ABS kicks in on speed bumps, is this normal for you?

[Seanz0rz]

so after finally getting the correct caliper, my tundra swap is complete and works beautifully!!! except for one minor issue i noticed today.

while going over a speed bump at about 10 mph, if i am on the brakes at all, as soon as i hit the speed bump, the right front tire locks, makes a screeching sound (stopped tire on painted smooth surface), and then the abs kicks in.

is this normal? i have never had this happen prior to today, and i frequent parking lots with speed bumps.

my theory: tire bounces up and brakes grab hold, stopping the tire flat out, but the abs sensor tells abs to kick in because the rest of the wheels are not stopped.


i have not had this happen on the left tire (though i will go and try to make it happen tomorrow).

so yea, need some input on this, and if it is a problem, a solution. i will be driving over 500 miles next weekend, and would like the truck to be in working order.

Thanks guys! you guys are the best

[d0ubledown]

interested in any thoughts on this also. does it happen when youre going straight or is the direction of travel irrelevant? i ask, because ive got a similar issue with my abs kicking in inadvertantly. although mine only happens when i make a slow left turn to a stop, like turning left into a parking spot. i dont think anything locks up, but the ABS just kicks in. not really worried about it since its only at 2-0 mph.

has your ABS light come on since the swap? have you tested to see if your ABS works properly when its supposed to?

[Seanz0rz]

no abs light, no brake warning light, nothing!

as far as i can tell, only in a straight line. as i said, never had this happen before. i should add that the truck tracks straight when hard on the brakes, so the left caliper is not sticking or anything like that.

ill play around with it tomorrow, see if i can get it to happen on different scenarios.

[arjan]

I've had that issue when my shocks were bad. The shocks didn't keep the wheels planted on the road and the wheels had a change to lock up.
I haven't had it since I replaced the suspension with a ome setup.

[Seanz0rz]

any other advise? shocks have less than 10k miles on them, so i highly doubt they are bad, green tokico trekmasters.

im going to check if the shock is leaking from anywhere, but i didnt notice anything this past weekend when i was under there.

[arjan]

Not likely the shocks then, that was just what I found to my problem at the time.

Maybe the bigger brakes lock up the wheel just a bit easier. It could also be that the new pads grab a bit more when you loose traction. Dunno, just bouncing some ideas of you guys.

[garrett]

thats happened to me before, its scary actually. it happens every so often when i'm braking at a decent speed and i hit a bump or pothole and the abs will kick on for 1-2 seconds and then resume normal braking. the first time it happened i actually had to change lanes to avoid rear ending someone, but that was when it was raining.

edit: i should add that the few times that this has happened to me, neither tire has locked up on me, the abs just kicks on for about a second and then regular braking resumes.

[Seanz0rz]

thats happened to me before, its scary actually. it happens every so often when i'm braking at a decent speed and i hit a bump or pothole and the abs will kick on for 1-2 seconds and then resume normal braking. the first time it happened i actually had to change lanes to avoid rear ending someone, but that was when it was raining.

edit: i should add that the few times that this has happened to me, neither tire has locked up on me, the abs just kicks on for about a second and then regular braking resumes.


same exact thing happened to me here on a road the other day, rough spot on the road, hard braking, felt the abs kicking in.

this weekend ill check the sensors in the front and rear to see if one is misaligned or something.

[dontdo_that]

I don't know much about the Tundra brake upgrade.. but to me it just seems like the calipers are so damn effective that they are causing the tire to lock up. But then again it doesn't make sense since the other wheel is not having problems. I guess if all else fails you could try to bleed the offending side in case there is a discrepency in fluid dispersion on that side.. although I don't even know if thats possible.

[garrett]

by the way, i DON'T have Tundra brakes... OEM here.

[corax]

if you only upgraded the front brakes, you may need to adjust brake bias - i.e. the front brakes are way more effective than the rears and thus lock easier. Did you also swap the proportioning valve when you did the swap or do anything to give the rears more pressure?

Disclaimer: I know nothing about the Tundra brake swap or what's involved, but I am an experienced ASE Master Tech & Field Engineer for an Asian Auto Manufacturer

[Seanz0rz]

for future reference, fixed, blown right front shock. replaced shock and no more problems with abs on speed bumps or other irregular surfaces.

[YotaFun]

I guess this means that I need to put my lift on now.
I hit a man hole and the ABS is going