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Thread: Brake Dive

  1. #1
    I post a lot... knucklehead0202's Avatar
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    Default Brake Dive

    So i'm sure this has been covered somewhere through history but i can't find specifically what i'm looking for and wanted to get a discussion going about this. We all drive pretty much the same car, we've discussed brakes in a lot of forms, but i consider this to be as much or more suspension-related. Maybe i'm the only one but i doubt it. My car brake dives to the point where it stresses me out to drive it sometimes. The other car did it too, which may partially have accounted for it's shitty stopping and unfortunate piling into an asshole in an explorer.

    Anyhow, it seems to me like this may be the result of multiple suspension issues and perhaps these cars just having a weird pivot point balance-wise. In the other car if i had to do a hard stop sometimes it would dive and then lock up one or both rear tires. Sometimes it'd lock the fronts a bit too but seemed to be mostly the rears. I attribute this to the dive unloading a lot of weight from the rear and making the already lock-prone drums easily do the deed. Is there any good way to combat this? I've read that the big brake swap with newer master cylinder/etc. definitely helps with the touchiness, and i reckon going rear disc may help too, but it seems to me that the car under braking will still feel like it's full of water that's all sloshing to the front, lol.

    Interested in opinions/statements from those who have perhaps lowered their cars, modified suspensions in other ways, sway bar setups, shocks, etc. For reference, my car is a '90 CV LX with KYB gas-a-justs(non-police) all the way around, addco sway bar in front and PI rear bar. Suspension is otherwise original, including bushings that could probably stand to be replaced. Recently replaced front calipers, rotors, ceramic pads. Running 17x8 wheels with 255/50/17 Nitto 555's.

  2. #2
    I post a lot... turbo2256b's Avatar
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    cOULD BE THE FRONT SPRINGS ARE SHOT. coil springs weaken quickly if driven with wore out shocks. shocks are not replaced as often as they should be.
    Have had cars before were i replaced shocks helped a bit . then replaced all the springs soon after and road like a new car
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  3. #3
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    Adjust the rear shoes. better yet upgrade to disks.
    I never got it right until big brakes in front, disks in back, modified pressure valve. Then tried different pads. Finally all came together with Centric Extended wear pads on 4 corners. There will always be some "dive"
    Suspension was also tight and had the weight distribution of a wagon.
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  4. #4
    drink a beer, grow a beard, cut it, grind it, weld it back His Royal Ghostliness's Avatar
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    Brake dive is natural, the only way to effectively combat it is by electronic-control shocks which ramp up the damping based on brake pressure. Obviously not a feasible solution for an older vehicle.

    Brake-diving puts a certain amount of extra compression force on the front coils. Force is spring rates multiplied by distance of compression. The force being more or less constant, if you up the spring rate (stiffer coils) you will effectively decrease the distance they compress (the visually perceivable part of brake dive). Stiffer springs also call for shocks with more damping, so you get that additional benefit as well.

    Most people who lower their cars use stiffer coils in the process, so that's part of why they're less prone to dive. Mine ran coils for IIRC halfton Dodge truck, over 1000 lbs/in spring rate, yeah there was very little brake dive there

    Big brakes and rear discs allow more braking force without lockup. Meaning if your suspension isn't as prone to brake diving then you can stop harder and faster.
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  5. #5
    I'm an air-conditioned gypsy gadget73's Avatar
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    Tired front shocks and springs and poorly adjusted rear brakes make it worse though. The shocks don't really have any effect on how much it will dive, but it will slow the rate of dive a bit vs ones that have no working resistance. Mushy tires won't help either.

    Mine has a lot of stock replacement parts. Stock replacement springs, Motorcraft front shocks for a late 90s P71, original late 80s Motorcraft rear shocks. Front brakes are 98-02, rear disc, 98-02 booster and master cylinder. It has no significant brake dive. It does dip, sure, but not enough where it would be alarming. The tires are also not prone to locking up at all, it just stops.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  6. #6
    No mean-spiritedness here. IPreferDIY's Avatar
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    Quote Originally Posted by knucklehead0202 View Post
    ... Suspension is otherwise original, including bushings that could probably stand to be replaced. ...
    I'm inclined to think changing the bushings would give a noticeable improvement. I was dumb enough to change the ball joints on my 2000 MGM without changing the bushings, and it became clear that the bushings were shot. My impression was that the bushings really get hammered from braking.

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    GMN Regular DerekTheGreat's Avatar
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    Another thing to try and do is "squeeze" the brakes when getting on them, don't just mash the stop pedal to the floor but gradually get the weight to shift. By gradually I mean 2 seconds or so, makes a huge difference. Town Car dives but I've never had the rear wheels lock on me nor have I had to swerve to miss hitting anyone. I have had people behind me lock tires & swerve in "modern, better engineered machinery." This is with stock brakes and stock everything, all dubbed shitty and whatnot by the majority but they work just fine for me. I did make sure the rear brakes were in good working order and properly adjusted though.
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  8. #8
    I post a lot... knucklehead0202's Avatar
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    I've definitely re-developed my braking style, this thing is night and day compared to the '98 p71 i drove for years. It dipped a little under braking but never felt unstable. This thing is scary if you more than breathe on the pedal. Yeah i figured the bushings, etc would definitely need replacement but i don't really want to do anything until the big-brake swap. Wish i had limitless time and/or money so i could do all this shit at once but alas, i do not. Does anybody think that rear suspension comes into play here as well? I do have a pair of adjustable rear upper control arms that Merc91 made. I wonder if putting those on and dicking with the length might make a notable difference.

  9. #9
    I'm an air-conditioned gypsy gadget73's Avatar
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    Drove the Continental tonight, it has a whole lot of dip. Struts are who knows how old, and its got the softer air springs. Also may have a wee bit of air in the back brakes, so basically all of the bad things.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  10. #10
    Stow It! GM_Guy's Avatar
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    Don't mind me, just dropping these in here. Brake dive, just normal ford behaviour. =-)

    https://www.youtube.com/watch?v=bUrpigJXVM8
    Laughable commentary sometimes.

    https://www.youtube.com/watch?v=QPK8vy8n9PM
    and this one sums up my feelings about ford suspensions pretty spot on. =-)

    https://www.youtube.com/watch?v=WbGK7lSmP28
    in all fairness, gm wasn't doing much better in the dive department.

    The lesson to take away, soft spring ain't all that great except for the floaty ride in a straight line.

    Alex.

  11. #11
    I'm an air-conditioned gypsy gadget73's Avatar
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    Wow, I swear the tires on that 69 Impala went away completely in a hard turn. Sure looks like they were running rim to road a few times. Yay 1969 radial technology.

    Kinda funny, my Towncar handles and accelerates better than the big block cars of the 70s, yet people assume its worse in all respects.
    Last edited by gadget73; 01-12-2018 at 10:31 PM.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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