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Discussion Starter #1
I recently installed some Tein Type Flex coils I got new from Japan and I'm getting quite a bit of bounce out the rear. I installed them as they came assuming they were spec'd from the factory for install. When I let down the car the rear was a bit tall for my liking so I jacked back up, released the lower ring and twisted the threaded body down to reduce the height. When I let the car down again it looked a bit lower (still not as low as I would've liked) and I took the car for a test drive. It was very bouncy so I checked the dampening and it was set to fully hard so I went to the lowest setting but nothing has changed.

When I checked the US manual (the Japanese manual is pretty useless as I don't know the language) all measurements except 1 were different to factory spec. In the pic below "D", for the rear, on my coils is approximately 8 inches as opposed to the 7.3 inches listed. Can any of the suspension gurus tell me what effect this would have on the ride quality and what do I need to do to get rid of the bounce?



Thanks in advance guys...

CL7-R

P.S. - I'm getting a thump primarily from my left rear...sounds like it's coming from the top mount.
 

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Let's start the answering process with a question, have you ever owned a lowered car before or is your complaint coming from a fairly new perspective?

I ask this question because I just installed a set of "Flex" on my 06' and although the springs are softer then I would normally like I wouldn't call it bouncy I'd just call it soft. The US market Flex are intended to be for "fatties" and only ship with an 8K spring so without anyone in the backseat I could see the rebound of the shock being a bit more than most would like but it is a 4 door vehicle and that infers rear passengers at some point that the suspension needs to accommodate.

Let us know a little bit more about your perspective and maybe we can help with your expectations. Oh, and the "thump" is probably the sound of the coil binding, spring to spring rubbing, but it's not something to worry about and you can minimize it by threading rubber hose around the coil to buffer the issue.

J.
 

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Discussion Starter #3
Thanks for your response J. Yes I've owned lowered cars before and I've had experience with Teins as well just that those experiences were long before the days of the Type Flex and Mono Flex. I had tein S-techs on TRD shocks (in my Toyota days), I've had Tein HR Coils on another Toyota and I've had the S-techs and Neuspeed Konis on my current car but they became noisy with a lot of clunking and I decided to change them.

My HR's never clunked but I did expect the rear to ride firmer with the higher spring rate. My thing is I've read through quite a few forums and there are persons who have installed with no problems and some have experienced similar problems but I can't seem to get a concrete reason for the thumping. Some postulate that it is the top nuts that need tightening and others suggest it's the pre-load settings. The thumping occurs on rebound which suggests to me that the spring is forcing the shock down at a much quicker rate than dampening would allow when the dampers are set to fully soft. I dialed in some dampening in the rear, 8 clicks from soft to be exact, and the thumping only now occurs at very low speeds which might very well mean that the damper is now slowing the rate of return caused by the spring releasing its tension.

I have an engineering background so I have an understanding of how these things should work but I'd just like to gain more insight on pre-load and it's effects. If I back off the rings under the spring, i.e. lower the spring seat, what will the outcome be?
 

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Discussion Starter #5
Check the Preload make sure its within spec.
Thanks for the advice ES. I went at the preload yesterday and took more measurements. Like I mentioned in my first post the distance "D" in the pic I posted is out of spec by about 0.7 inches. When I tried to adjust the spring perch I could only get the locking ring to move. The ring for the spring seat would not budge. I mean honestly, I'm a big dude, i weigh in at 265 and I'm 'relatively' strong but for the life of me I could not get the spring seat to move. I was fearful that if I exerted too much force I would either hurt myself or damage the shock so I decided to leave it till the weekend when I can remove the entire shock and work on it.

My question is, will spinning the ring down the threaded body to the base of the shock bring it back into spec or do I have to do a combination of movements between that ring and the height adjusting locking ring.

CL7-R
 

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The distances marked on the diagram should not change whether the shock is on the car or not, as they are all referenced to the top of the shock body to various points on the shock.

The difference of 8" vs. 7.3" would mean that your car is not lowered as much as the "standard specs". Can you confirm that your spring is not loose when the shock is fully extended? If so, then, you have some preload. As EuroSpec suggested, check the preload. You may need a spring compressor to move the spring perch. If there is a significant amount of preload, you will have a hard time turning the perch.

I think that you may either have too much preload = too high spring rate or shock adjustment is not working thus you are not able to reduce adjust the stiffness of the shock.
 

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The distance of "D" will only be adjust by the movement of the shock clockwise motion. The two collars above "C" are the preload adjusters. Loosen the spring all the way, and then re tighten to about 10-15mm of preload. I think the preload is out of back because nothing else will control the rebound on the these coilovers.
 

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Discussion Starter #8
The distances marked on the diagram should not change whether the shock is on the car or not, as they are all referenced to the top of the shock body to various points on the shock.

The difference of 8" vs. 7.3" would mean that your car is not lowered as much as the "standard specs". Can you confirm that your spring is not loose when the shock is fully extended? If so, then, you have some preload. As EuroSpec suggested, check the preload. You may need a spring compressor to move the spring perch. If there is a significant amount of preload, you will have a hard time turning the perch.

I think that you may either have too much preload = too high spring rate or shock adjustment is not working thus you are not able to reduce adjust the stiffness of the shock.
The distance of "D" will only be adjust by the movement of the shock clockwise motion. The two collars above "C" are the preload adjusters. Loosen the spring all the way, and then re tighten to about 10-15mm of preload. I think the preload is out of back because nothing else will control the rebound on the these coilovers.
Thanks to you both...yvr, the spring is not loose with the shock fully extended and I believe both of you are correct about the preload. I'm going to address this today and let you guys know the end result.

Thanks again...

CL7-R
 

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Discussion Starter #9
Adjusted the pre-load and the car is now riding perfectly. Only thing is I now have to either raise the car back up a bit or lower the front...decisions decisions...lol. I'm really impressed with this setup and how my handling has improved over the previous Koni/S-tech setup. No more axle tramping, turn in is so crisp and precise, I can go into corners a little harder, brake later, exit faster...I love it.

Thanks to everyone who replied to my post.

CL7-R
 
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