report back with my findings.

[mfanatic325]

Okay, just measured my 'A' and 'B'.

'B' came out to 25.25 inches
'A' came out to 23.5 inches

'B' - 'A' = 1.75 inches

Hope that helps

From some research that I did a few weeks ago, I found that some aftermarket coilover companies incorporate a separate pre-load system and allow the shock body area itself to twist/turn for height adjustment (separate pre-load and height). This has the advantage of potentially allowing suspension travel even if ride height is lowered.

As for systems like my TCK D/A and seemingly your KW CS, we do not have a separate height adjuster, in which case if we happen to lower the car too much, then there would most likely be insufficient suspension travel. If that happens, then theoretically, we would hurt handling as opposed to improving it.
However, a local race shop (where I got my TCK's corner-balanced and custom-aligned) informed me that typically only higher-level racing will the difference in system design really matter, which is why a decently high-end company such as KW and TCK do not incorporate separate adjustments. That it is only a gimmick for cheaper coilover companies to try and grab sales, etc.
I'm not certain of the credibility, but there's no reason for the shop owner to lie to me, as he wasn't selling me the coilovers or anything. I merely asked for his expert opinion, etc.
He apparently used to be a sponsored ALMS driver back in the day, before the economy took a dump, and a lot of sponsorships pulled out last minute. He ended up opening his race shop instead =]
He also told me that he charges somewhere along the lines of $800 an hour for track instructing, and that he doesn't usually work with noobs (that would be me LOL!)

[krnnerdboy]

I really doubt that your wheel lift is due to lack of droop/travel. It's more related to sway bar and spring rate. your sway bar is limiting the amount of droop in a turn....I'm pretty sure your problem can be solved w/ correct spring rates to your setup

[mfanatic325]

Originally Posted by krnnerdboy

I really doubt that your wheel lift is due to lack of droop/travel. It's more related to sway bar and spring rate. your sway bar is limiting the amount of droop in a turn....I'm pretty sure your problem can be solved w/ correct spring rates to your setup

Good point. Now that I think about it, it poses a question. If for instance we upgrade the stock sway bars to something stiffer, wouldn't that induce more inside wheel lift upon cornering? Or is it the opposite: reduce wheel lift, since the bar is so stiff?
Logically, I would think the aforementioned, rather than latter
I'm u sing my MR2 as personal experience, albeit what I'm thinking of has to do with going up driveways, in which my outside wheel would lift since my ST sway bars were very stiff. I'd three-wheel all the time. But this outside wheel lifting at low speed is totally irrelevant I'm guessing, compared to inside wheel lifting at high speeds?

[Master Apex]

Originally Posted by mfanatic325

Okay, just measured my 'A' and 'B'.

'B' came out to 25.25 inches
'A' came out to 23.5 inches

'B' - 'A' = 1.75 inches

Hope that helps

It does....Thank You very much for taking the time and doing the measurement.

This confirms what I have heard from others that the aftermarket performance coilover for Z4M does reduce the droop travel.
From what I heard about shock dyno design, it is easier (cost effective) to control over shorter range of travel so may be the KW CS and TCK d/a are improving the suspension "control" at slight expense of the travel.

The stock front has low droop travel to begin with, only 2.5" so at 1.5" (in my setup), the inside wheel lifting may be expected.
Both the stock and aftermarket rear has a lot more droop travel, I am not experiencing any inside wheel lifting with the rear.

With Z4M limited front droop travel and the camber roll that can go positive, it may make sense that a stiffer front sway bar will actually reduce understeer rather than add understeer (known response on typical setup).

[Master Apex]

Originally Posted by mfanatic325

Good point. Now that I think about it, it poses a question. If for instance we upgrade the stock sway bars to something stiffer, wouldn't that induce more inside wheel lift upon cornering? Or is it the opposite: reduce wheel lift, since the bar is so stiff?
Logically, I would think the aforementioned, rather than latter
I'm u sing my MR2 as personal experience, albeit what I'm thinking of has to do with going up driveways, in which my outside wheel would lift since my ST sway bars were very stiff. I'd three-wheel all the time. But this outside wheel lifting at low speed is totally irrelevant I'm guessing, compared to inside wheel lifting at high speeds?

If you turn right, then the front inside wheel is the right side, while the car is leaning to the left. So it is not likely that the left (outside) wheel is lifting since it is under compression.
Stiffer bar will force the inside wheel to lift (typical response) since the outside is under compression. So your MR2 experience is relevant, one side of the wheel is compressed so the other is being pulled up...

[mfanatic325]

So if you go with a stiffer front sway bar, wouldn't the inside wheel lift even more?

[krnnerdboy]

Originally Posted by mfanatic325

So if you go with a stiffer front sway bar, wouldn't the inside wheel lift even more?

that's questionable b/c if the bar is stiffer than the aforementioned outside spring rate should also be stiffer since the stiffer bar is allowing more of the insides spring rate to transfer to the outside. I think a stiffer spring rate is in order since you are running r comps. I really doubt droop travel is the limiting factor here. EG: have you ever lifted your front 2 tires off the ground simultaneously? does your car lift the inside tire that much?

All this travel talk is making me think I'm in an offroad suspension forum

[Master Apex]

I agree that the stiffer sway bar does add roll stiffness such that the reduced roll could reduce the inside wheel lifting.
However, if the spring is not stiff enough, the weight shift could still exceed the new stiffness, then it will make the inside wheel lifting more.

I don't know what the situation is with my case , only experiment can tell.

[mfanatic325]

For now, I'm going to stick with my OEM sways. Until I can outdrive the car

[krnnerdboy]

I'd give kw a call to get specified spring rates or you can always call up ground control. They are a local shop that can talk suspension all day. They can probably even set you up w/ a custom spring rate

[Master Apex]

Good idea..I will contact KW.

This guy did a good journal on his E36 modification and he had low droop travel on the rear (35mm = 1.5") but was able to increase it via shock mount modification, not quite sure I fully understand the new mount. http://www.steerbythrottle.com/hccyo...suspension.htm

[mfanatic325]

I put in Rogue Engineering rear shock mounts. Maybe the guy was referring to the inverted (upside-down) shock mount?

[Master Apex]

After talking and looking at other cars taking on the same corners where my Z4M has front wheel lifting, it seems like the Z4M does not have excessive roll but the front inside wheel lifting is really due to the small 1.5" front droop travel on KW coilover. The rear has almost 3" so there is no issue with wheel lifting in corner.
mfanatic325 TCK D/A coilover also has only 1.75" front droop travel, I wonder what trade-offs are being made to make the front with such a short droop travel.
See the following pictures comparing the cars at the same corners, do you think my Z4M lean excessively (need front sway bar)?
Z4M:
http://www.hart-photography.com/phot...wImage=1144106

Z3M:
http://www.hart-photography.com/phot...wImage=1144105

GT-R:
http://www.hart-photography.com/phot...wImage=1144004

M3:
http://www.hart-photography.com/phot...wImage=1144030

Chasing Race M3:
http://www.hart-photography.com/phot...wImage=1144454
http://www.hart-photography.com/phot...wImage=1144455
http://www.hart-photography.com/phot...wImage=1144456

[mfanatic325]

Hmm interesting. But honestly, looks about the same as the GTR and M3. Z3M probably has less lift on the inside cuz it's lighter?
In any case, it's not as bad as I had thought from when you originally posed the issue. At least your tire is still on the ground plenty haha.
If it really bothers you, then maybe adjust the front coilovers and see if it helps?

[Master Apex]

Thanks for the comments and kindda agree with your observation from the photo.
However, the inside wheel lifting was so quick that it is not captured in any of the photo.

Anyway, just sharing the pics to show body roll comparison and the limited droop travel on the front suspension.

[BookerM3]

I am pretty sure that the lifting of the inside front wheel issue you are
concerned about is occurring after the apex of the corner, under
acceleration. In this situation front wheel lift is usually associated to weight
transfer to the outside rear wheel. (your can actually see this in you pics.)

Stiffness the rear suspension (via Spring rate / Sway bars / Shock valving)
will limit the weight transfer and resolve this situation. As mentioned,
the front travel is limited by the front sway bar preload. Progressive /
lower rate springs used in the stock / performance street suspensions
potential have this issue as part of a compromise, in order to maintain
driveability under street use.

If you just increase rear roll stiffness / decrease weight transfer it should
cure this, however in order to maintain balance and keep the car driveable
you will need to adjust the front suspension to be in line with the changes
made to the rear.

Front drive cars have similar issues however associated corner entry inside
rear wheel lift again this is associated to weight transfer to outside front wheel.
This can be more difficult to solve given the weight bias to the front.

The Z4M Coupe with its close to 50/50 weight distribution it is quite easily
addressed, the question is how streetable will it be...