Speedo Gear Question

dkins419 said:

I have a 88 GT 5 spd and the trans took a fly. I put a t5 from a 90 GT and it seems that the speedo is off a little bit. Do I need to change to a different speedo gear? I used the speedo gear that was in the 88 t-5. Now i know that the t-5's were upgraded from 265 to 300 lbs of torque rating, but did they change anything else?

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Purely speculation here, and I really can't remember the specifics from one model year to the next but the 88's had an 85mph speedo right? The 90 I believe had a 140mph speedo, I think....
I don't know if the tailhousing gear in the transmission might be causing an issue. I assume you have the proper speedo gear for your rearend gear set.

Is the speedo needle moving fluidly? or is it bouncing? or is it just off a little?

sounds like rear gears are not stock and you have the wrong speedo gear in the tranny to match the rear gears. Simple fix.

Ok, here is the deal. You need a yellow 18 tooth speedo cable gear (Ford p/n CODD-B or go to 50resto #LRS -17271H) for 2.73 gears and a '90 T5. You will be dead on with the 140mph speedo, I don't know if the 85 mph speedo makes any difference since I used to pin my gone but not forgotten '89's speedo needle on the BACK side of the pin so I don't think it makes a rip, but I am not sure of my facts re this part of your question. I do know that they changed the gear in the tranny tailshaft for 90 through 95 from a 7 tooth (what you had) to an 8 (what the 90-95's have) which is why you are off with your pre 90 speedo cable gear. Hope this helps you out.