AC Ace steering box?

[Flyinghorse]

To be consistent when comparing the steering wheel play test the steering wheel diameter needs stated as if you fitted a larger steering wheel the play ( although the same) will appear larger.

[B.P.Bird]

Greg,
Looking at your photographs and reading about your steering woes I am left wondering what exactly the 'TR Revington' steering box top cover is ?
If, as I suspect, it is some kind of modification to introduce spring loading to the peg engagement with the cam then my view would be that your steering will never be right til you return the steering box to original Bishop Cam specification. If Bishop had wanted compliance in their system they would have included it: It would seem to me that their whole purpose was to eliminate compliance. Introducing any kind of compliance will appear at the steering wheel as excessive play.
Incidentally I should observe that when checking and setting play at the steering wheel rim only light force should be applied - the front wheels should not move nor the tyre sidewalls flex.
I find the steering system on the Ace, Aceca and Mk. I Cobra quick and accurate - threading the A.C. through a series of corners on a quite country road is a joy.
Barrie

[AEX 31]

Gentlemen,

I finally managed to find time to reset the toe-in on 31 to 12-13 minute degrees, which should be the equivalent of 1/16 of an inch. I had planned to do a drive test yesterday but a torrential down poor ment that I had to spend yesterday afternoon looking after a bilge pump, and sweeping floors!

So this morning I eventually took the car out for a longer test drive. The steering behaved better than before so I’m convinced that 1/16 is for the total toe-in. The steering has open up a bit and at the same time straight ahead stability was better. I did take the car up to something like 125 kph, which is a bit more than 75 mph. My next careful adjustment has to be to adjust the peg “until the slightest drag is felt over the dead ahead position”. Any idea just how slight that should be, hardly noticeable or just a bit more?!

Great thanks to Michael, Berrie, Andy and everybody else that helped out with this.

Jonas

[59 Aceca]

Gentlemen,

The diameter of my steering wheel is just under 15" and the Revington modified top plate is, indeed, the type with a spring-loaded pin.  I replaced the original top plate a number of years ago with the Revington version and, to my recollection, it did improve things a bit.  I still retain the original top plate and will definitely have it available as I work to resolve the larger issue of considerably excessive play.  Thank you for all of your comments.  They have been very helpful.

Greg

[Flyinghorse]

Greg,
One way to check if the play is due to  an issue in your linkages (ie track rods) or the steering box is to jack up one wheel and check for play at the wheel that's jacked up (the steering wheel ought not to move as the wheel on the ground has it locked) followed by the other wheel (with side you just checked on terra firma). Assuming no play you can assume its in the steering box.
Graham

[59 Aceca]

Graham,

Thank you very much for the helpful suggestion.  I will definitely perform this test.

Greg

[brucerudin]

I am surprised no one discussed converting to rack and pinion. I did that on my Ace Bristol and it transformed the car. We use it for long distance rallies and it has been brilliant.

[B.P.Bird]

Set up properly the Bishop Cam system is very effective and very quick. Going to a rack loses the quick ratio and originality: The former loses a great part of the car's character and the latter will decrease the car's value.
Barrie

[Michael Trotter]

Good morning gentlemen
Jonas : I have learnt more about how Trackace works and understand their angle is the included angle betwen the two wheels - what we have been calling the 'total' angle, the sum of the two angles A at the two wheels. I am pleased to hear that AEX31 is now 'better' at higher speeds. It has been a bumpy ride to get there but if you followed the Trackace 'pre-measurement' procedure and have measured around my 12' or Trackace's 13' (what's 1' between friends?) I feel sure you now have the 1/16'' toe-in which AC decided was best for the Ace. However, I am surprised and concerned that you now tell us you have 2" free play at the wheel. Not sure whether you mean at the steering or road wheel, but in either case this is excessive and you must eliminate it to get your car driving as it should. Your question about 'slighest drag' implies that you think the free play is in the steering box. I cannot define slightest play. The danger in steering box adjustment is overtightening the screw. Hence my advice above to ignore 'slightest drag'. It is difficult to distinguish 'too much drag' and 'slightest drag' but easy to distinguish 'slightest drag' and 'slight free play'. Hence my advice to aim for slight free play, say 1/8 " at the steering wheel, which you will never notice when driving. I sense you are not entirely convinced about toe-in. Howabout finding a garage workshop with a 'drive over' alignment gauge to confirm it shows 'Toe-in OK'?

Greg : Your 5 and 1/2 inches of free play sounds to me frightening, indeed dangerous. I think it would, rightly, earn you an MOT failure. You need to identify the cause of the free play and I suggest : 1. Drive it into your workshop 'straight ahead'.  2. Have an assistant turn the steering wheel slowly and gently (finger and thumb only) through the free play telling you when the direction is reversed. You will be feeling the drop arm under the steering box. 3. If the drop arm moves throughout the free play your problem is not in the box but elsewhere and will be obvious or can be identified.  4. If the drop arm does not move at all your problem is only in the steering box. 5. If it moves partly you have a bit of both.  6. If, as I suspect, you have a steering box problem you have to question your Revington steering box cover plate. Like Barrie, I don't know the detail of it but, like him, I am suspicious of it and recommend that you replace it with the proper Burman cover plate with its adjustment screw. 7. Note my observations above re other relevant matters.

Jonas and Greg : If you think a conversation would be more helpful than exchange of posts here do give me a call.

Michael

[Michael Trotter]

Jonas

I said above 'I cannot define slightest play'. I meant to say 'I cannot define slightest drag'. Just confirms, as I said earlier, elderly folk get confused sometimes. Talking of typos, they had them in 1954 when AC said 'on rim' but meant to say 'on rims'.

Michael

[AEX 31]

Good afternoon gentlemen,

Thanks Michael for helping out again. I do also think that 1’ shouldn’t matter very much. I’m also rather certain that Track Ace isn’t accurate down to the last decimal!

I’m afraid that I do find myself rereading what I have written, and unfortunately conclude that I have been unclear, or not precise enough.
Sorry about that. Let me try to rectify that.

I did mean that the play was at the steering wheel. I redid the test and I now I tried to replicate Greg's test down to using a similar tape and ear swabs!
Since I perform this test on my own I basically move the steering wheel to either side until I feel, again, the slightest drag, or shall I say resistance in the steering wheel on either side.
I suppose I have to get an assistant so I can perform the drop arm test. Either way, when no applying any force at all the play in the steering wheel is not as much as I previously mentioned.
It’s something like 14-15 mm which is something in-between 9/16 and 5/8 of an inch, which is a whole lot more than the 1/8 you mentioned. Please see the attached images.

I do think that I have to perform the “drop arm test”, in hindsight; I should have done that a long time ago…

But, and I think this is important, do I understand you correctly Michael that I should aim for a free play of 1/8 at the steering wheel when adjusting the steering box?

Something that springs to mind is that the peg that goes into the worm on 31 was visibly compressed on the sides that moved against the worm. I did press it out, turned it 90 degrees before pressing it back on again…

I have asked around the “classic car circle” in southern Sweden and so far nobody has admitted to be in possession of a 'drive over' alignment gauge. I also have a feeling that the old Dunlop toe in gauges with two mirrors
are more accurate than the Track Ace version, they are also a lot more expensive!

So the quest for the optimal steering experience goes on.

Jonas

[59 Aceca]

All,

This string has been an eye opener for me in terms of confirming what I have suspected for the many years I have owned AEX734.  The steering definitely has some issues.  What's ironic is that I have simply grown accustomed to all the play.  Initially, the play was simply attributed to the vague feel of the antiquated Bishop Cam box.  Seeing my ear swab test duplicated (thank you, Jonas!) provides some quantifiable evidence that what I have been accepting all of these years is far from in spec!  What's frustrating is that I recently had my car at a "reputable" shop in northern California for some unrelated work and I asked them to look at the steering box for wear.  They pulled it apart, reported that all appeared okay, and proceeded to put it back together.

Yesterday evening, with the help of my wife turning the steering wheel, I performed the drop arm test.  Sure enough, the drop arm remained fixed as my wife gently moved the wheel from side to side through its range of motion.  More quantifiable evidence that something is amiss in the steering box.  Very exciting stuff as I now know where to focus the attention!  My first step will be to rotate the pin 90 degrees and see what kind of improvement results.  As suggested here I will also remove the Revington top plate and replace it with the original plate, although I don't believe that is a contributing factor to all of the play.

Thanks very much to all who have contributed to this string as it has been incredibly helpful.  I'll be sure to report back once the changes have been made to my steering.

Best regards,
Greg   

[Flyinghorse]

Greg,
This is from the UK M.O.T testing manual (annual vehicle check though many older cars exempt)-so 75mm for a 380mm diameter wheel.
You should be able to make a quick calculator in excel for different wheel diameters  or mark your wheel with tape at the 380mm dia/190mm radius.

To check steering play:

    Make sure the road wheels are on the ground and pointing straight ahead.

    Lightly turn the steering wheel left and right as far as possible without moving the road wheels.

    Check the amount of free play at the rim of the steering wheel.

If power steering is fitted, the engine must be running.

Steering wheel free play should not be more than:

    13mm for rack and pinion steering, or 48mm if there are several joints between the steering wheel and the rack
    75mm for non-rack and pinion

These limits are for a standard 380mm diameter steering wheel. The limits should be adjusted up or down accordingly with larger or smaller diameter steering wheels.

Play due to wear or maladjustment must not be confused with apparent play due to the construction of the mechanism, such as caused by the deflection of flexible joints or spring compression in external power steering systems.

[Michael Trotter]

Jonas

Sorry for delay - tme flies!

I am confident that your toe-in is now what AC meant by 1/16" and that when you get rid of the free play at the steering wheel your car will drive as an Ace should. It sounds like you have owned AEX31 from new - very impressive. If you have not adjusted the steering box before, 80,000km sounds like a good time to do so. By the way, when I suggested a drive-over gauge I was thinking of the Volvo dealer or independent garages in Malmo.

Yes I did advise you to aim for slight free play, say 1/8", at the steering wheel. I should have advised AC's slightest drag and no free play. But that gives rise to your question and I cannot define slightest drag. It is many years since I adjusted a Burman box but my recollection is that it was tricky and sensitive. It was all about 'feel' and 'judgement'. I think the range from slight play to too much drag is covered by not many thou of axial movement of the screw. Hence the sensitivity and the locknut issue. AC in their instructions refer to adjustment as 'extremely critical' and emphasise that you must 'avoid excessive tightening of the adjustment screw' which brings us back to slightest drag.

My advice is to take your courage in your hands, select a screwdriver which is a good fit in the screw, have a go and experiment. Better to end up with slight play than with too much drag BUT slightest drag and no free play is the holy grail which you should aim for. Good luck and let us know how you get on.

Michael

[AEX 31]

Michael,

Sorry for the delay in replying, I celebrated Bonfire Night in England! Thanks for your comments. The steering on 31 is another step closer to being as good as it can, I think!

I haven’t owned 31 since new but I have owned “the mistress”, as my wife calls her, for 23 years now. I did drive her a lot the first 6 years, and as far as I remember the steering box wasn’t touched at all in those 6 years. So I guess some previous owner or mechanic did indeed find that sweet spot or the perfect adjustment of the peg if you like.

I have used up a lot of courage this year when trying to find the exact spot where slightest drag and free play are in harmony. I have always adjusted the steering with the front wheels jacked up but I’ve also done very slight, road side adjustments which I believe has been helping me get closer to a good balance. I very much agree with you that the setting is very, very sensitive and that the difference in between a good and bad setting is very slight. I also have to say that after having adjusted “en route” to satisfactory result, checking afterwards with the front wheels up gives me more than a feeling of slightest drag…

Jonas