LT95 driveline angle queries - 109V8/One-Ten/RRC

[twodoorgaz]

Hi everyone,

Bit of a geeky question here, looking to better understand a standard transmission set-up. If anyone has the time to read on and to help me learn a bit I would appreciate it.

I’m looking to the forum to help me understand a few queries I have regarding the front driveline angles on Land Rovers fitted with the Lt95 gearbox. The main vehicle I am interested in is the Stage 1 V8 (I have one in bits) but there are obvious parallels with the 1971-1983 Range Rover and the 1983 One Tens (before the LT85 was used). I am familiar with the Stage 1, but less so the One Ten and Range Rover.

Known Facts:

1. At the front of the Stage 1 V8 is a double cardan front propshaft.

2. The Stage 1 front axle casing looks like a standard Rover item, however has its own part number and the diff pinion points slightly upward (instead of parallel to the ground).

3. The Stage 1 also has unique front spring shackle plates though uses the standard 109 front springs. The assumption being that the shackle plates and axle casing work in union to angle the diff pinion upward.

Internet ‘theories’

1. Description of vehicle: Due to the steep angle that the front propshaft has to travel upwards in order to connect the front output on the LT95 with the diff pinion, the diff was pointed upward at an angle of 10-degrees (in line with the propshaft) to reduce this angle (the picture below is from a Chevy site but seems to illustrate this well):

a. Explanation?: While the angle was reduced, the diff pinion and LT95 front output flange faces were now no longer parallel to each other. This resulted in the need for the double cardan front propshaft.

2. And/Or… the engine and gearbox were mounted in the chassis with the engine-end pointing slightly upward (this seems to match with the photo of a Stage 1 V8 below, which shows the engine tilted backward):

a. Explanation?: Because the engine was tilted up, the gearbox output shafts are not quite parallel with the differential input shafts so a double-Hookes c.v. joint was fitted to the transfer case front output shaft”

3. The diff pinion of the 1983 One-Ten V8s and Range Rover (1971-1983), both of which combined the LT95 with a Rover diff were also pointed up at the same angle.

a. Observation?: Neither of these featured a double-cardan front propshaft.

Questions:

1. Is it true that the Stage 1 V8 engine and gearbox were mounted at an angle (with engine tilted upwards)? If so then presumably this was a clearance issue. Where would the likely contact point be? Oil filter to diff? Crank pulley to diff? Sump to diff? or even to correct a low hanging sump?

2. If the nose of the diff is pointed upward AND the output flange of the LT95 is also rocked back to allow the engine to point upward, then the pinion flange and output flange would be doubly out-of-parallel. Is this right as it seems like a real flaw? In the image below it would be the one marie "absolutely not":

3. Were the One Ten V8 and Early Range Rover engine and gearbox similarly tilted, or were these mounted horizontally?

a. If so, how was this achieved (particularly on the One Ten) – was the gearbox mounted higher? The engine dropped lower? Is it a case that the increased height of the coil spring suspension allowed the engine to clear the axle? Or were the chassis rails deeper?

4. Is it true that the diff pinion of the One-Ten V8s and early Range Rovers were also pointed up at the same angle as the Stage 1 V8?

a. If so, and if the engine and gearbox were mounted horizontally then surely the diff pinion and LT95 flanges would not be parallel. If this is the case then how did they avoid the double-cardan front propshaft?

[Davo]

Crikey, are you a lawyer??? That's a good series of questions, though. This is a subject which comes up regularly because it's hard to figure out what the factory did. And even harder to work out why.

The V8 is at a slight angle because that's how it's meant to be. It helps the oil to drain back, I think is the reason. It started life as a car engine so the prop angle question wasn't so important.

The cheap clever way the factory got around the front shaft being out of line on the RRC and 110 was to simply assemble the sliding joints slightly off. There are documents floating around that cover this, but basically the two UJs aren't supposed to be parallel, which normally they would be. This "out-of-phase" assembly seems to work well enough. I've seen a few fronts RRC shafts that have been reassembled in phase, no doubt because someone came along later on and thought it was wrong.

The Stage I got special treatment for unknown reasons, though it was in development for a long time so maybe they got the chance to do things properly. I'm not sure, but I don't think engine-to-axle clearance was a problem.

I've only read about the other application of the V8 and LT95, the 101 Forward Control, where apparently despite some owners' best attempts there is still a driveline vibration because of the steep propshaft angle.

Oh, look what I found in my collection. Unfortunately, it doesn't tell you how much - I think it's about two splines worth.

[garrycol]

I am not going to try and answer all that but there is one other LR with the LT95. The 101.

It has the engine/gearbox horizontal, the diff input shaft is also horizontal and the front drive shaft is the steepest of the lot and does not have a double carden - just a UJ at either end. (your no option)

Works Ok but there is a designed in rumble and vibration from the front driveshaft on trailing throttle. Without major mods to change the engine/gearbox unit or tilt the diff, no mod to the driveshaft has worked.

Garry

[twodoorgaz]

Thanks Guys just what I was looking for - the info on the coiler props being out of phase was just what I was looking for, Once you have a thread you can pull, and know the terms to use, it opens up a whole other world of google search results.

[western]

only the front prop on 90/110 is out of phase by approx 30 degrees, the rear props are in line [in phase] this is to assist the front axle,suspension,gearbox angles when axle is moving around while vehicle is on the move over all types of surfaces.

[Davo]

Thanks Guys just what I was looking for - the info on the coiler props being out of phase was just what I was looking for, Once you have a thread you can pull, and know the terms to use, it opens up a whole other world of google search results.

You're very welcome. I was happy being able to use such obscure knowledge!

[Soren Frimodt]

Another thing could be the fact that as the stage one is leafsprung, with the shackle at the back. This quite significantly changes the angles as the axle moves up and down, and combined with the unpredictable movement by a leafsprung axle could've left them with no other option. I know the 101 is very similar in suspension setup, but it would be easy to imagine that vibrations was much less of a concern on a military vehicle compared to simplicity and serviceability. (neither of which is the double-cardan)

[jai_landrover]

Diff angle was for clearance of the track rod on coil Spring models 22 degrees? they rephrased the front propshaft ie not in phase to combat the dreaded vibration I suspect they kept with the same angle as it was proven to work.

As for the engine tilting up that I wouldn't know.

[Daan]

The original poster showed a link to the hot rodders page about propshaft angles. The 'absolutely not' reference is referring to the W-configuration, rather than the Z configuration (parallel). Every coil sprung landrover has the W configuration at the front and this works very well, as long as the angles are the same on both ends of the prop. It does help that the diff tilts in right direction when traveling through the suspension. The phasing is mainly done if the u/j angles at the diff end is not the same as the gearbox end. the fluctuation is very small though.

For leafers its a bit different. I don't agree with sorens' statement that the shackle makes the diff tilt. The hight change as a result of the shackle pivoting is 0.02 of nothing, you can safely assume the diff stays horizontal during the suspension travel. That makes the double cardan a pretty bad solution, as it only works properly when the gearbox u/j has 0 degree angle.

[Davo]

The original poster showed a link to the hot rodders page about propshaft angles. The 'absolutely not' reference is referring to the W-configuration, rather than the Z configuration (parallel). Every coil sprung landrover has the W configuration at the front and this works very well, as long as the angles are the same on both ends of the prop. It does help that the diff tilts in right direction when traveling through the suspension. The phasing is mainly done if the u/j angles at the diff end is not the same as the gearbox end. the fluctuation is very small though.

For leafers its a bit different. I don't agree with sorens' statement that the shackle makes the diff tilt. The hight change as a result of the shackle pivoting is 0.02 of nothing, you can safely assume the diff stays horizontal during the suspension travel. That makes the double cardan a pretty bad solution, as it only works properly when the gearbox u/j has 0 degree angle.

I have heard somewhere of people using "plain" propshafts on the front end of their Stage I when the double-cardan wore out, with no problems, (apparently).

[Daan]

If you fit longer shackles to the front, the diff tilts backwards, potentially getting it the same or near the angle of the gearbox, eliminating the need for a double cardan prop. Gives better castor as well.

[Roverdrive]

This was a perennial problem with the 101 due to the larger offset, although it tended to only be the front prop not the rear affected. Scared the cr@p out of me the first time I heard the "bark" decelerating from speed.

There was an article in the club magazine some time ago about the science behind what is going on, but as is always the way, I have had a clear out and dumped my back copies!

Mike

[Roverdrive]

A quick google led me to this page.

http://www.nealonline.net/101/101sh.htm

He fitted a prop with a double carden joint at each end to the front of his 101 to cure the rumble.

IIRC the double carden act as a cv joint and cancels out the variation in angular acceleration that you get with a single joint as the prop turns.

If the diff nose points up at the gear box, a single UJ is almost aligned giving minimal vibration as the change in rotational velocity is also minimised. The double carden would then take care of the other end.

At least that is how I understand it!

[Bowie69]

Is there any reason why a CV joint hasn't been used? Pretty sure it is quite common in the states for lifted rigs, and my Audi has CV's as standard...

[Roverdrive]

Ok this is the last post this morning, or I won't get anything done!

Have a look at this video as it explains far better than I did as to what is happening as the prop rotates.

https://m.youtube.com/watch?v=gmV4qwLfOMY

[garrycol]

He fitted a prop with a double carden joint at each end to the front of his 101 to cure the rumble.

Doesn't actually say if it actually worked - just that it was fitted and who made it.

Also - the have an ambulance which is a lot heavier that a GS so sits lower so the front driveshaft is not quite as steep and in most Ambos the rumble is not there or is very mild.

Garry

[Daan]

on a leafspring car, if you brake hard the axle is trying to wind up the leafs, therefore the diff tilts up and your prop angle changes, that would certainly give you the problem you describe. The 101 has very thin (parabolic?) springs, so I imagine that to happen. That double u/j would solve all problems, because as mentioned, there is a constant velocity both ends, regardless of the angles.

Most cars, including the new disco and rangerover(I think) have cv's for the driveshafts going into the diff. Its just a bit less durable offroad. Main reason to use a cv on both sides of the propshaft is to remove the vibration altogether. Even if you have a propshaft with u/j that are exactly the same angle, there is still a secondary vibration going on, because the propshaft is getting accerated and decelerated twice during every rotation, so there is still a vibration going on.

Daan

[Roverdrive]

Daan

On the 101, the noise started as soon as you came off the throttle. No braking required.

Could be quite pronounced when feathering the throttle, do I do not believe it was a rotation of the axle, although of course coming off the power will cause a reaction.

[garrycol]

The 101 has very thin (parabolic?) springs, so I imagine that to happen. That double u/j would solve all problems, because as mentioned, there is a constant velocity both ends, regardless of the angles.

Daan

You obviously have not seen 101 springs - yes they are parabolic but are not thin. Each leaf is at least twice as thick as the spring leaves in any other landrover. The spring does not measurably flex under braking or acceleration so no real changes in the angle of the diff.

As mentioned the noise has nothing to do with braking but is heard on trailing throttle above about 80kph.

The cause is a combination of the steep angle of the driveshaft (the standard UJs operate outside their design limits), the offset front diff, and the high rotational speed of the driveshafts due to low diff ratios. Changing to higher speed diffs reduces the rumble as does loading a 101 up with weight as it changes the driveshaft angle. People who have put in double carden joints have reported that it reduces the rumble but does not remove it.

I have heard of many proposed solutions to fix the issue not not as yet heard of any that actually work. Lowering the engine.gearbox unit in the chassis will reduce the angle and changing to 4.7:1 diffs will lower driveshaft rotational speed. This raises the speed that the rumble starts to a speed higher than the 101 is capable of going.

[Daan]

I have seen 101 springs, and to prove it I have a picky:

That picture only reinforces my thought: you have a spring over axle with 9x16 tyres and a heavy car to stop. the leverage from the ground is about 600 mm to the spring .Even lifting the throttle would bend that spring like buggery.

In my humble opinion of course.

Daan