|
|
|
|
| Author |
|
|
Registered
Join Date: Aug 2009
Location: Ottawa, Ontario
Posts: 289
|
Transmission question
Hi Guys,
I have a question that may seem rather simple or even dumb, but I am pretty new to this stuff. I have an 86 3.2 coupe and from what I am told the synchro in second gear is basically gone. My mechanic took me for a drive to show me how to drive it properly in its current condition. He was able to shift great from first to second by blipping the gas coming through neutral before engaging second. This was quite a shock to me as I shift very slowly from first to second and at low rpms, anything else I would get a pretty significant crunch. I was amazed how he could accelerate hard in first and then shift smoothly into second, no crunch at all. I have tried this a few times, and although I am getting better, I was hoping someone could explain to me how this actually works, internally I mean. I am the type that if I can clearly undersatnd the therory I can apply practically. Any thoughts or tips here would be greatly appreciated. Thanks guys |
||
09-24-2009, 05:56 AM
|
|
|
Registered
Join Date: Oct 2001
Location: San Carlos, CA US
Posts: 5,523
|
The synchro's job is to speed up or slow down the spinning speed of the gears so that it matches the speed of the engine as you are shifting. What your mechanic is doing is emulating the synchro in reverse by changing the speed of the engine to match the spinning gears. As he blips the engine and the rpm falls after the blip, there will be that one perfect engine speed for the spinning gears in the transmission and when you shif at that speed, no crunch will be heard.
I do this religiously on down shift, but not up shift.
__________________
Porsche 2005 GT3, 2006 997S with bore-scoring Exotic: Ferrari F360F1 TDF, Ferrari 328 GTS Disposable Car: BMW 530xiT, 2008 Mini Cooper S Two-wheel art: Ducati 907IE, Ducati 851 |
||
|
09-24-2009, 06:37 AM
|
|
|
Registered
Join Date: Jan 2009
Location: Marietta, Ga (Atlanta)
Posts: 2,970
|
Remember the old term "double clutch", well that procedure is what it is! Many years ago before syncronized transmissions, that was the only way to shift!
__________________
'80SC Widebody 3.6 transplant Anthracite "The Rocket" Long gone but still miss them all: '77 911 Targa, '72 BMW 3.0CS Coupe(finest car I ever had!) '71 911T Coupe White, '70 911T Coupe Blue '68 911 Coupe Orange, '68 911L Soft Window Targa |
||
|
09-24-2009, 06:50 AM
|
|
|
Registered
Join Date: Aug 2009
Location: Ottawa, Ontario
Posts: 289
|
Thats what I was thinking that it made sense on teh downshift as you are speeding teh gear up before coming into gear therefore rev matching, but when up shifting I don't understand how it works. Is second gear spinning faster then first, so when you go to upshift, wouldn't you just be making second spin even faster. I am not sure what it is called, crankshaft maybe, but is this is what gets sped up to catch up with second making a smooth shift? If it sounds like I don't know what I am talking about, there is a good reason for that, haha
|
||
|
09-24-2009, 06:59 AM
|
|
|
Registered
|
On the up shift just double clutch. No gas.
When you let the clutch out in neutral it slows the tranny down to match the next higher gear.
__________________
Pete 79 911SC RoW "Tornadoes come out of frikkin nowhere. One minute everything is all sunshine and puppies the next thing you know you've got flying cows".- Stomachmonkey |
||
|
09-24-2009, 07:31 AM
|
|
1979 Porsche 911SC
