Drive shaft misalignment?

[Checkerhead]

How much misalignment is acceptable? I know the input and output flanges should be parallel. I can sort that at ride height, but if my pinion angle changes by 12 degrees through out the full range of suspension travel, is this ok?

This not just a crawler. I expect this thing to be able to get up towards 200kph.

[mudlva]

No expert here but....
Ride height would be critical as when doing big speed that is where the stress would be.
When the suspension is moving full travel then technally its proberly off loading so no real load on the ujs etc.
Whats it like under fill compression? As that is when full load can to delivered as well and ujs take a real hammering

[Checkerhead]

This is all theory at this stage, and I'm ignoring the extra angle changes that would come with bush flex etc.

Whats it like under fill compression? As that is when full load can to delivered as well and ujs take a real hammering

Unfortunately this is where I'm at my worst. Just under 11 degrees of misalignment. (11 degrees of pinion change at full compression. -1 degree at full droop).
From what I understand this angle would be split between two UJ's so 5.5 degrees each at full bump.

I am wondering about setting it up such that I have a about -3 degrees misalignment at ride height, then as it compresses it would go through 0 degrees, and to 8 degrees at full bump. If I'm understanding the material in Churchills link (in my build thread) correctly, then with these angles ie 4 degrees at each UJ then I would be good for about 4000 driveshaft rpm. This would see me through to about 160 kph.

[mudlva]

Again im no expert but that does sound like a lot

[meatc]

Darinz only has a few ( like 3 degrees) total change, and only about 5 mm length change and it is eating driveshafts. The spline is the problem so not sure if an alignment thing. One thing to consider though is you rarely run at ride height, even on flat ground you will squat under acceleration, rise under brakes, and then throw some ground change, and yeah you prob want less than 11 degrees of change

Solution, longer arms all round

[Checkerhead]

Thanks Dan.

Bugger.

Back to the drawing board a bit then I guess.

[Checkerhead]

One thing to consider though is you rarely run at ride height, even on flat ground you will squat under acceleration, rise under brakes, and then throw some ground change, and yeah you prob want less than 11 degrees of change

Good call Dan.

If I make my uppers only one inch longer (doesn't do terable things to antisquat), I get a worst case of 9 degrees over full travel. However this is my highest anti squat setting ie what I envisage to be winch challenge mode. For the high speed stuff (lowest antisquat) then I'm looking at only 2.5 degrees of change over the full range of travel. I will work on this.

[De-Ranged]

My personal preference (opinion) is for a comp truck (or HP motor and muppet driver) set the parallel drive flange a bit into compression.... the reason why is AS will sqaut the rear suspension when the UJ's are under the greatest load (acceleration) as the inbalance from change of alignment is going to accelerate wear.... on a road going truck where they are low on power or are going to do big k's I like to set it up at ride height
That said I can't give you any examples of why I do this as I didn't really work on go fast trucks lol most of them were club trucks.... and I've never had an issue with UJ consumption (even with a 350 chev on a hilux ds's)
The speeds you put up for the miss alignment sound about right, from the calcs I've done in the past.... don't have the site I used to use for UJ speed vs angle calc's in my favorites any longer (think it may have been "high angle drive line" site )

Oh this assumes you arn't of the opinion 100% AS (or greater) is the ideal but thats another opinion based discussion lol

Something to consider CH.... its a nice idea to change the AS depending on the style of comp, but as I get older I'm tending towards one setting and learn it's limits.... I know this sounds like a handy cap, but think about it... we arn't talking about a sports car where the change is minor (due to limited travel and consistent grip) we are talking about long travel on varied terrain and in your case and Darinz a whole different style of comp.... knowing how the truck is going to react on a certain change of terrain is going to allow you to push to the limit of the handling instead of having to "think" past your body's reaction and need for brakes or accelerator and doing the opposite and potentially screwing up... kinda a turtle and the hare thing lol

Hey Dan, whats Darinz damage like is he twisting the spline or damaging the spline shoulders.... the dezert boys are very concerned about DS plung movement and will build to eliminate it because even a little bit can cause failure (shoulder profile damage), as the suspension movement at speed will cause the spline to heat up and bind/gaul or has this got more to do with the Nissan v8 pushing it and the 35" wheels free spinning (twisting and shear damage)

[Checkerhead]

Sounds good Reece (Rhys?).

With my bike I usally play with shock settings for the first month or so then find a happy medium and forget about it for the next year. So like you say, I hope to just use one setting.

I would like to run a small positive AS. Somewhere around 10-15%. That said I'm trying to build something that I can get closer to 50 or 60% if the low doesn't climb well for which challenging and bush days.

Haven't thought too much about drive shaft plunge. Guess I need to.

I like your idea of setting up the zero point a little into the compression travel rather than at "ride height". That's what I had been planning on. (Because I'll be a shit driver with decent power )

[Team Tonka]

Maths aside, if the drive shaft is not nice and straight, or there is wear in the spline between the two halves its gonna chew out the UJ's and commit suicide. For 200kmh balancing it is not an option either. When Mitsi put the 3.5L in the Pajero the whole driveline got longer and left them with a very short rear drive shaft with an acute angle out of the transfer case (in the SWB). Their answer was to fit a CV. I have one in the parts pile, and I gave one to Crosby a while back that he didn't use in the end. They are a bit different to a standard cv, in fact I may have shown you one before? Anyway they would handle your HP and the speed you'll turn it. Angle is not an issue as long as its within its range. The main issue with UJ's and angles is the acceleration and deceleration of the shaft as they turn through an angle. Probably stuff you already know but I can't sleep anyway!

[wjw]

This it?

[meatc]

Hey Dan, whats Darinz damage like is he twisting the spline or damaging the spline shoulders.... the dezert boys are very concerned about DS plung movement and will build to eliminate it because even a little bit can cause failure (shoulder profile damage), as the suspension movement at speed will cause the spline to heat up and bind/gaul or has this got more to do with the Nissan v8 pushing it and the 35" wheels free spinning (twisting and shear damage)

Not sure really we haven't looked that hard. We were chasing a rear drive line vibe ( that wasn't there originally but developed) and tracked to the D/S, had one rebuilt and balanced (machined circlips and all). Rebuilder said splines looked ok, it was horrid at anything over 120k and was pulled after one run. Put one out of Darinz wife's daily in for NZ1000, it was good up to 160ish day one by end of day 2 120k and it sounded like it wanted to climb into the cab. We need to have a good look, but I'm leaning towards CVS and seeing the above post re Mitsi ones may look harder at that

[churchill]

I just remembered the figures from mine. With the parallel flange setup and single uj's on each end of the drive shaft I had 15° on each uj and this caused bad vibration on coast.
I changed to a double cardan uj at the gearbox end, a single uj at the diff end and rotated the rear diff so the diff uj was on 0° and this stopped the vibration. In fact doing that ment the gearbox end double cardan joint saw a total angle of 6° or 3° on each of the individual uj's in the double cardan joint. This looks like it had much more ability to handle angle variation that the parallel flange method.
This method seems pretty common on trophy trucks.

[Checkerhead]

This does make sense. The double cardon is basically doing the work for Suspension travel and the UJ at the pinion is doing the work for pinion angle change, bush flex etc. Also gets the pinion up a little so that I'm more likely to slide it over things. Might have to re-evaluate my plan for the lower link mounts.

[Team Tonka]

RE mitsi CV. No, does not look like a traditional front wheel drive cv. Rubber boot is sort of internal. If you cant find a photo and would like one pm and I'll sort one.

[Big]

RE mitsi CV. No, does not look like a traditional front wheel drive cv. Rubber boot is sort of internal. If you cant find a photo and would like one pm and I'll sort one.

this sounds very interesting.. a picture would be a great idea for those who think outside the square..

[lax2wlg]

I also enjoy thinking outside the square.

Jeep ZJ/grand Cherokee has a Cv type front driveshaft.

Also the Toyota t-bar ifs has a double UJ front driveshaft which are available cheap, might be a good donor option for cutting up when mucking around experimenting.

Great build thread by the way, I love the wide and low setup