switching from 5.12 diff gearing to 4.62 with manual trans.

[captainwayne]

Hello Everyone, I am new here, so forgive my ignorance on things. I am a new trackaholic or as the wife says trackaho. I have a 96 tracker that was 2wd and used a rusty 93 4wd tracker to convert it to 4wd. I have manual trans. and have been getting 25-27 mpg. I am getting code po135 and am pretty sure it's the upstream o-2 sensor. Bought a new sensor but the old one won't start out even with heat- so am waiting on that until I replace the whole exhaust next year and will take off the manifold so I can get up close and personal with the thing. I have been trying different tire sizes to try to improve mpg. started with 205 75 r15s went to 215 75 r15's then to 235 75 r15's. It seems to go better with the bigger tires, also seems like the diff ratio is holding me back going up the road. I don't really plan to do any serious offroading, so I'm looking for a balance between having enough pep around town, but also being able to go on a highway without having to make the engine scream. I'll get to the point. Have any of you folks ever tried using diffs out of an automatic tracker with a 5 speed and 4wd. I see that the ratio is 4.62 on the auto trans rather than 5.12 which the manual trans has. It seems to me that that may work, unless its too much difference. Anyone tried that configuration. Thanks in advance. Captainwayne

[razor02097]

It has been asked before and the consensus seemed to be that you would have to work the engine really hard to start from a stop and at highway speeds. Keep in mind these small engines have no problems humming along at 3000RPM all day long on the expressway. If you put taller gears in you will lug the crap out of the engine which will make it unhappy.

[Scudo]

If you still decide to go down the route of reducing your reduction it would be good to note that 4 speed autos are the same 5.125 finals as the manuals. The 3 speeds are what the 4.62 is attached to.

4 Speed autos have an o/d switch on the shifter so they are easy to identify at a quick glance. I don't think there was ever a 16v with a 3 speed either.

[razor02097]

The parts 96 tracker I have has a 3 speed.

http://www.suzuki-forums.com/suzuki-...95-4wd-vs.html

[captainwayne]

Thanks for that you guys. I'm not sure what I' going to do yet. Like I said earlier the larger tires have made a difference, with the 235's I'm getting 4-5 mph faster at 3000 rpm, but thats still only 55 mph at 3k. To go 70-75 it takes me over 4k. Am also thinking of going to 16 inch wheels, but that comes with a lift kit and expensive wheels. I was hoping that someone had already tried the lower diff ratio with small wheels and liked it that way. I saw one post somewhere that a guy used the 4.62 diff on a 2wd and got 38mpg on his first run with it. Either way to go for me with that is expensive and laborious- sometimes doing nothing is smarter- but no fun in that. BTW how is the 4spd auto with 5.12? does it sail right along? And how are the 3spd autos with 4.62 diff and the 8v engine? Maybe I could go to 13 inch wheels with the 4.62 diff. Then the tracker would look like it already had a lift kit in it (or a kids go cart)

[Scudo]

Wheel size doesn't mean much with out tire size. Eg. I have 16" wheels but 215/65/16 tires and they are only slightly different to most folks 205/75/15. Off by half a %.

38 mpg is a 30% increase over. Just from the 4.62 diffs and 2wd that doesn't sound too plausible.

The difference in transmissions aren't just their final drives alone but their gear sets are different. eg. The overdriven gear in the 5 speed manual is 0.87:1 where as over drive on the 4 speed auto is 0.7x:1 and the 3 speed doesn't have an overdriven gear. Just a direct drive 1:1

You might find a slight reduction in gearing reduction to be beneficial but too much and you'd be out of the power band and the poor small engine will labour. Our engines aren't the low revving power houses you get in many other autos. Just because our engine peak at 95 horses doesn't mean we'd be anywhere near close to that at 3000 rpm.

Poor engine trying to push a box through 70 mph winds with no leverage.

[captainwayne]

Scudo, I hear ya, but what you are running with your auto trans. with 4.62 diffs and .7 od gear sounds like about what i would end up with with if I went to 4.62 diffs and having .87 od gearing in 5th gear manual od. I have also been told that apart from tire diameter that the actual weight of the wheels and tires has a big impact on mpg as well. that seems to me to have some commonsensical truth to it, by just thinking back to grade school physics. I wouldn't be surprised as well to find out that narrower tires will get better mpg than wider ones. I guess the only real way to find out will be to actually give it a try. My biggest concern is more taking off from a stop than lugging in 5th gear-it would be easy to stay in 4th most of the time, whereas if i have to heat up the clutch taking off from every stoplight, it won't be on there long. In the meantime I will keep my eye out for a candidate for a diff donor. I am in ne usa, so lots of rust is the norm for ALL of these old buggys and it makes it all harder to accomplish. Where did you find your 16 inch wheels? I saw some that were supposed to fit a 99+ tracker and am wondering if those will bolt on to a 89-98 tracker? (the center holes looked small in the picture) I also have other issues to deal with in my tracker that maybe I should put in front of this gearing stuff. This is off topic,but going to ask anyway. What are your thoughts with the 16v 1.6 engines about pre-emptively rebuilding them. In my case, I have a major oil leak around the front of the engine. Looks like the timing cover. also some other small oil leaks. rear seal, maybe and a little around the distributor. About 1 quart for 500 miles. The engine runs really good though. My mechanic thinks I should do the timing belt, water pump area as this is an interference eng. I'm not sure but i think this eng has around 150k on it at least. My feeling is to rebuild the whole thing now before it has bearing wear issues or something else goes rather than just stopping the oil leaks. I understand that the eng. will have to be pulled and it will cost significantly more to do. I guess my question is could i just fix the oil leaks and reasonably hope the engine will go another 50 or more thousand miles before it flys apart. What nare your thoughts on that. Thanks for patience. captainwayne

[fuzzy1]

If you decide to do the gears, be sure to get them from the correct vehicle. Many of the 3spd autos came with 4.30 gears not the 4.625's. Below is a PDF of the ratios by year/trans/door count.
I think with your current tires you'd find the 4.62's would make it feel like a slug. These engines make their torque at high revs & will do it all day with no problem.
On the rebuild, do a compression test... if the #'s are where they should be, fix the leaks & drive it. 150k is mid miles provided it's been maintained.

[colonelhogan44]

I'd say go for it if you're not using the tracker for a lot of off road fun. I live in a relatively flat area, and a gear to drop the engine speed down to around 3k at 65 would be awesome.

What are the gear ratios of the manual transmission? I'm guessing that 4th gear is probably close to a direct drive 1:1. If that was the case, then you'd still have a stock-ish cruising ratio, and a "super overdrive" for flat highway cruising. I find my 3 speed top gear to be excessively low. I can climb the steepest mountain highway around here (close to 11% in some areas) in 3rd, with a friend in the car.

I'd not worry about getting going either, as chances are that the 1st gear in a 5 speed is much lower than the 1st gear on a 3 speed auto.

[captainwayne]

Thanks for that, fuzzy1, I must also apologize for my dyslexia to scudo about his gearing as i got it backwards. I will definitely go to smaller tires if i try the diff swap. Have 205 75 15's to try first. Too bad they never made diffs in the 4.8 range. Betcha that would be perfect. The more I think about it, I am leaning toward a 2" lift kit and 16 inch wheels to see if just a little larger tire will give the old girl just a little bit more legs. I'm glad to hear that 150k is midrange miles on the engine. It really runs sweet, so if I was't worried about the timing belt guess I could do nothing. How is your mpg with the 3 spd auto and your setup?. Thanks again, wayne