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AC Ace steering box?

Started by AEX 31, June 23, 2022, 15:06:01

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AEX 31

Dear all,

AEX 31 has done something like 80.000 km and so has the steering box. With the help of a knowledgeable friend we replaced all the moving parts that we could so I guess it's as good as it can get, without changing the worm and peg, so with modern Michelin X's it's tracking a bit at higher speeds.

So my question is simple, is there anybody out there that has a very good or even nos steering box or at least a new worm and maybe a column that they want to sell? To me!

I know one can buy new worms from TR specialists but I have also heard that the quality of these new worms aren't very good. Also if anybody has any experience with new parts and tracking problems in general it would be interesting to hear about the experience that others with old Ace's and Aceca's have had.

Many thanks in advance for any input.

Kind regards



The Ace is not prone to tracking or tramlining, neither are Michelin X tyres.
I wonder if you have lost the caster self centering action by over tightening the adjustment  on the peg ? There should be some play at the steering wheel rim.
The cam doesn't wear like the peg and I would fit just a new peg and adjust the clearance to allow the wheel to self centre as soon as you relax your grip on the steering wheel whilst turning.
Fitting the front uprights on the wrong side gives you reverse caster angle and some epic directional excursions - I hope '31 has not suffered this insult.


There used to be a gentleman in Westcott ,Surrey who specialised in worm and peg boxes and about 10 years ago he overhauled mine.
I had a quick look on the internet but cannot find him........maybe a more in depth look may uncover his whereabouts........or maybe somebody else on the forum can shed some light on the matter.......
Sorry to be a bit vague.....Luke

Robin A Woolmer

MarlesWellerBox David Cornwallis is probably the guy they are on the web!

AEX 31

Many thanks for your input.

Barrie, I do think the uprights are fitted the correct way. Both sides have a positive caster of between 3 and 4 degrees. So hopefully no insult to the old lady (31!).

I will definitely try to let the peg sit with less force and see if that changes matters. I have also enclosed an image of the worm. Maybe hard to see but there is some wear, especially in the center of the worm. I do think my worm Is just worn, maybe from historical over tightening?

Regardless I do think that the modern Michelin X's are rather different to the older ones. First of all the later versions have an almost 20 mm larger diameter, different thread pattern and probably a different rubber specification. I definitely feel a large difference to the older ones when cornering, the new type sticks to the road much, much better.

Robin, I have had some contact with the Marles company. I can see on their website that they have restored a number of the Bishops boxes for AC's. Do you or anybody else on the forum have any first hand experience with them and the quality of their work?

A last thought I have is that toe in should play a large part as well. 31 is set up with roughly 0,25 degrees per side, which should equate to the 1/16 inch as it says in the handbook. Anybody with different opinion/experience concerning  toe in? I run the car with the original 16 inch wheels.

Thanks again.



Do bear in mind that the cam is machined to give more clearance to the peg in the straight head area. This is the reason why the peg must not be set too close - it will bind as lock is applied


We used parts and advice from Marles to successfully rebuild the steering box in an Allard K3. The company was quite helpful. I sold the car a few years ago and all the paperwork went with it, so I can't provide any more details.

AEX 31


Thanks for your reply's. Barrie, are you a 100 % sure that the cam is machined to give more clearance in the centre of the cam? There is one thing that I find intriguing and that
is that the peg is past the centre of the cam in the straight ahead area, which would mean that the peg, theoretically, wouldn't have any contact at all with the sides of the cam,
unless the cam is machined with different angles.

To make things even more complicated for my little brain a friend of mine sent me this text:

The text is about steering boxes for MG TA-TC, but still a Bishops box that I presume would be designed, and machined in a similar fashion?

If that is correct this text assumes that the peg clinches, or meshes with the cam in the dead center position and towards the stop of the travel.

Greatful for any comments.

Kind regards


Ron Hollis

         Just for background, my Ace has never had tracking problems on Michelin, Cinturato or Avon Turbospeeds. It has the original unrestored box and has done about 450,000 km. The only problems are a leak at the oil seal and it's too heavy for my partner.
          I assume all ball joints are sound.

AEX 31


Thanks for your input. I have to say that 450.000 km is rather impressive, have you done many of these miles yourself?

I'm also curious as to what tires you are running with at present.

The funny thing for me is that I never used to have any tracking problems before 31 was restored, sometimes I wonder if it's also an older version of myself, that's more used to modern cars that's the biggest problem. I have had 31 for 22-23 years now...

Anyway. All the ball joints were changed when the car was restored, which is now only some 6-7000 km ago.

After having rechecked everything I found that the front steering idler was a bit stiff and after sorting this my car isn't tracking as much. However I am still wondering if possibly I should set it up with a bit more toe in, at the moment the total toe in is 0,5 degrees.

So still interested to hear what toe in  other members have on their cars, that have 16 inch wheels.

Thanks in advance for any input.


Ron Hollis

Hi Jonas,
             I have done about 315,000 Km over 52 years.
             I am using 165x16 Avon Turbosteels, which are good enough.
             My official AC handbook says that if you adjust the steering box correctly, it will give unlimited service!
             I run mine with i/16 inch toe in on each wheel at the wheel rim. This is as recommended in the handbook.
              I agree that old cars and poor roads need a certain technique.
              If the idler was stiff could there be wear in the mounting bolt fixing holes, allowing up and down movement?

AEX 31

Hi Ron,

I take my hat off for your 315.000 km. I wouldn't be surprised if you have driven more miles in an Ace than anybody else. I guess I have done roughly 20.000 km all in all in 31.

Out of curiosity could I ask were you have done all these kilometres?

Thanks for answering my questions. I really don't think that there is anything very wrong with my steering box. So by fine tuning everything I hope to reach an acceptable result.

I will recheck the idler again.

Talking about the handbook I also believe it says that the steering when properly adjusted should be "finger light", I wonder if anybody has experienced that!

Thanks again for helping out.

All the best.


Ron Hollis

Hi Jonas,
              my mileage is all in The British Isles, furthest North being Orkney. Previous owners had borrowed the Bristol Overseas kit from Thames Ditton on occasion so it has been to Europe, I assume. When I bought it, it was just a stepping stone but somehow the cars character and Bristol exhaust note made it a constant companion for work, holidays, shopping, fishing trips.......
              It should say "with wishbones supported and wheels in the air" don't you think.
             Happy Motoring

Michael Trotter

A very interesting thread.  I feel I have a number of observations, comments and suggestions to make but am restrained by the fact that I don't understand the question. What is tracking?  Is it what I would describe as directional instability? Can you be more specific? I should add that over the past 50+ years I have owned four AC's - three Aceca Bristols and a 428 but know nothing about 'tracking at high speed'. My current Aceca Bristol is 33 JPD which was the factory demonstrator from 1959 to 1961 and was road tested by Autocar (8 April 1960). Their report said the steering was 'direct and precise but heavy at low speeds - tiring to manouvre' - we know what they meant ( on Michelin X tyres). Autocar also said that ' at near maximum speeds, the front of the car started to weave on crossing the central ridge between areas of concrete.... noted with other fast cars .... ceased almost immediately....without any action on the part of the driver. Is this a clue to your tracking at high speed? And how high?  Autocar got 116 mph out of my car but I've never been near that!


AEX 31


Thanks for replying. I indeed mean directional instability, or maybe even that the car wants to "self steer" to some degree. It has gotten a bit better after I have adjusted the angle of the steering arm vis-à-vis the steering box and I also had a bush in the idler that protruded some thousands of an inch, but all that is now corrected.

So  when I go faster, say above 60-65 mph I still experience a little bit of this, and that's basically as fast as I go these days, but it would be nice to do 75-80. As I think I mentioned earlier in this thread I have had 31 for many years now and before I took it off the road in 2005 to start a restoration I used to regularly go almost flat out, say 90-95 mph and never think twice about the steering having a life of its own.

One thought I have is that the most recent Michelin X's are different compared to the older ones, that could make a difference.  Another  thought is that the toe should be more pronounced and lastly I'm also wondering if my wheels are well balanced enough. I have checked the two last things at a tire shop and the digital readings are correct for both toe in and the balance of the tyres.

Sorry for the rambling but interesting to hear what other members of the forum thinks.