Identifying Rear End Gear Ratio
 

OK - I did the Advanced Search and located a reference that helps to interpret the rear end gear ratio on the label located on the differential. I took a look today and the only thing I find is a dog tag like stamping that is held on by one of the bolts. It doesn't appear to have the same information as noted in the reference subject item I located. I also took a look at the label in the door jam and see some kind of reference to the rear axel. On the rear axel is paper/plastic decal, but it's mostly obscured by the ubolt for the leaf spring assembly.

On the dog tag, the top line show 'S328S' if it helps any. Basically, I'd like to find the ID that helps me determine what the gear ratio is in my truck.

Thanks folks!

Kevin

my 2000 2.5 came stock with a 4.10

Built for Quick Starts! ;-)
 

Thanks greeny - if I have the same rearend gearing, it might explain the whiplash-like starts I've come to expect (or dream about)! I have never driven to determine top end, but a friend with the 3.0 had it screaming at around 85 so I figured there was no point in it. The truck runs pretty well at highway speeds, but I have no idea what RPMs I'm running and basically everything sounds like it's loafing along relative to my S2000 (around 3500 RPM @ 65 mph). I tried some informal 0-60 times and I'm around 13-14 seconds which had me thinking that my gearing may be lower to achieve better gas mileage at highway speeds (purely a guess on my part). Do you have the dog tag on your differential?

Kevin

at the highest it is a 3.73 but most came with 4.10 with the 2.5L four. My 99 Sport Supercab 2.5L four and 5 speed stick has the 4.10 60mph is about 2500rpm.

Common Rear Gear Ratio
 

Thanks 99. How did you come by the data? I wish I had kept the window sticker with all the specs on my truck, but that's long gone.

I peaked under the truck and didn't see a tag. My driver side door jam has a sticker that has 87 under Axle which is 7.5 - 4.10 for the rear.
Ford Ranger Rear Axles - The Ranger Station

Link to Rear Axle Gear Ratios
 

Thanks Greeny!!! I appreciate the supersluething (and will bump your Charma if the system will let me)!! The link you provided deciphers the tag in the doorjam for what axle I have. The 'axle tag' (dog tag) appears to identify the production plant. Given the table in the link, I have the same gear ratio (axle code 87 = 4.10). I grew up understanding that the lower ratios were better for top end speed and cruising and the higher ratios better for off the line performance (and towing?). But through the various discussion threads here, it's only part of the overall equation on how the gear ratio translates into performance and economy. More food for thought for me.

Kevin

Greeny - the system wouldn't allow me to bump your reputation charma; pop-up says I have to spread the charma about, which I do, but it appears that there is a limit spec. Thanks again!!

I got as high as 28-29 mpg with my 4.10 rearend. When I installed 31 inch tires that essentially raised my rear gear ratio and threw my mpg in the toilet. I'm lucky to get 21 now :-X21:-X21:-X21

Information in the facory brochure from Ford.

Ahhhhh....the trade-off. Style for some loss in economy. I put on some Bridgestone Duellers in 2002 just after the Firestone tire issue with the Explorer. 225/70R15s I think which were a little larger than the Firestones I had. I noticed during one emissions test where they put your vehicle on a dyno and run the vehicle at 20 mph that my speedometer was around 25. I wondered if the size difference translated in overstated speeds, at least at the lower speeds. It seems to get corrected nearer 55 as compared to the GPS.

99 - Thanks for the response. I didn't think to keep the window spec's for the vehicle back when I bought the truck. I never have. But after watching Meccum, I see that if you ever do have a potential collectable, keeping the paperwork is a benefit.

I put larger tires on My 99 last December 2010 and went to 225/[B]75[B]/15.
made my road speed per GPS 2 MPH faster to 62 VS 60 on speedometer. Also now i only clock 95.5 miles per 100 driven.
Stock tire size on mine was either 215/75/15 or 225/70/15, just that small bump in aspect ratio made a noticable effect.

Take your VIN (Vehicle Identification Number) to a Ford dealer and ask them to look up the specs on your truck. That should tell you what you want to know about the rear axle.

VIN
 

Thanks Michigan. I was going to do that to see what else I can learn about my truck. I suppose having that information could be/would be useful in making future decisions about repairs/replacement upgrades, etc. I guess what surprises me a bit is that I have gearing for quick starts, which a 13-14 second 0-60 mph isn't. The gearing in the auto-tranny must be set up for towing or something, which could explain why lots of folks here are impressed with the ability of a 4 cyl Ranger to be a reasonably good towing vehicle. I had a 2" reciever on my truck along with the usual thru holes in the bumper for the ball.

I'd like to see an improvement on acceleration, but given the 4.10 rearend it looks like the only way to get an improvement will be to increase the hp to the extent necessary. It may seem that my focus should be on fuel optimization instead, but that may be limited too. FTE has been a great benefit in that I can tap into the knowledgebase here and find folks with similar vehicle configurations and folks with different. For instance:

• Would changing the rear gearing to a lower ratio improve gas mileage? I would try to locate someone with a configuration I might opt for and question them on their gas mileage.
• Would moving to a manual transmission improve drive ratios where accelaration would significantly improve? I would try to locate someone with a manual tranny and 2.5L engine and ask them about their 0-60 mph times.

Of course there is more to it than the two examples I put here, but I can say that I wasn't thinking along the lines I'm thinking now with the input folks have generously offered here. It might end up that Ford did the thinking for me: what I have is optimal given factory offerings. Then I move into aftermarket offerings to see if they are of benefit (e.g. Flowmaster exhaust, K&N intakes, etc.). I'm fairly sure I wouldn't go as far as a turbo, but the folk here on the internet that have certainly make it an interesting proposition. I wonder what their configurations were/are now and how fuel efficient their vehicles are after the mods?

Thanks for chiming in.

Kevin

As you can tell by my signature, the configuration I have may help you answer some of your questions. Some qualifications should be stated first. Your engine produces more horsepower than mine does - a result of improvements over time and more displacement. The other is that my rear axle ratio is 3.45 compared to your 4.10, so we may be comparing apples to oranges.

I've never held a stopwatch on my acceleration time, but it seems fairly sprightly. I am able to merge with expressway traffic without difficulty. I do use the manual transmission's gears and typically run up to 3,000 to 3,500 rpm before shifting when I want to get up to speed quickly. I get about 18 mpg around town in winter; 20 mpg in the summer. After a recent tuneup with double platinum plugs and a good cleaning of the air intake system, I get about 25 mpg on the highway. These numbers are close to the corrected EPA figures for my year and engine.

The questions that follow are: (1) is this difference good enough to justify all that is required to switch from an automatic transmission to a manual one and (2) is it also woth changing from 4.10 gears to 3,75 or 3,55 gears? Swapping rear axles is easier than swapping transmissions. One tradeoff is the loss of towing power.

I hope this helps you, at least somewhat. Let us know what you decide.

The Options
 

Michigan,

When I was steel brushing the scale off of the frame this spring, I took a look at the underbody and various other items (rusty exhaust and rusty differential). Off course the exhaust is a likely candidate, but I was a little surprised at a large flake of corrodid scale that came off the differential (about the size of a half dollar and maybe .030"). It doesn't worry me, but I was thinking what would I do if it rusted through. Would this be an opportunity to re-gear the vehicle to get better acceleration? Well, I suppose now that I know I have the highest gearing available, that answer is relatively moot. I'm open to researching this more and getting the feedback from the FTE community here on potential options, but I'm probably more curious about it than actually ready to commit to. It's one of those things: if someone says something is a low cost, quick change bound to improve performance, I'm more interested in getting engaged. If it is more trouble than it is worth, I'm content to move with the status quo.

I really enjoy the feedback you and others here provide. I wouldn't be half as inspired to get more out of my truck without the input. We'll see where this research takes me.

Kevin