Tire Size&&what i can get away with.

[1987cp]

Ever thought of trying those old Drag-Pak speedo adapters? Supposed to be good for a 25% ratio reduction IIRC.

[sly]

never heard of that

[1987cp]

Yep, the idea was that somewhere around 1970, Mustangs that came with really deep gears ("Drag Pak") needed this speedo adapter thing to get accurate speedo readings. I spent some time a few years ago looking into them, and I don't remember now what I found in terms of price and availability.





Interesting link: http://www.transmissioncenter.net/sp...n_______va.htm

Also found a couple of places claiming to offer custom ratio adapters (and also a couple of message-board references).

[mrltd]

already up to a 23 tooth speedo gear. It's still off by 5 over at 60mph. though I will have a gander at the tires before making a purchase... if they look too obnoxious... I'll pass and hope I can score a 7 tooth output shaft for the trans.

uhm, yeah. It's a car, they all are off by roughly that much. Even My BMW speedo lies by 5 mph. That's as good as it gets!

You could send the speedo out for a rebuild and calibration.

[Southern_Pride]

255/70-17 in the stock rear fenders. 33x12.50 will fit on the back no mods if your springs aren't toasted. But they fit really tight. Really tight.

[sly]

uhm, yeah. It's a car, they all are off by roughly that much. Even My BMW speedo lies by 5 mph. That's as good as it gets!

You could send the speedo out for a rebuild and calibration.

my 88 is DEAD on across the board (1 low with new tires, 1 high with bald tires). my 93 is 2mph off across the board (think I put the face back on that one a little off when I replaced the odometer planetary gear) with new tires and 4mph off with bald tires.

rebuild and calibration can be done... but starts at around $250. I like the gear ratio box idea better since it's under $100. but like I said... taller tires may work fine for me - pending the look factor.

[1987cp]

Yeah, $70ish for a speedo gearbox is seriously cheap compared to that. I actually hadn't really realized until my search a couple of nights ago just how common such parts have been, and I'd also been pretty ignorant of their use in vehicles of other descriptions (such as vans) and of the availability of aftermarket bits in different ratios.

I assume you're already taking into account that tall tires effectively give you taller gears, but with 4.10s I guess that'd be less of a performance-killer than with 2.73s!

[sly]

Yeah, $70ish for a speedo gearbox is seriously cheap compared to that. I actually hadn't really realized until my search a couple of nights ago just how common such parts have been, and I'd also been pretty ignorant of their use in vehicles of other descriptions (such as vans) and of the availability of aftermarket bits in different ratios.

I assume you're already taking into account that tall tires effectively give you taller gears, but with 4.10s I guess that'd be less of a performance-killer than with 2.73s!

pretty much.