Anyone fitted a panhard rod?

[Snagger]

Hi folks.

I thought I had bad axle wrap issues when I did my axle swap, but it was really just a pitifully small clearance between the diff pinion and the engine mount. The third leaf on the parabolics seems to do a pretty good job of minimising the wrap, but seemingly at a small cost. I seem to have a bit more down-slope following on cambered roads than before, and given that I retained the same castor angle, I think it's likely due to the slightly more cambered springs swaying a little, allowing the chassis to swing down slope, applying a steering input as the steering relay moves closer to the down-slope swivel. It's easy enough to hold, but can need as much as 20 degrees of steering wheel input to drive in a straight line. I plan to fit PAS in the next couple of years, either the TIC kit or P38 bits with a Defender column, and think that this may also be an issue with that amount of force pushing and pulling the axle laterally.

I kept the panhard brackets on the axle when I made up its leaf spring mounts, just in case, so am now considering adding the rod to beer stabilise the axle laterally. Has anyone ever tried it on a leaf sprung LR? What problems did you have and how much benefit was it?

Slightly off topic, does anyone have any experience of the TIC steering kit? I have read one report of it reducing but not eliminating the steering wander, with the owner then fitting P38 steering to cure it. I don't find too much wander on my standard steering, just the camber-following and heaviness at low speed.

[discomikey]

i could see it putting stress on the bushes as the springs compress as a panhard rod moves in an arc so when compressed your body will move to the right in relation to your axle, in order to cancel out this effect on the steering, the panhard rod needs to be at the same angle and the same length as the drag link.

with a standard leaf spring setup when the front suspension compresses, the axle moves backwards, but laterally it stays in the same place. there would be more stress on the panhard rod bushes from the for/aft movement of the axle, and also because the rod would try and push the axle out of its "natural" suspension cycle with the leaf springs, also effectively sharing that lateral stress with the springs and their bushes.

I have no idea what this would actually do when fitted in a real life situation, but theoretically a watts linkage, although much harder to package, especially on a series vehicle, would be the ideal for this.

out of interest, what springs are you now running? have you checked all your suspension bushes, the torque setting on the u bolts, and the condition of all your steering linkages?

it sounds to me more like the swivels may need adjusting, this along with slack in the steering system would give you your symptoms. the change in springs may just be coincedence, or may have contributed to castor angle changes which could in effect amplify this problem which may have developed over time.

hope this helps

[Soren Frimodt]

Have never tried it, but have thinking about doing it for a long time! I see no reason why it wouldn't work, I've actually seen leafsprung Ricers with a panhard, so no doubt it'll work on an LR as the rest of the suspension was stunningly similar. But if it were me I'd probably fit a defender/RRC PAS on your Series. for the reason that you then could use the panhard bracket from that vehicle as well. Meaning that a std coiler panhard would fit in your application. That said though I love my P38 box to bits and the steering is just like butter. But think a coiler system would act pretty similar.

[Snagger]

I understand about the slightly different movement of the Series axles. I was considering using a panhard rod with rose joints at each end to allow the axle movement without binding or imposing other forces, but coiler axles also move in an arc around the chassis-end of their radius arm and suffer axle wrap with soft bushes without any ill-effect on their standard rods. I am quite aware that drag links and panhard rods need to be as close to parallel as possible, and should ideally be horizontal. If this is achieved, then there is virtually no lateral movement induced by the panhard rod articulating by the amounts available by SII/SIII suspension.

I'm using three-leaf TIC stage two front springs, so they're pretty stiff. I have Polybush polys, which are in mint condition. The axle is a Discovery axle with new swivel bearings and pins, all set up exactly to spec. The changes to the cambered road steering pull was coincident with the axle swap. The springs were uprated from 2 to 3 leafs at that point and I ditched the after-market 8-spokes and went to LR wheels, so their offset was returned to standard. So, it would appear to be either the wheel offset or the spring camber that's responsible.

[bill van snorkle]

The changes to the cambered road steering pull was coincident with the axle swap. The springs were uprated from 2 to 3 leafs at that point and I ditched the after-market 8-spokes and went to LR wheels, so their offset was returned to standard. So, it would appear to be either the wheel offset or the spring camber that's responsible.

Are you certain that your castor angle is the standard 3 degrees? Also, as the front axle is no longer constantly driven, and due to the spindely track rod behind the axle, the steering geometry should be adjusted to toe out as opposed to standard series axles toe in.

[Snagger]

Yep, the castor angle was very carefully set up to match the standard 3 degrees of the SIII axle and, I believe, as used on coilers. I have set the tracking to to-in. The reason for this is not the track rod position but the fact that it's usually 2wd, so the wheels are not driven - that means that their drag will tend to pull them back to parallel. With 4wd, you set toe-out because the wheels' thrust pulls them forward to parallel, regardless of track rod siting.

[bill van snorkle]

Yep, the castor angle was very carefully set up to match the standard 3 degrees of the SIII axle and, I believe, as used on coilers. I have set the tracking to to-in. The reason for this is not the track rod position but the fact that it's usually 2wd, so the wheels are not driven - that means that their drag will tend to pull them back to parallel. With 4wd, you set toe-out because the wheels' thrust pulls them forward to parallel, regardless of track rod siting.

According to my book 'New Directions in suspension design" Un driven wheels will tend to pull parallel, regardless of whether they are set up to toe in or toe out. The reasoning behind toe in/out is to preload the ball joints and put the track rod in tension. Therefore Trackrod in front of axle should be set for toe in. Trackrod behind the axle should be set for toe out.

[Snagger]

OK, Bill, I'll give it a go with toe out and see what happens. Thanks for the information - it might negate the need for a rod, though I have heard that PAS tends to make the axles move around quite a bit. I'm leaning towards the P38 system with a clamp-on mounting plate for the box - I can fit a panhard bracket to the bottom of the plate similar to the bracket on the P38, so it won't be hard to do if required. I need to get a friend to help take some measurements of the lateral movement of the axle by parking on some side-slopes and heaving against the steering.

[o_teunico]

Snagger, is there a thread about the fitment of those axles in your series?

[Gremlin]

Snagger, is there a thread about the fitment of those axles in your series?

Go to his website, all info is there, (in signiture)

[bill van snorkle]

OK, Bill, I'll give it a go with toe out and see what happens. Thanks for the information - it might negate the need for a rod, though I have heard that PAS tends to make the axles move around quite a bit. I'm leaning towards the P38 system with a clamp-on mounting plate for the box - I can fit a panhard bracket to the bottom of the plate similar to the bracket on the P38, so it won't be hard to do if required. I need to get a friend to help take some measurements of the lateral movement of the axle by parking on some side-slopes and heaving against the steering.

I have no knowledge of P38 steering boxes, but being in Australia, I went for what is plentiful and cheap over here, and had a proven reliability record , the Toyota 60 series PS box, also with a clamp on mount and integrated Panhard hanger, albeit on coil springs.

Possibly the parabolics have less lateral stiffness than original semi elliptics, causing the chassis to shift sideways relative to the axles, although my minds eye tells me that with positive castor the force of the sideslope acting upon the kingpins should cause the front wheels to steer uphill slightly.

[Snagger]

I think that's exactly the lateral stiffness issue - that parabolics have less lateral resistance, and that the restored camber (having being flattened by the extra vehicle weight with the original two leafs) has increased the leverage for the axle to sway the springs. I also use 1-ton shackles, which may exacerbate the problem.

The P38 box is not that dissimilar to the Saginaw or Toyota box. The mounting bolt lugs are very close to the tall, thin vertical shaft housing and are spaced enough vertically that you could run the bolts above and below the chassis rail with no drilling. On the P38, the box is bolted through brackets welded above and below the chassis rail, the lower bracket extending further down to double up as the panhard bracket. I took some photos of one at Rogers yesterday, so I'll try to upload them here. I believe the box is made by Bosch, and is reputed to be much stronger and more reliable than the Adwest type, and also to give lighter steering. That latter detail may be due to the hydraulic pressure, though - skimming through various forums, I have read that the Defender, Discovery and RRC system operates at 800-1000psi, while the P38 operates at 1500. So, I'll make sure I use a full P38 system mated to the Defender upper column (apparently the splines on the bottom of the column are the same, so the P38 link and UJs are a direct fit).

[Pollywog]

There's a good pic of a P38 panhard / steering box mounting half way down this page: http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/45625-what-you-doing-your-p38-weekend-21.html

I fitted a P38 box to my Series 3 recently and I'm very impressed with it, the steering is much lighter than any of the Disco's, Rangies or Defenders I've owned. Not sure about the pressure though as that would be more down to the pump than the box wouldn't it? I'm using a 200tdi pump. There are photo's of my steering over on the Series 2 club forum: http://www.series2club.co.uk/forum/forum/index.php/topic,67964.0.html

[bill van snorkle]

Thanks For that information Snagger and Polly. The P38 box appears to be a great option in markets where scrapped P38 Rangeys are plentiful. Unfortunately over here, a used P38 box would generally have to come from a specialist Rover wrecker/breaker at bulk $$$. The Toyota box has a much more compact hydraulic section at the column end, so there wasn't much of the box that sat over the top of the chassis rail, and this allowed a bit more freedom when juggling radiator and intercooler on a TDI conversion I did for a friend.

[Snagger]

Thanks for the links, Polly. Your steering column is pretty much what I have in mind. As far as I understand, all Defender columns have the same splines at the bottom end, which match those of RRCs and P38s. I believe it's just the upper end that varies, which is why only steering wheels from most 200Tdi Defenders fit SII/III shafts, and vice versa. I think the 90/110 and 300Tdi and later Defender columns have the same upper splines, allowing a Puma wheel onto an early 110 shaft. I stand to be corrected on that.

As for the discussion about the coupling shaft, most seem to be in-line shafts with a clamped joint where each square sectioned half is narrowed to a triangle for their overlap. This might be intended as collapsible, but I had assumed it to be for length adjustment, LR tolerances being what they are. I think the other shafts mentioned are where the halves are circular section and bend through about 15 degrees near their clamping, so they slip past each other on a shunt. I think one poster was suggesting taking two of these latter shafts and using the short ends of each to make one shorter complete shaft.

That length is of issue to me as I'd prefer to keep my existing smaller (Metro) wheel and the SIII column shrouds. That means the Defender column may need to be mounted further in. I also plan to mount the PAS box so that the end of the drop arm is in the same longitudinal position as the existing one, and I think that means mounting the PAS box slightly aft of the relay (the drop arm looks longer on the P38, from photos). I can get away with that and also having the box mounted with the mounting logs clear above and below the chassis (no cross-drilling) as I have coiler axles - the swivel flanges are well outboard and have no risk of impacting the PAS box on spring compression. What I have in mind is to use the square sectioned link shaft, cut down if necessary and the overlap "flats" milled to suit. The question will be whether that gives sensible UJ angles. Mounting the Defender column at SIII depth may have a further issue: the steering lock will become inoperative because the column slots will be too close to the bulkhead. I may yet use the column in the standard position with the Defender trim and switchgear - I need to see how it goes at trial fit stage.

As for the pump, I planned to use the P38 pump to ensure full pressure, though it's good to know that a 200Tdi pump works well. The lower pressure pump would put less strain on the entire system, hydraulic and the mechanical lower end. It would also be easer to fit as it already has the V-belt pulley, though I'm assuming the P38 pump will accept a V pulley too. Something to look at when I get to sourcing parts, but I have my eyes on a P38 system (still fitted) where there is also a spare 200 pump...

[Pollywog]

Yes I believe the bottom splines are all the same on the Defender columns and most coupling shafts will fit (Disco 1, RRC, Defender, P38), apparently the lower UJs on the shafts can vary, I found my Disco1 shaft mated straight to the box but others have had to change the UJ to suit so you'll have to keep an eye on that. From the sounds of your plan you will need quite a short shaft, I never looked into shortening anything so can't help there but good luck and let me know what you end up doing, perhaps going the American route and machining a shaft from scratch would be better for you?

From what I have seen the Defender steering wheels started out as 36 spline then at 200tdi went to 48 spline (same as Series) and then back to 36 spline sometime around the TD5? I'm not sure about the 300tdi?

With regard to the steering column lock, as you can see from that thread my main goal was to have a comfortable driving position, I aimed to keep it near the Series driving position but having now driven it for about a month I believe the steering wheel is probably actually slightly further away from me than it used to be, i.e. closer to the bulkhead which feels good for me. I used the Series 3 ignition switch and it mates to the column perfectly however it now mounts on the top of the column and points toward the passenger so unless you can turn the lower bearing around and mount the column upside down I don't think you'll be able to keep both the column lock and the Series shroud. My intention all along was to use the Defender switch gear and shroud, for my use it made more sense to have the extra stalks and free up some switches on the dash.

My drop arm is quite a bit further forward than the original would have been - again accentuated by how I've mounted the box further forward, I don't know if it would be possible to swap the drop arm for that off another box? The Series drop arm certainly won't fit but I didn't have any others to try so perhaps worth looking into?

If you can get the full setup from the P38 complete with all the pipework I say go for it as I found the pipework to be the most difficult thing to source at a reasonable price. If you read all of that thread you'll note I resorted to having mine made up by an agricultural hydraulics firm and they weren't sure how well they would work but I'm pleased to say so far I've had no jerky movements but only time will tell as to how they stand up to the steering fluid.

[Snagger]

I've been reading up across a plethora of sites, forums and uploaded documents and have learned something new, Bill: while Series axles have a positive scrub radius (the centre of the tyre foot print sits outboard of the axis of the swivel pins), so in 2wd the wheels will drag back will want to toe out, needing toe in to be set on the track rod to compensate, LR coiler axles have a negative scrub angle, which will make the wheels want to toe in, so the rod needs to be set toe out to compensate. So, though it's apparently not the position of the track rod that is the reasoning but the reversed scrub radius, you are absolutely right that I need to reset my tracking to toe out. I'll do that on my days off late this week and will post the results on this thread. Thanks for steering me in the right direction. See what I did there?

[bill van snorkle]

I've been reading up across a plethora of sites, forums and uploaded documents and have learned something new, Bill: while Series axles have a positive scrub radius (the centre of the tyre foot print sits outboard of the axis of the swivel pins), so in 2wd the wheels will drag back will want to toe out, needing toe in to be set on the track rod to compensate, LR coiler axles have a negative scrub angle, which will make the wheels want to toe in, so the rod needs to be set toe out to compensate. So, though it's apparently not the position of the track rod that is the reasoning but the reversed scrub radius, you are absolutely right that I need to reset my tracking to toe out. I'll do that on my days off late this week and will post the results on this thread. Thanks for steering me in the right direction. See what I did there?

I would have thought that the RRC/Defender front end with the same 7 degree kingpin inclination and 3 degree castor angle as a series front end, but with zero camber angle, would produce an even more positive scrub radius than a series axle rather than a negative one. But then again, I have just woken up so not thinking clearly yet til the caffeine kicks in.

[Snagger]

I was searching for some measurements, but only found comments on several forums, mostly Ausie ones, about the scrub radius being negative to give better response to bumps and latterly because of its better behaviour with diagonally split brake systems with a single circuit failed (ie early RRCs) and lately with ABS operation. Apparently, according to the steering and suspension technical guides I found, positive radii are associated mainly with older rear-wheel-drive cars, and negative radii with FWD or 4WD and modern cars. It might all be rubbish, though - it's all new to me; I'd assumed that the factory standard scrub radii were nil, and that the swivel axis pointed at the centre of the foot print line (forward of centre due to the castor, of course). Of course, this is affected by wheel choice and tyre diameter (5.5-6" rims and 6.00-9.00 on the Series, and 5.5-7" rims and 205/75s to 235/85s on coilers). But it's not just the KPI that affects the difference between Series and coiler - the swivel pins may be nearer to the hubs' wheel mating faces. I don't know; just a plausible explanation if the information I found is correct.

[bill van snorkle]

Due to the coiler swivel assemblies being a little smaller than series units, there is about 1/2" difference in the distance from king pin axis and stub axle mounting flange, which could offset the difference that the coilers Zero camber would make, but all in all I can't see there being a significant difference in actual scrub radius between both types. Do you know of any others running Parabolics that have similar issue with following the slope of the track surface ? Possibly the relative lack of wrap resistance of Para's is allowing the castor angle to vary too much as the wheels transition different terrain?

[discomikey]

can i ask what make paras they are? sorry if youve already said.

[Snagger]

TIC, aka Heystee. The spring bushes are Polybush (orange), but I have original genuine bushes in the chassis eyes for the shackles.

[Snagger]

Due to the coiler swivel assemblies being a little smaller than series units, there is about 1/2" difference in the distance from king pin axis and stub axle mounting flange, which could offset the difference that the coilers Zero camber would make, but all in all I can't see there being a significant difference in actual scrub radius between both types. Do you know of any others running Parabolics that have similar issue with following the slope of the track surface ? Possibly the relative lack of wrap resistance of Para's is allowing the castor angle to vary too much as the wheels transition different terrain?

This isn't serious off road side slope stuff I'm talking about - I'm getting this big steering input on main roads with a heavier than usual but not extraordinary camber (UK roads are almost all cambered with a gentle curve so that the rain drains off to the sides). Gremlin said he had some lateral axle movement induced by his PAS when turning the steering with the vehicle stationary, though how much he gets I don't know. The movement on my axle may be very small, and the steering correction needed to counter the effects of the road camber exaggerated by the tracking being toe-in; I looked very closely at the tyre treads and can see faint toe-in feathering, which seems to confirm Bill's assertion that a coiler axle should be set statically to toe-out even in 2wd applications. I'll try to get some axle translation measurements at the weekend and will post the results of the tracking adjustment too. It might be that with the tracking sorted, the steering correction required is so small that a panhard rod is unnecessary, which would be welcome.

[discomikey]

TIC, aka Heystee. The spring bushes are Polybush (orange), but I have original genuine bushes in the chassis eyes for the shackles.

therefore i would assume that they would be good quality springs, the set that i mabaged to disform (bearmach) were quite obviously cheaper made. i would assume your springs would be on a quality and strength level as my RM paras.

personally i would give your front axle and steering system a full health check over before going down the route of a modification as it may well be a few things all building up to create one set of symptoms

[Snagger]

Thanks Mikey.

TIC/Heystee springs are the best on the market, hence their eye watering price! Apart from a spring eye fracturing a decade ago because the factory fitted bushes had a batch issue where some were slightly oversize, I have had no problems with the springs - they retain their camber and are still symmetrical, with no lean of the car, after 16-17 years and over 100'000 miles of use, sometimes very heavily laden. They have no faults. I need to check that lateral movement measurement on my days off - it may be a red herring with all the steering problem being simply down to the tracking - I remember how bad my RRC was when its tracking was out, and the steering was fairly precise before I swapped the axles. I had not considered tracking to be a cause when I started this thread because I set it up very accurately with the SII/SIII setting (I went for exactly 1.5mm toe in, the range being 1.2-2.4mm), but Bill has managed to show me it's the most likely culprit, so the suspension may be alright after all, with some normal small lateral flex as they all have. I also fitted the third leafs to the front springs at the same time as changing the axles because they used to sit fairly flat with all the extra weight, and I wanted to regain their camber to offset the effects of the taller saddles that coiler axles need when fitted to leaf springs - this extra camber gives more leverage for the axle to shove the springs when side forces are present; the fact that several changes were made simultaneously have seemingly led to me making a misdiagnosis of the problem.

The axle was rebuilt with new swivels and bearings before fitting it just over a year ago, and the whole steering system was rebuilt along with the rest of the car with several new components inside the steering box and a new relay and rods. It's all in top condition, but this cambered road correction input issue was immediate on changing the axle. I had thought it was just due to the new axle's swivels and because I went over to genuine LR wheels in place of the steel 8-spokes I had on the SII axle, affecting offset and scrub radius (which used to be relatively large).

The reason for wanting PAS is the same as most people want it - to have lighter and more precise steering. The heaviness is not due to vehicle faults - it's due to the weight of the vehicle, the slighly wider 235 tyres, the shorter arms on the coiler swivels and the smaller Metro steering wheel. There is no play in the system anywhere, so apart from rectifying the tracking (and fitting a bigger steering wheel, which is only going to help the loading a little), there's little I can do with the standard system. Our Lightweight was easy to steer, with light steering, but it's parts still weren't in as good condition as on the 109. I've just put too much bling on it for manual steering!