Rear Disc Brakes.............the build...............

[Snagger]

If I remember correctly (and those saddles were made up nearly three years ago!), it was 8mm. It gives just enough space for the track rod but also for the diff housing, now inclines, to clear the top of the spring - the diff is much further to the right and the flare of the axle case is over the right spring, so the inboard face of the right saddle was a very peculiar shape. I should still have the cutting drawings I took to the fabricators, and the pices needed fairly little trimming after getting them back prior to welding up. I have heard of peple notching the axle tube to allow the spring to sit into it at that point, but I wouldn't want to weaken the casing like that and you'd run into track rod trouble again.

However, that 8mm may be good for TIC parabolics, but standard springs may need more if the springs' camber is less than on mine. The easiest thing to do is mock up a single saddle for the left side (so the sides are symmetrical and you just have a simple semi-circular axle interface), set the axle inverted on stands so that the steering swivel pin axis is correct (3 degrees, just like Series axles), sloping forward towards the true bottom of the axle (remeber the axle is inverted, so the axis has to appear to slope forward to the top, ie with the swivel pins vertical, lift the diff nose just a little more). Then, tape your saddle mock up on to the axle so that its spring face is horizontal and test fit a spring for track rod clearance. Allow another few mm for sag if it's tight - you don't want the rod to be pressed against the spring when the axle is hanging on the spings bending them downwards, but that sag is usually only small.

For working out the shape of the right saddle, I made a cardboard mock-up of the left saddle, marked the position of the saddle on the axle (with it still inverted on the stands with the swivel alignment maintained) and used one of those DIY profile cutting gauges - the black plastic box with sliding yellow or red strips that slide in or out around the shape you want to mimic, a bit like a 2D version of those executive toy steel pin toys that you create 3D impressions of your hand or face. The shape was transferred to the carboard mock up, which was then fettled to fit the axle properly before cutting the corners to use it as a template.

Incidentally, I got those 8mm back by installing a third leaf in my parabolics (it'll also help with resisting axle wrap/tramp and helps the springs which were a little over-laden with my 109's weight). With normal springs and chassis, you could regain the height lost by using 1-ton shackles to drop the rear of the spring down away from the axle, rather than lifting the axle up in relation to the vehicle. Just remember that the saddles will have to sit at a new angle on the axle to compensate, and that different angle relative to the swivel castor axis would have to be measured but measuring the angle the centre of the spring sits with the existing shackles and then with the 1-ton shackles (measured on the spring directly or just on the axle bump stop plates), rotating the saddles by the same difference frther forward on the underside of the new axle (ie, with the axle inverted on the stands, drop the diff nose towards the floor by that number of degrees so that the saddles will still be fitted horizontal to the floor). As a guess, I'd estimate the angular change to be about 5 degrees.

[ejparrott]

I'm pleasantly surprised, I thought you going o say more like 20mm! That said though, the only previous experience I've got is of my brothers 109 leaf converted rangy axles, and I still think he buggered them up and the angles are all wrong but anyway....

I remember a friend fitting 1-ton shackles to an 88, I think it was a kit from Bearmach, when they fitted paras. There was a tapered wedge which fitted between axle and spring to rotate the diff back to were it should be. I've got 1-ton shackles on the back of my 88, but no wedges..the shackles are there to try and pick the back end up. We think that when the rear half chassis was fitted they buggered up the length, 'cos she permanently looks like she's got a lot of weight in the back, and the shackles are well back. Its also possible that my paras have gone soft and flattened. when she gets a new chassis, she's getting new springs...again...

[Gremlin]

Final update...............

Axle is in, and done, started this morning at 8am and was done by 4.30pm. I am all aches and pains from man handling the two axles, plus its was 35deg and 85% humidity, so i was sweating like a pig! Job went flawlessly with no problems. Brakes bled first time round,no leaks from anywhere and stopping power have improved. I am pretty pleased with myself.

I have a bunch of pics, which i will upload later, just trying to have a rest now.

Minor glitch on the test drive is the propshaft has developed a barely audable rumble while axle speed matches the engine speed, its not constant and come and goes, not much of a concern and not at all axle related. (might have been there and i never noticed it)

My main concern with the axle is the pinion bearings, on my test run of about 10km the axle case got pretty warm/hot, bareable to keep you hand on it. Is this normal?? as i do not want to fry my new bearings! ( i never took notice how warm the other axle got to be honest)

G

[Snagger]

Well done!

I wouldn't worry about any temperature that low - have you ever tried touching the transfer box after a similar run? Given time to warm up on a high speed trun, a transfer box will get hot enough to properly burn and scar your skin... It's not the bearing friction doing that but the gear meshing and energy loss in that meshing; all energy has to go somewhere.

[Gremlin]

Oh i see, anyway here are the final set of pics

Jacked up ready for surgery

Off with the old

Old next to new, put some wheels on so i could roll it under the landy

Rolling it in

On the springs

All done

Thats it for this tread, untill the next project.........................

G

[ejparrott]

Top job! Working ok with the servo and master then?

[Gremlin]

Yes brakes are the best they have ever been, now its all matched up. Running drums at the rear with a disc brake master setup was not ideal as i have now noticed!

G

[Snagger]

Well, mine is up and running to. I took it for a test at the MoT station and it passed easily enough, but I am not happy with the brakes at all - they're far worse than with drums. The mechanic reckons it might be the brand new discs and pads needing to bed in, but I think it's the SIII master cylinder, so I'll be fitting the Discovery servo and Defender master next. The steering lock is great and the suspension feels good.

Looks good with the new wheels, though... http://www.nickslandrover.co.uk/109-post-axle-fitting/

[Gremlin]

Nick, i had the same issue with the fronts, give them time to bed in, it will improve. I am very happy with mine, the pedal now is much more responsive, when i had the rear drums the pedal travel was not right due to the drums needing constant adjusting. (thank god i have no more adjusting to do)

In the last couple of days i gave the axle a work out and all seems fine, the propshaft rumble is gone ( both props need changing soon, next project?)

One little niggle seems the oil seal at the drive flange, it looks like its very damp, i just hope it does not spring into a major leak!

G

[Snagger]

Bedding in didn't work, so I replaced the servo and master cylinder. The brakes are fantastic now.

[Gremlin]

Ok, well done.........

Little update on my end, the propshaft rumble is back!! it seems that my old diff had a slightly different diff pinion hieght from the one i fitted, this is causing some sort of misalignment of the working angle of the propshaft (i have a double cardan at the rear) I have come to this conclusion due to the fact that when i load the rear up with 300kgs the rumble goes away. This happens as the angle changes at the diff as the springs get loaded.

I will try to put in my old normal propshaft in and see if things change, if not i will have to shim the axle to get the correct pinion hight back to where it was.

Its rather annoying as i thought that replacing an axle (early) with an indentical axle (late) out of a series 3 would not have cause such an issue!

G

[Snagger]

What road speed do you get the rumble? If it's at about 60mph (85-90kph), then it's the prop, but if it's at lower speeds, it could be some fault in the diff. Swapping the prop is the easiest way to find out, though.

Just noticed you have 1-ton shackles on the springs. Do you have a 1-ton chassis to match? If you have a standard chassis with the single mounting position for the front of the springs, then the shackles are your problem - they rotate the diff nose up and screw up the prop geometry; the flanges must be parallel to avoid vibration (which leads to premature UJ, prop slip joint and half shaft wear). Only use those longer shackles where the front end of the spring is mounted in the lower holes of a 1-ton or WD (War Dept, ie. MoD) chassis. I had that problem myself - the new UJs would go bad in about 500 miles.

[ejparrott]

I potentially have the same problem...my 109 is on a military chassis, except for the front of rear spring. Those outriggers have been replaced at some stage with civvy outriggers with the civvy single hole hanger...i really should replace them, but havent found out how yet.

[ejparrott]

..and the answer...a quick email to Richards and a very prompt phonecall back from Spike and they'll be emailing me with a price for a pair of 1-ton front of rear spring hangers...anyway...back to the disk brakes!

[Gremlin]

The rumble comes on when engine speed matched the road speed, it will do it at any speed over 20kmh. I have had this problem in the past so i know what it feels like. I doubt its the diff (or lets say i hope its not the diff!!!)

Yes i have civvy spec front mounts on the rear springs, and longer shackles, but i had solved the propshaft problem by installing a DC propshaft. The diff nose must point at the gearbox in my case. All was well before the diff swap. I will install a normal prop to see what happens and report back, if that fails then i will shim the diff to make it point at the gearbox again.

G

[Snagger]

Double Cardan jointed props can be trouble if you have enev the slightest wear in the joint, and it's not as easy to detect or replace as a standard UJ.

You might have a slight bit of play in the transfer box output shaft, so removing a shim from the speedo might help, but obviously you don't want to do that if those bearings' preload is about right as is. I reckon the problem os the prop shaft, and that running a standard shaft will sort the issue if you refit standard shackles or lower the front end of the springs (the lower holes on a WD or 1-ton chassis are 40mm below the standard holes).

[Gremlin]

Update.........

Another prop did not solve the problem, rumble got worse at high speed. So back to the DC shaft and i shimmed the axle nose to point at the gearbox. Problem solved, smooth as silk, no rumbles or other funny noises.

Did the front prop as well, new UJ's and a good grease up.

Sorry no pics, no time, and i am rather exhausted...........................

G

[Snagger]

Update.........

Another prop did not solve the problem, rumble got worse at high speed.

A standard prop won't fix anything if you don't align the pinion and transmission axis first. The shackles or spring hangers would need replacement firts, but once done, you'll have no more trouble. I had exactly the vibration you had when I fitted 1-ton shackles with a standard chassis before my rebuild, and I swapped the shackles back and forth three or four times to be certain of the diagnosis. before that, UJs would last 500 miles before the vibration returned...

Glad you have found a solution. If it does come back, then sorting out the diff alignment and using standard parts would be the easiest and cheapest option - double cardan props are pretty expensive.

[MECCANO]

Sorry to high jack the thread. Can anyone rememeber what the stock saddle height is on a sereis axle (pre-extension).

Cheers

Chris

[Snagger]

Just measured them for you - 16mm front and rear.

If anyone is interested, I found 30mm worked perfectly for my RR/Discovery front axle with 3-leaf parabolics.

[MECCANO]

Cheers

From memory, my lwt is 40mm running 2 leaf chris perfect (Ti-console copies).

The problem is the springs suffer from wrap, and although they cleared the track rod when i first fitted them, now they don't when unladen.

Fitting a lighter more power engine hasn't helped either.

What castor angle did you guys use? and how did you measure it?

I built the axle up with swivals and track rod (with no toe in/out).

Then set the flat on the top of the swival ( where the king pin is) to 3 degrees.

Apologies for all the questions, its just interesting to get other peoples take on the conversion.

just seen previous post.. oops!

Thanks

Chris

[Snagger]

Axle wrap or tramp was one of the principal reasons I added that third leaf - the 50% increase in spring rate should help reduce it very effectively. It is a problem with normal axles, but with conversions that need raised saddles like ours, it's even worse because the axle has greater torsional leverage to bend the spring (usually just a problem when braking, but could be an issue in low range and low gears). The only axle mod that I'd suggest wouldn't need an extra leaf to avoid wrap is a portal axle sitting atop the springs, where the new wheel (and braking) axis will be brought more in to line with the spring centre, reducing the axle's torsional leverage on the spring. The other reasons were to retain the ride height and to try to stiffen up the roll when cornering, since the Tdi rad and intercooler prevent me from fitting a 109 ambulance front anti-roll bar like I did at the back.

[Snagger]

Actually, now I think more about it, taller saddles may in fact help combat spring wrap - when braking, the reactive torque will try to rotate the axle in the direction of wheel rotation, but the vehicle's inertia will try to pendulously carry the spring centre forward of the axle, which counters the braking torque. The opposite applies when accelerating, once again combating wrap. Portal axles would decrease the pendulous linear effect and possibly even reverse it if tall enough, adding to wrap. I don't know if that's what actually transpires, but it seems logical.

[MECCANO]

Definately helps, i've only started to nice the problem since i shaft the saddles down slightly.

My intention is to install anti-wrap linkges to the top of the axle. Just need to finish them off.

I'm surprised about your comment on the the steerign becomign lighter. Mine became stiffer. I put this down to the arm on the swival that connects to the drag link is shorter than a series.

Do you know if your 109 has the lower ratio 1-ton steering box?

[Snagger]

My steering is lighter because I have gone from the steel 8-spokes to alloys - the offset from the swivel pin axis has come in by 42mm each side - it's not the axle itself which has made the difference. Fitting standard LR wheels has also got rid of most of the camber and rut following and should also eliminate much of the pull of any brake asymmetry from puddles and alike. It is possibly heavier than it would be with a SIII axle with standard wheels and the existing tyres, but not much I wouldn't think.

My 109 has the standard steering box, but also has a damper and a Metro steering wheel, which makes it all pretty heavy when combined with 235 tyres and all that extra weight on the vehicle. I had hoped the steering would be closer to what Helena's standard Lightweight is like, but alas it's only about half way between that and how it was with the old axle and wheels. Still, I find it comfortable to drive - it's just a little heavy for Helena when she's manouvering it in tight spaces. I have no intention (at least for now) of fitting PAS.

Did Fridge ever post up his anti-wrap system for his 109? I seem to recall him posting pictures of the rear ssyem, but can't remember more than discussion about the front.