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I just installed my 6 piston CTS-v calipers up front with the ZL1 14.6” rotors (swapped from my 5th gen 4 piston setup). I did the brake pad bedding/break in a few days ago (fresh Ferodo pads). It was a raining this weekend right after the brake swap and even though I had an auto-x event, with the wet track I didn’t get to try the brakes out under heavy braking. Yesterday, I took the car out to get a wash and it was a nice day so I decided to really get on the brakes to see how they feel. The brakes work awesome! My only complaint is now I am having the “low trac” light come on during every hard braking event. I am also experiencing even heavier nose dive now, which is most likely my “low track” condition as there is no weight over the rear.
In darths AFCO/UMI review, I talked about the issue I am having with the possible “spring bow” with the current 600lb springs up front. With the recent brake upgrade I am wondering if the upgrade to the 850lb spring UMI recommended for the spring bow would possibly help with nose dive issue I am having.
The car had a nose dive issue with the previous 4 piston setup just not as noticeable and pronounced as it is now.
The rear brake setup is still stock calipers with baer eradispeed rotors with some normal pads.
I am running the Strano sway bar setup front/rear as well.
I have attached some pics of normal sitting ride height and some hard cornering pics (sadly no hard braking ones)
Last edited by Chrisingermany; 09-27-2017 at 03:02 PM.
You might try dialing in a bit more compression damping on shocks and see if you get the OVERALL results that improve. As you know, stiffer springs will certainly help with front end travel, but #850 will probably be brutal over bumps. I have #725 fronts, and it is certainly an eye opener over street bumps.
He doesn't have compression adjustment only rebound, so that option doesn't exist for him.
I think you are experiencing the "low trac" from your front brakes overcoming the traction of the tires (not the rear tires) and your nose dive is because of your brake bias.
I autoX my car as well and have the UMI/AFCO setup.
Here is my experience... I have 4 pot front brakes Carbotech xp12 and had Carbotech AX rear pads. It would stop very well, but under a full hard brake it would rear wheel hop. Also under trail braking the rear would oversteer quickly. So I opted to change out the rear pads to Hawk HPS to effectively change the brake bias. Overall braking has suffered, nose dive increased and I get into ABS more readily. BUT, I get zero wheel hop and trail brake oversteer has been eliminated. I wish I had more rear braking than the HPS, maybe the HP+ would have been a better choice.
So my opinion your problem is related to brake bias. If you swap rear pads to something more aggressive you will improve overall braking and lower nose dive. Go too aggressive though and you will run into hop and trail brake oversteer.
You might try dialing in a bit more compression damping on shocks and see if you get the OVERALL results that improve. As you know, stiffer springs will certainly help with front end travel, but #850 will probably be brutal over bumps. I have #725 fronts, and it is certainly an eye opener over street bumps.
Yeah, as @00PewterSS stated no compression adjustment as Strano set that to what he preferred. Not super thrilled with the though of making the ride harshness increase but this car is not a daily so I may be able to deal with the increased spring rate.
Originally Posted by 00PewterSS
He doesn't have compression adjustment only rebound, so that option doesn't exist for him.
I think you are experiencing the "low trac" from your front brakes overcoming the traction of the tires (not the rear tires) and your nose dive is because of your brake bias.
I autoX my car as well and have the UMI/AFCO setup.
Here is my experience... I have 4 pot front brakes Carbotech xp12 and had Carbotech AX rear pads. It would stop very well, but under a full hard brake it would rear wheel hop. Also under trail braking the rear would oversteer quickly. So I opted to change out the rear pads to Hawk HPS to effectively change the brake bias. Overall braking has suffered, nose dive increased and I get into ABS more readily. BUT, I get zero wheel hop and trail brake oversteer has been eliminated. I wish I had more rear braking than the HPS, maybe the HP+ would have been a better choice.
So my opinion your problem is related to brake bias. If you swap rear pads to something more aggressive you will improve overall braking and lower nose dive. Go too aggressive though and you will run into hop and trail brake oversteer.
Again, my opinion based on my experience.
Thanks for the info. I am still running stock style pads on the rear and was afraid to get any more aggressive as I don't want to introduce wheel hop. I may have to play around with some pad material. I do have the 4 piston brembo setup for the rear waiting to go on but will have to wait until non c-clip axles are installed.
I did have an auto-x event this last weekend and I am in awe of these brakes now. once I got some heat in the rival-s tires there was zero "low trac" issues when getting hard on the brakes. I may have just been as you stated and the front may have been getting loose and not the rear. I still may go with stiffer springs over winter and try them in the spring as there is only one more event here this year.
I'll attach a vid of a ride I gave to one of the spectators. Not my fastest run of the day but the old guy riding had a good time. Track was still a little damp as well. Was pushing a little too hard a few times.
Brake dive is ultimately due to front spring rate. Rear rebound (or a lack of it) can make it a faster transition which makes it feel like the car is "flopping onto the nose". Soft springs can "toss" the rear end upwards; stiffer rear springs will reduce rear lift which reduces the total pitch of the car, but can also cause other issues (you may want a lower rate rear anti-sway bar, for example). Stiffer rear springs are not exactly the same as reducing front brake dive, but it still limits the total attitude change of the car.
In addition, changing the piston area, floating vs fixed pads, and effective rotor radius alters the stock brake balance. Ideally you want to keep the percentage close but not go too aggressive in the rear to avoid axle hop.
I had used some cheap knock-off rear pads for many years because I was scared of increasing rear brake force too much and adding axle hop. Stopping always had a nose dive and stopping in rain was not as reassuring as I desired.
Last year I went through a process of trying 3 or 4 rear pad compounds that you can get from a local parts store. Using the DOT pad codes stamped on the pads, I went from the lowest coefficient of friction (EE) to the highest I could find at a store (GG). I stayed with the GG compound as it caused a noticeable improvement on the street with street tires, both in dry and wet performance. The GG compound I chose was the Akebono ASP750's, it was originally mated with C6 G-Loc R6 pads in the front. I switched to Carbotech 1521's now, but they're not what I want either. Hard to find a front pad I'm truly happy with all around for street use, the closest is probably the DS2500. I have not driven the ASP750's in anger though, so I cannot speak as to whether they cause brake hop when they get hot.
That's the direction I think I am going to go towards. Stiffer front spring as well as more aggressive rear pad. I would like to do springs first, run a couple of events then check out pads but the rear pads are pretty old and in the lower 50% of their remaining life. So I may just end up doing both at the same time.
So the 850# front spring should be here tomorrow. I’m excited to get them on and hopefully hit up a few auto-x events here before LSFest in May. I talked with UMI a little bit about the spring bow issue I am having as well. There was a post on their facebook page with their coilovers with helper springs so I asked about them. Seems like they are looking at running an 1100# 8” front spring with a helper spring, but hinted that that may be a little too much rate. No room for helper springs with the 10” 850# I am getting so I will most likely drill a few small holes and safety wire the spring to the upper perch.
Not OEM, they are C6 style. Black with machined face, 18x10.5 all around. I bought them used and have only seen one set from some guy here local and asked him about them. He said he got them from tirerack clearance.
Like JimMuller mentioned, it's all about weight transfer and how to control it. Increase rear shock rebound setting (UMI shocks have a TON of range and you can go too crazy if you don't pay attention) and or increase front spring rate. When everything is stiff, rate of weight transfer is sped up and oversteer/understeer occurs.
I can occasionally get low trac light, but with LS! front brakes with HP+ and stock rear brakes with Durmast pads, I haven't experienced rear axle hop under breaking. Granted I don't have very large courses to run in my region either. I'm thinking about going to something that dusts less (HP+ are horrible with dust) and to upgrade rear pads too.
Going from stock to Strano springs and Koni sport shocks was an obvious and nice improvement...going from Strano/koni to UMI with 850/250 was just as impressive.
I had the same issue with hard braking and fender to wheel contact with 315/30/18 rivals. I shimmed the koi shock to LCA a tad to gain some height, but ultimately went with UMI setup.
850/250 rates are not for the faint of heart. It can get FIRM on the street if your roads are particularly bad. But the good thing is that coilover springs are cheap to try. Oh and I have no issues with spring bow/rub with 850/250 and no helper springs. I feel the higher rates give you better initial turn in response and with the better shocks, slalom transitions are a no-drama scenario. Everything remains composed and calm when the shocks are adjusted.
Looking forward to the Popp 4th gen to get going and see how it does with the larger spring rates.
Last edited by smitty2919; 01-31-2018 at 06:48 PM.
Not OEM, they are C6 style. Black with machined face, 18x10.5 all around. I bought them used and have only seen one set from some guy here local and asked him about them. He said he got them from tirerack clearance.
Thanks. They look nice.
I really like the look of C6 wheels on the 4th gen Camaros, but would prefer OEM, which limits both sizing and purchasing options. It's a conundrum. If I went aftermarket, CCW apparently makes a good wheel, but to me their "C6" options don't closely resemble OEM, and they are very to ridiculously expensive.
I really like the look of C6 wheels on the 4th gen Camaros, but would prefer OEM, which limits both sizing and purchasing options. It's a conundrum. If I went aftermarket, CCW apparently makes a good wheel, but to me their "C6" options don't closely resemble OEM, and they are very to ridiculously expensive.
So received the springs yesterday. I can't remember how the current 600# feel by themselves, but these seem pretty stout. I'm debating keeping the 600# ones on until I do one or two auto-x events here to do a back to back comparison or if I should just throw them on now and start the season fresh.
Last event last year I threw the 850# on the car and didn't recognize anything negative. My ride was actually better and the car was more stable and turn in was improved. I think it was a tiny bit quicker. Like any change the car will behave a little differently so you will have to adjust your driving. Your call, but I would just throw them on the car.
Got a chance to work on the car tonight. Pulled the 600# springs off and got the 850# ones installed. Just a real quick pushing down, its hard to get more of an 1/2" movement out of it. Also safety wired the spring to the upper cup to hopefully stop the coil contacting the spring body. Its riding nose high by about and inch so I'll adjust a little bit and give it some miles to settle them in.
Looks good. I zip tied mine and haven't had any issue with contact... since I have had them apart multiple times now I'm happy I did that vs safety wire. There was a hole in mine.
So you chose a longer spring? I chose the same length of spring just a different coil diameter. You likely know this but the given a spring diameter the number of active coils and coil diameter determine the rate.
09-27-2017, 02:21 PM
Nose Dive Durring Hard Braking 
