Speedo gear differences: SROD vs. T5

[grabbergreen84]

FYI

I think I've discovered that the teeth on SROD speedometer driven gears, the one on the end of the cable, have their teeth pitched differently from those for T5s.

I got the speedometer working on my '77 F150 with a 3.03" Top Loader 3-speed, but it was inaccurate. So I went to my stash of speedometer driven gears, and tried the one from my old '92 GT with T5 and 3.08s. I also found the original gear from my old '82 GT, and it was the same color, but I noticed that the teeth were backwards. I ended up with a gear from the junk yard, and of the few I looked at there, which were all from trucks, they were all pitched like the gear in my truck, and the gears for T5 cars.

When we put the T5 in my old '82, I didn't change the gear, and it seemed to work fine! But I would've thought that the SROD gears would be the same as the 3.03" gears, seeing that they are both basically Ford Top Loaders.

Anyone have any other info? I don't remember ever seeing this discussed here.

Here's the 18T SROD gear on the left next to the 18T from a T5, and a 19T from a truck:



Pardon the cat hair...

[xctasy]

The chatter on the SROD gear has existed, but is not SROD specfic, its T5 and AOD conversion specific info.

http://vb.foureyedpride.com/showthre...eedometer-gear

The SROD takes the same speedometer gear as a toploader 4-speed with the cable
attached to the passenger side. The gear has an opposite slant to what's used with
other driver-side cable transmissions like C4, AOD, and T5. That's because the SROD
speedometer gear engages below the mainshaft, while the others engage above it.

You need to shop early Mustang parts vendors, or David Kee toploaders.
http://4speedtoploaders.com

Where it can get confusing is you may see the gears listed as "left hand" and "right
hand". This has nothing to do with what side of the transmission the cable connects
to. What it's referring to is the slant of the teeth. Toploader and SROD gears have
a left-hand slant (\\\\) while the C4, AOD, and T5 style gear has a right-hand slant
(////).

http://vb.foureyedpride.com/showthre...ar-works-wrong

The SROD takes a different driven gear, with the opposite pitch. Basically the same
gear as a top-loader 4-speed, with the cable connection on the passenger side.
It's also supposed to have the top-loader style drive gear inside the transmission.
This is because the SROD places the speedometer driven gear underneath the
output shaft, unlike most other Ford transmissions.

It sounds like both gears are the wrong ones. The key clue is your speedometer
works in reverse...

I would suggest David Kee Toploaders.
http://4speedtoploaders.com/shopsite...etergears.html

Notice how the green gear has the opposite spiral from the pink and black gears.
The yellow gear you have now is the same spiral as the green gear. The direction
of this spiral is what is causing your speedometer to work backward.

from "TOPLOADER IMPOSTERS"

When you look at the shifter mounting holes on the tailhousing you will see that there is no way this tailhousing will work in an early application. The speedometer pickup is also on the wrong side.

An SROD is a reversed Top Loader 9 bolt 3 speed, with the over driven top created by re-purposing the shorter 3 speed gearbox to get a 4 speed over driven. It is a truly Autobahn style Porssche/VW/Audi style top gear....so its not a knock off Top Loder 4 speed 3.03 at all, its a cheaper, shorter 3 speed 3.03 Top Loder with a servere component down grade.

The 4 speed Top Loader 3.03 is much longer than the 3 Speed 9 bolt Top Loader 3.03.

It is one of the heaviest, strongest transmissions ever, born for the NASCAR and F trucks. Built Ford tough, like a 9" diff, an FE, FT or MEL Lima Vee Eight. The "father of the Falcon" Robert McNamara era ensured Ford re-earmarked its money to where it counted. The amount of money Ford saved on the throw away Falcon and its under built 2.77 gearboxes and 6.8" and 7.25" axles, Ford spent on making the other lines over engineered.

The SROD was a return to "built down to a price", and did so at whatever the cost. A dollar saved, a dollar earned.


Hence Fords weight and gear ratio tragets for 1976-1977 were initially reached by making the SROD in a 3 speed case, via the outsourced Orion/ Tremec revisions, a contracted out transmission based on 3/4 of Fords Top Loader parts. Then, come 1979-1983 MY, it became alloy cased in the light duty low GVW F trucks, and Fox bodies.


Ford didn't have the money and capacity to keep making gray iron Top Loaders, so it subcontracted out the alloy transmission SROD's, BW's SR4 was a similar response, a sub contracted out inventory filler. The demand for the T5 ment Ford couldn't get T5's for another year.

Since the the SROD T170
SR4
T4
and T5 were made under sub contract, Ford coudn't standarise on one speedo drive.

Same with the European outsourced Rocket/ET 78 and Bordeux C3 gearboxes.


Ford changed things to suit production parts, always has.