is it possible to use a speedcal unit on a fox?

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just like the title says, can we use any of the speedcal units available out there for the 87-93's? i'm doing a gearswap soon, and was curious to know if this was a viable option... for some strange reason, i'd like to keep my speedo as accurate as possible. if it is at all possible, where can i purchase one?

 

[TheUser]

the speedcal units you see in the mags from DallasMustang and such, nope, can't use those on foxes because they manually adjust the speedo via a gear, which you can change, although, they aren't 100% accurate with any rear gear above 3.55:1. However, there have been posts on this subject and they do have units that will correct your speedo for any gear ratio, tire size, etc, but they are expensive. Sucks huh? My speedo was reading around 100 one day and I was in the slow lane on the interstate doing probably 65 or 70 tops...I'm just gonna get the speedo gear for the tranny and call it good enough

 

[maverick0716]

...they manually adjust the speedo via a gear, which you can change, although, they aren't 100% accurate with any rear gear above 3.55:1.

Except 85-89 T-5's where they're accurate up to 3.73 gears due to the 7 spline drive gear (instead of 8 spline like 90-93 T-5's)

 

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However, there have been posts on this subject and they do have units that will correct your speedo for any gear ratio, tire size, etc, but they are expensive. Sucks huh?

i don't mind the expense for something that will be accurate... it's a piece of mind type thing i guess. know anywhere i could find more info on one of these units? btw, the car is a '90 gt with a t-5, so i guess i do have the 8 spline gear drive. thanks in advance guys, i appreciate the help.

p.s. the gears going in are frpp 3.73's and i also changed the tire combo (running 245/45/17's all around) so i know that will throw off the speedo even more.

p.p.s. not to hijack my own thread, but whereabouts can i find a complete rebuild kit for my 8.8 as well? when i have the gears swapped, i plan on having the rear end all rebuilt while it's open. so i guess i'm looking for bearings, seals, trac loc, clutch packs, and anything and everything i guess.

 

[jrichker]

Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 2%-3% or less. The drawback is that it isn't cheap.

Some of the auto parts stores will also carry them See http://www.stewartwarner.com/ to find their distributor in your area

 

[red-]

jrichker to the rescue again. thanks man, i think you've successfully answered every question i've ever posted on this site.

regarding my p.p.s. question, is this everything i need to have the whole rear end rebuilt? http://secure.50resto.com/product1.cfm?SID=1&Product_ID=1904&Category_ID=652 i already have the gears, but i need to supply all parts for the install/rebuild and i'm not exactly sure what that entails. best price? what about the trak lok? is there a more complete kit available somewhere else? again, thanks to all that reply.

 

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bump

 

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ttt again.

 

[maverick0716]

p.s. the gears going in are frpp 3.73's and i also changed the tire combo (running 245/45/17's all around) so i know that will throw off the speedo even more.

Actually those tires won't throw your speedo off more because they're the same overall diameter as the stock tires (25.7")