Slow 4000

[jtwat]

I have a 72 Ford 4000. It had the SOS trans. but it went bad and was swapped with a 8 speed. Now the problem, I have no high gear for road travel.
Can I swap Ring and Pinion? and if so, which one do I need? And where can I find one?
Thanks for any info.

 

[shaun wallace]

You need one for a 8 speed. Salvage yards be first place to look. Someone on here mite be parting one out. Earlier someone had about same problem.

 

[souNdguy]

just a lil clarification needed.

are you getting all 4 gears in both high and low, but are saying that 8th is not fast enough due to the r/p ratio?

soundguy

 

[woodbutcher]

I have a 4500 and a 4000. They both have the 8-speed transmissions, but the gearing in the industrial transmission must be a lot slower than the ag one. Top speed for the 4500 isn't more than 6 mph. The 4000 will do 15 or so. Do you think you might have an industrial transmission in your 4000?
Butch

 

[jtwat]

Yes. All gears work. 8th is still too slow to take down the road. I will get the numbers from the tranny to post.

 

[souNdguy]

I thought that was what you were saying.. but just checked to make sure you wwere getting 5-8

soundguy

 

[souNdguy]

are the 8spds any different? or would it all be r&p??

soundguy

 

[Ecnerwal]

I suspect it's all rear end. The sos (and 4 speed power reverse, aka shuttle) was like a 30:1 rear end ratio, while the manual trannys were more like 16:1 (on 4500s) - too much like work to dig out the right manual to get the exact numbers.

As such I suspect woodbutcher has a SOS/PR rear end with a manual tranny (as does jtwat, but jtwat knew that) - per the owner's manual, a 4500 with 8 speed should do 13.8mph at 2200 rpm in 8th. 6 is about half that, which is what you'd expect with twice as much reduction as the transmission that's been swapped in needs. Should pull like crazy in first (at 0.7 mph @2200 - or about 1 foot per second...)

 

[Sean in PA]

My parts manual shows the ring and pinion gear ratio for the SOS (listed as "10 Speed") was 6.67:1 and all other transmissions used 3.50:1. The part numbers for the various ring and pinion gear sets for the '65-'75 400 are:

C5NN4209U 1 Gear Set, Matched, 6.67:1, 10 Speed, Transmission Only, No Longer Serviced, Start Year: 01/01/1965

C5NN4209J 1 Gear Set, Matched, 3.50:1, L/Handbrake, Except 10 Speed, Start Year: 01/01/1965

C5NN4209L 1 Gear Set, Matched, 3.50:1, w/Handbrake, Except 10 Speed, Start Year: 01/01/1965

The L/Handbrake means "Less handbrake", which would be the correct one for most US sold models. If you have the European style handbrake, then you want the last one.