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Auto to Manual swap

Discussion in 'The Garage' started by laketex, May 28, 2002.

  1. laketex

    laketex 3/4 ton status

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    Bet this has been covered a few times but I'm asking anyway. What do I need to convert my '79 Blazer from a TH350 auto to a standard tranny? Which one is it, the 420 or 465? I'd like to have a 205 case with this thing for some serious beef. So how tough is this swap? Can I keep my existing steering column? Hydraulic or manual clutch? How difficult is that junk to hang? ect ect. More trouble than it's worth? Estimated costs??? Enough Questions?

    Thanks for any info.

    Bryan
     
  2. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Where to start... I am ALMOST done with my swap - 400/205 to 465/205. (So that answers the 420 or 465 Q) You can keep your auto column just remove the linkage and the auto lever at the top, and its set. Everyone who I asked said HYDRO is the only way to go, so I put that in mine. All I have to say is that the clutch is very easy to operate! Glad I did that one... The weight on the complete 465/205 is about 375lbs if I had to guess... so I would recommend the use of a tranny jack for the install. I happened to have one in the garage, so made my install, well... EASIER... and we'll leave it at that for now. /forums/images/icons/laugh.gif Easy? Well, the auto removal is a piece of cake. You'll need a flywheel ~$170, you'll need the slave and master cylinders, ~$70 master and $60 slave, the hydro flex line ~$20. Then you'll need your choice of clutch assembly $200-300. Hmmm... then you'll have to redo your driveshafts. Great time to upgrade the size of your joints too... I went 1350's when I dropped the 400 combo in, so I didn't have to do anything with that this time around.

    Trust me... You'll have A LOT more questions! /forums/images/icons/wink.gif IIRC, you can even reuse your 350's crossmember with the 465...

    Some folks have issues with the clearance of their floorpan... but mine was originally a standard tranny, so I had no problems there either... but drop the 1" ORD body lift ~$100 and that cures that problem if needed. /forums/images/icons/smile.gif

    Is it worth it? Hell, I think the auto takes all the fun outta driving... so I HAD to have the std. tranny! That and this setup is "bulletproof".

    What else... that's all I can dredge out of the ol' ticker right now... so try back later!

    Good luck! /forums/images/icons/smile.gif

    -Dan
     
  3. BLUESMAN

    BLUESMAN 1/2 ton status

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    I just finished this swap two weekends ago!I went from a TH350/203 to a SM465/208 on my '78.You will need to drop the steering colomn and remove the brake pedal assembly and replace with the new clutch/brake assembly.drill a hole in the right spot for the slave cylinder/rod.Cut a hole in the trans tunnel for the shifter and t-case.I had no clearance problems with the trans tunnel(no body lift).I used the manual trans x-member but had to drill 2 holes.The toughest part was the slave cylinder/rod hole.I do not have frt. wheelwells so that made it easier.I don't think you could do it without at least removing the wheelwells if not the whole frt. clip.I used the auto steering colulmn.Do yourself a favor and remove the trans tunnel to install the trans.....It's a long ackward shifter.I said I would never do it again.....BUT I've said that before.I'm real happy bout what I have now.The 6.55:1 granny gear with 2.6:1 lo range(NP208) really crawls!!!! It figures out to be 70:1 with my 4.10 diff gears.If I can be of any help let me know.
     
  4. Mudzer

    Mudzer 1/2 ton status Author

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    Bryan,

    I did this exact swap a while back. I had the TH350/NP203 setup and swapped in a SM465/NP205 setup. Several things to ponder - with swapping from my combo, I did not have to move the crossmember at all! Same bolt holes. I acquired the pedals and hangers, bracket from the frame, manual linkage, bellhousing, flywheel, clutch/pressure plate, tranny and T-case. I had to drill a 2" hole in the floor for the manual linkage to go through. Amazingly, there already was a dimple in the body for this hole. Plus, my frame was pre-drilled for the dogleg bracket. Now, I would recommend you get hydraulic linkage like Dan installed. Dan should be a guru by now on hydraulic clutch setup! Lastly, I shortened the front driveshaft and used a 3/4 ton long bed 2-piece shaft for the rear. I removed the carrier bearing and the front section of the 2-piece driveshaft. The rear portion was almost perfect in length. I trimmed about 1" off the splines to keep it from bottoming out. I then installed my factory rear driveshaft yoke (front slip portion) and it worked great! It is still in my truck to date! 1350 rear portion and 1310 at the T-Case.
     
  5. laketex

    laketex 3/4 ton status

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    You did the mechanical clutch but you'd reccommend the hydraulic? Why? I have no idea of the differences.

    Thanks to you 3 for the advice so far. I'm thinking about buying FWP's mechanical setup and then I'd just have to get the clutch, tranny and tcase. What's the downfall of the mechanical?

    Btw, taking the inner fenders off sounds good since I've been looking for an excuse to do a tubing frontend!
     
  6. TopOff

    TopOff 1/2 ton status

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    I am in the middle of this myself.

    I went to Hydraulic, because it is supposed to be easier and smoother to work the clutch.

    If you go Hydraulic, get the hydraulic pedals. The hydro pedals have two reinforcing mounting rods that go through the firewall. On the engine compartment side these bolt holes mount the master clutch. Voila'!!

    I could hardly believe how easy this was mounting the Hydraulic master in my '73!
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The mechanical linkage functions, but there are some drawbacks. Number one is the pedal is heavy to depress. No big deal on the freeway, but on the trail or in traffic it can give you leg cramps. The hydro set-up on the other hand has a light pedal feel to it. This would also make it easier to feather the clutch. Also, on the trail when you get it all twisty the linkage can bind or fall part...the one part is attached to the frame and the other half to the bellhousing. There can be some movement between the two. i have manual linkage but am converting to hydraulic (if emmettology 101 ever sends the parts./forums/images/icons/tongue.gif J/K Mike)

    I'd also remove the tranny tunel for installation. The long-assed shifter comes off really easy and then you could use an engine hoist through the passenger side and just lift it into position.

    As for durabilty, it's pretty tough to think of another combo as durable as the SM 465 and NP 205. Compression braking and the ability to tug start it are bonus's in my opinion.

    You'll need pedal hangers etc, but that's been covered.

    Rene
     
  8. chevyracing

    chevyracing 1/2 ton status

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    <blockquote><font class="small">In reply to:</font><hr>

    Do yourself a favor and remove the trans tunnel to install the trans.....It's a long ackward shifter

    <hr></blockquote>


    Why didn't you just take the shift out, it takes about 4 seconds......

    John
     
  9. Mudzer

    Mudzer 1/2 ton status Author

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    Rene is correct, there are several issues which are very important to a rig like yours. First of all, when you are sitting on a 45 degree incline waiting for someone to get out of your way, the clutch gets a little stiff. The other major issue is linkage bind. I have had mine bind and leave me stuck on a School Bus at Mudstock. The only way to do anything about linkage bind is to get under the truck and either tighten or loosen the adjuster. Sometimes this is in less than ideal situations - Like in mud up to your elbows; snake infested rock... you get the point. One other thing is you will actually feel the pedal move during flexy situations. The body and frame move independantly so you have mounting points on the frame and body and tranny, which all move separately. If you are going with manual linkage, it can be converted without using the hydraulic bellhousing. Advance Adaptors makes a bracket for this setup. I have one for sale, which I never installed - didnt have time. Jeff Holsted did a manual to hydraulic swap using Circle track race car parts. Check with BIGJ to see if he still has pics. One last thing, if you go with manual linkage - save your leg and go with the Diaphragm style pressure plate. Go with a 12" setup too.
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I think I have the worst set-up for leg cramps...a Borg&amp;Beck 3 finger clutch and manual linkage./forums/images/icons/shocked.gif
    I've had the linkage fall apart when flexed up...had to fix it in the mud and burnt my arm on the exhaust./forums/images/icons/frown.gif

    Rene
     
  11. Mudzer

    Mudzer 1/2 ton status Author

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    Rene,

    I had the same setup when I got stuck on the School Bus at Mudstock. Actually what happened is some of the springs collapsed in the brand new pressure plate, causing it to not disengage properly. I was stuck in Granny and could not go any further up the front of the bus! /forums/images/icons/crazy.gif

    I had to have a 1 ton Chevy pull me backwards while the clutch was smoking! Not fun. Anyway, those days of stiff leg were eased by installing the diaphragm style pressure plate. It was much easier on my leg. It actually felt like a hydraulic compared to the old 3 finger pressure plate. But, I drove Ken Brown's 72 with hydraulic and it felt like driving a Honda Civic. /forums/images/icons/laugh.gif
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Emmetology 101 is slowly sending me pieces of a factory hydraulic set-up...I can't wait./forums/images/icons/cool.gif I've driven a hydro clutched K5, and it was pretty tough to get back in mine.

    When my linkage fell apart I had just crested the top of a muddy bowl. I tried to stop at the top because there wasn't very much room, but i couldn't get it out of gear so I just shut it off and fixed it where it was. I used a large screwdriver to pry the fork enough to get the linkage back where it belonged and then tightened up the free play...on my back in the mud/forums/images/icons/frown.gif

    Rene
     
  13. TopOff

    TopOff 1/2 ton status

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    Mudzer,

    How much do you want to sell the Hydro adapter pieces for?

    PM or email me!
    PICS too!
     
  14. m j

    m j 1/2 ton status

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    you still didnt find a cheap BH?
    how much are you willing to pay?
    I will stroll down to Dharneys and grab a truckload of them
     
  15. TopOff

    TopOff 1/2 ton status

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  16. m j

    m j 1/2 ton status

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    they are $170 BRAND NEW FROM GM
    pn15530202
    <a target="_blank" href=http://www.gmpartsdirect.com>http://www.gmpartsdirect.com</a>
    I just checked it

    15530202
    Engine Clutch Housing
    HOUSING
    1
    LIST $283.33
    WHOLESALE $212.50
    OUR PRICE $170.00
     
  17. laketex

    laketex 3/4 ton status

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    whoo...it's starting to sound expensive. Maybe I wouild just be better off with a 200 buck TH350 rebuild...I sure do like the idea of a manual gear jammer though. This truck is my very first auto and I just cant get used to it...
     

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