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drivetrain question

Discussion in 'Truck & Equipment Repair' started by Megunticook, Feb 26, 2009.

  1. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    I know I'm kind of an oddball plowing with a standard transmission, but I figure some of you still use 'em (truck is a '73 Dodge W100, 318 motor, n.p. 435 transmission and n.p. 205 t-case).

    I was just wondering about something--in general I try to treat my truck pretty gentle (after all, she's 36 years old!), but every once in a while I'll be pushing some wet heavy snow and the truck will slow down even though the rpms are constant. On a rare occasion she'll even start to shake a little. What is actually happening with the motor and driveline? Is the clutch slipping because of the extreme torque being exerted?

    When this happens I stop, back up, and re-assess my tactics. I know it must be putting an awful strain on the drivetrain. Just curious what is actually happening down there.

    There are certain conditions and situations, though, where I work the truck pretty hard. I just try not to get abusive with it.

    I replaced all my u-joints with Spicers last year, removed and r&r'd all the drive shafts, so things down there should be in pretty good shape.

    One thing that makes me cringe is a few times I have taken a run at pile or slab, just 5 mph or so, and been stopped right short, so the truck actually bounces back slightly. This has got to be brutal on the drivetrain...I will avoid this at all costs from now on.
     
  2. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    if your letting the rpm's get to low your lugging the motor. if thats happening you will either have to downshift to a lower gear of just go a little faster.
     
  3. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    No, it's not lugging. What happens is I'll be pushing snow at, say 10 mph in low range at, say, 1700 rpm (I'm just guessing at those numbers). Then I hit a slight incline, and the truck starts slowing down even though the rpms remain at 1700. What I'm wondering is, why is the driveshaft rotating at a lower speed even though the motor remains constant and the transmission is also constant?

    I assume this means the clutch plate is slipping...
     
  4. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    ok that explained it better ya it sounds like it is slipping, maybe try a heavy duty clutch next time
     
  5. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    Yur clutch is telling ya its reaching the end of the line and its time to replace it. Hopefully youll be able to get the rest of the winter out of it.
     
  6. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Dang, I was afraid of that. It's been 7 years since it was replaced....

    Will I know when things get critical or is it already at that stage?
     
  7. mnic

    mnic Junior Member
    Messages: 19

    if you try to drive up a steep hill and the rpms are higher while the speedo drops or feels like the engine is revving up or the clutch is grabbing high youll probably need a clutch
     
  8. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    Im doing a clutch today on a Chevy 3500HD, a time consuming job. Actually I only wanted to replace the hydraulic slave cylinder inside the tranny housing, but with all the time it takes to get to it I'm going to replace the clutch and p ressure plate,AND I DONT WANNA BE DOING IT AGAIN FOR AT LEAST ANOTHER 10 years
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Sounds more like its spinning the tires. It takes much more effort to slip a clutch in low range than in hi...and by your description you are plowing in low range.

    In other words...in low range it'll spin the tires long before it'll slips the clutch due to the gear reduction low range adds. The clutch would have to be worn to the point that it would be virtually useless in high range before it would be that easy to slip in low.
     
  10. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Hmmm, that makes sense. I also think I would've smelled some serious hot clutch odor if it was slippping badly.

    I wasn't aware of the wheels spinning but I suppose maybe that's what was happening.

    Is there a surefire way to test a clutch and know if it's bad or not?
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    1) Clamp the e-brake on good and tight or hold the brakes down good.

    2) Place trans in 2nd gear

    3) Hold it about 1300-1400 rpms and then fully release the clutch...

    If it stalls the truck or drags it through the e-brake/brakes then the clutch is good.
     
  12. rocknrollrednec

    rocknrollrednec Senior Member
    Messages: 108

    what B&B said:salute:
    ya may wanna drive the truck for a bit, and get all the components warm first. I've seen old glazed clutches slip, only after they're warmed up.
     
  13. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    If you do need to replace the clutch do it right. New pressure plate, throw out, pilot bearing and have the fly wheel machined. Use the search function on the gray line above. Search "plowing with a manual transmission" There should be a lot of posts on the subject.
     
  14. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Good advice. I bought a kit that includes all that stuff. And I will remove the flywheel and take it to a shop. Probably r&r the tranny as long as I'm at it (although I don't look forward to removing that 435--weighs a ton!).

    I plowed 6 inches and then another 2 on this last storm...clutch felt just fine. Wonder if I'm being premature. I'll try the test B&B recommended above.

    At this point I may wait until plow season's over, then take the truck out of service.
     
  15. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    If it's done right it will last a long time and perform great
    I have pointed this out to a few people I know. They just replaced the friction disk. Then revisited the job 6 months later. Way to buy the disk twice!
    I was taught by an old timer how to plow with a manual transmission. There are tricks and cautions that will help a clutch to survive (in the posts on the forum).
     
  16. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Where exactly are these tricks and cautions? I'd love to read them. Can you provide me a link?
     
  17. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

  18. unit28

    unit28 PlowSite Fanatic
    Messages: 6,535

    you said it shakes sometimes but not always, that tells me tire slip/ wheel hop.

    alignment?
    front/rear -center pins good?
    axles aren't dog walking are they?.
    How's your balast, and what plow do you have?...just asking, other Q's.
     
  19. Dustball

    Dustball Senior Member
    Messages: 274

    Truck slowing down + mph increasing + rpms increasing = tires slipping
    Truck slowing down + mph staying the same + rpms increasing = clutch slipping
     
  20. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Thanks...I guess I've been doing that just out of common sense. Been driving manual transmissions all my life, intend to keep it that way.

    Thanks for the thread link--believe I'd already visited that one. A contentious topic, for sure!

    Personally I prefer the standard tranny for plowing, but then again I'm not out there doing it for eight straight hours. Still, having that degree of control is helpful.