4.10's? Speedcal???

9646gt · Apr 18, 2005

Ok ..I jsut got this 98 GT about 3 weeks ago...the speedo isn't working right at all..it doesnt really move until you get a decent speed then it shoots to 30mph its about 5mph off till about 50-60mph (5mph reading faster than I am actually going next to a friend on two ways..) Then on the highway/interstate it says I am running almost 90 and everyone is passing me..Do I maybe have 4.10's? The car only takes my foot resting on the gas to keep it moving at a desired speed even in fith gear at a really low rpm...it seems to rev high very quickly when taking off from a stand still and has excellent launch even from a rolling start..If it is possible..how hard is a speed cal to intall? will the 4.10's affect my odometer and trip meter? (may explain why I think I am getting like 14 mpg) any help will be greatly appreciated

green_fow_six · Apr 18, 2005

9646gt said:
Ok ..I jsut got this 98 GT about 3 weeks ago...the speedo isn't working right at all..it doesnt really move until you get a decent speed then it shoots to 30mph its about 5mph off till about 50-60mph (5mph reading faster than I am actually going next to a friend on two ways..) Then on the highway/interstate it says I am running almost 90 and everyone is passing me..Do I maybe have 4.10's? The car only takes my foot resting on the gas to keep it moving at a desired speed even in fith gear at a really low rpm...it seems to rev high very quickly when taking off from a stand still and has excellent launch even from a rolling start..If it is possible..how hard is a speed cal to intall? will the 4.10's affect my odometer and trip meter? (may explain why I think I am getting like 14 mpg) any help will be greatly appreciated

Well, if your speedometer is off, your odometer should be off exactly the same amount. Do a milege test, if your odometer is correct, that means your speedo is just messed up.

9646gt · Apr 18, 2005

green_fow_six said:
Well, if your speedometer is off, your odometer should be off exactly the same amount. Do a milege test, if your odometer is correct, that means your speedo is just messed up.

I guess I will have to do a mileage test with the mile markers on the interstate or something..ill see what I find and then I will post back...

chimchim · Apr 18, 2005

Go here: http://tchracing.com/tech/gearcalc....m&givenval=90&givenvaltype=MPH&selectedgear=5

This will tell you how fast you SHOULD be going at what RPM, but I don't know how you're gonna find out how fast you ARE going???

BlackenedSVT · Apr 18, 2005

I thought u cant use a speedcal for 96-98 stangs

green_fow_six · Apr 18, 2005

UDTBadkarma said:
I thought u cant use a speedcal for 96-98 stangs

Yes, they have 2 different ones from Dallas Mustang that works for 96-98. One works for 94-2004, the other is for 96-98 extended range(for those who swap to a tremec 3650 tranny)

97gtconv. · Apr 18, 2005

i got a dallas mustang speed cal for my 97gt auto for 4.10's. i called them to see if it work and they said yes. hopefully next weekend i'll see if works proplerly.

Erskine · Apr 19, 2005

wait a minute, is that web site right cause i was cal. stuff and at 70mph(2000rpm) in my car its sayen i have 355 in my car but the car is all stock i dont think that is right

Mel96GT · Apr 19, 2005

It sounds to me your speedo is flubbed up. If you have stock 3.27's you should be doing 70 mph at approx. 2100 rpm and 80 at 2350. The other option is to raise the rear tires and rotate the drive wheel once and count the driveshaft revolutions. Your D/S should rotate just over 4 times for every turn of the wheel if you have 4.10's. Just my $.02.

COramprat · Apr 19, 2005

4.10 ratio gears will knock your odometer off by about 10 percent. Just use mile markers and see where you make an odometer mile. It should be about at the 9/10ths of a mile if the interstate you are on has those 1/10th markers.

As far as the speedo not responding you may have a bad speedo gear. Remove the speedo cable from the tranny and check the gear to see if it is intact. If not...replace it and get a Speedcal. The instal is pretty simple but a little involved. Go to Dallas Mustangs web site. They have install instructions there and you can tell if you want to tackle it.

9646gt · Apr 19, 2005

Ok..I talked to the guy where I got the car and I know him personally and trust him..he told me that the car DOES have a 4.10 gear..I have seen the speed cals run about 80 bux...Few questions

1. how hard is it to install
2. does it have to always be hooked up or just wen calibrating it?
3. feel free to make any other notes you feel are need to be known...

chimchim · Apr 19, 2005

Here is an installation guide from dallas mustang: http://www.dallasmustang.com/index.mvc?s=SpeedCal_Inst

I got mine from www.brothersperformance.com in December. It was 79.99 with free shipping. The speedcal stays attached to your speedometer cable and your cigarette lighter for power.

9646gt · Apr 19, 2005

Is there an easy way to hide the box so that it isnt in plain view? like is there enough cable to the power port to do this? I will most likely need a splitter since I also have a radar detector in the car ...

4.10's? Speedcal???

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...I can take it. I think.

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