BC Racing BR Coilover Issue

[spadz93]

Maybe I just don't have these set up properly, but I can't seem to dial them in where I don't bottom out and scrape going over the slightest of divots in the road. I tried setting the dampening cranked up the way, preload set to 5mm, and the cars only dropped maybe 1"-1.25" from stock height. Am I set too low? Do i need to crank up the pre-load to something closer to .5-.75"? They're newer too, just installed back in February.

[VR Baron]

My old Pedders preload was 10mm. Same drop as yours roughly, no issues. And I think same spring rates. Recheck to be sure preload proceedure was done correctly. I did hand tight then 10 mm more.

[spadz93]

Originally Posted by VR Baron

My old Pedders preload was 10mm. Same drop as yours roughly, no issues. And I think same spring rates. Recheck to be sure preload proceedure was done correctly. I did hand tight then 10 mm more.

So you ended up with 20mm? Guess I shouldn't be shy

[VR Baron]

Originally Posted by spadz93

So you ended up with 20mm? Guess I shouldn't be shy

No, hand tight then 10 mm more.

[spadz93]

Originally Posted by VR Baron

No, hand tight then 10 mm more.

Gotcha. Ill move up to 10mm and see if that helps

[VR Baron]

Originally Posted by spadz93

Gotcha. Ill move up to 10mm and see if that helps

Give it a try. I had printed bc instructions years ago and they had a different method but it ended up the same I think. Also at one time there had been rear seal leaks that were fixed, but 10 mm helped reduce the risk. Then on height try not to go below 660 mm measured from lower wheel lip to fender arch at the rear,

[KillboyPowerhead]

I have the BR series and never had an issue with the recommended 4mm preload. Only bottomed out once so far (after ~10,000 km) on a big pot hole. 8kg springs in the front.

What's your ride height? I'm somewhere around 1 - 1.25" lower than stock (basically the bottom of the fender and top of the tire are flush/same height; 275/40/20 tire).

[spadz93]

Originally Posted by VR Baron

Give it a try. I had printed bc instructions years ago and they had a different method but it ended up the same I think. Also at one time there had been rear seal leaks that were fixed, but 10 mm helped reduce the risk. Then on height try not to go below 660 mm measured from lower wheel lip to fender arch at the rear,

I'm at about 10mm now and it's much better, but my dampening is all the way cranked still. Think I'm going to shoot for 15 and back the dampeners off a bit.

Originally Posted by KillboyPowerhead

I have the BR series and never had an issue with the recommended 4mm preload. Only bottomed out once so far (after ~10,000 km) on a big pot hole. 8kg springs in the front.

What's your ride height? I'm somewhere around 1 - 1.25" lower than stock (basically the bottom of the fender and top of the tire are flush/same height; 275/40/20 tire).

Same ride height, but 315 in the back and 295 in the front (10mm wider than stock zl1)

[VR Baron]

Originally Posted by spadz93

I'm at about 10mm now and it's much better, but my dampening is all the way cranked still. Think I'm going to shoot for 15 and back the dampeners off a bit.



Same ride height, but 315 in the back and 295 in the front (10mm wider than stock zl1)

I wouldn’t do 15 on preload. Only thing may do is make ride stiffer. You shouldn’t have these issues. Only thing is to go through proceedure again to be sure it’s right. Then set shocks in middle. Again, for ride, handling, axel protection and ground clearance, don’t lower more then 26” from lower wheel lip to top of fender arch.

And this may sound dumb, but make sure you aren’t going the wrong way on the adjusters, easy to get turned around and turn the wrong way if not paying attention.

[spadz93]

Originally Posted by VR Baron

I wouldn’t do 15 on preload. Only thing may do is make ride stiffer. You shouldn’t have these issues. Only thing is to go through proceedure again to be sure it’s right. Then set shocks in middle. Again, for ride, handling, axel protection and ground clearance, don’t lower more then 26” from lower wheel lip to top of fender arch.

And this may sound dumb, but make sure you aren’t going the wrong way on the adjusters, easy to get turned around and turn the wrong way if not paying attention.

I also raised up two corners that were slightly lower than the others to try and even it out, but only by a quarter inch. I don't really think my car is that low, but I'll measure. If I added more preload, and the problem subsided, wouldn't that mean I was heading in the right direction? Maybe I won't go to 15mm, but 12-13mm sounds like it could help. I just don't feel like having the dampeners cranked up all the way is the right way to have this set up

[VR Baron]

Originally Posted by spadz93

I also raised up two corners that were slightly lower than the others to try and even it out, but only by a quarter inch. I don't really think my car is that low, but I'll measure. If I added more preload, and the problem subsided, wouldn't that mean I was heading in the right direction? Maybe I won't go to 15mm, but 12-13mm sounds like it could help. I just don't feel like having the dampeners cranked up all the way is the right way to have this set up

You shouldn’t have to do more then 10. Even 5 doesn’t do that much difference. As to height it’s not cast in stone. The rears as I said you need to becareful. Mainly for the extreme angle of the rear axles. The grease gets hot and can run out of the boots, wrecking the axles, at high speeds or racing all the time. The fronts keep at 26”, or up to 3/8” lower then the rears, to keep factory rake if you like. That’s measured on a 1/4 tank of gas. Full tank the car will settle in the rear 1/8”.

It all sounds odd. Or maybe the coilovers are bad, but without being there hard to say

And did you retime the suspension bushings? Though that would be more of a bad bouncy ride, more then bottoming out. But if not timed to new lower height, the bushings could actually hold the car up and not let it settle down . And when you time them, the car will lower more

[spadz93]

Originally Posted by VR Baron

You shouldn’t have to do more then 10. Even 5 doesn’t do that much difference. As to height it’s not cast in stone. The rears as I said you need to becareful. Mainly for the extreme angle of the rear axles. The grease gets hot and can run out of the boots, wrecking the axles, at high speeds or racing all the time. The fronts keep at 26”, or up to 3/8” lower then the rears, to keep factory rake if you like. That’s measured on a 1/4 tank of gas. Full tank the car will settle in the rear 1/8”.

It all sounds odd. Or maybe the coilovers are bad, but without being there hard to say

And did you retime the suspension bushings? Though that would be more of a bad bouncy ride, more then bottoming out. But if not timed to new lower height, the bushings could actually hold the car up and not let it settle down . And when you time them, the car will lower more

Going from 5 to 10 made a world of a difference. Also I did time the bushings. I'd really hate to think 3 month old coilovers would go bad already, with less than 2k on the clock too

[VR Baron]

Originally Posted by spadz93

Going from 5 to 10 made a world of a difference. Also I did time the bushings. I'd really hate to think 3 month old coilovers would go bad already, with less than 2k on the clock too

Yeah that’s true. But made in China now. Them and Pedders. Try calling bc. Though they are hard to get ahold of.

[spadz93]

Just wanted to pop back in here. I ended up setting the pre-load based on overall spring legnth. IE, the 170mm springs I compressed down to about 158mm, and the 180mm springs i compressed down to about 168mm, so about 12mm preload all around. The car drives great, handles great, and significantly less if not no more bottoming out.

Going this route seems to be a bit more concrete as there's no guesswork in finding where 0mm preload is, which I feel may have been my problem (i think what I thought was 0mm preload was less than 0mm, so what I thought was 10mm preload was maybe more like 5 or 6mm). Because of this, I may lower to 10mm preload and see if I can get away with it, but for the time being, I'm happy.