Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Problem with 3/4t tranny?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ArrowheadK5, Mar 21, 2002.

  1. ArrowheadK5

    ArrowheadK5 1/2 ton status

    Joined:
    Aug 3, 2001
    Posts:
    252
    Likes Received:
    0
    Location:
    Northern MN
    The manual transmission in my 87 k20 (sm465, if I have it right?) has been funny--I am wondering if it's a clutch thing or a tranny problem.
    Sometimes it takes a lot of muscle to shift into first when the truck is stopped. It doesn't necessarily grind, just wond move down there without me really horseing on it. Then it's the same from 1 to 2 at about 20 mph, and then still a little weird form 2 to 3 at about 45-50. And the synchro for reverse doesn's seem ot work as well. This is not a constant thing, just arbitrarily sometimes, and It doesn't seem to matter what the temp is of the truck or if it's cold outside or not. It only happens right after I start driving and goes away after 5-10 min. Is there a fluid level I can check or some other factor to test? TIA, any help welcome.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    hey you driving my truck? lol

    Actually, mine is almost the same. 1st gear sitting at a light sometimes, it goes back towards first, then stops. It's happened enough now that I KNOW when its not back far enough (only moves about 2" further or so) but I really have to pull back hard on it to get it to go fully in gear. if you let out the clutch, it basically will just "rub" the gears together...no grinding, the stick just bounces and the gears buzz.

    Ask the guys from last night, I also have a problem with second...sometimes it "sticks" right before hitting second, so the gear shifter won't go far enough to the right, and it will grind (badly) trying to go into second. Have to clutch it again, move it away from second, then try again, slowly...if I try again quickly, it will stick again.

    Reverse, as long as I hold the clutch in for a few seconds, won't cause problems. But if I push in the clutch, and try to immediately go into reverse, it will grind too. I don't mind that, usually don't need to hit reverse quickly, but it is kinda annoying. I attribute that to age and wear.


    My dad has a REALLY high mileage (1974) beat on 465, and his does none of this, and I drove it for 6 months straight.

    The shift thing I'm pretty sure is either the "rail assembly" (in the top plate with the detent balls and all that) or the shift forks. I brought this up before, apparently the shift forks were coated with nylon, and it comes off, causing some "shifting problems".

    Usually none of this is a problem, and I still like the Sm465 ten times more than an automatic, but when you need to accelerate quickly, the 1-2 can be a problem, and the 1st gear thing is just annoying. As long as I'm not having to rush shifting, there is no problem. However, I am keeping my eyes out for a cheap Sm465 I can take apart and rebuild.
     
  3. bigmack

    bigmack 1/2 ton status

    Joined:
    Jan 3, 2002
    Posts:
    478
    Likes Received:
    0
    Location:
    Tennessee
    I would say it's not a clutch problem. You probably need to have it rebuilt or find another tranny to put in its place.
     
  4. TopOff

    TopOff 1/2 ton status

    Joined:
    Jan 16, 2002
    Posts:
    1,760
    Likes Received:
    0
    Location:
    Folsom, ca
    Have you checked/replaced fluid?
     
  5. Anteak

    Anteak 1/2 ton status

    Joined:
    Nov 7, 2001
    Posts:
    105
    Likes Received:
    0
    Location:
    Hemet, Ca.
    I'm having the same thing on my 1973. I just replaced the front input seal (unrelated to shifting) and all the fluid and it's still hard to shift. This mainly happens after morning start-ups and goes away when warmed up. This is not a daily driver. Seems like it just likes to warm up a bit.
    Does anyone know how to stop the input shaft from leaking??

    73 Blazer, So. Ca.
     

Share This Page