Ride height.

[ndevans]

Evening.

I'm trying to get the ride height sorted. O/S is significantly lower than N/S.
When the manual talks about moving the arm 1 spline to raise or lower by 38mm (1 1/2" for those still using Roman units), does it mean the rear arm, that is the one at the rear of the torsion bar, or does it mean the lower suspension arm at the front that attaches to the lower trunnion?
Or does it matter which one you change?

Cheers N

[philthehill]

The reference to 1 1/2" (3.8cm) is regarding the front arm - that is the one attached to the eye bolt and lower trunnion.
Once you have the initial setting of the front arm and finer adjustment is needed the rear am can be moved up or down (not on the splines) and by using the plate adjusting torsion bar (Pt No: AAA1852 which has the series of holes in it) the correct ride height can be obtained.
Each hole in the plate adjusting torsion bar gives a difference in ride height of 1/4" (6.3mm) when moving the rear arm up or down.
See Morris Minor wksp manual Section K1, K2 & K3 for full details.

[don58van]

To make a major adjustment, the usual approach is to move the front torsion bar arm a spline or two rather than the rear.

The rear arm is not usually moved on its splines. For fine-tuning of the ride-height the fixing point of the rear arm is adjusted by passing the bolt through a different hole on the vernier plate.

There are unnecessarily laborious ways of taking the front suspension apart to move the front arm and there are much simpler and quick ways. Do a search on this site and you will find plenty of information.

The main things to remember is safety, safety, safety:
* make sure the car is secure when raised
* make sure the very considerable energy stored in the loaded torsion bar is released gently.

Don

[ndevans]

Ok thanks, front arm is the one it refers to, that's what I needed to know.

It's on 2 axle stands, so pretty safe!

cheers N

[ndevans]

Evening.

Would adjusting the ride height alter the tracking in any way? I have now got it raised a bit, but the steering wheel no longer centres when going straight ahead. The track rod ends have not been disturbed, but it's still slightly higher on one side than the other, only now the o/s is a bit higher than the n/s.

cheers N

[don58van]

As the amazing Roy always used to point out, if the offside is set a little higher without a load in the car, it is likely to be level with the driver on board. And it is often the case that these cars only carry the driver.

Obviously, once other passengers/cargo is added this argument no longer applies.

I suppose it is possible that disturbing old rubber bushes might have changed the tracking just a little.

Don

[philthehill]

Adjusting the body height will effect the tracking because the suspension moves in an arc - raising the body will bring the wheel closer to the centre of the body therefore effecting the tracking.
It is always better to have the O/S slightly higher than the N/S if the majority of the time the only occupant of the car is the driver.
When the driver sits in the drivers seat their weight brings the car level and normalises the suspension.
Any time the suspension is repaired/serviced/modified the tracking should be checked.
I have set the suspension on my Minor so that when I am sat in it the car is level.

[amgrave]

And don't forget a soft rear spring on one side can affect the front suspension height too. A quick check is to lift the rear of the car with a jack under the diff so the wheels are just clear of the ground (on level ground) and then check the front.

[Chipper]

Good to hear that; I've fretted that my Traveller sits a little bit higher, perhaps half an inch or so, on the offside front compared to the nearside front, when I'm out of the car, but perhaps it's fine once I'm on board - it certainly drives pretty well, so maybe nothing to worry about...

[ndevans]

Ok, so this puzzles me.

I have adjusted the ride height on both sides of the car. Two weeks ago, after adjusting the n/s, the difference between the inner & outer fulcrums was 16mm on the n/s, 5mm on the o/s.
Tonight, after adjusting the o/s, the difference is 47mm on the n/s, 58mm on the o/s. How come? Does raising it on one side also raise it a little on the other?
The other thing I can't understand is why the actual height of the outer fulcrum from the floor is 10mm higher on one side than the other. Both trunnions are screwed up the same number of turns, I made sure of that. Any ideas?

I know it may seem a little pedantic, but I like to get it right, or at least understand where I've gone wrong!

cheers N

[panky]

As has been suggested if you have a weak spring on the back it can affect the diagonally opposite height on the front. The way to check is to raise the back of the car and leave the springs and axle dangling. Do this by jacking the rear of the car up by placing a stout plank across the car in front of the rear springs and, using a trolley jack, to lift dead centre. Any difference in the front can then be measured when the weight is on the front alone.
To check the rear springs jack the front up by the front cross member (suitable supported with a balk of timber) and any anomaly in rear spring height can the be measured. All this must be done on a flat and level surface.

[jaekl]

Yes, adjusting one side will affect the other. When one side is low, the torsion bar is not carrying it's full share of the weight. The other side must compensate as well as it unbalances the load at the rear. So as you put more load on the low side by twisting the bar more, the other side goes Ah. How far the trunnions are screwed in will not change the measurement you have taken directly, but will raise or lower the body and that will affect how much load is supported by each spring and that will affect your measurement. The effect would be minimumal per each rotation of the trunnion, so they should be as close as possible, but also isn't changed while adjusting the torsion bars.

[ndevans]

Thanks for that.

It does puzzle me why one outer fulcrum is lower than the other. I carefully counted each trunnion's turns when I took them off, and screwed them back on the same number of turns. It was either 19 or 20, can't remember which, but even if one was 19 & the other 20, the pitch is only about 3mm from memory, so that's the maximum difference there should be.

Not in a position to try jacking from the rear at the moment, maybe tomorrow.

Cheers N

[ndevans]

Ok, just checked both front tyre pressures, they are the same. Re-measured the fulcrum height differences, they are now 50mm n/s, 60mm o/s.
Also checked the rear spring hanger heights, the n/s rear hanger lower bolt is 20mm lower than the o/s, so there may be something in the weak rear spring theory. Not currently in a position to jack up the rear and leave the rear axle dangling, I don't have a suitable piece of wood.

Where do you get quality rear springs from?

cheers N

[ndevans]

Tried a little experiment this evening. I jacked up the rear n/s, under the rear spring hanger at the back, by 20mm (the difference between the height of the two rear spring hangers, see post above). I then measured the front inner & outer fulcrum heights. Both inners were the same height, the o/s outer was 5mm lower than the n/s. In other words, the height difference between the inner & outer fulcrums was 50mm on the n/s & 55mm on the o/s. This is still greater than the 41mm spec in the book, but I think it proves the point about weak rear springs, and that the rear n/s spring is weaker than the o/s. So I've come to the conclusion that I need new rear springs, despite them only being 10 yrs old, and having done about 25000 miles. So where do I get decent rear springs from?

What still puzzles me, however, is that the o/s outer fulcrum is about 5mm lower (i.e. closer to the ground) than the n/s. Both tyre pressures are the same, they are the same make and size of tyre, and both look evenly worn. As the outer fulcrums are unsprung, I would expect them to be the same, unless the tyres were different in size, wear or pressure. So how can that be?

cheers N

[amgrave]

Instead of taking the measurement from the fulcrums to the ground take it to the wheel rims, that will eliminate the tyres altogether just in case the difference is in the tyres taking up a difference in ground level.

[ndevans]

Why didn't I think of that? Thanks, will do.

[ndevans]

Ok, a quick measurement from outer fulcrum to wheel rim reveals both sides to be within a couple of mm of each other ~130mm. There must be some difference in the tyres. Also, I guess, with one weak rear spring, the weight distribution is now uneven, so that tyre load, and therefore tyre compression, will be different at the front, even with equal tyre pressures.

Bottom line still is I need new rear springs, but I'm now happier that I understand what is going on

cheers N