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Ford L7000 tranny swap

Discussion in 'Trucks' started by Labparamour, Mar 27, 2020.

  1. Labparamour

    Labparamour Senior Member

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    6E9BA0DA-70B5-44C4-9880-43F07262904B.jpeg 47139203-5CDC-4563-BC1F-89CECA877BDC.jpeg Hoping to get some input.
    ‘82 L7000 6yd single axle dump
    CAT 3208
    SAE 2 steel clutch housing
    14” dual disc push-type clutch
    Spicer CM 50 tranny 1 1/2”-10 spline input.
    Eaton 2-spd diff
    10-22.5 tires

    I have to run with engine wound out about 2400-2500rpm (tach bouncing) to get 55mph.
    I’m not looking for faster road speed just lower engine rpm’s.
    Empty, running 5th-over, I can run as slow as 35mph and she seems happy (approx 1800 rpm).
    At 26,000# gross, she still seems happy pulling at lower rpm’s on the level.

    Ford repair manual shows different clutch housing support between 7000 and larger 8000, 9000 trucks.

    Wondering about RTO9513 or maybe even Spicer 7231 brownie?

    Just thinkin’ out loud right now.
    Thanks for any input.

    Darryl
     
  2. RZucker

    RZucker Senior Member

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    In the long run it might be cheaper to switch the drop in in the rear end to one that has the ideal high range ratio for cruising. Of course you will have to re-calibrate the speedometer.
     
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  3. Labparamour

    Labparamour Senior Member

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    Thanks.
    Guess I can research what ratios Eaton offered.
    The rear axle has inboard brake drums so was thinking of changing out axle at some point- didn’t want to pay for new diff if was swapping it all out later.
    Weller said there’s a Spicer CM 5spd w OD of 0.85.
    But, 1st would go from 7.28 to 5.70 (reverse, too).
     
  4. petepilot

    petepilot Senior Member

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    agree with rz easiest cheapest way to go
     
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  5. RZucker

    RZucker Senior Member

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    I have the same dilemma with my F-800, i would like less rpm cruising, but 1st gear in the 10 speed is not low enough as it is in soft ground. Maybe the little RTO 13 speed is the answer... or a nice 4 speed overdrive aux. Wouldn't have to shift it on the road much, but the reduction would be there when you need it.
    I've had mine for 19 years and it's probably a little late to change much now. We're both getting closer to retiring. ;)
     
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  6. repowerguy

    repowerguy Senior Member

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    Can you install some 11- 22.5 tires instead for a little more road speed?
     
  7. Truck Shop

    Truck Shop Senior Member

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    Mounting the fudge brownie and shift rails can be a bunch of work. A 6613 would be the best choice, 9513 is a howler monkey. Either way you will end up probably changing clutch discs
    to accept 1/3/4 shaft. Changing axle ratio would be the simplest.
     
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  8. crane operator

    crane operator Senior Member

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    Just in case you didn't know, it won't hurt the little cat at all to turn the rpm's. 3208's can run 3,000 + rpm's and were set there at the factory, for different applications. Its not that hard to back off the high rpm screw and let it run.

    If you are swapping trans, I'd agree with truck shop and rzucker on the 6613. Good low down gears, close together all the way through, which is great for low hp engines, keeps you in the powerband. They are not as common as they used to be, they are getting harder to find.

    I don't think I'd do the spicer with the big overdrive, you will hate the fast backing up to dump.
     
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  9. Labparamour

    Labparamour Senior Member

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    Fellas,
    I appreciate the input.

    Repowerguy- the rubber is new so hesitate buying more tires.

    TS, RZ- thanks, I’ll surf the net and see what’s out there. Thanks for heads-up on linkage and clutch issues.

    Crane Op- good to know I won’t ruin the engine running hi turns.

    I agree I about low speeds- forward and backing.

    There’s no tag on the pumpkin so I’m gonna spin the wheel and see if I can figure current ratio and then what else Eaton offered.
    Will also play with on-line calculators to see how speeds would change at low end (1st/rev).

    Kinda seeing how this looks on paper.
    Just a farm truck so not many annual miles. Fun to tinker with, though (just not as pretty as what Truck Shop is tinkering with ;)).

    Thanks again,
    Darryl
     
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  10. Birken Vogt

    Birken Vogt Charter Member

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    I'm with C.O., high RPM is just how these engines were.

    Back in these days, they seemed to use the engine governor x the rear axle ratio to set top speed and that's just the way it was. When you got out on the open highway you just put the pedal to the floorboard and left it there.

    If it is for low miles per year, and you are satisfied with top speed, I would not change a thing. You don't want to lose any granny/reverse ratio for low speed maneuvering. Maybe use ear plugs.
     
  11. Labparamour

    Labparamour Senior Member

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    Thanks BV.
    Yea, the earplugs already hang in the cab ready for use!
    This truck was a Cali emissions law refugee... Ran from Manteca up to Seattle. Quite a trip! Most memorable was dumping WD-40 into wiper air-motor lines while snowing by Yreka:( (would get two swipes then stop). Moved wiper arm manually to pull it through motor. It worked :D

    But, been a handy rig.

    There are certainly other areas I can focus the love on this girl.
     
  12. Nige

    Nige Senior Member

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    We had a case of a pair of Cat 3208 Marine engines on HEF a few years ago. During the investigation into those engines we found that the highest rating developed 425 BHP @ 3000 RPM. Not for long though - Performance (coke smuggler) Rating, but it was an official factory HP classification.

    I get where you're coming from but you ain't gonna break a well-maintained 3208 running it at 210 BHP @ 2400-2500, despite the need for ear defenders.

    I can't add anything to the debate regarding the best way to change gearing.
     
  13. Truck Shop

    Truck Shop Senior Member

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    The RTO 6613 will have a ratio of 14.38 in low hole and 0.80 overdrive. But 6613's are not all that easy to come by, and most of the time a pretty penny.
     
  14. Tenwheeler

    Tenwheeler Senior Member

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    That won't add much. Good thought.
     
  15. petepilot

    petepilot Senior Member

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    one other thought IF truck has budd wheels and is running 11x22.5s now` changing to 11x24.5s would gain approx. 7 mph. road spd. as for ratio end of pinion shaft should have numbers stamped into it
     
    Last edited: Mar 28, 2020
  16. Labparamour

    Labparamour Senior Member

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    F857F0D7-691F-420F-BBD0-987EA8751444.jpeg
    Thanks, I’ll check end of pinion.

    Oil analysis said everything within spec. Added sweetener to coolant this year. Trying to treat her right.

    Weller gave me a copy of Spicer CM60 ratio options.
    Might be easiest swap. 7.28 in first now vs 5.70 but would have .85 in direct.
    Online ratio calculator (if I did it correctly) says would be 1.5mph diff in 1st at 1800rpm. (5.3 vs 6.8mph)

    I did quick search for 6613’s- you’re right, not cheap!

    Replaced engine rear main seal and clutch two years ago trying to dry up oil leak at rear of engine- still have the leak.
    I understand there’s a gasket between block and flywheel housing .
    Doing tranny swap would also let me attack that.

    Thanks again for the help.
    Nothing going to happen until drier weather anyway.

    Have a good weekend!
    I’ll be painting walls and crown moulding :(
     
  17. crane operator

    crane operator Senior Member

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    Too bad you didn't change that gasket while you were there. It wraps around into the oil pan also. Its not a rare problem.

    I fixed two of those that were leaking there, on one the housing bolts were loose, the other one, the housing itself was cracked. Check yours over really close for cracks in the aluminum when you get to it.

    There is a whole micrometer to crank measuring procedure to ensure the housing gets tightened straight on the block, when reinstalling the housing. I did mine by the goodenuforwhotisfor method. I was poor and didn't have the equipment to do it right, and I guess I got lucky because it held.

    Personally, I wouldn't swap transmission just for that little bit of overdrive. You are going to spend a lot of $ for not much return, and you may like it less. You probably aren't using this everyday all day for hauling are you?
     
  18. Labparamour

    Labparamour Senior Member

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    CO, no, she doesn’t run every day. Mostly summer projects and the every other month during winter just to get some exercise. All short runs.

    Thought the main seal was source of leak and didn’t realize there was the other gasket.
    Changed oil pan gasket last year chasing the leak at the back.
    I didn’t realize the block was a bolt-together assembly until I did the pan.
    Thanks for pointing out what to check.

    Given her age and relatively decent shape, I guess I’ll just maintain what I have.
     
  19. Truck Shop

    Truck Shop Senior Member

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    Sounds like a good idea.
     
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