What gearing does my car have?
At 55 MPH-2800 RPM
At 60 MPH-3000 RPM
At 70 MPH-3400 RPM
I had hard time trying to go over 70MPH. thanks.
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What gearing does my car have?
At 55 MPH-2800 RPM
At 60 MPH-3000 RPM
At 70 MPH-3400 RPM
I had hard time trying to go over 70MPH. thanks.
At 55 MPH-2800 RPM
At 60 MPH-3000 RPM
At 70 MPH-3400 RPM
I had hard time trying to go over 70MPH. thanks.
Lambros, what size tires do you have? I had the 165 SR 15 Kelly Springfield tires on my VS and my tach to speedometer readings were pretty close to yours. My car had the 3:88 ring and pinion ratio.
John H
Question....should we have a chart posted on the knowledge section which would show the R&P X tire size combinations and what they would yield in engine RPM for a given speed (perhaps 70mph) ? Does someone have a ready source for this information and would they be willing to post it?
John H
Question....should we have a chart posted on the knowledge section which would show the R&P X tire size combinations and what they would yield in engine RPM for a given speed (perhaps 70mph) ? Does someone have a ready source for this information and would they be willing to post it?
Thanks for the reply John.My tire size is 165-SR 15 (Michelin XZX).
Hi!
www.et-studios.com/motorsports/gears/gears.html
Use this link to CB Performances gear ratio calculator. It takes input on tire diameter, Ring-Pinion ratio, and each gear ratio. Then it calculates your speeds and RPMs for each gear in a spreadsheet.
At CBs site, (www.cbperformance.com/)you could look up their transmissions and see what gearing is standard on your model of tranny... and I would assume you have a 4:12 R/P. Start with that number and your tire size and see if it matches what you are experiencing. You can play with the numbers from there by changing your 4th gear and also your R&P to a 3:88 or 3:44 although I doubt if you have these R/Ps with the higher RPMs you are seeing at cruise. Some Trannys have a higher geared 4th (Freeway Flyer). CBs Tranny section shows you the alternate 4th gears (so you can input them in the gearing spreadsheet). You may want to change your 4th, or change R?Ps to a 3:88. There are two schools of thoght on that.... and I think they are all dicussed under a thread; "3:88".
There is also a tire calculator linked from CBs main page if you scroll down and look on the right bottom list of links.
Also,you should check & see how accurate your Speedo is by matching it with another car. Many of our VDOs are off by up to around 5mph+-. Mine shows around 3 mph faster than my actual speed.
Hope this helps.
www.et-studios.com/motorsports/gears/gears.html
Use this link to CB Performances gear ratio calculator. It takes input on tire diameter, Ring-Pinion ratio, and each gear ratio. Then it calculates your speeds and RPMs for each gear in a spreadsheet.
At CBs site, (www.cbperformance.com/)you could look up their transmissions and see what gearing is standard on your model of tranny... and I would assume you have a 4:12 R/P. Start with that number and your tire size and see if it matches what you are experiencing. You can play with the numbers from there by changing your 4th gear and also your R&P to a 3:88 or 3:44 although I doubt if you have these R/Ps with the higher RPMs you are seeing at cruise. Some Trannys have a higher geared 4th (Freeway Flyer). CBs Tranny section shows you the alternate 4th gears (so you can input them in the gearing spreadsheet). You may want to change your 4th, or change R?Ps to a 3:88. There are two schools of thoght on that.... and I think they are all dicussed under a thread; "3:88".
There is also a tire calculator linked from CBs main page if you scroll down and look on the right bottom list of links.
Also,you should check & see how accurate your Speedo is by matching it with another car. Many of our VDOs are off by up to around 5mph+-. Mine shows around 3 mph faster than my actual speed.
Hope this helps.
Lambros,
I just realized that your tach vs speedo readings are just about the same as my drag car! I'm running a 4:11 Detroit Locker. You must have a 4:12 in your transaxle.
TC
I just realized that your tach vs speedo readings are just about the same as my drag car! I'm running a 4:11 Detroit Locker. You must have a 4:12 in your transaxle.
TC
I guess I'm surprised. Apparently, the person who sold me my VS either didn't know what he had or misrepresented it. I suspect the former. Thanks fellows for straightening me out. Lambros, don't listen to me ;-)
Not so fast, guys. With a 24" diameter tire, a .89 fourth, and a 3.88 R/P, I get 3400 RPM (or thereabouts) at 70 mph, and 3200 RPM at 60. If his tires are only 165s or something close, TC's drag car tires are probably QUITE a bit bigger, and the smaller tires will cause his motor to spin faster than those with larger (diameter) tires are used to seeing. Also keep in mind that the calibration of his speedometer is probably off, and I'm not 100% sure of the reliability of our Brazilian VDO tachs either. I'm not saying it's a 3.88 for sure, just that it looks like it to me...
DUH!?!
Great point ! Never even thought to factor in tire size. Old age really sucks some times . . .
Great point ! Never even thought to factor in tire size. Old age really sucks some times . . .
It's not the old age, but all that Alzheimers BS we all have to contend with......
BTW: What size wheels are you running on your Drag Car, and what color dress does it wear?
BTW: What size wheels are you running on your Drag Car, and what color dress does it wear?
i've heard tc's drag car is "fabulous".
The drag car has 295 60 15's with around 14 or 15 inches of foot print mounted on Centerline clones in the rear. The fronts are 165 65 15's mounted on 3.5 inch wide Centerline front runners. Between the rubber and the raised front and the fiberglass panel truck kit, it looks like an Anglia Sedan/Delivery gasser.
Of course the car is in primer
Of course the car is in primer