Spring Rates - Page 2

RET_COP · #21 (**permalink**) 09-08-2011, 04:07 PM

Infletcher and Wayne
Ok here is some more information. I've had to really push the brake pedal hard to get the car to stop. No fade or anything,as a matter of fact a hard pedal and close to the top. I had a 1 1/8 bore MC Ford oem. I figured through this forum that my line pressure was inadequate, probably 475lbs or so, and I needed about 700 or more. I called master power brakes and they said whach out for the GM metric low drag as the piston retracts more in the bore (to eliminate rotor contact) and therefore will require alot of fluid volume to get the piston back in contact with the rotor. It works good with the 1 1/8 bore except of the low line pressure. GM had a warning out and had a different MC made for the situation.
Wilwood said I would need a 7/8 bore MC to get in the area of 700+ lbs.
Ok so I bought and installed the tandem M/C and went out for a test. I felt the line pressure and the car stopped much better except for the fact that the pedal went almost to the floor. It did not fade and it held at that low position, but it takes getting use to to say the least and a bit scary. I researched this and found out that a mid 70s [nova, camaro chevelle]intermediate 5.5" bolt space caliper would work,as this was not a low drag caliper. I opted for the direct replacement from Wilwood (D-154) I will let you know how it works.
Wayne, MT s/t are close to the cooper cobras, the s/r are a high performance, sticky directional tire with a little more sidewall flex. I beat a new dodge charger off a traffic light (just first gear) and the tire hardly spun. It was a costly mistake on my part on the purchase but hey it happens. I'm looking to get 450.00 for them. I paid 800.00. I also now need wider rear wheels. Does it ever end.

Wbulk · #22 (**permalink**) 09-08-2011, 04:25 PM

Lou, I am wondering if we have the same master cylinder. I don't remember others complaining of stopping problems, or was it one of those "just the way it is things" that was accepted.

Wayne

RET_COP · #23 (**permalink**) 09-08-2011, 04:37 PM

Wayne,
It is the Wilwood aluminum tandem MC# 260-9439 7/8 bore. I hope the new calipers will give me less pedal travel. In theory it is suppose to. I could just get use to this low pedal but if there is an option to get it right I'll go for it. If anything I have nice new RED brake calipers from Wilwood!!!

Lou

Wbulk · #24 (**permalink**) 09-09-2011, 09:46 AM

Since you are working on your alignment this is an excellent article, Tire Tech Information - Alignment.

RET_COP · #25 (**permalink**) 09-12-2011, 03:18 PM

Wayne
Thanks for the information, it was very informative.
Lou

RET_COP · #26 (**permalink**) 10-23-2011, 04:30 PM

Larry, I finished my brakes and here are my results..and story. I put the D-154 calipers on with the 7/8 MC. The pedal had about 5" of travel and the car stopped good. I did not like the long pedal travel for my comfort level ( as there was not much left of pedal to floor) and too long of a time period to get the car to brake. I replaced the old brake pads with the ones that came with the calipers. Med aggressive and low dust. I took the car out to the Stop & Shop proving grounds and the pedal was going to the floor. The car would stop but wow!. I found out that if I moved the brake pedal once before actually braking the next push was good and the car came to a screeching halt. I knew this was not right and bled the brakes again, but the same happened. I called Wilwood and explained the situation to them and that I wanted to try the 1" MC, so I ordered one. They said that I would see a shorter brake pedal with a little less PSI, which was alright with me. In the mean time I combed over my calipers and discovered that I had a gap on one side of the brake pads on both left and right front. hmmm..... I looked at my old pads and noticed that they were worn in a wedge shape. The bad brake pedal I was having was due to the gap that had to be taken up before the pads squared up with the rotor, which was about .050", yea!! can you believe this. I found that I could square up my caliper flange with the rotor by filing on a spacer which is between the bolt and the spindle. Once I got this matched the pedal came back to the 5" real solid. I ended up putting in the 1" MC and found that this moved my pedal travel to 3.5" which was perfect for me. As for losing PSI, it was not that much. MY brakes are done!!! whew

FUNFER2 · #27 (**permalink**) 10-23-2011, 05:22 PM

Lou, think about scaling the car on all four corners, it's well worth it !
I thought my setup was real close, boy,..... was I wrong.

I started off just wanting to replace the coil overs and lower the rear ride height, then included getting new heim joint's on the rear, so I borrowed a friends electronic weigh scales. Man, each corner was way different. I made a threaded rod strut tool with heims that mounts to the shock mounts to get the height I wanted, then measured what length of springs I needed. Worked great. Even with a BB, the percentage now is 48

51%.

RET_COP · #28 (**permalink**) 10-24-2011, 02:50 AM

Nice work Kevin and thanks for the information. I have a few circle track friends who can help me out in this area.
Lou

FUNFER2 · #29 (**permalink**) 10-24-2011, 05:52 AM

If you're interested, I can send you the strut, or their easy to make and low cost. I just used my old heims one each end, not new.
Their actually sprint car "Radius Rod's"

I was amazed on how well the car drove after scaling and adjusting the load on each corner. And keep in mind, raising or lowering the suspension will effect the weight bias front to back.

RET_COP · #30 (**permalink**) 10-25-2011, 06:56 PM

Kevin my buddy ran modifieds for quite some time,he has something like you are talking about. He was pushing me to do this, and maybe, just maybe take a run at Limerock next year. I want to go to some auto-crosses next year, i'm not looking to beat my car up, just have some fun and feel some type of competition.
Does anyone belong to any national clubs like scca, is it beneficial to do so?
Lou