so i need to fabricate motor and tranny mounts in my truck, whats the guidelines? carb base has to be level correct? is less than 5* variance ok? i have one of those cheapie craftsman magnetic angle finders how much clearance should the top of the transmission have to the floor?
I like level, and have been known to go through a lota extra crap to make 'em that way. Someone is gonna say that 5* is OK. Do you like to nitpic? If it has to be a little off leaning toward the oil pickup is better than awayfrom it. But, if you're settin' it up anyway why not do it right? How hot do you want the cab? as long as the tranny isn't touching you should be alright. I built a new floor and hump in the latest project, made lotsa room around the tranny. The cab'll stay a little cooler and it'll be easier to pull the tranny if I need to. Luck Bro.
You want the carb float bowls to sit as close to level as possible with the vehicle at rest on the ground. A few degrees shouldn't hurt it much, but shoot for level if you're running a carb (especially a Holley). (You can also buy or make angled carb spacers if your particular application makes mounting the carb pad on the intake level to the ground difficult). You don't really NEED a whole lot of clearnace between the top of the tranny and the tunnel, except for shift linkage, cables, etc. The trans will be bolted to the frame or a crossmember and the body shouldn't bounce up and down on the frame or anything...so you can get away with tight clearances in many cases. Phasing the driveline IS important, though. The engine crankshaft/transmission output shaft centerline needs to be positioned so that your drivshaft is not out of phase...or you'll be chasing some nasty vibration issues and dealing with accelerated u-joint failures! The engine can be offset to the side, or even tilted slightly...but it needs to be straight in the chassis. I'm sure that there are diagrams available that illustrate this concept better than it can be explained, but I don't have any handy at the moment. SMALL corrections can be made with the motor mounts in place...adjusting the transmount position or pinion angle can sometimes get an improperly phased driveline back into spec. Use a level, park your vehicle on level ground with the wheels touching the pavement, and check your work often as you go. My personal trick is to make things with a degree of adjustability built into them so that everything can be 'fine tuned' before bolting or welding things into place.
What they said above is correct in my books too.I usually set the car/truk on stands at the rake that I want,usually bout an inch or two.Then get at it.I also put about 3*down pinion angle in the rear if I'm using leafs,because your usually on the gas and this will twist the leafs up so then everything will be phased in properly.........Shiny
thanks for the info. i knew bout the parralel to the frame thing, just wanted some more input on the clearance stuff. now, i just need to be on christmas break so i can get the fabbing done.
[ QUOTE ] what is that driveshaft phasing?...i'd like to hear some more details on that please [/ QUOTE ] agreed, maybe i havent been reading my books slowly enough, but please do explain phasing a bit more thanks!
I would think tht phasing means that each end of the driveshaft where U joint is located is in same orientation[ a line drawn from one end cap on one end to the end cap on other end is in a straight line with each other- also means that if an imaginary line were drawn thru transmission and another thru the pinion of rear end and were extended towards each other -they would be about paralell[pinion lower than tailshaft of trans by a few degrees of tilt.this would allow for the pinion to "tourque-UP"under a load and be in alignment with transmission. correct me if Im wrong.
That's it, choprods. I remember seeing a really good article about this in a magazine years ago with diagrams that clearly illustrated the concept, but I don't think I still have whatever issue that was! Hopefully someone else does and can post it here for us! U-joint's work best when they are operating at a slight angle...but the combined angles of the front and rear joint have to compliment each other. I wish I knew the math and physics better so I could explain it more clearly...but in short...you don't want the front joint operating at a 2 degree angle and the rear joint at a 7 degree angle or something. You want the tailshaft paralell to the ground, and the 'under load' pinon angle to be about paralell to the ground as well...but you DON'T want them directly in line with each other (the pinion will be lower in almost all cases). Check out my really bad drawing here... Note how the thin imaginary lines are paralell to one another, even though the u-joints will be operating at slight angles.
The front U joint needs to be at the same angle as the rear joint at rest.This is because a U joint working at an angle does not turn smoothly and needs the rear joint to counteract the nonsmooth action.
[ QUOTE ] thanks for the info. i knew bout the parralel to the frame thing, just wanted some more input on the clearance stuff. now, i just need to be on christmas break so i can get the fabbing done. [/ QUOTE ] Not paralel to the frame, paralel to each other and the ground. If the car has a 2deg nose down rake, the drivetrain will have a matching rake so it stays paralel to the ground. Play with range of motion too so you don't have things running into each other when the rear suspension travels. Don't forget about exhaust and fuel/brake line and routing too. TZ
As far as "phasing" the joints, if you look at the back of the trans, the caps on the out-put yoke are say at 9:00 oclock and 3:00 oclock. The caps on the front of the drive shaft should be at 12:00 oclock and 6:00 oclock. The back of the drive shaft should be at 12:00oclock and 6:00 oclock. The caps at the imput shaft of the rear should be at 9:00oclock and 3:00 oclock.On large trucks you might have up to 5 u-joints and slip shafts. Get one out of phase and you will really feel it.
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