4tt

Ok, thanks to a post from a couple of weeks ago, I know understand the concept of double-clutching and rev-matching and, how this helps prolong the life of the syncros. My question is this:

On a 225Q going from say 3rd to 2nd, what rev's am I trying to "match"? 3500 rpm? 3700 rpm? More? Less? Is there an optimal "match" for each downshift point or does it depend on the type of driving? What is the optimal "match" to minimize wear on the sycros?

Thanks

stontt

The manual actually says not to downshift until 19k. Personally I wouldn't downshift into second at 3500, I have a 180 though and shifting at this point makes the car lurch forward. 2nd-3rd for me is best at about 2200-2500. But really its all about finding the "sweet spot" on your own vehicle. Test it out yourself.

sTTanford

first of all, on any modern car, double-clutching really isnt necessary. syncros should easily last 100K miles of normal driving. that being said, a well executed double-clutch is like shifting thru butter, and i do it every now and then for fun.

per your example, 2nd gear is 2.105:1 and 3rd is 1.429:1. If you are at 3000RPMs in 3rd, you need to up your RPMs proportionatly, thus rev to 4420rpms EXACTLY! hehe, jk =)

the less work the syncros have to do, the less wear. double-clutching means you are matching the revs instead of the syncros, thus, less wear. optimal "match?" well, the lower the rpms, the less the torque the syncros have to deal with =)

JohnLZ7W

3rd -> 2nd, increase revs 1500rpm (so if you're at 3000, blip to 4500)
4th -> 3rd and 5th -> 4th about 1000rpm
6th -> 5th about 500rpm

And of course if you're skipping a gear just adjust accordingly. 5th -> 3rd would be about 2000rpm

Count Floyd

http://www.driversedge.com/dblcltch.htm

AWDGIRL

I've shown this to other people (all men) and they had NO idea what i was talkin about. Nice to see others know how to drive