B13Birk
B13Birk GRM+ Memberand HalfDork
11/21/22 9:05 a.m.

As some of you know I am currently piecing together a 280zx challenge car. I have found that S13 (240sx) coil overs can be easily adapted to work on my Z. The Build So Far

My question is... How bad is good enough? I have ZERO experience with Chinese coil overs like Maxspeed and rev9 or even ones with ZERO brand name on the internet.  I have found a set of off-brand coilovers for $100 and I'm just curious what the Challenge Hive mind thinks about running this type of setup. Not saying these exact ones, even new Chinese ones are $200 on ebay. I know they are junk... But are they usable junk? What if the springs are swapped out to something more pro? Anyways... tell me what yall think? 

The other option I know is to run normal struts with Coilover sleeves. Does that tend to be a better option than a true coilover? 

BoxheadTim
BoxheadTim GRM+ Memberand MegaDork
11/21/22 9:15 a.m.

Unknown condition coilovers = three are blown, not sure about the fourth one and I can't tell the difference anyway?

My guess is that you'll be better off with stock shocks and sleeves, as long as the stock shocks are in decent shape. At least if you can't rebuild the coilovers yourself.

DeadSkunk  (Warren)
DeadSkunk (Warren) UltimaDork
11/21/22 10:08 a.m.

I ran Chinese sleeves and springs on my stock Miata Bilsteins a few years ago. The whole thing cost $40. The shocks were in good condition when I bought the car. Ended up tied for second at the Challenge autocross. I wasn't able to find cheap coil overs that didn't have at least one shock leaking.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/21/22 10:28 a.m.

The ones I tested had fundamental geometry problems that prevented them from being usable. Had the geometry worked, adding more pro springs would have just meant they were poorly damped - they managed to be both over and underdamped at the same time.

The springs are probably the most reliable part, as long as the metallurgy isn't total trash they'll easily last the Challenge.

Just drop it on to the bumpstops and pretend it's a kart. It's not like the Challenge involves any real roads :)

Stampie
Stampie GRM+ Memberand MegaDork
11/21/22 12:51 p.m.

In reply to Keith Tanner :

There's actually a significant dip in the north west corner of the autocross area. I'll have to look later but I'll try and find Pete's comments about it in my underdamped Q45. 

hobiercr
hobiercr GRM+ Memberand UltraDork
11/21/22 12:56 p.m.

I built a set of coil overs using a set of cheap eBay (found on CL for even less $$) and a set of closeout Gabriel private label struts off Rockauto (less than $3.00 each). Look hard before you buy potentially blown-up stuff.

Stampie
Stampie GRM+ Memberand MegaDork
11/21/22 6:04 p.m.
Pete Gossett said:

In reply to Stampie :

To expand on Stampie’s comment:

  • We had major issues with damping. That needs to be fixed first.

I took the first autox run so I could debrief our pro driver - for those not aware, we only get 4 pro driver runs per course, so we didn’t want to waste one of their runs if we needed to address issues with the car, or if there were certain “quirks” that we needed to warn them about. The power steering has also been deleted, and I wasn’t sure if it would cause problems on a couple right spots on course. 

Knowing that Stampie upped the spring rates significantly, but still had the stock shocks, I expected we may be underdamped, but I absolutely DID NOT expect what happened...

There was a rough patch of pavement at the end of a slalom into a tight left turn, which then crested the center of the lot, followed by a right. I expected there may be some washboard effect of the bumpy area, and there was. I was shuffle-steering to get setup for the right turn, when all of a sudden the steering went completely light. Keep in mind the deleted power steering, so when this happened the wheel went almost full-lock to the right. At that moment it grabbed & jerked the wheel hard back to the left. I pulled hard right to counter it, at which point the wheel when light again, going back to the right. It caught me completely off guard & was a complete bizarre experience. 

What we figured out was even though there’s no abrupt bump there, the seam in the pavement dropped a couple inches over a couple feet. The combination of speed, the crest of the lot peaking at the same point, and our blown shocks, caused the front tires to bounce like basketballs as we crossed this point. However, because the driving line was slightly different on the reversed afternoon course, it wasn’t nearly as much of a problem then. 

It easily cost us 2-seconds, even on Jon’s fastest run. It looks like that would have moved us up about 10 spots in AM runs. 

 

B13Birk
B13Birk GRM+ Memberand HalfDork
11/21/22 7:47 p.m.

All of your feedback has been very helpful. Thank you. Anyone else feel free to chime in. 

KyAllroad
KyAllroad MegaDork
11/22/22 9:11 a.m.

Any suspension design works if you don't let it move.   (Or something to that effect)

 

I dislike roll in an autocross car and want all the spring rate I can get. YMMV

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
11/22/22 3:28 p.m.

No-name-at-all coilovers are very questionable even by Challenge standards, but the good news is that if you're willing to gamble on them and put in the effort, you can try them out and if they're too awful, then you can switch to something else and there's no budget hit. Also keep in mind that at least 1 car has done well just running on the bump stops...

Andy Neuman
Andy Neuman SuperDork
11/22/22 4:01 p.m.

Just use washers as springs... ask the guys with the echo. Super stiff for autocross works except on the bump, a stock setup would probably work best for the drags. 

Toot
Toot New Reader
11/25/22 3:23 p.m.

I know a lot of people don't like max speeding coil overs but we have run them on 2 Miata's and a 350z and they worked really good for what they are.  I feel they would be better that great shocks and springs.  I'm basing this off my experience which I mostly have run feal and Olin's coil overs on Miata's and Porsche.  They will not last on a big track but for autox they will be fine 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/25/22 9:50 p.m.

In reply to Toot :

How did you get around the lack of rear bump travel on the Miata? Were you using them in a lifted application with oversized tires?

Toot
Toot New Reader
11/26/22 5:22 p.m.

In reply to Keith Tanner 

it's funny you ask.  I actually just took them out of the box and put them on on adjusted them down about 1".  Never had a problem with bottoming out on the miata at all.  The 350z had separate rear springs/ shocks.  I sold 2 Miata's with those on it.  1 for a drifter and 1 that has already done 2 8hr races.  Let me be clear they are not Olin's or feal but they worked better than the bilsteins at Sebring.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/26/22 6:33 p.m.

Then the geometry of yours was different than the geometry of the set I was sent. "Drop it down an inch" wasn't actually physically possible. If you had tried to race with my set at Sebring you would have pounded your spine shorter while getting passed by stock Miatas with blown stock shocks.

The damping was also obviously crap, but the constant slamming from the back overwhelmed that. 

Toot
Toot New Reader
11/26/22 11:23 p.m.

In reply to Keith Tanner :

I found the spring rate was to soft on the ones I tried.  Actually driving this miata (first time ever in a miata) made me park my m4 and build my own.  I drove that car for an hour straight at Sebring.  I don't want anybody to take this like they are good coil overs but I can tell you they are good enough for the $2000 challenge.  

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/27/22 2:09 a.m.

We'll have to agree to disagree on that one. In my experience, they would have been a waste of good budget on a Challenge build.

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