Standard propshaft UJ max operating angle?

[o_teunico]

Hi all,

As the title says, whats the limit for standard rover UJs in propshafts?

Are coiler ans series UJs the same?

Thanks

[disco2hse]

I vaguely recall 15º, but I think that's not right (seems too much).

There are a number of variables and so the series would be different by virtue of their age and design.

http://spicerparts.com/calculators/driveline-operating-angle-calculator

[Davo]

Not to be a pain, because I'm sure you already know this, but I've found that the less angle, the better. It makes a huge difference in how long a UJ lasts. 

[o_teunico]

I'm now taking measurements in my 88 inch for for a six pot engine swap. Mine is already a 5 speeder ( Santana factory spec), but  I will use a divorced LT230 with a Daihatsu/Bertone 5vh box, and will like to relocate it lower and centered between axles, so, when resting, props will be flat. That setup will result in a prop legth of 600 mm / 24".

I need to know the operating angle to calculate the suspension travel that they will survive. I have seen 30 degree aftermarket props, but they are pricey.

[Bowie69]

My understanding is that having props at zero degrees is bad for them at ride height, you want at least 3 degrees offset, otherwise the needles will never rotate properly, and die in short order.

Also, I wouldn't want my transfer box hanging down as low as the diff pumpkins!

I'm not sure on the other stuff, sorry.

[o_teunico]

I have gone to the scrapyard for a more practical approach.

Rover gearbox, mounted in the chassis of a 109, with the short part of the propshaft still attached. Length 130mm, distance to chassis when pararell 180mm, distance at max angle with yoke touching gearbox drum brake is 210mm.

So just 30mm of "travel" for every 130mm of lentgth.

In my case the 600mm prop will have 138mm of travel up, and another 138 down. Not enough, as I was looking for some ProComo 93600 with 16" of travel.

[Bowie69]

Bear in mind the prop droop doesn't need to match the shock, as the prop flange is further forward than the shock mount (maybe 500mm?)

And then depending on suspension setup, the axle may roll up with droop, raising the pinion relative to the axle/shock mount, so reducing the droop needed from the prop.

Same goes the other way, axle may roll down when compressed.

12” of travel or so may be enough.

 

[o_teunico]

I will have to build some mock up props and move the axles to see what is hapening in real life...

 

[Snagger]

On 05/07/2017 at 2:19 AM, o_teunico said:

I have gone to the scrapyard for a more practical approach.

Rover gearbox, mounted in the chassis of a 109, with the short part of the propshaft still attached. Length 130mm, distance to chassis when pararell 180mm, distance at max angle with yoke touching gearbox drum brake is 210mm.

So just 30mm of "travel" for every 130mm of lentgth.

In my case the 600mm prop will have 138mm of travel up, and another 138 down. Not enough, as I was looking for some ProComo 93600 with 16" of travel.

That works out as about 16-17 degrees, which tallies up closely with what disco2hse said (15 degrees).  

Bowie is right that a UJ which is run straight at all times will not self lubricate properly and will quickly wear grooves on the bearing cup and spider surfaces in continual contact with the needles.  However, the amount of rotational oscillation caused by the joint increases exponentially with deflection angle - that is why a double-cardan joint produces so little rpm variation while a single UJ deflected the same amount creates so much.  It is important to make sure that the UJs at each end are deflected equally or that you set the correct phasing to compensate.

Bowie is also quite right in voicing concern about having a transfer box hang so low to give level prop shafts - apart from giving the same breakover angle as an LA pimp's low rider, it'll guarantee prop shaft damage the first time you take it off road.

[miketomcat]

If it aint broke don't fix it land rover knew what they were doing so I would mount the t box as close to original position as you can get it. Why not work the other way find the shortest prop land rover used then mount the t box in the same relative position as used on what ever vehicle it came off of.

Do not run uj's flat with no deflection they will self distruct in very short order.

Mike

[Disco-Ron]

In my mind the max angle of the uj is more dependant on the yoke its fitted to.... 

[missingsid]

IIRC RRC prodshaft yokes are wider than Series ones with the same bolt flange.

[Snagger]

5 hours ago, Disco-Ron said:

In my mind the max angle of the uj is more dependant on the yoke its fitted to.... 

It's certainly a factor, but even with wide angle yolks, it's not a good idea to go much beyond 20 degrees.  Even that is pushing it.  The geometry of the prop starts changing too much and shakes things about - the centreline of the prop will move every 180 degrees of rotation, and that will cause it to slide in and out on the slip joint correspondingly every 180 degrees.  All that pumping and wobbling is great in the sack, but not on the car.

[Bandog]

The wide angle yolks are essential for the negative suspension bounces, big humps and air make the springs decompress and the gap in the wheelarches widens, the prop yolks bind up, and try to drag the transfer box down to the road, sounds really good when your doing about 80 over a hump back bridge, sounds like you drove over a 45 gallon drum, half full of scrap!

Speaking from experience, you really need to either, lower the transfer box, or neutralise the pinion angle, so the pinion flange is pointed directly at the pinion flange, then the only steep angle is the transfer box uj.

Or even better both.

Double cardan joints are very expensive and in my opinion too fragile, but instead of having a 20 degree angle you have two ujs at 10 degrees, lessening the extreme.

But by neautralising the pinion angle (straightening it) you do eleviate the transfer angle too. Hope this helps.

 

[Snagger]

1 hour ago, Bandog said:

Speaking from experience, you really need to either, lower the transfer box, or neutralise the pinion angle, so the pinion flange is pointed directly at the pinion flange, then the only steep angle is the transfer box uj.

Or even better both.

Double cardan joints are very expensive and in my opinion too fragile, but instead of having a 20 degree angle you have two ujs at 10 degrees, lessening the extreme.

 

Lowering the transfer box not only negates the benefit of any suspension lift, but also makes it more vulnerable and creates a problem with extended levers in the cab having excessive throw unless you start messing about with pivot points.  Not complicated, but an unnecessary faff.

Re. the point about double cardan joints, do you mean having two UJs at the same end of the prop shaft?

[Bandog]

yes nick

[discomikey]

On 27/08/2017 at 11:11 AM, Bandog said:

The wide angle yolks are essential for the negative suspension bounces, big humps and air make the springs decompress and the gap in the wheelarches widens, the prop yolks bind up, and try to drag the transfer box down to the road, sounds really good when your doing about 80 over a hump back bridge, sounds like you drove over a 45 gallon drum, half full of scrap!

Speaking from experience, you really need to either, lower the transfer box, or neutralise the pinion angle, so the pinion flange is pointed directly at the pinion flange, then the only steep angle is the transfer box uj.

Or even better both.

Double cardan joints are very expensive and in my opinion too fragile, but instead of having a 20 degree angle you have two ujs at 10 degrees, lessening the extreme.

But by neautralising the pinion angle (straightening it) you do eleviate the transfer angle too. Hope this helps.

 

Regarding pointing the diff pinion straight at the transfer box output, that's not neciserially a good idea. The straight UJ at the diff end effectively running a constant velocity V.S. a large angle ~12-15°+ (which is therefore running a non constant velocity) at the transfer box end can cause the prop to "slap" the centre diff on overrun at higher speeds. This sounds like a terribly rough bearing inside the T box! Horrible

You're better off trying to equalise angles than at both ends and phase the It's to suit.

 

If you keep the prop straight at one end and want all the angle to happen at the other end that needs to be a double Cardon joint that runs at effectively a constant velocity  

[Snagger]

On 27/08/2017 at 10:22 PM, Bandog said:

yes nick

Having two ordinary UJs at one end will allow the prop shaft to sag and run off axis, causing enormous vibration and probably disintegrating.  That is the whole point of the double cardan joint.

[ejparrott]

Out of interest, do some vehicle not use CV type joints?  Would they fare better in a near straight configuration?  I suspect they would suffer from offroading though

[discomikey]

a cv joint must be run at an angle otherwise they seize up over time. similar to UJ's they dont like being run dead straight

[Bandog]

ejparrot... some land rovers were fitted with a double cardan joint mounted next to the transfer box on front props. I think td5 disco and some defenders though I may be wrong. There are many American vehicles that run them like Jeep Rubicon too etc. Better for high speed applications (road) than pure off roaders, which would benefit from the wide angle single u.j.option. As a rule parallel flanges should be adopted , whatever the angle, as the prop u.j. speeds up and slows down it causes vibration. If it is in phase and with parallel flanges, the opposite u.j. cancels this out.

Vibration will occur when the prop flange angles are different to one and other.

There is another option of a two double cardan prop, one at each end for extreme driveline angles, and cost!

Tom woods Australia also are the only company that I know of that do a wide angle double cardan joint propshaft.

As with most things of this ilk, maintenance is  more complicated and important. The double cardan joint has a ball in between the two u.j.s. This can fail and become stiff if not greased often enough.

ttps://www.youtube.com/watch?v=Idk3BVDVHq4

https://www.youtube.com/watch?v=hgsetMU58lk

https://www.youtube.com/watch?v=MrY0qvRZkVM

https://www.youtube.com/watch?v=_OOvYhKIUoA

last video shows how the two angles cope better and run at less severe angles and smoother,cheers

 

[Bandog]

On 27/08/2017 at 12:41 PM, Snagger said:

Lowering the transfer box not only negates the benefit of any suspension lift, but also makes it more vulnerable and creates a problem with extended levers in the cab having excessive throw unless you start messing about with pivot points.  Not complicated, but an unnecessary faff.

Re. the point about double cardan joints, do you mean having two UJs at the same end of the prop shaft?

lowering just enough to "tilt" the transfer box in slight adjustments only, if for instance its a modded vehicle and the transfer box front output flange and rear output flange are at different angles. for example, front pointing down by 5 degrees, so rear pointing up by 5 degrees.

This can help in some cases. cheers

[ejparrott]

Stage 1 V8 has a cardan joint shaft I think

[Bandog]

I have a double cardan joint prop on my 200 tdi series. Because of linear misalignment (Side to side) the parallel u.j. will NOT wear and disintegrate. cheers.