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Old 03-07-2018, 08:16 PM   #26
Trevor57
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The biggest bang for the buck, in terms of lap time benefits are camber, and rear end. I cannot disagree more with mocambique-amazone about the differential issue. Open differentials are garbage. You will never leave a corner well with an open diff. We would spin 235/40/17 star specs leaving corners when the 240 was still NA! We gained 2 secs+ a lap just by doing a welded diff. Of course there are better options, but unless your drivers are unskilled a welded diff is better than an open diff if you actually want some exit speed.

Find a way to get a decent amount of camber in the front. Not only for tire wear, but to actually get some turn in. We extended the lower control arms, and tie rods. No fancy plates, but it was cheap, and effective. Lots of trial and error to get it set up though, since it is not as adjustable. I think it ended up about 3 deg, and I am very happy with it.

We run ipd springs and konis. Compliant cars are easier to drive fast for a long time, and nobody touches us in the rain. I value the ABC's of endurance racing. Always Be Comfortable! I would bet if you did some real testing with soft springs and a good shock, vs stiffer springs and the same shock the lap times would not be significantly faster, but I'm sure there may be some people that will disagree.

We run stock brakes with carbotech pads. I have tried damn near every pad available in the stock shape, and these are the ones we have had the most success with. I forget the compound, but if you call them, and tell them what you are doing they will get you set up, and they give a lemons discount.

We are entering our 9th season in our 240, and over 16,000 race miles. A few wins, a few trophies, and a lot of people with this face as they are passed by a "station wagon"
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Old 03-08-2018, 11:12 AM   #27
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Originally Posted by Trevor57 View Post
The biggest bang for the buck, in terms of lap time benefits are camber, and rear end. I cannot disagree more with mocambique-amazone about the differential issue. Open differentials are garbage. You will never leave a corner well with an open diff. We would spin 235/40/17 star specs leaving corners when the 240 was still NA! We gained 2 secs+ a lap just by doing a welded diff. Of course there are better options, but unless your drivers are unskilled a welded diff is better than an open diff if you actually want some exit speed.

Find a way to get a decent amount of camber in the front. Not only for tire wear, but to actually get some turn in. We extended the lower control arms, and tie rods. No fancy plates, but it was cheap, and effective. Lots of trial and error to get it set up though, since it is not as adjustable. I think it ended up about 3 deg, and I am very happy with it.

We run ipd springs and konis. Compliant cars are easier to drive fast for a long time, and nobody touches us in the rain. I value the ABC's of endurance racing. Always Be Comfortable! I would bet if you did some real testing with soft springs and a good shock, vs stiffer springs and the same shock the lap times would not be significantly faster, but I'm sure there may be some people that will disagree.

We run stock brakes with carbotech pads. I have tried damn near every pad available in the stock shape, and these are the ones we have had the most success with. I forget the compound, but if you call them, and tell them what you are doing they will get you set up, and they give a lemons discount.

We are entering our 9th season in our 240, and over 16,000 race miles. A few wins, a few trophies, and a lot of people with this face as they are passed by a "station wagon"
Thanks for the detailed description of your car and what you found that works for your team. It seems like welded differentials and rear bars are a hot topic! I think I am going to leave the differential alone until I can get my brakes working the way they should. Nobody complained about not being able to put down power coming out of the corners except in one turn. I imagine as we get faster that will start becoming an issue.

I will have to experiment with different springs to find the right balance. We are just starting out and two of my drivers have very little experience.
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Old 03-08-2018, 12:11 PM   #28
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There is a lot of terrible information on brakes out there. Much of which is passed down knowledge from a bygone era. Pad technology has changed a ton in the past twenty years, and many old rules no longer apply. I checked my email, and we are using xp-8 compound from carbotech. You should use plain rotors no matter what pad you choose. I have never seen 7 series brakes up close, but if it has 4 piston fronts, 2 piston rears like the 240, you do not need to do any upgrades but pads, and to make sure the calipers are in good condition. Do NOT re use rotors that were used with a different pad. Rotors are cheap, and you can run in to issues that can take you out of a race. If you are overheating the stock brakes with a race pad, it is no fault of the brake system. Most importantly, you need to bed the pads correctly. This is often overlooked, and can be a huge cause of problems if not done correctly. Make sure you follow the procedure outlined by the manufacturer! Good luck! I did an arrive and drive at Sonoma in a 240, and had a great time. I know the west coast races are pretty hardcore.
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Old 10-17-2018, 05:05 PM   #29
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I thought I would follow up on this post with results. Here is what I did:

Front:
- Bilstein HDs
- New bearings redrilled to add more camber/caster
- Kaplhenke 2.5" spring perches
- 10" x 2.5" 300# Summit Springs - ended up cutting 1.5 coils off
- Stock struts and used PVC pipe to keep spring centered

Rears:
- KYB Gas-adjusts
- Moog-8599 - cut 1.5 coils

When I installed the springs/shocks, the car sat very high. I ended up cutting 1.5 coils (maybe more) off each end to get down to a decent height. It's not lowered much, if at all. When the front end is in the air, there is slack in the springs, so I have to be careful to seat the perches before I let the car all the way down.

Overall the car handled much better, but I wouldn't recommend the spring setup. I will eventually go full coil over with adjustable perches when I have some funds. I think just having working struts/shocks made the biggest difference.

I still have braking problems, but I am tracking down those issues.
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Old 10-17-2018, 05:10 PM   #30
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I still have braking problems, but I am tracking down those issues.
F1 brakes from a 240?
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Old 10-17-2018, 05:20 PM   #31
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F1 brakes from a 240?
I have stock Girlings with a 4 line master cylinder. I am getting lockup in the rears. I am thinking one of the master cylinders is not working so I have 50% braking in front and 100% on a rear maybe?

I have bled in the correct order many times, race fluid.
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Old 10-18-2018, 12:28 PM   #32
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If the 740 wagon is anything like our 240s, the rears will always lock first, especially in a straight line with decent tires. This is why I'm so obsessed with ABS - someone that knows more about suspension geometry might have better ideas about managing weight transfer / dive to avoid it, but computer-controlled brake bias was a solution I could handle.

Once you stop locking the rears, you will start setting the rear pads on fire. A good pad on the front will cope (especially if you can get some airflow onto them), but we were tossing a set of heat-distressed rear Hawk Blues per race even with our best efforts at getting airflow onto the caliper...
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Old 10-18-2018, 12:33 PM   #33
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Originally Posted by rb92673 View Post
I have stock Girlings with a 4 line master cylinder. I am getting lockup in the rears. I am thinking one of the master cylinders is not working so I have 50% braking in front and 100% on a rear maybe?

I have bled in the correct order many times, race fluid.
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Originally Posted by DrZiplok View Post
If the 740 wagon is anything like our 240s, the rears will always lock first, especially in a straight line with decent tires. This is why I'm so obsessed with ABS - someone that knows more about suspension geometry might have better ideas about managing weight transfer / dive to avoid it, but computer-controlled brake bias was a solution I could handle.

Once you stop locking the rears, you will start setting the rear pads on fire. A good pad on the front will cope (especially if you can get some airflow onto them), but we were tossing a set of heat-distressed rear Hawk Blues per race even with our best efforts at getting airflow onto the caliper...
Get the rear to sit a tad lower than the front. Worked great on our lemons car. Hawk DTC60 fronts, DTC70s rear
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Old 10-18-2018, 12:52 PM   #34
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...Hawk DTC60 fronts, DTC70s rear
Hawk blue pads are OLD brake tech. The DTC60 pads last 2-3x longer on the rally car than the "blue", and offer more bite. Bonus, they shoot sparks when you're bedding them in.
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Old 10-18-2018, 01:24 PM   #35
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I am running ST43 pads all the way around.

The lockup is severe, something is wrong with the system. If I can't get the system to work better, I am going to re-plumb and put bias adjusters front to rear.

I do need to add airflow to the front and I am not opposed to taking more height out of the rear.

I am going test the master this weekend. Last brake bleed we did, my pedal pusher complained it was much harder to push the pedal to bleed to top nipples in the front as opposed to the bottoms.
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Old 10-20-2018, 01:51 PM   #36
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Hawk blue pads are OLD brake tech.
And yet, they're cheap(ish) and work very well. *shrug* 240 is kind of 'old tech' too.
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Old 10-21-2018, 05:32 AM   #37
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You are locking up the rear brakes because you have too much rear brake. Has nothing to do with suspension. Put an adjustable bias valve in, or put in a low friction rear pad. These cars weren't built for modern tires and brake pads you [should be] getting a lot more weight transfer under full braking. I'd also check temps. Depending on what pads you are running when they get hot they may get grabby which exacerbates the problem.

What calipers are you running on the car? There were multiple options offered in the front for the 700/900 family and at least two different piston sizes in the rear. Sounds like you don't have ABS but did it used to have it?
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Old 10-21-2018, 07:28 AM   #38
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You are locking up the rear brakes because you have too much rear brake. Has nothing to do with suspension. Put an adjustable bias valve in, or put in a low friction rear pad. These cars weren't built for modern tires and brake pads you [should be] getting a lot more weight transfer under full braking. I'd also check temps. Depending on what pads you are running when they get hot they may get grabby which exacerbates the problem.

What calipers are you running on the car? There were multiple options offered in the front for the 700/900 family and at least two different piston sizes in the rear. Sounds like you don't have ABS but did it used to have it?
I’d say what I posted above contradicts what you said. Do you have specific experience with this on a track in a 2/7/9?
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Old 10-21-2018, 03:51 PM   #39
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...There were multiple options offered in the front for the 700/900 family and at least two different piston sizes in the rear...
That's right, didn't the wagons get 40mm, and the sedans 38mm rear ATE calipers? OP: What about trying some sedan rear calipers on your 745? Maybe that alone will help the brake balance on yours?
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