Okay here's my question...

Are Mini's known to jerk back and forth towards the end of the braking curve during mid to hard braking?? Actually even during slow braking....

When I brake at times it just feels like either the throttle body is flapping semi-open and causing the car to want to move forward some more or is that just the way Mini's brake??

 

I'm on my second Mini (both R53s) and have never felt what you're describing. Do you have an auto or manual? If manual does it make a difference if you're in gear or have you tried pushing in the clutch and putting it in neutral (or heel-toeing)?

 

I have an automatic... It doesn't happen throughout the braking curve...

Just towards the end as I come to a stop....

 

Is your MINI a Cooper or a Cooper S? Sounds like a transmission problem.

 

It's a Cooper S... I just picked it up in August 2008...

It's not a transmission issue... My car shifts just fine...

The jerking forward & back is only when I brake and towards the end of the braking curve... It's not severe or anything like that... Just annoying as hell....

Just feels like as if the throttle body isn't closing completely and it's flappin open or something... It's hard to explain in words...

 

To me it sounds like the lock up torque converter may not be unlocking as it should. You might want to pay your dealers service dept a visit.

 

warped rotors maybe?

 

Nah, it's not the rotors cuz my steering wheel doesn't shake...

I may have to just take it to get warranty work... Just wanted to check here first to see if it was common with Mini's...

I remember seeing something about Mini's having some type of "yo-yo" effect and I wasn't sure if that was it or not... I remember seeing a part that one of the vendors is selling that supposedly eliminates Mini's "yo-yo'ing"...
What is that anyways??

 

First description of the "Yo-Yo" issue on motoring file
Detroit Tuned Bypass Valve

The yo-yo issue should theoretically be felt even when not braking or just letting off the gas. Even though it is an automatic, if the issue is repeatable and it only happens when you brake: get up to speed, put the car in neutral and brake and see if the issue still occurs.

 

Sounds like what happens when the ECU turns on the fuel injectors at about 1800-2000rpm's. You will feel a bit of a jerk as the engine starts burning fuel. The MINI's actually will shut off the injectors when you take your foot off of the gas and coast in gear.