News

308 better rear braking

Discussion in 'Technical Q&A' started by cnmorse, Nov 9, 2003.

  1. cnmorse

    cnmorse Rookie

    Nov 9, 2003
    1
    I do not yet own a 308, so I read the chat with great interest, particularly the common problems, improving engine performance, braking and suspension tweeks. It seems that Brembo does not offer an improved rear brake, so, I was wondering if someone had manufactured a rear caliper mounting spacer that allowed the use of a bigger rotor.
    What is the diameter of the rear piston. The 914-6 caliper is a few milimeters bigger than the standard 914 caliper - does ATE manufacture a rear brake caliper for another application that offers more piston area?? I installed a 911 caliper spacer in the 914-6 ATE caliper to enable me to run a vented cross drilled rear 911 rotor. Bigger "off the shelf" parts could be a very cost effective solution.
    Slowing for a beer, I remain, CNM.
     
  2. zff

    zff Karting

    Nov 1, 2003
    145
    Hawaii
    Full Name:
    Ken
    I've seen a Brembo kit for the rear of a 308, but it required giving up your parking brake. I think for this reason, many places don't offer it.
     
  3. Trinacria

    Trinacria Formula Junior

    Aug 7, 2002
    665
    Long Island, NY
    Full Name:
    Baldassare Guzzo
    What parking break?
     
  4. Trinacria

    Trinacria Formula Junior

    Aug 7, 2002
    665
    Long Island, NY
    Full Name:
    Baldassare Guzzo
    Oh, the parking "brake". I call it a parking "break", that useless handle next to the driver that is supposed to lock the rear wheels. Anyone have one that works?
     
  5. Auraraptor

    Auraraptor F1 World Champ
    Owner Lifetime Rossa

    Sep 25, 2002
    10,903
    MO
    Sometimes...no not often though. When it does I am always like wow! and get all excited.
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,384
    The twilight zone
    Full Name:
    The Butcher
    Yeah, mine works nicely. I've even been considering keeping the stock calipers when I install a set of very large rotors I bought...although I probably should just bite the bullit and buy better calipers. I went up to 18" wheels, so I'm going to install 355 mm x 32 front and 332mm x 32mm rear. Stock is 282mm x 22mm front and 297mm x 20mm rear.
     
  7. Dave

    Dave F1 Rookie

    Apr 15, 2001
    2,722
    Little Rock
    Full Name:
    David Jones
    There are a number of brake options out there for the 308,
    But before you start sweating over the supposed lack of rear brakes on a car you don't own, let me say this...
    The brakes on a 308 are fine in normal driving situations as long as you keep them in top working order.
    But if you are running a 1.8 mile course hot and heavy,
    then up-sizing your calipers/rotors would be a good idea.
    As mentioned, the current offering in a rear Brembo upgrade does away with the parking brake.
    I have yet to hear of alternative options in this regard.

    Here is a shot of the rear rotor from my 77 308GTB.
     
  8. pma1010

    pma1010 F1 Rookie
    Silver Subscribed

    Jul 21, 2002
    2,556
    Chicago
    Full Name:
    Philip
    Remember, 90% of the braking is done by the fronts (so why did Enzo use smaller rotors on the front?).

    A cheaper solution likely involves ducting cool air to the center of the rotor and a different pad material and brake fluid choice. Once the (race) pads are warmed and plenty of cooling air flows, my 308 brakes pretty well at the track and they'll last the distance. Having said that, I've been through countless combinations to get there.

    Of course, bigger rotors when supported by all the other stuff will be better...and cooler looking..but it is a big $$$ investment.
     
  9. zff

    zff Karting

    Nov 1, 2003
    145
    Hawaii
    Full Name:
    Ken
    Running brake ducts to the front is simple enough, but if I wanted to run ducts to cool the rears, where should I pick up the cool air?
     
  10. pma1010

    pma1010 F1 Rookie
    Silver Subscribed

    Jul 21, 2002
    2,556
    Chicago
    Full Name:
    Philip
    I've seen a couple of different systems. For the fronts, as you say, the job is simple enough. On my car, I used a scoop sold by one of the race shops and located below the parking/side light/indicator. I had made up an adaptor that replaced the backing plate with a circular fitting that the (female) hose could fit over. Works well. Unnoticeable unless you look closely.

    I've not found I've needed anything on the rears, but Butch Hooper (I think) sells ducting that picks up cool air on the rear 1/4 panel, in front of the wheel well and ducts it into the rotor.

    The 360 Challenge cars use an interesting ducting system on the fronts that, it seems to me, could be modified/copied for use on the rear. The air intake is below the lower control arm (with a small grill on the opening) and a (beautifully made carbon fibre) duct to the wheel center. My guess is something similar could be fab'd for the rear of the 308. Sorry, I don't recall the ducting on the rear of the 360C

    HTH
     
  11. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Two Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    28,462
    Birmingham, AL
    Full Name:
    Tommy
    I put the Brembo kit (caliper and Rotor) on my 308. I can't imagine that modifying the rear at the same time would be cost effective on a street car that is used on the track a few times a year. The front kit stops the car really really well.
     
  12. Dom

    Dom F1 Veteran
    Rossa Subscribed Owner

    Nov 5, 2002
    7,519
    Southern California
    Full Name:
    Dom V.

    My GT4 has ducts on the fronts. I had assumed all 308's have this. Is this not the case? Is the GT4 different? Or, is it possible that it was added afterwards by on eof the PO's?

    Dom
     
  13. zff

    zff Karting

    Nov 1, 2003
    145
    Hawaii
    Full Name:
    Ken
    Sounds like it requires cutting a hole into the sheetmetal. Ouch.

    I was actually wondering if I could use the the ducts that cool down the catalytic converter area if I take the cats out. I realize these ducts are behind the rear tires, but tubing to bring the air right up into the rotors should work pretty good, huh?
     
  14. pma1010

    pma1010 F1 Rookie
    Silver Subscribed

    Jul 21, 2002
    2,556
    Chicago
    Full Name:
    Philip
    No, the one I've seen for the 308 sits on the body surface...beauty is in the eye of the beholder...
     
  15. atlantaman

    atlantaman Formula 3
    Rossa Subscribed

    Mar 31, 2002
    1,726
    Roswell, Georgia
    Full Name:
    Charles
    There are several brake kits for 308 cars but I did not like any of them and designed my own.
    I now have 12.25 rotors in front and 11.95 rotors in back with calipers to match the original front/back bias. this took me about a month to design and build. cost about 3000 for everything

    only problem now is no rear parking brake--was going to buy the mechanical units from Brembo but the JERKS quoted me 100.00 per side and then tried to raise the price to 300/side when i wanted to order--i'll never use Brembo again.
     
  16. enjoythemusic

    enjoythemusic F1 World Champ

    Apr 20, 2002
    10,671
    Worldwide
    Full Name:
    Steven
    How did you deal with brake biasing? Does the 308 have some adjustment? Since improving the suspension and lowering the car she feels as though the rear brakes are a bit weak as the front like to lock up faster than i'd prefer (during aggressive driving). Am going to wait and see how she does with new tires (using Kumho Supra 712 now, upgrading to Yoko A312R as soon as they come in). Lastly, what was the cost including installation of the Brembo front kit? Thanks as ALL help is ALWAYS appreciated.
     
  17. TommyA

    TommyA Formula Junior
    Silver Subscribed

    Oct 7, 2002
    287
    Sharpsburg, GA.
    Full Name:
    Tommy A
    Steve,
    The Brembo front kit is around $2,500.
    According to the salesman, it's not expensive!!!
     
  18. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
    2,149
    way north california
    Full Name:
    chris morse
    Hey mike,
    It has been a few months since this post have you had the time or inspiration to do better brakes.
    Which 18 inch wheels?
    How much bigger pistons on the front and rear?
    Pads??

    Lord knows you have enough power.

    To the other worthy respondents--

    What brake improvements have you made??
    What did you learn in the process??

    IMHO, if you are going to drive fast, it makes sense to look at the improvements in brake materials and technology that have evolved in the last 20 to 30 years.
    I do not mean to denegrate the stock equipment, rather to learn and do what I can to improve all of the car's performance.

    vroom & screech,

    chris
     
  19. maurice70

    maurice70 F1 Rookie

    Jan 25, 2004
    3,886
    Sydney
    Full Name:
    maurice T
    #19 maurice70, Jun 2, 2004
    Last edited by a moderator: Sep 7, 2017
    No Dom I think that all GT4s have them and like you am surprised that the GTB/S dont have them.On the issue of the parking break does anyone out ther have any suggestions/fixes/mods to get this thing to work properly? Ive adjusted all that i could and it works on a slight incline but I need to have ARNIES arm to get it to workbetter.My theory is I think that the lever arm (as referenced in the diagram as 13) is to short and am considering modifying/lenghtening this armto get a better lever action. Any thoughts or other imputs or is this just another one of those issues that we just accept as it is? All imputs are highly appreciated thanks
    Image Unavailable, Please Login
     
  20. enjoythemusic

    enjoythemusic F1 World Champ

    Apr 20, 2002
    10,671
    Worldwide
    Full Name:
    Steven
    maurice70,

    Like you, had e-brake problems. The BEST BET is that over the years the INTERNAL E-BRAKE PART in the rear brake units need adjustment. This means taking apart the rear brake unit, adjusting the e-brake section, then reassembling the unit. The small screw DOES allow for some fine-tuning, yet i would suggest doing it right by taking apart the rear brake and adjusting it. We must remember these items are decades old so adjusting it properly would be in order.

    FYI: My adjustment screw attached to the wire was adjusted BEFORE i had it done right. The difference IS NOT subtle between using the screw and doing it right.
     
  21. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    The standard parking brake is never great, but it can so easily be a lot worse than it should be.

    Many are adjusted incorrectly or not at all.

    Firstly, the little caliper lever needs to rest against its stop when off. If the cable has been adjusted badly, the caliper lever will be held partly on and it's leverage and travel is greatly reduced.

    So, fully slacken the cable. Then adjust each screw on the caliper.....remember the outer one turns anti clockwise to tighten, the inner one turns clockwise to tighten (once the cap is removed).

    Always tighten the screw until you can't turn the disc any more, then back it off. Do NOT stop turning when you feel the first bit of drag. Adjustment is very coarse, so small movements are needed. If you over do it, or are changing pads, you need to push the piston back in with a lever while you de-adjust it. If you try to pull it back with the adjuster, you'll pull the sliding bobbin out of the piston inside.

    Once each caliper is adjusted, then remove the slack from the cable. With the suspension on droop, it's ok to have a little drag, as at ride height the cable length is reduced slightly. 246 Dino are worse than 308 for this. Very early S1 Dino's are very bad, as their calipers are fitted up side down, with the lever at the bottom.

    Properly adjusted, the brake will hold the car on a slope. But if the brakes are hot when parked, it'll most likely roll away when cooled!!

    Back on topic....The pressure regulator can be replaced or removed to increase the braking to the rear. But in my experience, a well set up 308 only needs the front brakes up-graded. the rears can be made to be perfect with pad choice.
     
  22. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,384
    The twilight zone
    Full Name:
    The Butcher
    No...the rotors are still sitting on a shelf...they don't help much there I guess ....the ferrari budget took a real beating about the time I was getting ready to do the brakes, the clutch absolutly melted and I ended up dropping $3500 for a triple disc carbon-carbon unit...really nice clutch, but pricey... and I've been fighting a naging fuel injection problem that I finally track to the ECU not being able to supply quite enough power to run the monster fuel injector I need, so I'm just finishing up installing a new bigger better ECU.....then I can get back to the brakes. (plus I didn't want to add any rotating weight until after I get the car on a dyno :)..I'm hoping that will be Saturday)

    I put 550 wheels on it, I like the way they look.
     

Share This Page