mostafaberg

Hey guys, tried STFF but couldn't come up with anything similar !,

What happened yesterday while i was reversing into a tight spot with my steering wheel locked to the left, the brake pedal got really heavy and the car was nearly breaking..

i took her out again and examined every part and everything is intact, even took the wheels off and checked the break lines, but no , nothing.

note this only happens when the steering is locked to the end, as soon as i turn it back to the center position the brakes come back after pumping once or twice !

any tips ??? it surely has to do with the front brakes i assume since it's affected by steering position..

EDIT: I just noticed i didn't actually take a look with wheels fully locked cause i'm alone and had no one to help and no lift, but could it be something pinching the lines ? since the pedal gets extremely hard i suspect the fluid gets stuck somewhere ?

Glyn M Ruck

If your booster is OK & your brake fluid full it seems that the steering angle sensor is interfering with BAS/ABS. (possible via the ESP circuit.)

Try turning your steering from lock to lock 5 times to reset the SAS & tell us if anything changes.

Boom vang

A guess: sounds like your flexible brake line gets kinked when lock to lock or was kinked in the past when working on the brakes and gets affected when the steering is at the extreme It might be as simple as changing both flex lines and re-bleed

jack up the car, take the wheels off and get a helper to press the brakes when at lock to lock and see if you can turn the wheels. Try again with the engine on and if this happens then it could be an electrical issue with the ABS/ESP/BAS

I had a similar issue but reversed on my TR6, the pedal would sink to the floor after a full lock turn. The culprit was worn wheel bearings allowing the rotor to push in the outside piston on my fixed 2-pot calipers as there was too much play, so the next time I used the brakes it needed the full stroke to energize the piston so that they were back to the preferred position. A set of new bearings solved the issue. Strange but true

mostafaberg

Yeah booster is perfect and fluid level is in the normal range, nothing wrong there..

i'll try the lock lock and see what happens, stay tuned !

mostafaberg

Ok i see where you're going, seems straightforward, will get that done this coming weekend then !

Yeah I know about the bearing issue, it can be really confusing to troubleshoot that !, but my bearings have less than 1k on them, brand new (Had a little incident i'm not so proud of, if you check my posts you'll know )

Will test the lock-lock x5 and see first !

mostafaberg

Ok just tried the lock to lock reset, didn't help, but i did some more troubleshooting and now i think it's something in the electrical system, here's what i did

1- Only full lock to the right produces this

2- If the steering wheel is centered and i'm reversing, it happens the faster i reverse !

3- If i'm reversing then place the car in Neutral and brake while rolling it doesn't happen !

What the heck ?

i should probably pull the codes, i'll get my scanner out and do that tomorrow, but do you see what could that be ?!

Glyn M Ruck

Yeah ~ the other problem is classic caliper over return in one of it's forms. In that scenario once you have pumped the brakes to regain pedal you should have fully boosted brakes. You should not have to push the pedal hard to achieve braking.

Glyn M Ruck

Pull codes. I think it's ESP/ABS/BAS related unless you have an SAS failure.

Glyn M Ruck

BTW ~ make sure your scanner can read Benz ABS codes. Many can't.

mostafaberg

Ok i just scanned and got nothing beside some old MAF + O2 sensor codes..

hmmm probably my scanner doesn't scan ABS errors ? it's a cheap eBay ELM based Bluetooth scanner..

what do you recommend to do next ?

Glyn M Ruck

All you can do is re seat the yaw sensor in the trunk behind the spare wheel. Unplug & check the ESP plug, clean & replug. The ESP module is mounted on the front face of the ABS block.

You can try bleeding the brakes.

If this does not work & as this is a potential safety issue I would get the car onto a Star.

mostafaberg

Ok that's surely a weekend project !, i think it's time to bleed the brakes anyway so i'll be on it, do you recommend braided brake lines by the way ? i noticed the rear lines are starting to get old ant was thinking braided ones might be a nice upgrade !, thoughts ?

I'll get her on STAR ASAP, I've been trying to find an indy or someone with STAR hear besides the dealer..