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Old 07-06-2014, 04:05 PM   #1
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Default Brake peddle pulses over bumps when braking

Anyone know what would cause the brake peddle to feel like ABS is kicking in when braking and rolling over small bumps in the road? I don't have ABS.

The only work I did recently was pull off the drivers front wheel to inspect my suspension and put it back on.
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Old 07-06-2014, 04:10 PM   #2
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Wheel bearings
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Old 07-06-2014, 04:15 PM   #3
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Someone needs to peddle you some bearings.
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Old 07-06-2014, 04:24 PM   #4
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First thing to check is to make sure you got the rotor seated properly on the hub.

Wheel bearings are easy to diagnose. Any side to side play in the wheel, it's time for new ones.
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Old 07-06-2014, 07:28 PM   #5
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I'd like to think it was wheel bearings, but I just replaced all four wheel bearings.. I'll check the rotor though. Who knows, maybe the lugs are loose or something simple. Could it be because the GC sleeves are shot and perhaps are rocking under braking?

New precision front bearings, timken rear, rpkg tie rod ends.
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Old 07-06-2014, 07:45 PM   #6
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Was it doing this before you replaced the bearings?
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Old 07-06-2014, 08:29 PM   #7
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On my RX7, you often have to retorque the wheel bearings after initial replacement and any spirited driving.
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Old 07-06-2014, 09:22 PM   #8
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I'll second Supe's idea. Gotta re-torque the bearings.

Or, do it the old fashioned way, which is to over-tighten (to fully seat them), back it off and then torque to spec.
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Old 07-09-2014, 03:41 AM   #9
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I've elected to pull my suspension and swap in my NB subframe+suspension as I'm getting the vmaxx xxtreme track pack delivered Friday after work, together with a full set of eccentrics from 949 I am hoping this problem goes away. However while disassembling things tonight I noticed my driver-front pads+caliper are grabbing more on one area of the rotor than the rest. In any case I'll update as more information comes to light.
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Old 07-09-2014, 12:05 PM   #10
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Quote:
Originally Posted by Der_Idiot View Post
I've elected to pull my suspension and swap in my NB subframe+suspension as I'm getting the vmaxx xxtreme track pack delivered Friday after work, together with a full set of eccentrics from 949 I am hoping this problem goes away. However while disassembling things tonight I noticed my driver-front pads+caliper are grabbing more on one area of the rotor than the rest. In any case I'll update as more information comes to light.
Sounds like your hubs are out of round. Time for a new hubs and a new rotors.
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Old 07-09-2014, 01:29 PM   #11
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Don't forget to thoroughly clean the mating surfaces of the hub/ rotor as well as rotor to wheel. It only takes a very small amount of rust or grime on the hub, to run a rotor wayyy out on the big end.
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Old 07-09-2014, 03:09 PM   #12
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<<<@[email protected]>>>

+1!
Here is a video that i use to explain lateral runout, and thickness variation. it's a coppy of a vhs tape, but it explains it perfectly.
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Old 07-10-2014, 06:49 AM   #13
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might be a long shot but is your firewall flexing over bumps? do you have a master cylinder brace?

I DIY'd my Master brace and the difference in peddle feel was amazing.
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Old 07-10-2014, 09:51 AM   #14
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It could be your Brake hoses. Do you still have factory rubber ones?
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Old 07-14-2014, 11:20 AM   #15
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So far I'm still in the process of installing Grease Zerks and it's taken a lot of time; I just have my rears to go, then mount the rack+tie rods and bolt everything up.

4sfed5: I DO get a fair amount of flex, it's like the more I tighten things up, the more things I notice need to be serviced lol. I'll figure something up for the flex, might cave and get a premade since I'm so strapped for time.

duffbuster243: I have SS lines, however it could maybe be air in the lines, so I've opted to bleed them if the above doesn't work. It's good practice anyway though.

OG Racing: Good news: I'm swapping for NB uprights, so I'll get to see if those help fix the problem.
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Old 07-14-2014, 12:30 PM   #16
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Quote:
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OG Racing: Good news: I'm swapping for NB uprights, so I'll get to see if those help fix the problem.
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