Request for technical information re: Vibe 5MT shift rpm's

[DAP]

Greetings!After emailing the Service Manager at my local dealership, as well as the Sales Rep who sold me the car, and receiving absolutely NO information, I turn now to the Generation Vibe community.I hope that you may be able to provide me with some information about my new 2007 5MT Pontiac Vibe.I have been unable to find this information either in my owner's manual or on the internet.The manual presents a table of optimal "speeds" at which the various gear transitions should occur (Shift Speeds, page 113).I am rather more familiar with the tachometer as the gauge to rely on to hit the "sweet spot" for gear transitions on a manual transmission, and was wondering if you could provide me with the target RPM value to watch for on the tach for this particular vehicle.Thanks, in advance, for whatever information you may be able to provide.DAP

[RIT]

Why not look at your tach when you are at the various speeds and write them down? Optimum is a vague term, are you trying to optimize power, efficiency, or engine life? The shift point will be different depending what you are trying to optimize on.

[joatmon]

I shift at different RPMs depending on conditions. If accelerating hard, I wind it up over 6K. Just getting up to speed leisurely (my usual method) I shift under 3K. There used to be a thread here titled "Hit lift in 6th?" It was http://forums.genvibe.com/zerothread?id=9053 but for some reason it is no longer here, I assume it was deleted for some valid reason, but it had some really good info in it, I used to refer to it from time to time (If a mod remembers why that thread was deleted, respectfully request you IM me the reason)Anyway, in that thread, MadBill did the math, converting RPM to MPH. It went like this:In the 5 speed transmission, the gear ratios are 1st : 3.172nd : 1.903rd : 1.314th : 0.89 (overdrive)5th : 0.73 (overdrive)Reverse : 3.25Final Drive Ratio: 3.94The engine spins at a certain RPM, the tranny output rotates at a speed of input RPM / gear ratio. The output speed of the transaxle is reduced by the final drive ratio or (engine RPM / gear ratio) / final drive ratio. This is the RPM speed of the tiresThe stock tires on a 5 speed are 205/55/16, which according to the tire size calculator at http://www.miata.net/garage/tirecalc.html means that the tire circumference is 78.2 inches.(Engine Revolutions per minute * 1/gear ratio * 1/final drive ratio) * 78.2 inches/revolution * 1 foot/12 inches * 1 mile/5280 feet * 60 minutes/hour = vehicle speed in MPHfor the five speed with final drive ratio of 3.94, this simplifies to (engine RPM /gear ratio) * 0.0188 = MPHso at 2000 RPM in 5th gear (ratio 0.73) the car is moving at (2000/-.73) * 0.0188, or 51.5 mphif you know the mph and the gear, then the corresponding RPM would beMPH * gear ratio /0.0188in 3rd gear (ratio 1.31) at 30 mph, the engine should be at (30 * 1.31) /0.0188 = 2090 RPM.The 2007 Vibe owners manual, page 113, says that the optimum shift points are1 to 2 or 2 to 1 15 mph 24 km/h2 to 3 or 3 to 2 25 mph 40 km/h3 to 4 or 4 to 3 40 mph 64 km/h4 to 5 or 5 to 4 45 mph 72 km/hso, shifting up would be 1 to 2 15 mph 24 km/h 15 * 3.17 / 0.0188 = 2529 RPM2 to 3 25 mph 40 km/h 25 * 1.8 / 0.0188 = 2526 RPM3 to 4 40 mph 64 km/h 40 * 1.31 / 0.0188 = 2787 RPM4 to 5 45 mph 72 km/h 45 * 0.89 / 0.0188 = 2130 RPMI'll leave it up to you to calculate the corresponding RPMs for the downshifts, which will be lower than for the upshifts since they start in the higher gearif RPM = MPH * gear ratio /0.0188then RPM = KPH * gear ratio / 0.01175

[engineertwin2]

I just wanted to sit here and say thanks to joatmon who has responded quite well to the question. I was expecting a range of answers with an approximation, but joat has provided the best answer possible. - way up!

[joatmon]

I was just remembering what MadBill had said.Turns out that thread I remembered is still in Google's cache, and it had been in the"racing" forum" which is now "The Track" perhaps it was deleted as part of that transition. I copied the text from google's cache and pasted it into http://forums.genvibe.com/zerothread?id=23292 google's cached version of page 1 is http://64.233.161.104/search?q...cd=15 and the cached version of page 2 is http://64.233.161.104/search?q...cd=16(see page 2 to view the terrible signature I had for April Fool's day)