Installed 4:30's, how do I calibrate my speedo with several influential mods?

[Shiroelex]

Your speedo will never be 100% accurate with a speedo gear change, if you have 4.10s. They only have a gear that gets the speedo close to right, because of the number of teeth they can put on the speedo gear. I've seen some of those speedo gears lose some teeth, because they are so brittle, and the way they change the gearing of it makes the teeth on them very thin. There's a website out there that better describes what I am trying to say, I just don't remember where it is. The speedo gears are usually color coded for what rear end gears they go with. I'd make sure you have a stock speedo gear in there, if you get a speedcal installed. If you put the speedcal on, and have the different speedo gear, your speedometer won't be accurate.

 

[blackfang]

+1

 

[tmoneyballin]

Let me clarify to clear up any confusion. I removed the 410's and put in 430's. The previous owner had the 410's installed - I didn't even know they were in there until I looked. So the 410's may or may not have been properly configured with the speedo - I couldn't tell you anything beyond I could previously drop the car going "60 mph" according to the speedo and catch 2nd gear well into 6,000 rpms - and then hit 3rd immediately. So those that have 410's could potentially verify if that is an accurate read based solely on the fact that the speedo said I was doing 60 when I dropped it into 2nd.

My question is should I go ahead and order the speed cal that we talked about several posts ago and if so, will I be able to play around with the settings and be able to get it "close" to accurate - like pacing it with a car that is accurate after each adjustment... I am just trying to get it to be more accurate(obviously) because right now my car does 0-90mph in about "5-6 seconds" if you see where I am going! The car might be a 12 second car, but it ain't truely hitting 90mph THAT fast! I am about to order it I just need to make sure we are all on the same page. Thanks

 

[Dusstbuster]

You need to drive the car and record various RPM to Speed incriments. What are you taching at 55, 60, 70mph? That will help people figure out if your speedometer is correct for your 4.30's

 

[youwin]

there are 2 ways to adjust your speedo/OD with a pre 99 car either calebrate the puter when you tune it, or go to ford and buy a tranny sensor gear (like 8-10 bucks) prolly a 25 or 27tooth and i think its the red gear you'll need, i have a 23tooth red gear for my 3.73's and its spot on. if its post 99 the only way is a tune

 

[tmoneyballin]

No, I am confident it is definately off, that was my point. I mean the speedo is definately off at high speeds when I am doing about 50 it is saying 60+mph,70 I am doing 90 etc. My question is do I need to go ahead and order the speed cal that was refrenced earlier in this thread, or is there a better more accurate way of calibrating it - my question pertains to the fact that the previous owner "possibly" switched a SPEEDO GEAR when he put the 410 in - I have no way of knowing unless I traced where the speedo gear would be an looked(which I have never messed around with trannies so I would be pretty LOST...) My question is if he did switch a speedo gear will it complicate using the speed cal to correct my speedometer and if so can I still mess around with the calibration of the speed cal unit and eventually dial in a more accurate speedo reading, knowing it will never be PERFECT, but at least close.

Translation is my EASIEST option ordering a speed cal unit for my 98 cobra (5 speed) and playing around with the settings on that to try and make a more accurate reading on my speed? I am done trying to "open" things to diagnose them - I looked and didn't see a speed cal unit(no wiring from the tranny, no unit underneath my shifter...) so I am confident there is not one and I don't want to try and figure out if the speedo gear is changed because I am sure that is very complicated and would require a lot more time than necessary...

Thanks

 

[LaserRed01GT]

Tmoney, I've got a couple Speedcals laying around here at the shop. Let me know if you want one.

 

[tmoneyballin]

I am lost why is "youwin" saying I just need to swap a tranny sensor gear - I mean guys to be honest, all I want is my speedo accurate using the CHEAPEST alternative - I don't even care what the speedo reads it just bothers me that I am putting "inflated" mileage on my car because the speedo is off - I don't speed and if I do I am going 140mph - in which case I am not looking at the speedometer!

 

[youwin]

pull your existing tranny sensor gear and count its teeth if its 19 then its the stock gear, i researched this ALOT and for a long time before i just went with the gear, A. for the money, and B. i just wanted to be close

i own a pair of 98's a V6 and a GT both had 3.73's put in

the v6 had a stock rearend gear of 2.73 and its tranny gear was a 17 tooth
the GT had a stock rearend gear of 3.08 and its tranny gear was a 19 tooth
EDIT: if your car has the 3.27 rear gear option then the tranny gear will prolly be different.

we originally thought we needed the 21 tooth gear and bought a pair of those, but it turned out we were still of about 10% over so i went back and picked up 23 tooth gears and thanks to my last 2 speeding tickets i am right on the money with the cops radar guns, kind of an expensive way to be sure but hey, sure is sure

As far as your rims the tires will balance that part out...
if you originally had 17" rims with say...275/45/17 tires, and you got 18"rims with 275/35/18 tires they are about the same diameter from top to bottom basically making little to no impact on you speedo or OD

 

[youwin]

opps

 

[tmoneyballin]

So is there any way to figure out what gear/how many teeth a 430 gear would need before I get in there and check - I am POSITIVE it is way off, so it's pretty irrelevant what aftermarket, if any, gear there is already in there. Based on your numbers would it be closer to a gear with like 27 teeth?

Also, how hard is it to install the gear, and do you know of any links that outline the install?

THANKS

 

[youwin]

i couldnt find any links to install i was just pionted where it was and said there ya go.

but it is extreamly easy i did both in 15 minutes.
its located on the drivers side of the tranny all the way back towards the drive shaft, its just inside the tranny and has a cable leading to it (this is the cable leading to your OD and speedo) remove the cable and count the teeth on the gear and go from there (but remember you need to know what you originally had either 3.08 or 3.37 rear gear). the only thing with this is how you re-install the new one...you must be care full and not force it in, we did and after about 15 miles it broke, had to replace but it should slide in quite easily and smoothly.
im not 100% sure if its different for a stick, but a friend that helped has a 1990 fox with a 5 speed said his too looked just like these also, so heres a pic of what they should look like...

 

[youwin]

oh yeah and the little gear failing didnt harm the tranny at all just cost me anoth 10 bucks

as for how to tell which one you need the dealerships i went to get the part from say that for every 5mph your off at 50 go 1 tooth more, so we paced the cars at 50 with an accurate car next to us and just found out how far off we were then counted our teeth and pick those. we originally just got the 21 cause thats what the net was saying, but they was wrong, it happends.

 

[tmoneyballin]

Cool man I REALLY appreciate this advice! So what you are saying is if I go out and pace a buick or something that in theory is accurate, I need to line up with it when someone I know is going 50mph and I see what my speedo reads and if it says 60mph then I need 10 more teeth and I find out what gear is in my car and then add 10 to it and that will be the new speedo gear that I need? So if its 20 teeth I would need 30, based on this example?

Also, since I purchased my car from a dealership originally(had one previous owner) he had already had a 4:10 in there, so do I look at the original stock ratio which was a 3:27 (if I recall) or do I now compare to the 4:10 - because like I stated I am NOT positive that my speedo was accurate to begin with...

Also can someone verify that this works on a manual cobra and isn't just relevant for automatics?

 

[mustang023yes]

430 fun bad ass

 

[youwin]

Cool man I REALLY appreciate this advice! So what you are saying is if I go out and pace a buick or something that in theory is accurate, I need to line up with it when someone I know is going 50mph and I see what my speedo reads and if it says 60mph then I need 10 more teeth and I find out what gear is in my car and then add 10 to it and that will be the new speedo gear that I need? So if its 20 teeth I would need 30, based on this example?

Also, since I purchased my car from a dealership originally(had one previous owner) he had already had a 4:10 in there, so do I look at the original stock ratio which was a 3:27 (if I recall) or do I now compare to the 4:10 - because like I stated I am NOT positive that my speedo was accurate to begin with...

Also can someone verify that this works on a manual cobra and isn't just relevant for automatics?

nonononononono for every 5mph you're reading over 50 @ 50 its 1 tooth so if you had a 20 tooth gear and you were reading 60 @ 50 you would in essence need a 22 tooth gear. and all i know is that for the 90-98 mustangs an auto GT, auto V6 and a manual 90 gt all looked like that and were in roughly the same place on the tranny itself . so i wouldn't think its be too much different. so with your 4.30's pace any car thats going 50 see what your speedo says, pull the gear and count the teeth, then add 1 tooth for each 5 miles you were over and go to a dealership and get that one in the same color yours is in.

you can also ask the parts guy a few questions while your there cause for 98 and older stangs this is the most often saught fix for gears.

 

[tmoneyballin]

This will be fun, I am actually "having it out" with the local Ford dealership, they didn't have an IMRC module so I drove 2 hours away to get one and bought 2 clips that cost 9 bucks a piece at the dealership NOT near where I live. So I am making my rounds returning unused parts Saturday - aka those clips - and my local dealership is like "oh, you have to return this where you bought it...." I was like "oh there is no way in h e l l I am driving two hours + to return 18 bucks worth of parts...." I was bit#ching out of the principle because one of the managers fed me some crap about how they are all individually owned and therefore are serparate - kind of makes you wonder how they find that "yellow 5 speed" that you can't find at the local ford dealer, but magically they can get that same car from a dealership 50 miles away with NO problems.

The manager was like "I can't do anything, but if you would like I will give you the 18 bucks out of my wallet, if that will make you happy..." I should have taken him up on that just to show him whats up, but I kind of felt bad for him....so I didn't....


Anyways, so I need the same color but different teeth(more)? Or does the color change when the number of teeth change?

THANKS

 

[Dusstbuster]

IMO the speedcal is a better buy than the gear itself. Eventually you'll probably spend just as much replacing the speedo gears as a speedcal would cost, PLUS the speedcal is DEAD ON accurate. We tested my car with our GPS and it was on to -+ .2mph...

 

[youwin]

Anyways, so I need the same color but different teeth(more)? Or does the color change when the number of teeth change?

THANKS

as far as i know the teeth just change the color shouldnt, but in that area i could be wrong i just know all the stangs that have done this all said red, and red worked for me as well you just need more teeth. deff. go pace the care then jack that beast up when you get a chance and pull the gear, cause i wanna see how many you have first then go from there.

 

[youwin]

IMO the speedcal is a better buy than the gear itself. Eventually you'll probably spend just as much replacing the speedo gears as a speedcal would cost, PLUS the speedcal is DEAD ON accurate. We tested my car with our GPS and it was on to -+ .2mph...

i agree the speed cal is more accurate, but if your planning on keeping those gears, or even tuning it later then the tranny gear is the way to go. but you will be off abit more like 1.5-2mph over/under compaired to a speedcal that can get you to within tenths. when it all comes down to it you get what you pay for, 8 bucks 2mph, (however much the speedcal is) .2mph over/under