Setting angles of engine/drivelines in chassis

Just spent quite a few hours, "fine tuning" the placement of where the engine and transmissions are needed to sit,got it down to 0.6 *, but there is a 10mm offset to the passenger side. Have the engine and trans sitting on the rubber isolators, on the crossmembers, bolts dropped through the holes but not done up yet. Doesn't look too bad just sitting there, although all the angles are within 0.6 degrees, the diff flange is near enough to dead centre between the chassis rails, but that very slight offset at the back of the auxilliary box, don't know how I'll get that right, I can kick the whole rearmost tranny to one side so it's parallel to the main tailshaft from a vertical plane, but then I'll be making the jackshaft skewiff. Maybe if I can split the 10mm between the two shafts, end up with 5mm out of alignment for each shaft, reckon I'll get away with that?? Dave

Set the whole engine/trans in a straight line parallel with the centreline of the chassis (left to right) but 10mm to the Near side.

As long as the the flanges are all parallel to one and other both horizontally and vertically the offset won't cause any vibrations.

Zuffen,
Sent you a P/M,
Dave

Well, with the help of some knowledgeable people on this forum, just about got the VERTICAL plane angles sorted out, got them to within 0.2 degrees and can fine tune them later by adding/removing shims when all bolted up and weight is on the vehicle.
Spent half the night trying to find how I can check the HORIZONTAL plane. Most hotrod sites or even truck driveline sites assume that the centreline of the engine/transmission is parallel to the chassis, from the manufacturer, but don't tell you how to either check it, let alone set it up from scratch.
Did find one site that suggested that with the driveshafts removed and the faces of the flanges cleaned off, lay a straight edge over each face, checking its level with a spirit level. They lost me a bit when they said that the straight edge should be long enough to extend past the OUTSIDE of the chassis rail by at least 12 inches, then with the straight edge clamped to the flange(s), measure the distances between, each side (outside the chassis). Sounds good if you can trust that the straight edge is true all the way along it's surface, although 2 X one metre long spirit levels may work. They then went on to say that there should be a MAXIMUM of one eighth of an inch difference each side.
That really isn't much to play with, if say the chassis is 30 inches wide outside to outside of the rails, plus 12 inches either side, adds up to 54 inches, bit wider than my meter long spirit level.
One eighth of an inch at the end of even a meter, is going to be miniscule at the centreline of the input/output universal joint flanges. Hope they (the flanges) are true and square, otherwise I'd never get it right.
Where the transmission mounting pad bolts to the crossmember, the holes have been elongated to about double the 7/16" mounting bolts. So, whilst not being a mathematician, even I can appreciate that up the other end of the engine/trans, should give me at least an inch or so sideways adjustment before I cobble the front mounts up. At the moment, whilst the rear of the engine/trans has been bolted down, very easy to back the bolts off until they are loose. The front of the engine at this stage is simply sitting on a piece of channel clamped to the chassis rail and supported with an adjustable stand. I reckon I'm pretty close to the mark (going by my iPhone angle meter anyway) of setting the INCLINATION at 3 degrees (suggested normal practice), and can move the front of the engine side to side with the aid of a posthole crowbar. (Don't you just love this modern equipment?).
But, I'll say this, anyone who can suggest an easier or better way of setting the HORIZONTAL plane parallel, I would certainly like to hear it!
Alternative tools on hand for this precision maneuver include "come-along-billy" hand winch, miles and miles of rope, large hammers, but little patience.
Cheers, Dave_64

two straight edges sounds like the go to me
But you would have to take a step back further first I would think

When you are concerned about these angles perhaps you need to start at the start first and check the axle or axles are at right angles to the center line of the chassis and the chassis reasonably square before setting the flanges in a horizontal plane ??

Dunno if I was going to as much trouble as you are I would want to get the whole show right as I would be slightly miffed to say the least if I got to the end and found the axles werent spot on and had to start again

On some over dramatized US hotrod building shows I have seen over the years thats how they build hotrods
They start by checking the chassis is square and the axles and so on all the way thru
Once the axles are on the hotrod sits on axle stands on the hubs while been built as I guess this is how it sits when the wheels are bolted up

Paul

I'm with Mrs,

Once you're happy the axle is in the right place find the centre line of the chassis. Line the engine up off that and bolt the front end down once happy.

From there it's only a matter or slewing it sideways until happy with the angle.

Due to the size of truck wheels/tyres the propshaft isn't going around at 5,000 rpm so it isn't as critical as you may think to have it all 100% precise.

Bear in mind may diff centres are NOT in the centre of the axle due to the hemisphere forcing the crownwheel to one side. This is so they can run equal length axles and save money. Lots of Falcons have offset axles and they seem to have worked.

Thanks Mrs. and Zuffen,
Mate down the road has one of those large industrial set squares if I snivel to him he may let me borrow it for an hour or two. About all I can do is check that the diff flange face is at right angles to the chassis rails, really should have done that BEFORE I started ripping into it. The chassis is after all, although in good nick, coming up sixty years old, running a tape from diagonal corner to corner, would be what I consider within the ball park. This mate has a bit of rectangular steel tube I can buy off him to use as two straight edges, so all I can do is try and get it as you guys suggest.
Yes, there is a very slight offset of the centreline of the diff flange, got it written down out in the shed, I know it's not a huge amount,but probably for the reason of having two axle shafts the same length.
Be a bummer if I have gone to all this trouble so far and then find out that the chassis is out of square, you'll hear me bellowing from your place!
Thanks again, Dave

A nice piece of square cut ply from Bunnings.
The longer the sides, the more pronounced and measurable the error becomes.

You can cut the corner out for the diff housing and then use the axle tube to get the square. (just a couple of hose clamps though some holes to hold it on the tube.) And a couple of axle stands to jack it to the right hight.

Then use a laser to project the centre line down the edge to the motor.

I love my little magnetic laser level thingy.

A pen laser is great for projecting a line though space. Perfectly straight, just need to align it carefully. (and the longer the projection, the more measurable the error is.)

jon_d,
Lasers? WAY too technical for this old goat! I have enough trouble reading a protractor! Technology and I just DO not get along.
Ended up spending the best part of the day going back over what I had done and decided to bite the bullet and start again. Not wasted, but learnt a few tricks.
Using the diff as a starting point and after checking it was square with the chassis, (it was), worked forward from there.Meant moving the complete engine the 10mm to the drivers side so it is now centred within the chassis. Just meant shimming the bellhousing mounts a bit. So, being a believer in Mr Spicer's driveline bible which I downloaded, set the engine inclination at the recommended 3 degrees. Fair bit of ginning around with the jackshaft and the auxilliary box keeping them all within specs as well as parallel on both the vertical and horizontal planes. The input flange of the auxilliary ended up slightly higher (about 5mm) than the output of the main transmission, but still maintains it's parallel planes, had to do a bit of minor surgery on the front auxilliary crossmember and use spacers at the rear mount and crossmember. Parallel and vertical planes are near enough to spot on by the time I got to the diff flange, alleviating the immediate need to shim the axle perches. If they have to be done by the time the vehicle has the tray body and bits and pieces fitted, won't be a big issue.
Clamped everything in place with G clamps for the time being, bloke over Bendigo way thinks he may have an original Dodge 6 cylinder rear engine/transmission isolator in a box of mounts, will head over and see what we can garner tomorrow.
I dunno, maybe I'm being too pedantic, but ginned around most of the day cutting shims, measuring, jacking components up etc etc.
Using the two straight edge principles, and measuring the relevant distances in between, got nearly all angles down to about 0.2-0.5 degree differences between components, that was on both planes. If you drew an imaginary line through the centreline of the engine/transmission to the diff, there is an offset to the near (passenger) side of 10mm, in the auxilliary box positioning but still maintaining the parallels. This was more to do with the remote tower and gearshift linkage setups, didn't want to have to rework them again, easier to just push the auxilliary 10mm off centreline. So, I was pretty chuffed with the end result. If I can get hold of the new rear mounting pad, should slot straight in where I've packed it out with spacers, that's always reliant on my measuring it correctly.
Jam the new mount in, I can then drill the crossmember to chassis rail holes and lock it all up, few brackets to be fabricated to secure the auxilliary transmission front mount to the chassis rails. Bit of a pain, going to try and bolt them in with hi-tensile bolts rather than mig weld them in.
That's about it for the moment, maybe add a few photos once everything's in it's correct place.
Thanks for the interest, the comments and advice, Cheers, Guys!
Dave_64

Dave I think all the stuffing around is worth it in the end
I look at things a but different than most, if I drive a stock standard Falcon the unis last for ever pretty much with little to no maintenance
Even on a truck and a big truck at that when they are unmodified they seem to last forever in the tail shaft
Once we start chopping and changing things they dont seem to last as well and I think a lot of this is in the fine details as in tail shaft angles etc
so I reckon its a good investment in time and effort to get it right

Paul