I have a 5 speed Clark transmission in my 64 F350 dually flatbed with 292 motor... I'm told that these came in overdrive and non-overdrive versions.... can I assume that if the shift **** has an "OD" in the shift pattern that it's an overdrive version..??? Is there any other way (short of tearing into it) that I can tell if it's an overdrive...??? Rear gear is 5.14 Rockwell.

Does anyone know the gear reduction of the overdrive on one of these units..???

Does anyone with a 5 speed Clark have a shift **** with a "5" instead of "OD" on their shift ****..???

thanks for any help.

 

You could jack up the rear wheels, put it in O/D and turn the engine over five times. I think the ratio is .8; if so, the driveshaft should turn exactly four turns.

 

where can i attain a clark 5 speed?

 

thanks for the replies, I guess turning the motor over while it's in overdrive is worth a try... As for where to get a 5 speed Clark, I believe they were available on the 1 ton and heavier trucks, but I don't know how common they were... I'd guess the overdrive units would be quite rare, but I think I've probably got one, I'll do the test and post an update...

They're the old square cut gears, so they're noisy and kind of a pain to shift until you get the hang of the weird shift pattern, but it's a very beefy tranny and can handle some abuse.

Anyone else out there with a 5 speed Clark that can add any info or experiences...???

 

the only clarks i have had any experiance with were in 2 ton and larger trucks. but a freind of mine had a 1 ton with a clark trans and 391 or 361 init. it was an old u haul truck. very tough old truck for sure! we were both about 17/18 when he got it, and it is still running and driving today.


jim

p.s. that was almost 30 years ago!

 

Vinnie, The Clarks were in the 1 ton or heavier trucks for many years. They have also been swapped into the lighter trucks frequently. I looked for many years for an overdrive Clark but couldn't find one. I later gave up, bought a couple of Clarks with direct in 5th, and plan on changing my axle gears instead of looking for an overdrive. The Clarks were offered in many versions. I've seen some 260 series trannies, lots of 280s, and one 380 series. All of the shift ***** have read 12345R. Do you have any model numbers for that Clark ? DF

 

Thanks for the info on the shift ****, helps confirm that I may have an overdrive version... need to do the test by putting it in gear and hand turning the motor over, as was suggested above just to make sure...

I'd be happy to get any numbers off the unit that you might need... where do I need to look...???

 

It's been my experience that in an single overdrive transmission 5th gear is toward the dash and fourth gear is towards the seat whereas in a granny transmission 5th gear is towards the seat and 4th gear is towards the dash. This changes with a double overdrive but I don't recall any of the 5 speed Clarks being double over, that was one of Spicer's advantages.

 

Vinnie, the I clarks own have the number plate on the passenger side of the box, near the back of the trans, just below where the top cover bolts on. There was also a factory sticker in the cab of the truck I got the Clark from, it said the trans was a 285V. If yours is the highly elusive overdrive model, the cab sticker would say 285VO. DF

 

It's been forever, but I finally got around to testing the clark, and it is indeed an overdrive version... with 5.14 gear, she cruises down the freeway at 65 doing just under 3000 rpm.... very strange shift pattern, but now that I've driven it for a while, it's second nature....

So I guess if your shift **** has an "OD" instead of a "5", it's probably an overdrive model...

Still curious if anyone else has one of these OD versions...???

 

BVinnie, you have the only overdrive I have heard of then. My repair manuals have pictures and specs, but I never found one. Is your trans original ? DF, @ his Dad's

 

yeah, it's original, my grandpa said he had a bit of trouble ordering it with the overdrive, but the dealer was able to make it happen... he used the truck to haul doors and glass from L.A. to seattle for a few years, then sold the truck to someone in the L.A. area in the early 70s... then in the 80s, he saw it sitting behind a warehouse, inquired and bought it back for nothing... then he and I restored it, and it's been used lightly for a few years... it's been a great work horse and still looks almost new... he's gone now, but the truck is a great reminder of our time together.