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Moving engine and trans back a few???

Discussion in 'The Garage' started by TruckNutzDude, Mar 24, 2007.

  1. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    I was considering moving my engine and trans back about 4"-6" for an even lower COG in my rig (K10 cab on K5 frame). My main problem is that I have no weight over the rear tires and I mounted my winch on what's left of my front frame horns, even though it's close to the rad, it's still a lot of weight in front of the axle centerline. I'm also running a 465/205 which is rather short and ends about halfway between the door opening. With the 52" springs up front moving my axle 2" foreward I still have a crappy front driveshaft angle at ride height and 70% of the rig's sprung weight over the front tires, that doesn't include the D60 weighing about 150 pounds more than the 14 bolt which has disc brakes now.

    Here's the idea:
    -Lower COG and put more weight on rear wheels
    -Lessen angle on front shaft and lenghten it at the same time
    -shorten rear driveshaft that tends to get caught on everything (double bonus points for being able to remove all the dents I've aquired by the pinion yoke when I shorten it!)
    -It's free and adds to the list of custom home made mods :D

    What are your opinions and do you have any advise?

    Thanks,
    Rob

    ps in case you aren't familiar with my rig, this is what I'm working with...
    [​IMG]
     
  2. MuddinManny

    MuddinManny Banned

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    Hey Rob,

    I fail to see how moving your engine and tranny back 6" is going to change the weight distribution of the rig. Your center of gravity is not the issue here. You have absolutely no weight on the rear suspension and that will cause you a lack of traction in the rear.

    What I would suggest is that you make up a flatbed of iron and steel. It will weight in at about 500 lbs, estimated. It will give you the "bite" needed for the rear and also give you a platform to carry necessary items. Even a wooden deck would add weight and could easily be repaired.

    Best wishes....

    Manny
     
  3. Jason4x4

    Jason4x4 1/2 ton status

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    If it will clear the firewall start :hack: :grind: :weld:
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    To lower COG you would need to move the engine down between the frame rails, not backwards. Now if you mean to more evenly dispurse your existing weight from front to back then everything you've said would make sense and all be a help to you. Just remember that moving it back that far you're going to need some firewall massaging. Actually quite a bit of massaging. Probalby going to need longer radiator hoses, modify shifters or some sort of thing, and also modify the exhaust so it will bolt up again.
     
  5. Big91RustyBucket

    Big91RustyBucket 1/2 ton status

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    Manny How do you not see that it will move more weight to the rear? Obviously the motor, and such will move , and so will some weight. On the other hand you are right about needing some weight back there. On my last truck I had a Fuel cell , and Tool box and a 40" spare tire. It helped alot as you could feel the difference with more weight. Good luck Rob.
     
  6. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    In the rear I have a factory 31 gallon fuel tank, the 14 bolt and a hitch/bumper as well as 2 optima batteries. I'm adding a small flat bed/cage deal to the rear this spring to help with traction but I don't want to add 500 pounds to a rig I build with less weight as the main goal. If I move the engine back it will follow the down slope of the frame, lowering it about 2" as I move it back 4". I am not afraid to move the cab or chop the firewall to acomodate this part of the build. Also, I have no exhaust, just headers with 3' of tubing going to 40 series flowbastards the dump behind the cab... plus I work for a muffler shop. :wink1: Radiator hoses for K series trucks are "cut to fit" when you purchase them at the parts house so that isn't an issue.

    What else should I have to worry about? This is seeming fiarly simple on paper...:thinking:
     
  7. big dan

    big dan 1/2 ton status Premium Member

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    one thing to think about is your shifters being moved back. mainly the sm465 shifter cause you cant really move it foward like you could the transfercase shifter. might have to heat it and bend it a little to make it work.

    firewall clearance will be another issue but with a little cutting and custom work it would be possible.

    I think it would be a pretty good idea if youre up to the work involved. it will surely help your driveshaft angles and it will at least distribute some of the weight towards the rear.

    something other things you might try: since the tranny has pto ports you could get one of those pto winches like the military uses. something like 15-20000 pounds, that will add some weight to the rear. you could also fab up some custom battery boxes and put dual batteries over the rear wheels and maybe add a small tool box directly behind the cab to keep tools and spare parts in.
     
  8. MuddinManny

    MuddinManny Banned

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    I'm not saying it won't move the weight back. It obviously will, but it will, IMHO, not bring enough weight back to get it where you need it: over the rear wheels. I can also see a lot of driveline issues possibly coming about because of the changes, as with wiring issues, possible fuel line issues, etc. I would think that building a platform to give weight would be more practical, cost effective and serve a better purpose, as you stated above.

    One handi-cap I'm working with is that my Chevy is the first one I've owned. I've seen what flatbed Toyota's do in the MUD but I haven't seen a flatbed Chevy. I have to take my truck to the scales to see what she weighs in at, and I'm guessing it will be close to 3 tons. Don't know if you can build a Chevy on the light side, without 4 link and having a cage body. That's a question, not a statement of fact. I'll watch your build with curiosity. I'm hoping I didn't build a iron weight.

    Manny
     
  9. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    The shifter moving back will be a good thing, I might be able to shorten it if it were closer to my arms, I can easily trim the floor to accept the shifter and I have a welder to rebuild the transmission tunnel.

    The battery box in the rear is already there, and low mounted between the frame rails. I have a plastic tool box to hold spare parts for the back that is not mounted yet but will be when I get the materials for the flat bed.

    I was thinking of mounting my winch in the rear but I have found it's most usefull in the front. A second winch is on my list of things to buy, right behind a few spare driveshafts. :o

    Thanks!!!
     
  10. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    I've built at least a half dozen different K5's before this one. I started with a build similar to yours but I kept sinking in the mud and breaking parts on the rocks, that coupled with blowing beads on my 16.5" rims and having stiff, high arch springs forced my build-up's to evolve. The way I think is that I have enough weight now, I just need to arrange it so that it works to my advantage. As my rig sit's it's lighter than a stock K5 but stronger than a stock K30 IMHO, I just need to get some weight over the rear end. :crazy: I appreciate your input though and I enjoyed reading the hundreds of pages on your build. :waytogo:

    -Rob
     
  11. muddermilitia

    muddermilitia ThatTrazerGuy GMOTM Winner

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    Well seeing as how our trucks are very similar, I have been debating about how to get more weight in the rear of my trazer. Fullsize spare tire mounted as far back as possible, stock 31 gallon tank full of gas :D , tubular flatbed with toolbox, storage boxes etc. Also a rear mounted winch hooked to the rear axle to suck the rearend down for going down steep declines. These are a few of the things i came up with. Also going to a rear mounted radiator would help.

    If you do move the engine/trans/tcase back I would suggest moving the radiator behind the cab, moving the front winch farther back. Taper the front clip and lower the hood down so you can also increase your vision. Just a few things I thought of.
     
  12. justiz00

    justiz00 Registered Member

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    Just get you a few suitcase tractor weights. They are close to 100 lbs. each and are flat. Mounting shouldnt be an issue as you could stack them or hang them off a piece of angle iron. Easy fix if you can get them for cheap.
     
  13. 85mudbogger

    85mudbogger 1/2 ton status

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    i would move the cab back along with the engine and trans, u shouldnt run into shifter problems and such especially with the clutch pedal, and by movin all that weight back, it should even everything out since theres not much to your rig anyways, it will take a little time moving all these umpteen mounts to make it work but it will make ur rig way more capable and then if your front gets a little light then make u a custom stinger that u can hang some tractor weights on lmao, i have seen this on rigs that were built too light in the front and just like tractor pulls u can adjust the weight of your rig on the front, i think everything moved back 4" would be suficient. after lookin at your rig im thinkin of doin the same, i have a blazer frame just waitin for a cab, did you have to move mounts or make any custom ones?
     
  14. muddermilitia

    muddermilitia ThatTrazerGuy GMOTM Winner

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    You have to make custom rear cab mounts. But its real easy.
    Here's how I did mine, http://www.cardomain.com/ride/2186902/5
     
  15. DavidB

    DavidB 1/2 ton status

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    This is something I'm interested in too. Weight distribution. I have no weight to speak of from the middle of the cab (end of the tcase) back in my K5. Just the frame rails, tank and severely hacked/stripped body. I'm thinking about mounting a '70 cab in the middle of an '80something CUCV frame and putting my K5 drivetrain in it.

    Out in the back of our shop we have a big rough hole/hill. The blazer gets up it OK, but doesn't walk up it. Locked one tons, 46" tires. My stock crew dually K30 climbs the hill about as easily. The K5 won't even think about climbing anything in 2wd, and spins the 46"s easy. I think it needs more wheelbase and better weight distribution.

    The winch above the rear axle to suck the rear down is a good idea too.
     
  16. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    Bump... Still looking for more feedback. I'm either doing this mod or pushing my axle forward and dealing with steering issues. :doah:I added more weight in the rear (tube bed, mounted a spare tire, batteries and toolbox) but could still use more front driveshaft length. :rolleyes:

    Don't mind my drawn in seatbelt... I didn't want to be a bad example. :wink1:


    [​IMG]

    [​IMG]
     
  17. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    Start moving more stuff to the rear.

    Radiator is a good one. Not so hard to move either. full of water they can be pretty heavy.

    Start dumping more weight from the front. Your fenders full or skinned? Hood skin or full?

    Draw a line half way between your wheels(or weigh the front and rear halves and figure where your centerline is). Anything in front of that you can move behind it will help. Anything in front of it you dont need, ditch it. Anything infront of the line that can be lightened up will help.

    Front axle forward will help, Rear axle forward will help(weight bias only, mess up everything else.

    Do you have plans for a doubler? Use a 208 adapter to the between the 465 and 203. It's much longer and helps shoot the weight to the rear. Helps driveline angles in the front.
     
  18. deadlew

    deadlew 1/2 ton status

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    Have you weighed your Trazer? What is the weight bias? Moving the motor back will probably change the bias 10% to the rear at the most.

    PaulC
     
  19. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    I'm not running fenders anymore and the hood is pinned to what's left of the radiator support. The radiator is in the stock location but I had thought of moving it to the rear at some point.

    A doubler is another idea I'm toying with but the added expense is holding me back plus the addition of another 200# in weight. I love my 465 but that front driveshaft drives me nuts! :rolleyes:
     
  20. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Knowing actual weight bias (F/R) would really be helpful.

    As mentioned, shifting the driveline won't change your CG at all, but it will affect the weight bias.....probably in a pretty small way though.

    Adding "lightness" might be an easier way to go. Remove all the weight you can up front and you'll probably shift the weight bias in a more meaningful way.

    I'd also keep that gas tank full at all times. Fuel adds about 7 Lbs/gallon....so you have a weight variation of maybe 150Lbs depending on how much fuel you're carrying.
     

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