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but if you correct the suspension, so the rear doesn't pull the wheels up under braking, you don't get a chance for hop.
IF, it was just locking up the brakes, that would be one thing. The hop is caused by the changes in braking torque on the rear, causing the problems.
What is happening here, brakes are applied, the initial torque on the rear axle is high, because there is traction, this interacts with the intant center. the anti-lift and anti-squat work here, causing the rear to lift, this gives less braking toque, when that gets low enough, there isn't enough braking torque, cause the rear to drop until it gets traction, raising the braking torque, cuasing the rear suspension to lift again. Its a cycle.
If it was just a matter of weight transfer forward, then you would have rear lock up issues, the hop issue is one of the rear geometry being wrong.
Originally posted by Dewey316 but if you correct the suspension, so the rear doesn't pull the wheels up under braking, you don't get a chance for hop.
IF, it was just locking up the brakes, that would be one thing. The hop is caused by the changes in braking torque on the rear, causing the problems.
What is happening here, brakes are applied, the initial torque on the rear axle is high, because there is traction, this interacts with the intant center. the anti-lift and anti-squat work here, causing the rear to lift, this gives less braking toque, when that gets low enough, there isn't enough braking torque, cause the rear to drop until it gets traction, raising the braking torque, cuasing the rear suspension to lift again. Its a cycle.
If it was just a matter of weight transfer forward, then you would have rear lock up issues, the hop issue is one of the rear geometry being wrong.
We are both right in our points and just debating different reasons . You are correct about a car suffering from wheelhop, I am talking about a car that is suffering from too much rear brake pressure period. The only way I have ever seen a 3rd gen suffer from brake hop is too short of a torque arm or just too soft of rear springs/shock settings allowing too much squat. The mention of brakehop generally is prone to 4th gen cars only in CMC since the tqarm length is restricted to stock length. Now the brake bias reductions the 3rd gens are doing is do to them generally running too soft of rear settings and springs trying to keep the *** end from coming around. What causes the *** end to come around? too steep of a roll axis from the factory. What happens when you loosen up the rear setup (aka softer springs and bars) when running grippy race tires? you run the risk of braake hop. Lower the rear roll center and increase the spring rate and shock settings. Then you can increase the rear brake bias and not suffer from as much brake squat in the rear causing brake hop. You gotta correct the big picture of whats inherintly causing the whole problem to begin with. Then you are not getting the vicious cycle you speak of.
I keep preaching to everyone why I run progressive rate rear springs to induce some squat but the rapid increase of spring rate keeps the car from brakehoping under extremem rear braking forces- It why I can run the car with high rebound settings and a 25mm rear bar.
Last edited by BarrisCustoms; 01-02-2006 at 07:25 PM.
Guys, first of all, thanks for all the valueable info.
Ok, here's the short version of where I am at right now:
Last season, I had help with designing the geometry of a third link setup. I have everything installed on the car as far as the body side goes and have been stuck on fabricating the pickup point on the rearend. I found a 1/4" steel fabbed rear cover (Dana 44) and have fabricated a mount/pickup point which is welded to it (integral part of the cover). I hesitated using it last year because I was afraid of the the stress it would put on the cover studs since they are only 5/16" and there is only 9 or 10 of them (can't recall now). I am currently working on a brace that will at least make me more comfortable with trying the third link out.
Anyway, here is a drawing of how the geometry will end up when fhinished (the seemingly randomly place planes are bodywork and such that cannot be passed through):
This is what I'll end up with if and when I get this 3rd link installed. Thoughts?
Just thought that I would mention that Unbalanced Engeneering sells a kit that can lower both sides of the phb. Lowers the roll center and keeps the bar level.
Will your new Wilwood set-up work with Formula wheels? I am trying for a stock look on my '91 Formula street car. I am really curious and excited to hear about this as I race CMC, have been racing with a 3rd gen Firebird with the 12" Baer brakes set-up. I have never had any complaints about the braking or unusual wear with that set-up. I was planning an LS1 brake conversion for my '91 Formula, I think this changes my mind! What is the best way to keep updated on this kit?
Hi Julie..I'm sure it will fit those wheels but I won't have the setup back together for a few days, the brackets are getting finished. I'll keep you all updated as I progress, I'm close but I'm just waiting on parts now. Plus I just got really busy at my real job so I'm pressed for time as well.
Originally posted by 36ASedan Guys, first of all, thanks for all the valueable info.
Ok, here's the short version of where I am at right now:
Last season, I had help with designing the geometry of a third link setup. I have everything installed on the car as far as the body side goes and have been stuck on fabricating the pickup point on the rearend. I found a 1/4" steel fabbed rear cover (Dana 44) and have fabricated a mount/pickup point which is welded to it (integral part of the cover). I hesitated using it last year because I was afraid of the the stress it would put on the cover studs since they are only 5/16" and there is only 9 or 10 of them (can't recall now). I am currently working on a brace that will at least make me more comfortable with trying the third link out.
Anyway, here is a drawing of how the geometry will end up when fhinished (the seemingly randomly place planes are bodywork and such that cannot be passed through):
This is what I'll end up with if and when I get this 3rd link installed. Thoughts?
Update on this kit: I hope to have final fit up pics up over the weekend. The real job is keeping me busy at the moment (It's 2 AM and I'm at work) but I'll get it done.
Thanks for giving me my thread back.....
Ed
Last edited by ebmiller88; 01-25-2006 at 11:45 AM.
Originally posted by Julie Bergman Cool Ed, Does the kit come with a case of Corona light? Saw it in one of the pix! Seriously tho, I am very excited about this set-up!
Only if there's local pickup of the brakes, I'll be happy to throw one in.
They should perform better than a 2 piston caliper due to the opposed piston design. Ask guys who run them, I'm sure they'll have a more informed opinion than I would. Remember, I don't run these brakes...I only make them...
UPDATE: Brackets are done and back from the plater. Here's some assembly pics. I still have to do some lockwiring on the bolts and the rotor hats but other than that it's good to go.
I rely on the added track width (5 or 6 mm) of the 1LE brake assembly to keep my ROH wheels from hitting the outer tie rod. Does the rotor hub provide that additional track width like the 1LE package?
I use a standard hub here since the aluminum hat is .500" thick. The 1LE hub is .318" taller than the standard hub so this design would give you .182" more track width than the 1LE rotor does, plenty for your needs.
Ed
Last edited by ebmiller88; 01-25-2006 at 09:11 AM.
I think then,
that I want to put these brakes on my Trans Am in time for NFME at Indy in May. So, how about we look at getting something ready for delivery first week in March? PM me a price (without spindles, since I already have modified ones) and an address to which I need to send the money order. I should be able to put the check in the mail on February 25th. ZIP code 48840, residential address.
The car's in the air right now getting it's new rear suspension, including a new Moser 12-bolt and I've got a lot of welding to do between now and then to finish off the decoupled torque arm installation.
ebmiller, You are going to get me put in the dog house!!!!!! I just put an LS1 conversion on last summer, but after looking at this and seeing how easy it is, I would be afool not to upgrade Let me know when your going to sell some stuff.
Wow, I wish I had seen this thread earlier. Lots of good stuff in here. I do have a question though.
Ed & 36ASedan: do you guys think the small (stock) outer wheel bearing will last up to the abuse of an AS car? Wheel bearings are cheaper consumables then brakes, but still something I wouldn't want to have to change all the time.
__________________ 3rd gen Firechicken. Midwest region American Iron #134
nape, AFAIK, many of the guys in AS run modified std spindles with no issues. Most of the bearing issues I've heard of are related to use with aluminum hubs. I have been running 1LE spindles and bearings until now so we'll see I suppose .
I don't expect the outer bearings to be an issue. Good thing they aren't that expensive should you need to replace them. You could run a 1LE hub with rear wheels on the front to put yourself a bit more at ease but that would add just a bit to track width.
Originally posted by ebmiller88 I don't expect the outer bearings to be an issue. Good thing they aren't that expensive should you need to replace them. You could run a 1LE hub with rear wheels on the front to put yourself a bit more at ease but that would add just a bit to track width.
Ed
Well, I was warned to make sure I used a brake setup that uses the 1LE outer bearing so I'd definitely be interested in any feedback on how this kit performs.
Ed, to make that switch you would just have to increase the spacers that are welded onto the brackets in the picture you posted earlier, correct?
To use the 1LE hub, it would actually be a decrease in the spacer thickness since the caliper would be moved out. Or, now that I think about it, I could use a rotor hat with a deeper offset to make up for that added outward push of the 1LE hub.
Ed
Last edited by ebmiller88; 02-04-2006 at 02:57 PM.
So how are those brackets coming???? I Have some cash burning a whole in my pocket right now. I would like nothing better than to help out the local car guy community
I have 5 pair available but I'd need time to "tailor" them to the spindle and caliper. Also, would you want a set for a 1LE hub or standard hub like I used in Jeff's kit above? I can do either.
Well I am using a hub that I machined down out of stock 10.5 rotor. I am using it to hold an LS1 rotor that is 12.75 in diameter and 1.25" thick. So I am not sure where that lands in the scheme of things. I am also using LS1 brake calipers. By LS1 I mean the 98 and up F-body chassis.
Hmmm...OK. So you're essentially just wanting the brackets? If that is the case, there's a whole lot of issues with your setup as you described:
-You're using LS1 calipers, they won't work with these brackets;
-"LS1" rotors are 12" x 1.25"...are you using C5 rotors which are 12.75" x 1.25"? That style rotor will probably require a spacer to keep the wheels from hitting the calipers (Wilwood);
This won't be a direct install using the parts you listed. Can you elaborate a bit?
That would kind of be a deal killer for me. I spent a good bit of money on the Drift R Wheels to get away from spacers, as this car is regularly autocrossed and hopefully soon,,, will be spending time at Road America.
I know the debates that are being had about spacers and no spacers, but for simplicity sake, you can put me in the no spacer crowd, right or wrong as it may be.
So would I have to use spacers? The Drift R's make the brake combo I am running now look small. I have not had any problems on the autocross courses, but I am a little leary of running road courses with my current set up. Also the current setup gets a little squirmy when coming down from high speeds,, like the quarter mile. I have played with the caster, toe, and camber in that order, with limited success. I am wondering if it is a break pressure issue?
Anyway I will quit boring everyone with my problems and see what you have to offer. Thank you for your quick informative replies.
That's why I asked...and that's why I used a 2 piece rotor with a heavy hat offset. The C5 rotor is a flat rotor with little offset. I had to use a tall rotor so I could stay away from using a spacer and push the caliper to the inside, giving me plenty of room for the wheel to clear. IMO, unless your wheels have a large amount of hub offset, you cannot use just a C5 rotor for this setup, it throws all the measurements off and the wheel won't clear the caliper. Now, if you want a 13" x 1.25" rotor or even a 14" rotor if you want to go that big (14" = big money), I can look into those as well. It wouldn't be a far stretch do to that.
Any reason besides cost that keeps you with the C5 rotor?
I am not stuck to the C5 rotor. I am under the impression that is what is on my car now, but maybe not.
I am interested in the rotors you have in your first picture, as long as they are not entirely to pricey, as i have a bad habit of using wrong brake pad compounds when I am in a pinch. As you know this usually leads to early rotor replacement
You'll be glad to hear that I've learned of another rotor I can use that is close to the C5 in size so I'll keep you posted, I just have to find a vendor in the US. I can't tell which rotor you have by the pic, no way for me to tell what's behind the wheel.
The two piece rotors I used will run you $260-325 IIRC for the pair including hat hardware, depending on which rotor you use.
Originally posted by Mongoose You can run rears up front with the C4 kit if you use a .25" spacer. I had a post about this sometime back right after Ed and I put the brakes on my car. The rotor in addition to the spacer brought the rear wheels out to where the fronts would have sat on the OE brakes. With the .200" extra from the rotor hat it should be close enough to work without problems.
Goose,
What if I am not concerned about getting the rear wheel to sit exactly where the front wheel would have. In other words will the rear wheel positioned up front on the new c4 brake kit clear everything WITHOUT the spacer ?????
What if I am not concerned about getting the rear wheel to sit exactly where the front wheel would have. In other words will the rear wheel positioned up front on the new c4 brake kit clear everything WITHOUT the spacer ?????
To answer this, yes, the rear wheels fit fine, without a spacer.
Originally posted by RMK Assuming a 12 inch rotor, how much better are the brakes with the 4 pot Wilwood caliper compared to say, a two pot C4 or LS1 caliper?
Hi Robert..4 piston calipers will exert more clamping force since there's force of the pistons on both sides, not just one. Again, I don't run this kit or one like it but maybe a few guys who do can post with their opinions on how they perform.
Originally posted by ebmiller88 Hi Robert..4 piston calipers will exert more clamping force since there's force of the pistons on both sides, not just one. Again, I don't run this kit or one like it but maybe a few guys who do can post with their opinions on how they perform.
Ed
My expectations of switching from the 1LE's to this kit are to have 1/5th the pad wear and greatly increased rotor life. In the past with the 1LE, I would go through at least one set of pads and rotors every other race weekend. Sometimes, depending on the track, I could only get one full weekend out of a set of pads and maybe practice for the next weekend. I will not be at all surprised to run 4-5 weekends on a set of pads and only have to change the rotors once this year - right before the Runoffs. I will have the brakes installed by the end of this weekend (hopefully) and my first race weekend is April 1-2. I will definitely give my feedback after the event.
Originally posted by DM91RS Jeff if you don't mind the question what tracks do you run on other than the runoffs which IIRC are moving away from mid-Ohio?
DM
I don't mind at all .
I did not run the Runoffs at Mid-O. This year will be my first Runoffs (hopefully) which will be in Topeka at Heartland Park (HPT). I have been running Regionally in the Midwest Division of the SCCA for the past two years. I managed to win the Regional points race both years and even received the Rookie of the Year award for 2004. However, there is not a lot of Regional competition so it was not as big an accomplishment as it sounds. I live less than an hour away from HPT so if I can't do it now I probably never will.
Besides HPT, we regularly run at Hallet, Gateway in St. Louis, Memphis, and Mid-America in Iowa. It looks like we'll be going to the June Sprints this year at Road America but I will most likely not be bring my car (I also am the crew chief for Mike McGinley who runs a T1 Z06 and a CSR Radical SR4). I stay VERY busy .
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