Hello I want to put lower gears (3.80 vs stock 2.79) in my Mav for quicker acceleration and lower et's. But I have a stock torque converter and I've read that if you put lower gears in, the converter stall speed goes down.. so will the lower gears help me out? or do I need a new higher stall converter to go with it? How will the converter act with the lower gears? automatics confuse me. thanks, Jon
Your stall speed will change...but MAYBE 50 RPM and that's probably a high estimate. You'll never notice it. Gears are one of the very first mods that should be done, IMO. Don't worry about the rest of the car just yet...the gear change itself will be a huge improvement in overall responsiveness of the entire car. I've done many gear changes and none of them have done anything bad for performance. The only one that I ever "changed back" was my old F100 pickup that had a 514" BBF in it....It had 2.47 gears factory, I swapped them to 3.89 and a mini-spool but that proved to do nothing but cause LOTS of tire spin (radials) so I put the 2.47 back in. I actually raced it a few times with 2.47. Ran the entire 1/8 mile in low gear, shifted to 2nd RIGHT at the 1/8 finish line. STill ran some 8-teens, which wasn't too bad for a daily driver that pulled down 16-18 mpg believe it or not. Keep in mind that this example is a high torque application with very little weight on the rear wheels. The Maverick responds EXCELLENT to the gear change you're describing. Same thign I did when I had my '74. Went from 2.79 to 3.80. Totally different car. Also did a 2.73 to 3.73 in a 5 speed Mustang and that was the same result. Much more fun to drive.
Hey thanks! I thought it would be more than 50 rpms since the drop was even mentioned. Ok now.. when and why would you need a higher stall converter? What is stall anyways?
You need a higher stall converter after engine modifications. A larger camshaft will produce less low end torque, so the converter will *grab* at a lower RPM, slowing the acceleration of the engine, as well as the car. Rough numbers, the torque converter needs about 230lbs of torque at whatever RPM it is meant to stall, so if you have a 280* duration cam, you're looking at a minimum of a 2500 stall converter so the torque matches up. Stock is suppose to be something like 1200 RPM, but my factory C4 with factory converter stalled at 1800 RPM, flashed to 2000, could be my engine made too much torque, could be a looser converter on that year. The AOD stalls at 1200-1400, which really slowed down my car. The rear gear is as much of an issue as the engine and weight of the car, but it is the entire package you have to look at, not just one component. A matched set works, matching two components out of five is why most people that think they're car guys can't figure out why their car isn't faster.
All I know, is that the addition of 3.73 gears in my dad's '95 Mustang GT made a HUGE diffrence. There is a hell of alot more seat of the pants acceleration. You absolutely rip through first, second and third gear. However, it would suck to not have overdrive in a car driven regularly with those gears. The 5th gear in the Mustang is just enough to make it bareable at 75 mph on the interstate.
I agree. Gears, dual exhausts, & a 4-barrel intake are the very first mods that should be made (electronic ignition & disc brakes also if it doesn't already have it). BTW; my stock-replacement converter stalls at 1600RPM. I don't know what the original one did...
i have a 2500 stall in my car.. cant use it though... my tires break free at like 1500 rpms... lol.. probably not that bad.. but if i try to launch on the convertor i spin for the first 50 feet... i have new rims.. just need tires and gears... hopefully santa will visit me tonight... lol
yes, a higher number gear will drop your stall, & usually more than 50 rpm. but it almost always makes the car quicker, & is a very worthwhile modification. much of both changes depends on your current engine setup. when the lower stall moves down out of your engine's power range there is a greater effect. when i put gears in (from 3.00 to 4.10}, my son went .4 quicker, but the stall dropped over 300 rpm. wasnt worried by it, because i knew sooner or later i would get a looser converter. so, yes, do the gears. you'll love it.
I estimate my stall at 1800 with the stock converter (when I stomp the brake and accellerate, it will stop at 1800 rpm, until I give it more gas to break the tires loose, not sure if this is an accurate measure of stall or not). I am running a 3.80 with a mini spool, and it is MUCH quicker, seat of the pants or not. Completely different car. But 3.80 puts me at 3000 rpms at 60mph, so highway speeds are running kinda high rpms (I have 255/60r15 tires, smaller tires will make higher rpms on the highway). It is not really uncomfortable, just seems loud and kinda high for long highway drives. To keep up with traffic, 75-ish, you will be running close to 4000 rpms. Another cool or annoying detail, depending on how you look at it...you will be in 3rd gear by the time you pass through a red-light intersection on a stock transmission setup. I swapped out the vacuum modulator to one with the adjustable screw, and set it up to shift at a higher rpm on slow take-offs, around 2200 rpm where it used to want to shift at about 1500. If you get down on it, it will hold each gear until about 4000 in "D" unless you hit the B&M shifter one gear at a time. My car is not a daily driver, but a weekend "piddle-around" car, so the gearing is just perfect for me.
I seriously doubt that. Where do you guys get this stuff? If your foot is on the brake when you bring up the RPM, the gears have not had a chance to do anything yet. Also; the more torque your engine makes, the higher the stall speed (to a point)...
T.L., this isn't BS, its fact. In the same way the weight of the car affects the stall, the gear does. Footbraking is different, just punching it and getting rolling, your stall will be lower with numerically higher gears as you'll start to roll faster, the car/tranny/etc will put up less resistance to the converter. The reason the torque converter works is due to difference between the outer and inner parts of the converter. With a lighter car, gears, tires, etc, the car will move quicker and put up less resistance... I can see it in my head, but I can't explain it for crap. Its kind of like if you're pulling a wagon using a rubber band. If the wagon is empty, the rubber band won't stretch as far and won't bounce to you as fast as less tension is put on the rubber band. If its heavy, it will build more tension on the band, then when it does move forward it will move faster and harder. Put this together with fluid driven by fins in a converter... and it gets a bit more complicated than I have understanding yet. I've still never been into a converter.
in a footbrake car,the stall is when the car is forced to move. not whatever you preload it to, not where you overcome the brakes you have on, etc. with a higher number gear, the car will move at a lower rpm due to the mechanical advantage. if you have a manual shift valve body, go on the return road, put it in high gear while rolling about 5-10 mph. watch tach needle & floor it for a moment. where the needle goes is approx stall speed of conv. 2nd way is to check your race-pak data logger, but 1st way is much cheaper. thats your flash stall, & thats what makes the car perform. determined by car weight, gears, tire size, torque, converter internals, etc. when you take your foot off the brake, the higher gear moves the car sooner (lower rpm).
I don't know if I buy that or not. Everyone knows that a smaller diameter converter will load up to a higher RPM than a larger diameter (or stock). It's only gonna load up to a certain RPM and no more. It doesn't take much to "move" a car. Heck, you can push it yourself (though not very fast)...
