my housing association recently installed two speed bumps (big ones, as in, huge) on the ramp down into the complex car park. Fine on the way down... but on the way up they are quite an issue in my 2008 stick-shift Mini Cooper Convertible.
First let me say I'm not new to driving a stick-shift. I learned in a stick shift, and have driven only a stick shift for the last 16 years. I happen to think I'm pretty good at it, even if I do say so myself
Well, hey, my driving instructor said so too.So... the problem :I did some experiments when the bumps were new, and tore a jacking point off the underside of my car by taking the bumps at the idle speed of my car (ie. the speed it will do in first gear with my foot off the gas pedal). That was 7mph. So, that's the effective speed limit. 6mph doesn't damage the car but it is uncomfortable (whiplash). I currently have 3 methods for getting up the ramp over the speed bumps :
1) Stop at the bump. Creep over at 1mph. This works reliably, but I'm pulling over a huge bump that's already on a hill. It must burn a lot of clutch, and for that reason I don't think it's an acceptable method for the long haul (ie. every day).
2) Slip the clutch as I go up the entire ramp (maybe 150ft) and try to maintain exactly 4-5mph. This I can do, but it's very difficult. The problem is that while holding the clutch rock steady as you go up a hill is possible, holding it rock steady while going over bumps is really hard. If your foot moves you could be doing 7mph real fast, and then you lose part of your undercarriage. I figure it's also bad for the clutch to do it this way. So, again, probably not good for the long haul. I might manage it 9 times out of 10, but eventually I'll screw up and be minus another jacking point.
3) Put the car in first gear, and then, foot off the gas, push down on the brake. If I push hard enough I'll stall it, I know, but it turns out I can slow the car from 7mph (the speed it wants to do) to 5mph (safe bump driving speed) without stalling. It does make the car shudder though. This is my current preferred method.
So, my questions:
a) Is method 3 bad for the car/engine? What's all that shuddering about?
b) Is method 3 doomed to fail as the weather gets colder? I figure that as the temperature drops the automatic choke (or whatever its modern electronic equivalent is) will increase the idle rev count when the engine is cold (which it always is when I'm leaving the complex). Increased idle rev count presumably must translate to increased idle speed when the car is in gear... and if the car wants to do 12mph, will I still be able to get that down to 5mph using the brake, or will the car stall? I've assumed it will up to now, but I realize that's an assumption, and I might be wrong.
Thanks in advance
Rob
