View Full Version : new gears

07-26-2003, 09:00 PM
I just ordered a set of 4.10's for my 98. I was wondering what to do to correct the speedometer. Any help would be appreciated.

Jeff Lounsbury

07-26-2003, 10:45 PM

Most people buy the abbott speed compensator which will allow you to get the speedo correct. I think you can get them at Dallas Mustang Parts?

07-27-2003, 12:13 AM
Yeah good question, Im interested in 4.10s or maybe even 4.30s (mainly thanks to all of you all-out speed freaks in here) but anyways. When I went to one of my local ford dealerships around here they told me that on 99s like mine there was some kinda problem with the recalibration of the speedo and that (I dont remember very well to be honest) but it was either very hard or very expensive to get the speedometer right again. I know a lot of you guys with 99's have done the swap and I'd just like for somebody to please get me straight on what the problem/cost is on the 99's. If ya can just an all around estimate on the whole installation cost would be good too.

Thanks guys,

07-27-2003, 06:26 AM
Like Tony said, you can use a compensator from a place like Dallas Mustang. Very easy to install and costs about $100. Otherwise, you can get a chip programmed for whatever gears you have also.


07-27-2003, 12:19 PM
The chip won't work on the 96-98's but the speed compensator will. There's also the really cheap way to do it, and that's with a $20 speedo gear. They do wear out though. The speedo gear won't make your speed 100% accurate, but it's close enough if you're on a budget. On the 99's and newer, you can have your speedo recalibrated with any of the major chips (JMS, autologic, diablo etc.)

07-27-2003, 01:36 PM
Well for the money which chip is the best to go with and what should I expect to pay to get one rigged up for a new rear gear? I seem to read more about the Diablo's but Ive never really researched them much, although I have heard that a chip makes for a great first performance modification. So do you guys agree that a new rear gear and a chip would make for a really good start?


07-27-2003, 03:57 PM
It depends on the future plans of your car. It seems that most cars don't gain much from a chip as a first modification. It's mainly used when you have multiple mods, to tie everything together. If you plan on doing some mods in the future, a chip may not be that bad of an idea. I just wouldn't count on it for a major increase in power right off the bat. If you plan on doing just a few minor things like gears, shifter and maybe some exhaust, I'd go with the speed compensator. If your plans include a blower or nitrous for the future, or even a mass air meter, headers, pullies, x-pipe and everything, a chip is a must.

As far as which brand of chip to go with, I really can't say. Fordchip is definately a good one to go with, as is Diablo, Autologic (JMS). I have autologic. The best thing to do is to check for local dyno shops around your area, and see what kind of software they use. If they tune with Diablo chips, then a diablo should be your choice. If you plan on running Nitrous, then a flip chip should be considered. If you want a chip, and don't want to dyno the car, a "mail order" chip can be nice. If you go that route, get it from here: www.jmschip.com

07-28-2003, 12:33 PM
IMHO a speed-compensator is the best way to correct your speedometer. It's 100% accurate, can be changed by YOU at anytime (tire/rim size change, gear change, etc..) and is very easy to install and is inexpensive ($100 or so). A chip is a nice way to do it but if you need to send the chip off for a reburn your speedo will be wrong during that time, if you change your tire/rim size and want to be accurate you have to send your chip off to be reburned (time and a fee). A chip with minimal mods on the car is going to give you little (if any) gains and will cost in the $500.00 range.

I suggest getting an Abbott ERA and after you do mods (a lot of mods) then getting a dyno-tuned chip for that. If you are done with mods at that point you could have them program in your gear change (1999 and up only) and sell the Abbott ERA.

Right now Autologic is really the only 'tuned' chip. Diablo 'tuners' send in information on your car to Diablo and they email them a file to burn to your chip. In other words they don't actually tune your chip, they flash it with files sent to them by someone, somewhere else who looks at your dyno/A-F ratios and makes the changes. Autologic tuners tune your car on the dyno with software they have loaded on a laptop with an eprom burner/writer connected.

07-29-2003, 04:33 PM
what is the speedo gear? I've heard about it, but dont know exactly where it is. Also I know there are different ones out there, which one will I need with the 4.10's
Thanks Jeff Lounsbury

07-29-2003, 08:06 PM
You have a plastic gear in your tranny that spins a certain amount, mated to another gear in the transmission to tell how fast you are going. When you change your rear gears, your tranny is spinning faster than before and you'll be racking up miles on your engine as the odometer/speedometer will read faster than you are really going. You can replace the plastic gear with one of a different size that will allow more spinning of the transmission for each spin it does to signal the computer what your speed is. Unfortunately they don't make one that fits correctly for the 4.10 gears....and since it's plastic eventually it'll get chewed up inside your transmission and all the little 'teeth' of the gear will be floating around inside your transmission. It's also going to be off by about 6% so you still won't be reading correctly to what speed you are really travelling (6% off).

08-11-2003, 08:53 AM
You can correct your speedo via a Chip or get the Abbott Compensator or the Speedcal..

If you NEED a chip then get it done via chip otherwise order your SpeedCal from Brothers.. I think they are like 79.99+ Shipping.. Thier online price is listed higher, give them a call.

Dallas Mustang also sells the SpeedCal.. It is very easy to install and works like a charm.