Narrywoolan*

Front End: Steering, Suspension & Alignment- 2016

During last years (2015) Castlemaine Rally & Tour 1070 developed a nasty front end steering vibration and both sides of the front suspension lost all their damping oil. So this is the investigation and potential problem-solving page!

1. Front end vibration and wheel alignment.

Marc Bondini had recently acquired a large surface table and had successfully been sorting Aurelia front axles so I made the decision to remove the whole front end and work my way through the potential sources of the problems. After removing and stripping the front axle I took it to Marc's to measure and check on the surface table. We measured everything and could not find anything wrong. It wasn’t bent or twisted, the camber and caster on the king pins were virtually zero. I also inspected the insides of the king pins where the suspension damper piston runs for wear, but no discernible wear could be found.

After fitting the axle back on the car, assembling the steering and suspension the camber and caster angles were measured. Camber on the rhs was 1.5 deg and 2.2 deg on the left. I believe the correct specification is 2º17' or 2.35 deg. Caster was zero on both sides, which is correct. We did have some discussion that normally a negative caster is better for steering but a paper produced by Paul Mayo from the Lancia A.S.T. sketches and other sources quotes, "this is taken care of by the stub axle being placed 10 mm at the back of the centre of the front axle suspension cylinder."

Marc has a complete wheel alignment kit and with my garage floor being nice and flat I was able to set it up accurately. Toe-in should be 0-2mm, I had enough adjustment to set it to zero. Result: no front end vibration at all and steering much better.

To adjust the toe-in there are eccentric pivot pins on both ends of the track rod. Undo the bottom nut, knock the pin up and rotate to line up holes with the small locating dowel (not shown in the diagram but p/no 38-62545 on TAV 24) until required toe-in is found, then knock the pin home and lock nut with split pin.

Camber angle on left side 2.2 deg.

Caster angle is zero

2. Steering box & column; check and alignment.

Over the years others had commented that the steering on 1070 was heavy at low speeds, so with the whole front axle off it was time to see what could be done. I found a number of possible causes for the heavy steering.


First; the outer sleeve (38-61016) under the dashboard that the steering column goes through was inspected. Inside are two fibre bushes; both had a collection of dried grease and gunk on them. They were cleaned and a smear of fresh grease was applied.


Second; the rubber grommet (38-61031) the steering column goes through the firewall was rubbing, I had a new correct grommet I'd bought from Cicognani in stock so fitted that.


Third; there was a nasty noise from the right hand side suspension when the steering was turned. Closer inspection in the top sleeve revealed some nasty scoring in the top bush (TAV25a p/no 38-73049) , again I had a spare that I'd had made a few years back when the left side one had worn oval.


Forth; and finally I adjusted the steering box and checked that the column was true and straight.

Steering box adjustment:


This needs to be done with the box on the bench, be very careful when taking off the bottom that you don't lose any of the 84 needle rollers (49401)! Also take note of the shims (38-60228) under the top flange (38-60230). Before adjusting anything check all bearings and the worm & sector gears for wear.


Two adjustments are provided in the steering box, one for end play on the drop-arm spindle (38-60203) and the other to take up slack between the worm and sector (38-60225 & 38-60220).


End play is corrected by means of a slotted set-screw (38-60235) in the cover plate, which bears on the centre of the spindle, and is locked, after adjustment, by a nut and tab washer.


The meshing adjustment of the worm & sector is rather more complicated; it consists of an eccentric spindle bush (38-60017) which, when turned in the main housing, moves the drop arm spindle (38-60203) closer to, or farther away, from the worm shaft (38-60225). The eccentric bush is locked by a toothed washer (38-60206), which engages with internal splines in the eccentric bush. Turn the bush one serration at a time and replace washer with pin in nearest hole until minimum backlash with free movement is found.


After reassembling this time I filled the box with 140 gear oil.

Left front tyre wear.

Result of leaking front suspension.

Stripped front axle, early 1st series 38-601

On the surface table.

Badly scored top bush (38-73049).

Bottom of steering box.

Top of steering box.

3. Suspension leaks!

I've been down this path on a number of occasions and have never been successful in stopping the top damping sections leaking all their oil over time. I know they are supposed to seep a little as this lubricates the top bush and bearing collar, but regularly after a run the next morning there would be a small puddle of oil on the garage floor. My main suspect is the seal (3873081) under the top sleeve (38-73041). When I first got the car it was fitted with a pair of modified oil seals, I'd replaced these but the leaks continued. This time I bought some hydraulic seals and tried one on the rhs but that was no better.


After some consultation with those more experienced we decided a simple felt seal would be best. I turned up two punches for the inside & outside diameter and pressed a seal from a sheet of 12mm industrial felt (I've since used "Grade A" felt for a better result). We think the original seals were something a little more stiff and solid as they are only held in place with a simple wire clip (38-73090). To retain the felt seal I turned up a pair of alloy washers and located them in the sleeve with a circlip.


Now we come to the interesting bit! I only fitted the felt seal on the right side; the left side had an oil lip seal. After a couple of 100 km test runs the right side has a small seep, but the left side has not leaked a drop?? My only thought so far is I was more careful in assembling the suspensions using thread sealant for all the top sleeve components. As they say watch this space...

Fitted felt seal. (the green colour is the gear oil it was soaked in)

Summary:


1. The front end and wheel alignment was very successful in totally eliminating the front end vibration. Even though the camber angles are not correct I decided not to try and correct them, it would require a lot of work heating and bending the axle and probably would not make a great deal of difference given the speeds the Aprilia goes. I have been trying to source the Lancia factory specification sheets, called A.S.T. sketches, for the front end, I know they exist, but have been unsuccessful. The front springs are something I would like to look at in the future as a way of improving the handling.


2. The steering box alignment and adjustment improved the steering feel on the road and eliminated any slop but has not greatly improved the heavy feeling at low speeds. I cannot think of anything else to do so will have to live with it the way it is.


3. The front suspension leaks appear to have been substantially reduced.


NB: All the above refers to my early 1st series model, later cars, in some cases, will have different part numbers. Refer to the pages on 1st series changes and the publications page for downloadable copies of the manuals.


ngm

February 2016.


Postscript April 2016:

After the first long drive things are much better. (Autumn Leaves Run)

The steering has a slight pull to the left, fixed with a small toe out adjustment to the right wheel.

Steering feel is much improved.

Suspension leaks: Only from the bottom of the right hand side were I messed up the solder seal on the bottom cover. The left side only lost a bit out of the top of the bottom dust cover because of some very rough roads, the top damper section on both sides had no leaks.


Later post postscript, 2017:

The top section of the lhs suspension started to leak badly, again. This time I got some "Grade A" industrial felt, more dense, and now the leaks have disappeared!

Steering column sleeve fibre bush.

(photo is from a spare)