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308 REAR Brembo w/emergency brake

Discussion in 'MVPEurosports.com' started by enjoythemusic, May 18, 2006.

  1. enjoythemusic

    enjoythemusic F1 World Champ

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    #1 enjoythemusic, May 18, 2006
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    Ok, here it is. Many of us have the Brembo front package and have tried various ways to balance the car's rear braking ability to the uprated fronts. Many thanks to Eric Dahl of Girodisc for making excellent, lightweight aluminum hat/floating slotted rotor for the rear.

    So the question is, how much would a Brembo improved rear brake package be for the 308 that INCLUDES parking brake as a bolt-on package for existing 308s?

    As an FYI, Eric was kind enough to factor in my car's weight, tire choice, pad choice, etc and make an excellent analysis of the package. As many of you know, Eric of Girodisc is the original designer of the Ferrari 308 brake system for Brembo.
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  2. don_xvi

    don_xvi F1 Rookie

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    I'm interested... but price sensitive !
     
  3. RossoCorsaItaly

    RossoCorsaItaly F1 Rookie
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    Brembo tells me the current front brake kit is too small to justify an upgraded rear brake, they feel there would be too much braking in the rear making it imbalanced. They have no problems making a bigger rear kit, but a larger front brake kit besides the current 312mm kit.

    Regards,
    Kevin
     
  4. enjoythemusic

    enjoythemusic F1 World Champ

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    So that means... owner MUST have uprated (17-inch plus i assume) front rims to THEN use a 'new' larger Brembo front kit, to then have a new rear kit with proper balance. That seems a bit steep. Well, guys i tried.

    Back to my buddies at Girodisc who will hopefully have some solution in the future. My concern is the small rears, agressive pads, and HEAT dissapation. The guys at Girodisc have been VERY helpful. Many thanks Kevin for trying the Brembo side, much appreciated.
     
  5. RossoCorsaItaly

    RossoCorsaItaly F1 Rookie
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    Yes, a rear kit could be produced but Brembo thinks it would off-set the braking with too much in the rear. Sorry nothing else could be done. Brembo is always testing new concepts and products out and while I can't go into much detail by the beginning of next year there may be a solution to where people with the 312mm kits can have an upgraded rear kit but as of right now nothing will be available.

    Regards,
    Kevin
     
  6. velocityengineer

    velocityengineer Formula Junior

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    As the original engineer/designer of the Brembo 308 kit way back in 2002, maybe I can clarify things a bit...

    The only reason there is no 308 rear kit is because there was nothing in the Brembo aftermarket component selection that had a built in park brake. The only possible candidate was the caliper as used on the rear of the Lotus elise, and it is not sufficient for the rear of the 308, and not available as an aftermarket part. There is still nothing available from Brembo with a park brake built in for the aftermarket. Period.

    There was no issue with "overpowering" the rear. In fact it is the opposite. The front piston area is the problem in the balance of the system. It was my recommendation that the system not go into production. It was rushed into production anyway for reasons that arent relevant here. It is not unsafe, but it is not as good as could be.

    The reason the front kit is not perfect is that the caliper as used in this case has too much piston area in comparison to stock, and it was the smallest caliper available to use at the time (and still is). So the issue is that the front is overpowered and the pedal will be too soft and long.

    Anyway, the volume for sales of the 308 kit is still far too low for Brembo to be interested in dealing with this. Brembo makes more than 13 million brake discs a year and well over 200 thousand of calipers for OEM production per year. Aftermarket performance parts are a very small part of Brembo, and if a business case cant be made, they are certainly not going to make a new caliper. The other fact is that the cost would be silly high for a rear kit, and 308 owners arent going to spend twice as much on the rear kit as front. Thats a fact.

    Kevin, who at Brembo is telling you the rear is overpowered by a rear kit? Are you talking to Brembo, or Race Technologies people. (distributor) They are not the same. RT does not engineer brake systems, and last I knew, had no engineers working there. By this logic, is every F355 and F360 with Brembo 4 piston calipers unbalanced in the rear? They are not. The only issue with not doing the 308 rear is the parking brake.

    Hope this info sheds some light. Follow Stevens path if you want to have the Brembo front kit, with the right rear pad setup, the car will brake as well as should be expected with Brembo parts. There will not be a Brembo rear kit.

    Eric
     
  7. chrismorse

    chrismorse Formula 3

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    Steven,

    I know of a small handfull of guys, (one hand) who are seriously interesten in doing all 4 corners.

    Even if there were 50 308/328 guys out there who wanted to upgrade the rear, Brembo would have to charge something like $4000 or more to recoup a portion of their engineering costs. My guess is that it is not going to come from Brembo, but rather from the fine guys at Girodisc, (who are also going to have to charge about the same to cover their costs).

    So, where does that leave us?? Rummaging through the parts bins, (Ferrari parts) and looking at aftermarket components that can be made to work with a considerable amount of homegrown engineering.

    Eric has delineated the process very well in a couple of prior posts.


    The 360 uses a seperate parking brake caliper. Does anyone know the cost?

    The "Mr. Parker" unit looks well made but will need a mounting bracket fabricated and someway to convert from a longitudinal pull to a lateral pull. Unfortunately, i have a lot of maintenance issues to deal with before jumping on the brakes.

    I am curious as to how the 355, (and possibly the 360) can use calipers with the same piston sizes front AND rear on a car with about 60/40 weight distribution. IIRC, the rotor diameters are the same too.
    Is it a dual master cylinder or a proportioning valve, or both??
    It looks like the calipers use 36 & 40 mm pistons, (just like the brembo 308 kit)

    I am still thinking hard about this and have purchased a set of 355 Brembo calipers and a Tilton adjustable proportioning valve. I would like to see if i can get some rotors and hats from Girodisc that would work better than the stock 355, (heavy) units.
    Has anyone comu up with a suitable swap for the "small" 308 master cylinder? I have heard a report that the QV london 355/308 kit has an acceptable pedal and balance??? How do they do it??

    I know it is a bit iffy, but may go with a line lock untill i can get the time to pull the uprights for machining. Perhaps the proportioning valve and line lock could be installed at the lower edge of the drivers side dash. This would be quite close to the master cylinder.

    Where is the stock 308 proportioning valve?

    Has anyone else made progress with adapting a parking brake?? I know Wildegroot was getting close.

    Loosing sleep over this one :)
    chris
     
  8. velocityengineer

    velocityengineer Formula Junior

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    The 308 rear brake – park brake has become a white whale. Or maybe a dead horse.
    I feel like I have talked this issue to death and everybody is probably tired of hearing my crap. I am going to say my piece here for the last time and then I will not harp about this anymore.

    Current options….

    • The Girodisc brake kit is available now and makes drastic increases in braking performance at all 4 wheels, and fits under stock 16” wheels – all at a reasonable price like 308 owners want. It also KEEPS the OE parking brake in place. The kit works.

    • The Brembo front kit is available, and used with Ferodo DS2500 or DS3000 rear pads, the system is also capable of drastic increases in braking reserve and power. The pedal will be a bit softer and longer than OE. The Brembo is naturally a bit on the expensive side. But it is a Brembo. Steven Rochlin is using this system with Girodisc rear 2 pc rotors and is very happy with the performance on road and track. The kit works.

    • Mov-It makes a front kit as well, but I don’t even know if it is available in the USA currently. May be a similar situation as the Brembo, but I have no information about it.

    • There are kits from here and there using Wilwood, Ferrari 355 (Brembo), and other calipers for the 308. None have any solution for the rear parking brake. Buy at your own risk kits that come from garages or dubious sources. I prefer to use parts and systems from companies that carry liability insurance and back up their parts. ( I don’t bet my safety at the first corner after the straightaway on used parts bought off ebay with unknown history and maintenance)

    If you MUST have a 4 piston rear caliper…These are your options:

    • Eliminate the parking caliper. Design and mount a bracket and your choice of rear caliper. Ala-Wil DeGroot. Done. Go drive, and leave it gear on hills. If your 308 is so fast it needs mega brakes, then drive fast and don’t park it.

    • Design and fabricate a system, remove and machine the rear upright bosses for a bracket (your design) to mount new parking caliper, design and apply whatever brackets are needed to mate to the OE park cable. Make a new bracket to mount the new 4 piston caliper. Done. Simple right? Not hardly, and nobody has done it yet. You will spend more in time (what is yours worth?) and prototype machining and fabrication costs than the available options cost above, but you will have 4 piston calipers and probably be promoted and grow taller and better looking as well. Your car will not stop better.

    • Wait for Brembo or another company to make a magical bolt on system that doesn’t cost as much as an engine rebuild. Your hair will turn grey, your teeth will fall out, cobwebs will grow, and you will begin to forget things and mumble.

    • Buy a set of brakes from another source or shade tree engineer that are possibly badly mis-sized for the car and then spend more money and try to find a second band aid solution like a master cylinder to make them safe and functional and roll the dice with your car and life.

    • Buy a 348 or later model that has shiny 4 piston calipers that will impress everyone. Done.

    Point: If you do not drive your track IN COMPETITION OR IN ENDURANCE RACING EVENTS you do not NEED a four piston rear caliper. I understand that it is cool to have one, and yes they are generally better calipers. Steven Rochlin has been thrashing his car at track events and has not been left wanting for brakes at the end of the day. For club level and track day events, the ATE OE rear caliper is good enough with upgraded pads, (and better with the Girodisc rotors). If you do drive the car for hard track events, you should be willing to give up the parking brake. Serious racecars dont have them.

    I designed both the Girodisc and Brembo systems. I researched a rear system both times, there was no easy and cost effective way to set up a rear for a wide customer range of mechanical skill and budget as the upright requires machine work etc…. Considering that I have heard mostly complaints about the cost of both of these systems and neither sells well, I cant possibly see a 4 wheel kit with parking brake setup that will more than double the cost doing any better.

    There has been talk of line locks and other ways to lock the rear, but the POINT of a parking and emergency brake is to be separated from the hydraulic circuit. Loose hydraulic pressure = NO emergency brake. Bad news. I consider all these options as band-aids, and not something I would consider spending time on. I prefer to do it right and as complete as possible the first time.

    A ray of light is that Wil DeGroot of this board is playing with some ideas, and he is very sharp. It is possible that he may come up with a reasonably priced and easily installed solution. But I know nothing else about it. Keep your fingers crossed.

    Okay, that’s it. I have said my part. I will happily talk about any specifics or answer any questions I can by PM. I dont mean to be a negative nellie, but reason and logic seems to have flown out the window for this subject.

    -Eric
     
  9. enjoythemusic

    enjoythemusic F1 World Champ

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    Thanks everyone and please accept my apologies. MPV said i should ask here, with my hopes being something NEW would be designed WITH our White Whale e-brake.

    As i see it, Girodisc probably has the best easily available/bolt on four corner system. Agree with Eric about the pedal being a bit soft-long with the Brembo fronts, but is manageable/balanced with DS3000 rear pads.

    Sorry if we are beating a dead horse due to my post. Will gladly allow horse to die and find some other way to reduce the pedal length.
     
  10. RossoCorsaItaly

    RossoCorsaItaly F1 Rookie
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    Steven,

    No reason at all to apologize, this thread has alot of interesting information regarding rear 308 brake upgrades. I really appreacites Eric input in it as well as yours and everyone who is interested in this. Brembo/RT is closesly watching these threads so something may come of them.

    Regards,
    Kevin
     
  11. enjoythemusic

    enjoythemusic F1 World Champ

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    Thanks Kevin. The Brembo front is great and i have the system balanced with mighty aggressive rear pads, but i HATE the long pedal. Have begged SOMEONE, ANYONE to find a solution to reduce it WITHOUT me having to go with separate MC's/balance bar/etc. which also equals $$$$ and fabrication and testing.

    So how about i ask this... how do i reduce the peddle length caused by the larger piston area of the front Brembos?
     
  12. velocityengineer

    velocityengineer Formula Junior

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    If you can find a 25mm master cylinder with the right stroke and imilar in/outputs, it will make a big difference. maybe get friendly with a parts guy who can do some cross reference. or build a small adapter to put a Tilton or other 25mm MC on the OE location.

    Another way is to shorten your brake pedal (not so easy or ergonomic) to reduce the pedal ratio. Around 3:1 puts you back to OE feel. (4.5:1 OE)

    The brake booster could be played with. There may be a limiting valve or vacuum regulator you can apply to limit full vacuum to the unit and lower its boost amount. unplug the booster and drive around a bit -CAREFULLY- you probably wont have enough brake pedal to stop, but you can feel how much effect the booster has on your system.

    Maybe that helps

    Eric
     
  13. chrismorse

    chrismorse Formula 3

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    Eric,

    Isn't the long pedal due to the increased caliper volume rather than the amount of assist??
    Still think your 25 mm MC is the way to go.

    My particular interest in brakes is to make them more controllable at the threshold. I believe that using a longer lever arm, ( disc diameter), is a great help. Better and bigger calipers obviously reduce the effort and make them a bit more controllable.

    To that end, i am looking at using a high quality caliper, front and rear, (Brembo 36,40 mm from a 355). From my initial measurements, it looks like i can use a 332, max diameter rotor with these calipers). The 355 uses a 310 and 300 mm rotor. I am curious as to how Ferrari balanced the brakes with this obvious rear heavy approach. Was it through a dual master cylinder or a stronger, (.4 or .5) proportioning valve - and why???

    It looks like the center of gravity is almost the same height and the front/rear weight distribution is about the same as the 308 example, (or a bit more nose heavy), so why do the 355 and possibly the 360 use the same caliper volume front and rear, with nearly the same disc diameter??

    Does a properly set proportioning valve, (.4 or .5 or .6) provide a better match with the needed F/r brake balance than a split master cylinder.

    I have been searching for specs on the 360 calipers as far as the diameter of the pistons, f/r and haven't found them yet. The discs look to be 332 f/r.

    This has got to be accounted for with either a split master cylinder or a curiously strong proportioning valve.

    Once again i am at a loss.

    I am looking forward to working on a parking brake when time permits.

    thanks,
    chris
     
  14. velocityengineer

    velocityengineer Formula Junior

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    Hi Chris,

    Yes, you are correct. Given the 308 Brembo 36/40 front kit size, the master cyl. needs to be upsized to truly fix the issue of pedal travel.

    The suggestions of tweaking the booster vacuum and pedal are only able to add some resistance to the pedal feel, but will not change the travel requirement of the pedal with the given master cylinder.

    As for the 355, I dont have my information for that car with me now, but Ill throw out what I remember. The 355 has a CG that is lower and more centralized longitudinally than the 308 mostly due to engine/trans configuration and placement as well as a wheelbase increase. Due to this the 355 can use the rear wheels a bit more during braking. The front to rear split is closer to 60/40 f/r, and the 308 is more like 70/30. The 355 uses a prop valve for the rear, I dont have the exact reduction value here with me, but I will look to see if I still have it someplace. Using the same caliper front and rear on the 355 is a cost saving measure as well, as on the 360 etc...

    The 310 mm rear rotor isnt done to make more brake torque in the rear, but to allow for the drum-in-hat which requires a larger diameter hat section than the front rotor. The amount of brake torque from 5mm radius increase is insignificant, and the rear is proportioned down in pressure anyway. So it is accounted for

    As for why use a prop valve vs. dual mc's? from an OEM perspective it is cost. A prop valve in line with the rear axle is very cheap and works fine. Dual mc's, related lines and hardware is complex and expensive.
    Which is better? depends on how you use the car...
    I would always prefer to set up a car with duals for track use. Get the basic balance correct straight away, and use an adjustment knob in the cockpit to tune for fuel load, track conditions etc...

    F360 is 38/42 pistons f/r with a 330mm rotor all around (more cost savings, just a LH/RH rotor req)
    prop valve for the V8's since the 348 only needs to remove between 10-15% of rear pressure. Not difficult at all.

    If you put 36/40 calipers on all corners of a 308, it will have too much rear brake. You can compensate with a larger front rotor, different f/r pad choice, stronger-adj proportioning valve (only one, never run two in line!) and so-on. The hydraulic side can be adressed with a larger single, or dual mc's etc...

    I hope this helps a bit.

    Eric
     
  15. Mike C

    Mike C F1 Veteran
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    And of course, not just Steven. I've got a Brembo front/Girodisc rear combination and love the performance on read and track. I am using Porterfield R4S pads on the front and EBC Greenstuff on the rears -- makes for an excellent balance.
     
  16. staatsof

    staatsof Six Time F1 World Champ
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    Eric,

    I've been following your terrific explanations regarding braking systems and wondered if I might get a clarification on the point made by you in the above quote about never using more than one proportioning valve?

    I have a factory setup Maserati Race Car with ABS that has one valve at each rear wheel operated via a lever and then one between the ABS system (3 channel) and the rear calipers that controls both rear calipers. This valve is mounted in the engine compartment and I'd like to move that function to the cockpit.

    Do you have any comments about this design which clearly violates your recommendations?

    Bob S.
     
  17. velocityengineer

    velocityengineer Formula Junior

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    Thats a very interesting setup you describe in the Maserati. A single reduction valve post ABS system seems logical, but I dont understand the lever type valves you describe at the rear wheels.
    Do you have any pictures you can share of this?
    Is this as delivered from Maserati Corse?
    Is there a guide for tuning these valves from the factory literature?
    I would like to understand what it is they are trying to achieve here.

    Generally the issue with sequential reduction or proportion valves is that the pressure behavior can become erradic and unpredictable in the output of the second valve. I admit that I am at a loss to explain exactly why this is at this moment, but it is a "rule of thumb" no-no to put more than one in sequence. I will look through some academia to remember the exact physics of the answer.

    I am also not sure of the generation and capability of the Maserati ABS. An important part of this equation is if the OE road car uses the ECU with sophisticated algorithm programs in the ABS, and uses the ABS valves to dynamically proportion the rear brake circuit dependant on load, speed, brake pressure, yaw, etc...Most modern Bosch and Teves systems do this.
    Also if this is the case, is this system altered for the racing version to allow the mechanical addition of a driver adjustable prop valve. It would not make sense for the computer to be deciding the rear proportion and then have multiple other reduction valves in the same line.

    I am certainly very interested in this question. Does the Maserati have any difficulties in braking? do you find that the rear is unreasonably sensitive to fuel loads and track conditions?

    Ill hold off on more questions to do some research. I may end up calling Italy a couple times!

    Eric
     
  18. staatsof

    staatsof Six Time F1 World Champ
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    #18 staatsof, Jun 8, 2006
    Last edited by a moderator: Sep 7, 2017
    Before you call Italy ... This is a mid 90's car that they did for the Ghibli Open Cup series and there's probably nobody left who knows anything. If you do find someone who knows something please let me know!!!!

    I didn't mean to hijack the thread so if I should put this somewhere else someone let me know. It's just that Eric got into a lot of technical discussion
    that was so generic in nature I thought this discussion might be of help to a number of people. So here goes.

    This is how I think this "engineered" solution came to be. The street car originally had no ABS but it did have a single proportioning valve at the rear. . Then they added the 3 channel ABS to the street car in regular production so now it has a return line coming out of the proportioning valve.

    Then they went to a pair of proportioning valves, lever actuated, one at each rear wheel.

    For the second year of the racing series they added another valve directly after the rear channel output of the Bosch ABS unit.

    Pictures below.

    I've been sorting a number of things out on this car and so I've not had a chance to drive it at 10/10 ths for any period of time but I have pushed it very hard at times. I have engaged the ABS a couple of times and I'm reasonably certain that was the front system but the rear may have been involved as well.

    I've gone through 1 1/2 sets of pads and a set of front rotors but the rears
    are still in terrific shape. The car has the 355 Challenge brakes up front and a
    smaller set (F40?) on the rear.

    It's 54% front and 46% rear with a full tank and me in the car. The car has been corner balanced for just me in the car.

    I can't say anything about how sophisticated the ABS unit is but it has no connection to the Engine ECU(S). It does generate an ABS warning when on a dyno.

    I'd like to be able to tune the rear from the cockpit but I have been told by one observer that a team in the UK tried this and spent a lot of time going off of the track backwards. It does not swap ends at all now.

    This car is very similar to a BMW M3 in size weight etc.

    Another point. I have great difficulty bleeding the rear brakes even with the
    levers pushed up and the ABS system on or off so maybe the rear brakes are damn near turned off. There is an additional bleed port on the two rear proportioning valves but I haven't tried that yet.

    The street setup for this car has been very successful in Europe on their Ghibli Cup model so without the engine compartment mounted valve it must work well.

    Bob S.



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  19. RossoCorsaItaly

    RossoCorsaItaly F1 Rookie
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    Not at all, this thread wasn't really going anywhere. Eric, you, and others have done nothing but turned it into a very interesting thread, please continue by all means.
     
  20. velocityengineer

    velocityengineer Formula Junior

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    Wow,

    That is like nothing I have ever seen.
    The 3 channel ABS is 2 front and a rear circuit I believe. It is an early gen ABS, and does not have ECU feedback loop adjustment of the type I mentioned earlier. The adjustable prop valve in the engine bay is not of a type I have ever seen before.

    The rear appears to have load sensitive prop valves installed. I assume the lever is attached to a suspension member at some point and changes the brake pressure with ride height. But why one at each wheel...I dont know.
    This is the most unique setup i have ever seen.

    It would seem that the rear is reducing pressure dynamically as the suspension travels, which is not a bad thing. The only thing i can say is that I am a bit stumped by the whole setup. I have never seen anything like it.

    You can test this system easily. Many brake companies sell tuning pressure guage setups. Using a dial pressure guage for the front and rear. Attach one to a front and rear caliper, and record the F/R pressures through a entire pedal travel with the engine on, engine off, and with the rear raised and lowered (this will give the booster curve and the load sensitive prop valve data). then you will know what your f/r balance split looks like. You can then remove the rear prop valves and see what difference it makes. then replace the front with a modern adjustable cockpit unit, and see if you can match the original reduction curve for the rear, and how much adjustment you have.

    Whew, seems a lot of work? Probably. But there is no other way to know what the system is doing. You just need the guage kit and some fittings/hose assemblies, etc..

    Let me know if you do this, I am interested to hear what are the results!

    Cheers,

    Eric
     
  21. staatsof

    staatsof Six Time F1 World Champ
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    Yes I agree, wow. I am not very confident about the two suspension activated valves in the rear. In the cars stock configuration the springs and rear anti-roll bar were much softer and so I could see some benefit. The way this thing is currently set-up my chassis tuner says the springs and shock are way to stiff, especially in the rear, for a front engined car on the types of tracks we have here in the NE USA.

    What's worse is that there were no calibration marks for where the springs that retain the lever arms in the upward direction were attached to the shock body and I assume that this has an effect on how this would work.

    There is another potential point. Originally this series of races was intended to leave the owner with a car that could be easily converted back to street use. So maybe they just left this in place and made sure that these two rear proportioning valves were held static in the uppermost position thus inoperable?

    I guess I'll have to measure what it's doing now, eliminate the engine compartment valve and put one in the cockpit to achieve the same baseline results. Then I can play.

    Thanks for the input.

    Bob S.
     
  22. velocityengineer

    velocityengineer Formula Junior

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    I think thats the best plan, to test the system and simplify it.

    "nothing succeeds like simplicity" dunno who said that, but it it one of the truest statements for a racing car. You dont want to have 3 valves doing the job that other cars do with 1. I cant imagine trying to diagnose braking issue in a car with so many prop valves. Could spoil a weekend.

    Keep us updated. It is an interesting project. Hope you are on track soon!

    Cheers
    Eric
     
  23. staatsof

    staatsof Six Time F1 World Champ
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    Assuming I can get the valve moved to the cockpit and then hook the gauges up to both rear calipers I guess I could then lift one side of the car at the rear a bit and see if it has any effect? If not then I'll just bypass them I suppose. Just more **** that can leak. If it does have an effect that could be quite a tuning exercise, adjusting the height of the mounting points for those springs to effect when the valves start to have an effect. Yikes!

    Bob S.
     

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