Speedometer

Ieatcamaros · 06-27-2002, 09:43 PM

This is a question that popped in my mind. In My early 89 gt, I have that damn 85 mph speedo. Can I buy the 140 out of a 90 GT and just plug it up to my existing wires for the 85 mph? Or will I have to change the drive gear in the transmission too? I was originally going to buy a 160 mph from autometer and hook it up, but I have a friend who is selling his whole dash cluster out of a 90 GT. Are these stock speedos even accurate? Thanks.

cyberstang5.0 · 06-28-2002, 07:10 AM

The speedo gear is suppose to match the rear end gear ratio. The gauge it self doesnt matter. You can get a 140 or 160 gauge and it will plug right in and be accurate.

ChunkFunky · 06-28-2002, 08:39 AM

Just one question.. or comment... Does the speedo housing have a gear in it? cause the 85 MPH goes from 1-85 over, lets say 270 degress... but if the 140 goes from 1-140 in 270 degrees... you car would be going 85 but look like it was going 140. is there a transmision in the speedo housing that calibrates the speedo to a certain standard from teh cable...

other wise you'd have to change the gears in the transmission.. just curious... also.. doesnt the speedo housing hodl the ODOMETER? you might make your car look liek it's more miles OR LESS then it is... cant you just buy the OVERLAYS .. I know you can get the WHITEFACE overlays... couldnt you get the black face ones?

-as

Ieatcamaros · 06-28-2002, 10:22 PM

Thanks. I really hate it when someone new gets in my car with me for the first time and they say "It only registers 85 MPH?" And you know I have buried that damn needle on the trip odometer several times. Who that has a mustang hasn't? The odometer reading is not really a big thing to me because I don't plan on selling it at all. And even if I do, anyone who buys it will know that is an old car and should expect a LOT of miles anyway.

Chunkfunky has a good point. Does the speedometer have a gear in it that calibrates itself with the existing stuff? I am 99% sure that I can plug the 140 up and it will work, I just want to know will it be calibrated?

Agent_4573 · 06-29-2002, 11:54 AM

Yes there is a gear in the speedo. If you get the whole assembly, you could always roll the odometer before putting the assembly in your car so that it read the same amount of miles. If you just bought the overlays, you would also need the matching driven gear for the speedometer. There is also a driver gear in the transmission but you should only need to change that when you change your rear gears. So if you buy the entire gauge cluster from the 90 GT, the 140 speedo will be calibrated for the 90 GT rear gears and will be acurate only if your running those gears. i.e. if the 90gt had 3.73, the speedo will only be acurate if you have 3.73's. Otherwise you will have to buy the driven gear for your trans. You can buy a matching set of speedo gears(driven and driver gear) for about 30 dollars.

Ieatcamaros · 06-29-2002, 04:58 PM

Agent, you hit the nail on the head. So if I get the 140 cluster all I will need to get is the transmission gear to match the 3:73's, right? Thanks.

Agent_4573 · 06-30-2002, 01:16 AM

If the GT you got the cluster out of had 3.73's and you have 3.73's you should be able just drop the speedo in and it will be acurate. If the GT had the stock 2.73's or 3.08's and you have 3.73's you will need the different gear. I did a search and found this site, http://www.steeda.com/store/-catalog/speedometer.htm It should be simple enough to find what your looking for there. I believe all the colors are the same no matter who makes the gear, so before you put the speedo in, take a look and see if you have the right gear to match your rear gears. Take into account also this is for the stock 15 tires. If you put on 16's or 17's you will probably have to account for that also. Just do a search on google.com or somewhere like that for speedometer gear calculators and you'll get a shitload of sites that you can use.

Agent_4573 · 06-30-2002, 01:19 AM

BTW, i just thought I would add that my speedometer is 5 miles and hour fast and for every 100 miles i drive it puts 130 on the odemeter. I'm just to lazy to buy a speedo gear with one more tooth... but thats just me.

Ieatcamaros · 06-30-2002, 07:34 AM

Thanks agent, I knew about the gear on the website you posted a link to. I currently have the 85 speedo with the correct gear on the end of the speedo cable to match the 3:73's. I am not sure if he is getting rid of the cable along with the cluster too. I shouldn't need it should I?

Agent_4573 · 06-30-2002, 09:44 AM

No, you should be able to just unplug your cable and plug it into your new speedo.

Ieatcamaros · 06-30-2002, 10:24 AM

Thanks Agent. Now I will be able to tell how fast I am going past 85 mph. That is one thing that just irritates the hell out of me. Not knowing how fast I am going.

LetsGo · 06-30-2002, 01:31 PM

Thank you both, I was wondering about the same thing. I had a 85 lx with body damage and just puchased a 91 lx that had engine damage. I have finished installing the engine, transmission and the rear end which has 3.73. The same question came across about the calibration of the speedometer. Thank you once again.

RED92LX50 · 07-01-2002, 08:35 AM

Agent - just so you don't get a ticket...if your speedo is off from a gear change, it will not be off Xmph at all speeds, it will be off by a percentage of the speed you are going. For example, if you went from 3.08 to 4.10 and didn't change the speedo gear: when your speedo shows 60mph you will really be going 60*.75 = 45 (15mph difference), and when your speedo shows 100mph you will really be going 75 (25mph difference). True at lower speeds the changes are less, but if you are at highway speeds it is much different.

Agent_4573 · 07-01-2002, 10:41 AM

Well I've tested it at 30mph and it was off 5mph, then i tested it at 70 and it was still off 5 mph....

ChunkFunky · 07-01-2002, 12:01 PM

I suppose that makes sense if it's just not calibrated correctly.. and not so much a gear ration issue... that's like my gas gauge. It reads empty even though there's like 1/3 tank left.. it's just a couple gallons out of wack... tough it's not an electrical sender for the speedo, I would imagine it could be off
-as

RED92LX50 · 07-01-2002, 12:58 PM

Ah, I must have misunderstood... it looks like you have stock 3.27 gears and were just relating the accuracy of your speedo - my bad. I thought you had changed rear gears and then not replaced the speedo drive/driven gears in the tranny.

Agent_4573 · 07-01-2002, 01:58 PM

Yeah, It's still got 3.27's in the back. I'm not to worried about it anymore because I know its 5mph off and the title for the car already says exempt from mileage so the extra 30% on the odometer really means nothing to me.

Ieatcamaros · 07-01-2002, 05:16 PM

Agent, how did you get lucky enough to get an 89 LX stock with 3.27 gears? My 89 GT came with the 2.73s. And yes the do SUCK!!!!!!

Agent_4573 · 07-01-2002, 10:46 PM

I bought it used and according to the rpms and tire size and stuff i figured i have 3.27's in the rear of it. I don't know how they got there and i don't question it.

06-27-2002, 09:43 PM	#1
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Speedometer This is a question that popped in my mind. In My early 89 gt, I have that damn 85 mph speedo. Can I buy the 140 out of a 90 GT and just plug it up to my existing wires for the 85 mph? Or will I have to change the drive gear in the transmission too? I was originally going to buy a 160 mph from autometer and hook it up, but I have a friend who is selling his whole dash cluster out of a 90 GT. Are these stock speedos even accurate? Thanks. __________________ The sig says it all.

06-28-2002, 08:39 AM	#3
ChunkFunky Registered Member Join Date: Apr 2002 Location: Tustin, CA Posts: 465	Just one question.. or comment... Does the speedo housing have a gear in it? cause the 85 MPH goes from 1-85 over, lets say 270 degress... but if the 140 goes from 1-140 in 270 degrees... you car would be going 85 but look like it was going 140. is there a transmision in the speedo housing that calibrates the speedo to a certain standard from teh cable... other wise you'd have to change the gears in the transmission.. just curious... also.. doesnt the speedo housing hodl the ODOMETER? you might make your car look liek it's more miles OR LESS then it is... cant you just buy the OVERLAYS .. I know you can get the WHITEFACE overlays... couldnt you get the black face ones? -as __________________ '89 GT Convertible: TFS TW Heads, TFS Street Intake, TFS Stage 1 Cam, FMS 1.6 RRs, 24# Injectors, Pro-M 75mm MAF, No Name CAI, 3.73s, O/R H-Pipe, FlowMasters, AOD w/ Trans-Go Shift Kit

06-28-2002, 10:22 PM	#4
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Thanks. I really hate it when someone new gets in my car with me for the first time and they say "It only registers 85 MPH?" And you know I have buried that damn needle on the trip odometer several times. Who that has a mustang hasn't? The odometer reading is not really a big thing to me because I don't plan on selling it at all. And even if I do, anyone who buys it will know that is an old car and should expect a LOT of miles anyway. Chunkfunky has a good point. Does the speedometer have a gear in it that calibrates itself with the existing stuff? I am 99% sure that I can plug the 140 up and it will work, I just want to know will it be calibrated? __________________ The sig says it all.

06-29-2002, 11:54 AM	#5
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	Yes there is a gear in the speedo. If you get the whole assembly, you could always roll the odometer before putting the assembly in your car so that it read the same amount of miles. If you just bought the overlays, you would also need the matching driven gear for the speedometer. There is also a driver gear in the transmission but you should only need to change that when you change your rear gears. So if you buy the entire gauge cluster from the 90 GT, the 140 speedo will be calibrated for the 90 GT rear gears and will be acurate only if your running those gears. i.e. if the 90gt had 3.73, the speedo will only be acurate if you have 3.73's. Otherwise you will have to buy the driven gear for your trans. You can buy a matching set of speedo gears(driven and driver gear) for about 30 dollars. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

06-29-2002, 04:58 PM	#6
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Agent, you hit the nail on the head. So if I get the 140 cluster all I will need to get is the transmission gear to match the 3:73's, right? Thanks. __________________ The sig says it all.

06-28-2002, 07:10 AM	#2
cyberstang5.0 347ci of HORSE POWER!!! Join Date: Jul 2001 Location: Houston, TX Posts: 1,416	The speedo gear is suppose to match the rear end gear ratio. The gauge it self doesnt matter. You can get a 140 or 160 gauge and it will plug right in and be accurate.

06-30-2002, 01:16 AM	#7
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	If the GT you got the cluster out of had 3.73's and you have 3.73's you should be able just drop the speedo in and it will be acurate. If the GT had the stock 2.73's or 3.08's and you have 3.73's you will need the different gear. I did a search and found this site, http://www.steeda.com/store/-catalog/speedometer.htm It should be simple enough to find what your looking for there. I believe all the colors are the same no matter who makes the gear, so before you put the speedo in, take a look and see if you have the right gear to match your rear gears. Take into account also this is for the stock 15 tires. If you put on 16's or 17's you will probably have to account for that also. Just do a search on google.com or somewhere like that for speedometer gear calculators and you'll get a shitload of sites that you can use. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

06-30-2002, 01:19 AM	#8
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	sidenote BTW, i just thought I would add that my speedometer is 5 miles and hour fast and for every 100 miles i drive it puts 130 on the odemeter. I'm just to lazy to buy a speedo gear with one more tooth... but thats just me. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

06-30-2002, 07:34 AM	#9
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Thanks agent, I knew about the gear on the website you posted a link to. I currently have the 85 speedo with the correct gear on the end of the speedo cable to match the 3:73's. I am not sure if he is getting rid of the cable along with the cluster too. I shouldn't need it should I? __________________ The sig says it all.

06-30-2002, 09:44 AM	#10
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	No, you should be able to just unplug your cable and plug it into your new speedo. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

06-30-2002, 10:24 AM	#11
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Thanks Agent. Now I will be able to tell how fast I am going past 85 mph. That is one thing that just irritates the hell out of me. Not knowing how fast I am going. __________________ The sig says it all.

06-30-2002, 01:31 PM	#12
LetsGo Registered Member Join Date: Feb 2002 Location: from St Louis but in Texas Posts: 24	thank you Thank you both, I was wondering about the same thing. I had a 85 lx with body damage and just puchased a 91 lx that had engine damage. I have finished installing the engine, transmission and the rear end which has 3.73. The same question came across about the calibration of the speedometer. Thank you once again.

07-01-2002, 08:35 AM	#13
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	Agent - just so you don't get a ticket...if your speedo is off from a gear change, it will not be off Xmph at all speeds, it will be off by a percentage of the speed you are going. For example, if you went from 3.08 to 4.10 and didn't change the speedo gear: when your speedo shows 60mph you will really be going 60*.75 = 45 (15mph difference), and when your speedo shows 100mph you will really be going 75 (25mph difference). True at lower speeds the changes are less, but if you are at highway speeds it is much different. __________________ 1992 LX 5.0 Convertible Red/Blk Gears, Exhaust, bolt-ons... R.H.C. #51

07-01-2002, 10:41 AM	#14
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	Well I've tested it at 30mph and it was off 5mph, then i tested it at 70 and it was still off 5 mph.... __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

07-01-2002, 12:01 PM	#15
ChunkFunky Registered Member Join Date: Apr 2002 Location: Tustin, CA Posts: 465	I suppose that makes sense if it's just not calibrated correctly.. and not so much a gear ration issue... that's like my gas gauge. It reads empty even though there's like 1/3 tank left.. it's just a couple gallons out of wack... tough it's not an electrical sender for the speedo, I would imagine it could be off -as __________________ '89 GT Convertible: TFS TW Heads, TFS Street Intake, TFS Stage 1 Cam, FMS 1.6 RRs, 24# Injectors, Pro-M 75mm MAF, No Name CAI, 3.73s, O/R H-Pipe, FlowMasters, AOD w/ Trans-Go Shift Kit

07-01-2002, 12:58 PM	#16
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	Ah, I must have misunderstood... it looks like you have stock 3.27 gears and were just relating the accuracy of your speedo - my bad. I thought you had changed rear gears and then not replaced the speedo drive/driven gears in the tranny. __________________ 1992 LX 5.0 Convertible Red/Blk Gears, Exhaust, bolt-ons... R.H.C. #51

07-01-2002, 01:58 PM	#17
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	Yeah, It's still got 3.27's in the back. I'm not to worried about it anymore because I know its 5mph off and the title for the car already says exempt from mileage so the extra 30% on the odometer really means nothing to me. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

07-01-2002, 05:16 PM	#18
Ieatcamaros Domestic Rice really sucks! Join Date: Apr 2002 Location: KY Posts: 973	Agent, how did you get lucky enough to get an 89 LX stock with 3.27 gears? My 89 GT came with the 2.73s. And yes the do SUCK!!!!!! __________________ The sig says it all.

07-01-2002, 10:46 PM	#19
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	I bought it used and according to the rpms and tire size and stuff i figured i have 3.27's in the rear of it. I don't know how they got there and i don't question it. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

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