TC kline DA coilovers and coil bind

[hC1001]

Anyone getting bottoming out in the front due to coil bind? I have 350lb/in springs in the front and im at 4 clicks from full soft on compression. Noticed it on the highway when i hit a sharp sewer cement edge sticking out a little bit(like a 2" step). I would imagine it would be more apparent in the 300lb/in front kits they currently sell now.

I can see the marks on my springs indicating full compression. Gonna see if increasing bump 1 click will help but wanted to know if anyone else had experienced this. The recommended street settings are 2 clicks from full soft.

Thanks.

[M3SQRD]

How much have you lowered the front? IIRC, TCK DA front dampers have less bump travel than most dampers (e.g., MCS, JRZ, Moton, etc.). I doubt you’re experiencing coil bind; instead, you’re likely hitting the bump stop. The effective spring rate ramps up rapidly to “infinity” when you hit the bump stop. Try moving the bump stop to the top of the piston rod (i.e., upper spring seat on camber plate). After driving check to see how far down it has moved on the piston rod and whether it is contacting the top of the strut. If it is then you’re riding on the bump stop. The F 350 lbf/in VVS spring probably has at least ~5” of travel before it coil binds.

[hC1001]

Originally Posted by M3SQRD

How much have you lowered the front? IIRC, TCK DA front dampers have less bump travel than most dampers (e.g., MCS, JRZ, Moton, etc.). I doubt you’re experiencing coil bind; instead, you’re likely hitting the bump stop. The effective spring rate ramps up rapidly to “infinity” when you hit the bump stop. Try moving the bump stop to the top of the piston rod (i.e., upper spring seat on camber plate). After driving check to see how far down it has moved on the piston rod and whether it is contacting the top of the strut. If it is then you’re riding on the bump stop. The F 350 lbf/in VVS spring probably has at least ~5” of travel before it coil binds.

Im about 3/4" lower from stock. I thought i was hitting the bump stops too and called TC Kline to see if it was okay to trim 1/2" off and they said i was most likely getting coil bind and trimming the bump stops wouldnt help. They recommended i dont hit bumps or i can buy 400# front springs.

Im gonna try trimming the bump stops.

[M3SQRD]

Originally Posted by hC1001

Im about 3/4" lower from stock. I thought i was hitting the bump stops too and called TC Kline to see if it was okay to trim 1/2" off and they said i was most likely getting coil bind and trimming the bump stops wouldnt help. They recommended i dont hit bumps or i can buy 400# front springs.

Im gonna try trimming the bump stops.

Do you know the length of the spring? I’m guessing it’s at least a 6” long spring for a 350 lbf/in spring. I’m running a 600 lbf/in F spring that’s 5” long with my MCS 2WR setup on my M4, and a 400 lbf/in F spring that’s 6” long on my MCS 2WR setup on my 240ix. MCS remote reservoir dampers use a shortened strut body and the tire will touch the inner liner before coil bind occurs. I’m lowered 3/4-1”. I find it hard to believe you’d encounter coil bind unless the spring is only 4” long. Why do they offer a 350 lbf/in spring if it severely limits suspension travel? Doesn’t make sense.

[hC1001]

Its a 7" spring. I think your right and my initial thought that i was bottoming out on the bumpstops were correct. The front struts look like they need to be shortened if i want to drop the car more than 3/4". I understand keeping the height close to stock is better for suspension geometry but 3/4" isnt asking a lot. Will take a pic of the loaded strut and spring. I have about 1 1/4" of shock travel b4 the bumpstops make contact.

[hC1001]

Im gonna trim the bumpstops 1/2". The springs do look like they have a little more travel then the shock. Heres some pics of the loaded spring and wheel gap:



Thanks again.

[Malakas]

Call up TCK, he typically answers straight away... he could likely give some good advice

[hC1001]

I did. Read post 3. I told them i was bottoming out on the bumpstops and if it was okay to trim them. They said i wasnt and it was coil bind. They recommended i dont hit bumps or buy 400# springs. It didnt make sense to me because i wasnt getting coil bind when the car was 1/4" higher.

Anyways, im going to trim the bump stops 1/2".

[M3SQRD]

Definitely looks like you’d hit the bump stop before the spring tuns out of travel. However, be careful, the Koni dampers have limited travel. You don’t what the internal shim stack contacting the bottom of the strut.

[hC1001]

Originally Posted by M3SQRD

Definitely looks like you’d hit the bump stop before the spring tuns out of travel. However, be careful, the Koni dampers have limited travel. You don’t what the internal shim stack contacting the bottom of the strut.

I agree, i've heard of other ppl destroying the internal shims because they removed the bumpstops which was why i wanted to double check with TC Kline but they did not believe me... Maybe i will start with trimming 1/4" off and see how it feels.

[M3SQRD]

Originally Posted by hC1001

I agree, i've heard of other ppl destroying the internal shims because they removed the bumpstops which was why i wanted to double check with TC Kline but they did not believe me... Maybe i will start with trimming 1/4" off and see how it feels.

I’d recommend marking where the bump stop is on the piston shaft, remove the bump stop and then compress the piston rod to see how far it compresses. Then measure the distance between the original and compressed marks to the top of the strut. That’ll give you the max piston travel and then you can determine how much of the bump stop to remove. Also, remember the bump stop will compress before reaching its max stiffness. I’d conservatively assume at least a 1/4” of compression.

[The Choosey begger]

This is the reason why i wont buy TC Kline products anymore, i had this very issue with my E92 M3.

You can buy the black and yellow radial bearings from GC and hat, that'll fix your problem!

TC's camber plates dont come with radial bearings, only come spherical bearings.

You need both spherical and radial bearings for the camber plates to work properly.
Vorshlag and GC camber plates come with both!

[DavidStr]

Really seems you are running out of travel.
Relatively soft spring is not helping.

[hC1001]

Originally Posted by DavidStr

Really seems you are running out of travel.
Relatively soft spring is not helping.

It seems like the real issue is the struts. They are too tall and need to be shortened.

I have GC plates. I dont have any issues when turning, just bottoming out on bumpstops.

[hC1001]

I still want to lower the front another 1/4" but ill just live with it.

[M3SQRD]

Originally Posted by hC1001

I still want to lower the front another 1/4" but ill just live with it.

You’re definitely lowered more than 3/4” on the front. It looks like there’s about 1” of piston travel before the bump stop contacts the top of the strut. With TCK Koni dampers you’ll need to run higher spring rates if you want to run that ride height. I’m not sure a 400 lbf/in spring will solve the problem at that ride height because it’ll reduce dynamic displacement by only 12.5% compared to a 350 lbf/in spring. A 500 lbf/in spring might not be enough - it’ll take a 500 lbf dynamic load to hit the bump stop. For a ~3,600 lbm car, it’s possible to develop a 500 lbf load per corner which is only a ~0.5 G vertical acceleration.

[hC1001]

Originally Posted by M3SQRD

You’re definitely lowered more than 3/4” on the front. It looks like there’s about 1” of piston travel before the bump stop contacts the top of the strut. With TCK Koni dampers you’ll need to run higher spring rates if you want to run that ride height. I’m not sure a 400 lbf/in spring will solve the problem at that ride height because it’ll reduce dynamic displacement by only 12.5% compared to a 350 lbf/in spring. A 500 lbf/in spring might not be enough - it’ll take a 500 lbf dynamic load to hit the bump stop. For a ~3,600 lbm car, it’s possible to develop a 500 lbf load per corner which is only a ~0.5 G vertical acceleration.

I think the pic with the new wheels on might be deceiving. I mounted the new wheels without any changes to suspension since i took the pic of the stock wheel a couple days before. The new front wheel has a 265/35/19 tire which is ~.3" taller than the stock wheel so it might look lower because its filling in the wheel well more. On the stock wheels the front rocker panel was ~5 3/8" from the floor. I didnt take the height of stock suspension though =\. Thanks for all your help I'll see how the trimmed bumpstops work out. Worse case scenario, i add a little more compression or i raise the car up a little.
Here is a pic of stock suspension(non ZCP) for reference:

[AlterZgo]

Why do people want good ride quality, then choose light spring rates, then slam the car and expect the suspension to somehow defy the laws of physics?

What I have found is it is best to only modestly lower the car and, seems counter-intuitive, but running higher spring rates often IMPROVES ride quality b/c it keeps the car off the bumpstops. As M3SQRD states, once your car runs out of suspension travel, spring rate basically goes to infinity.

So if you're really going to drop your car that low, step up to much higher rate springs to keep the car off the bumpstops. When you've slammed the car, trimming the bumpstops 1/4" or 1/2" isn't going to keep the car off what's left of the bumpstops.

If you want to have your car slammed that low, get bags or have your shocks properly shortened so that you can get back some suspension travel. I doubt TC Klines are designed to be slammed that low. Just because the threads on the coilover lets you slam the car over 2" doesn't mean it's a good idea to do so.

[hC1001]

Originally Posted by AlterZgo

Why do people want good ride quality, then choose light spring rates, then slam the car and expect the suspension to somehow defy the laws of physics?

What I have found is it is best to only modestly lower the car and, seems counter-intuitive, but running higher spring rates often IMPROVES ride quality b/c it keeps the car off the bumpstops. As M3SQRD states, once your car runs out of suspension travel, spring rate basically goes to infinity.

So if you're really going to drop your car that low, step up to much higher rate springs to keep the car off the bumpstops. When you've slammed the car, trimming the bumpstops 1/4" or 1/2" isn't going to keep the car off what's left of the bumpstops.

If you want to have your car slammed that low, get bags or have your shocks properly shortened so that you can get back some suspension travel. I doubt TC Klines are designed to be slammed that low. Just because the threads on the coilover lets you slam the car over 2" doesn't mean it's a good idea to do so.

Have you seen the ride height in post 6? Its 3/4" lower than stock. The adjustment collar is in the middle of the threads on the struts. I dont consider it slammed or in need of airbags. I dont even have any clearance issues and i have a front lip. Almost all lowering springs have more of a drop. All coilovers have a minimum drop of .5 to 1"

TC Kline instructions are to adjust front height and leave at least 1" of space between bumpstop and top of strut. I have about 1.25" of space. The issue is with the design of the setup. It would've been better to shorten the struts by an inch.

[rborane]

That definitely seems like not enough travel before you hit the bump stops? They sell the kits like this? Have there been any other issues? I am in the market for coilovers, and was just on their site the other day

[hC1001]

Originally Posted by rborane

That definitely seems like not enough travel before you hit the bump stops? They sell the kits like this? Have there been any other issues? I am in the market for coilovers, and was just on their site the other day

Trimming the bumpstops helped a little but its still bottoming out.

This TCK DA coilover kit was one of the earlier versions . 60mm 350#F and 2.5" 600#R, rear rebound is not adjustable without disconnecting the rear shock mounts and there is also knocking noise from the front struts at low speeds.

Ive owned bilstein pss9, h&r, and kw v3 coilovers on other cars and the dampening is really good on these shocks. Its true these shocks can be setup comfy like stock with little body roll. I also think the stock non edc suspension is great on the car too. Havent gotten a chance to try the TCK coilovers on the track due to covid19.

[rborane]

Originally Posted by hC1001

After trimming the bumpstops i havent had anymore bottoming out.

This TCK DA coilover kit was one of the earlier versions . 60mm 350#F and 2.5" 600#R, rear rebound is not adjustable without disconnecting the rear shock mounts and there is also knocking noise from the front struts at low speeds.

Ive owned bilstein pss9, h&r, and kw v3 coilovers on other cars and the dampening is really good on these shocks. Its true these shocks can be setup comfy like stock with little body roll. I also think the stock non edc suspension is great on the car too. Havent gotten a chance to try the TCK coilovers on the track due to covid19.

Have they revised anything with the current versions to prevent this issue? How has your experience been with TCK otherwise? I am in the market for coilovers so trying to get some feedback on different setups