Can torsion bar trimming affect camber and cause tyre wear?

[Oldmogman]

Could anyone advise whether trimming the torsion bars can compromise the camber?

I raised the ride height on the left side of my car by half an inch to compensate for settling over the years, and replaced the bushes on both sides at the same time. I had the tracking checked afterwards to ensure everything was properly aligned.

However, 1,000 miles later, I’ve noticed increased wear to the outer shoulder of the left front tyre (the side that was raised), and wondered if this is because adjusting the torsion bar has affected the camber? (My car has the CS Autoclassics/Morris Minor Centre suspension system, which saw a small amount of negative camber introduced to the front.)

Since tracking checks for toe-in, I would have thought any mis-adjustment would have seen wear on the outer shoulders of both tyres, not one?

Or could it be that the previous tracking check wasn’t done correctly? (I’m having it checked again on Sat.)

Your thoughts, please!

[philthehill]

If the torsion bars are trimmed correctly as per the measurements in the BMC Minor Wksp man, the correct camber will be obtained.
You will have to enlarge on the CS Auto Classics suspension system fitted to your Minor as I am not aware that the CS Auto Classics suspension system introduces a small amount of negative camber into the front suspension.
Only if you space out the eye bolt can you increase the negative camber. Minor Mania produced a negative camber kit which comprised eye bolts with a longer shank which allowed up to 4 degrees of negative camber by the insertion of different thickness spacers. See photo below

Negative camber eye bolt 1.JPG (264.01 KiB) Viewed 1178 times

If your suspension is set correctly, I suspect that the tyre wear being experienced is down to incorrect tracking.

[Oldmogman]

Hi Phil

The CS Autoclassics system for camber adjustment works on the same principle as that of Minor Mania, and works in conjunction with telescopic dampers.

It's been fitted to the car since the mid-90s and I've covered some 55,000 miles without any problems - until I adjusted the ride height (albeit by just half an inch).

I'm hoping that, as you suggest, it is the tracking that is at fault, but I was puzzled that tyre wear should show up on just one side - which was the one that was adjusted.

[philthehill]

Thanks for the CS Autoclassics explanation.
I was not aware that CS Autoclassics / Opus Car Company Ltd did a Minor Mania type eye bolt.
I have several CS Autoclassics parts catalogues and I have never picked up or seen the modified eye bolt advertised in the catalogues. I shall have to look again.
CS Autoclassics did quite a few modifications over the years culminating in their Series 4 pack of modifications. I had a pair of their modified Minor swivels fitted with Marina stub axles and Marina discs on my Ser 2. I also had one of their modified Marina rear axles fitted to the Ser 2 as well.
I have a CS Autoclassics Ford gearbox conversion bell housings currently fitted to my 1380cc Minor.
I did visit their works outside Wells in Somerset and tried their Minor with the Ford 4 speed box on the local roads which convinced me to fit a Ford 2000E 4 speed box which has now metamorphized into a Quaife CR/SC Clubman box with alloy casing, alloy top lid and quick shift.
https://www.carandclassic.com/car/C1375421
Update to above.
I have just looked at CS Autoclassics October 1992 price list and the only reference to the eye bolts I can find is the fitment of uprated eye bolt pins and metalastic bushes.
CS Autoclassics list torsion bar micro adjusters in their price list - I would check that you do not have them fitted as it would make life much easier to set the suspension height.
I have converted a set of Marina torsion bar micro adjusters to enable them the be fitted to a Minor.

Marina adjuster 11 (1).JPG (901.88 KiB) Viewed 1092 times

[Oldmogman]

Hi Phil

No, I don't recall any listings for a modified eye-bolt in the CS Autoclassics parts list.

However, they adjusted the camber using shims fitted behind the original eye-bolts during final adjustments carried out at nearby suspension geometry specialist. I don't recall the exact amount of neg camber introduced but it was relatively small; sufficient for road use rather than track. (I observed the entire modification carried out on my car as part of a feature I wrote for Popular Classics magazine.)

That's a neat adjuster set-up you have, and looks to be Marina based. I'm assuming it uses the Marina torsion bars, which I think are slightly thicker than the Minor's?

[Oldmogman]

Thanks Phil - PM sent!

[philthehill]

The micro adjusters in my photo above can be used on either Marina or Minor torsion bars.
The Marina pickup/van has stronger (21mm) torsion bars, but the Marina car (19mm) torsion bars are very similar in strength to the Minor torsion bars. Because my car has been considerably lightened, I will be using the standard Marina torsion bars though I do have a pair of 21mm Marina torsion bars if needed.
You can pack out the eye bolt to give 1 to 2 degrees of negative camber at rest and under normal loading.
I did find that no two sides are the same as regards the packing required. I had to add additional packing behind the standard eye bolt on one side to get the camber reading the same. Fortunately, I do own a Dunlop camber gauge which is essential if trying to set the camber. My Minor tie bars are adjustable which greatly assists with setting the caster.

[dp]

Many years ago I remember using Marina torsion bars but with the original Minor rear adjuster (because the Marina adjuster would apparently bash through the floorpan) and had to cut one or other of the ends of the bar so it would fit.

[philthehill]

If you do not use the reaction plates (the large plates in my photo above) the Marina adjuster bolt will punch a hole in the Minor floor.
The reaction plates bolt to the Minor cross member and provide a strong base for the adjuster bolt to press against.

Marina adjuster 8 (2).JPG (712.46 KiB) Viewed 1004 times

You may have to reduce the overall length of the Marina torsion bar to fit between the Owen Burton adapter and the Minor front eye bolt. Any reduction in length should be done at the rear of the Marina torsion bar which has the circlip groove.
A 7mm length of the rear splines (with the 1/2" UNF spigot attached) of the Minor torsion bar can be used in place of the Owen Burton adapters.
The same splines and spigot can be used (with its front end reduced to 3/8" dia and threaded as a replacement for the front eye pin and cup washer if using the Marina thick suspension arm which is a much better set up than the Minor thick suspension arm.