Yesterday, there was a jam following an accident on the A406, so I joined it at a different point than I usually do.
I was coming onto it from a fairly small side road with a give way line, rather than the light controlled junction that I normally do.
The speed limit on that stretch is 50. It was fairly busy, but I found a decent gap with no traffic in the outside lane.
Thing is, because of the speed of the road (taking into account that people often do much more than 50) and the fact that it was fairly busy, I thought it prudent to get up to speed ASAP.
So, I put my foot right down in 1st and, with a bit of complaining, it got up to around 40 pretty quickly, but then sounded as if the engine gave up for a moment. I put it up into 4th and all was fine, up to 50 and put it into 5th.
I just wondered if you guys could give any advice on the best way to get up to speed in that kind of situation. Should I set off in a higher gear? Sometimes I have mistakenly set off in 2nd, and if accelerating quickly, it does seem to be smoother.
On the few occasions I have mistakenly set off in 3rd I have always stalled, although I guess it might work if I revved higher.
I don't really know the intricacies of the relationship between gears, revs and accelaration, was always just taught to set of in 1st, and then move up and down gears when accelerating and decelerating - but it seems to me that there are time, when accelerating quickly, that you don't want to have to make an early gear change, and it didn't sound as though the car really liked the idea of 0 to 40 in 1st.
Any advice appeciated (it is a 2 litre Diesel Mondeo BTW).
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You hit the rev limiter. Being a diesel it's obviously lower than a petrol. You should have changed to second more quickly. Then probably block changed from 2nd to 4th.
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Sounds like you hit the rev limiter.
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Thanks guys.
So, if I want to accelerate from 0 to 50 as quickly as I can do so safely, do I indeed start in 1st and then switch to 2nd, then 4th and then maybe 5th, or there anything to be gained in starting in a higher gear?
Of course, it is not just about getting from 0 to 50 as quickly as possible, it is about reducing the risk of obstructing those behind, so the early acceleration, say 0 to 30 is perhaps more important than the 30 to 50, if you see what I mean.
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I'd say that starting in second is risky unless you are confident of both your and the car's ability. If you launch yourself into a gap but either of you fluff it, it could be messy.
Try it out a bit beforehand to make sure it will work as expected. I often do it. Along with block changes - but I'm not sure that would achieve best acceleration in your circs - again, depends on ratios and what point you change at.
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Most likely you hit the rev limiter, a fault cuasing hesitation under those circumstances would cause the engine managment light to illuminate.
In diesels I've driven first is just for pullling away or creeping in traffic. Get it in to second almost straight away, change again around 3krpm and repeat until target speed achieved. Thed key is to keep the engine in its torqueband.
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But do pull away in 1st normally. Just change up quickly. I doubt you can get to more than 35mph if that in 1st on a Mondeo TDCi 130PS. And it will be screaming.
Peak torque is around 1800-1900rpm and will tail off near the rev limit. So change up before you get near the redline.
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Not a good idea to be taking off in second from a standing start, excess clutch wear and regular overheating of the DMF will result in expensive replacements .
You probably won't need to go above 3000rpm with your car to make quite rapid progress, practising getting your gearchanges seamless by balancing the engine revs with the next gear will make progress much smoother and will lead to longer drivetrain life, avoid clutch slip if you can.
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If you want to step smartly away from the line, you always use first.
Rev it to about 4k revs, then pull second or third. Either is good at 45-50.
On the vw units I always pulled max revs in 1 then 2, and then decide to use 3rd or block change to 4th.
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Get an automatic and floor it !
My Mk4 Mondeo TDCi 6 speed Auto is pretty quick through the gears after the initial lag from standstill (0-60 in 10.8 seconds IIRC).
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Sorry to disagree with AE, but found in my case (Passat 1.9TDI) that the best performance resulted from getting it rolling in first, straight into second and boot it up to the rev limiter, then third until the limiter. At this point you're doing nearly 80 and can slot it straight into 5th.
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I think I'd have probably waited for a bigger gap in the traffic. If there's a choice between holding up an impatient driver behind you or carving someone up when you pull out, I'd rather do the former.
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I think I'd have probably waited for a bigger gap in the traffic. If there's a choice between holding up an impatient driver behind you or carving someone up when you pull out, I'd rather do the former.
I completely agree. There was a massive gap, nobody anywhere close in the first lane, but still wanted to get away as soon as a could. Never know if you might get, for example, somebody in the middle lane move over because they haven't observed properly.
I just reckon that it is safer to get up to the same speed as the rest of the traffic just as soon as I can, and wanted some tips on that.
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I do agree that modern multi ratio autos are quite brilliant for that sort of occasion. I think I upset a 3 series driver the other night accelerating out of a wet dual carriageway roundabout in the Qashqai 2.0 diesel auto 4x4. He simply couldn't keep up as when he dipped his clutch mine just kept gaining speed. Of course he came hooning past when I backed off to settle at.....um....70ish.....er....officer.
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you're doing nearly 80
Not on the 50mph North circular you dont. Too many cameras
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I'd never start off in second gear in these conditions. If you stalled it, you'd be shafted, so to speak. I usually use first to get me up to about 10mph and then into second and foot to the floor.
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Absolutly
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My CC3 - same 2.0ltr diesel as the OP - has a red 'up arrow' light on the dash as you approach the red line on the rev counter.
I take this to mean: "Change up, you hooligan."
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It's at times like these that the combination of automatic transmission, 296bhp and RWD makes it a real hoot. From just about any speed my 335D just goes on accelerating without any let-up.
Only problem is you have to keep a keen eye on the speedo...
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In our PD130 Golf I use 1st as a "get you moving gear" only. On the odd occasion I have floored it in 1st, you get a massive wallop in the back, the rev counter zips round past 4000 incredibly quickly, and then it runs out of puff. Also it simply lights up the ESP warning on anything less than a perfectly dry, smooth surface. Far better to short shift into 2nd, then floor it where the pull is much more sustained and will take the car rapidly from 10 mph to 50 mph. In this car, even when making progress, I rarely take it much past 3500 RPM.
Powerful diesels and auto boxes such as Andy's BMW above work extremely well. My boss's Jag XF 3.0 diesel is effortlessly rapid, with a big, sustained shove in the back that doesn't even start to tail off until well into three figures. The autobox seems to naturally keep the diesel engine right in its sweet spot, and the speedo needle just winds clockwise at an eye opening rate, punctuated only by the odd gentle slur as the box does its stuff. Lots of performance for absolutely zero effort.
I put in a recent thread that my "affordable" lotto win car would be an XFR, but I wouldn't dismiss the diesel. It's brilliant.
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Any advice appeciated (it is a 2 litre Diesel Mondeo BTW).
I have done some quick "back of the envelope" approximations. Feel free to correct me if there are any errors in my calculations.
Assume that the approaching car is 150 yards/metres away, travelling at 60mph (just under 30 yards/metres a second).
At time zero:
Your position = datum zero
Other car position = minus 150 metres
Say it takes you time = t = 10 seconds to go from your standing start to get above 60mph (assume steady acceleration = a = just under 3 yards/metres per second per second).
In that 10 seconds, distance d1 you will have travelled (d1 = 0.5 x a x t x t ) = ( 0.5 x 3 x 10 x 10 ) = 150 metres
The other car will have travelled distance d2 = speed x time = 30 metres per second x 10 seconds = 300 metres
At 10 seconds past zero:
Your position = plus 150 metres
Other car's position = plus 150 metres
Therefore collision unless the other car brakes! [*]
In other words, you need to allow the other car a gap of about 200 yards/metres before you join the traffic or you need a car capable of accelerating faster than .
Notes: [*]
Actually there would be a few metres gap yet because 60mph is not exactly 30 metres a second, but is about 26.83 metres a second.
So in 10 seconds, the other car would have travelled 268 metres, giving you head start cushion of 32 metres. The other car would need to brake a little to increase the gap to about 60 metres in line with the "two second" rule.
Also, at a steady acceleration of 3 metres/s/s, your speed at the end of 10 seconds would be 30 metres/s which equates to 67.11 mph
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