Author Topic: Front Lower Ball Joint  (Read 7801 times)

nikbj68

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Front Lower Ball Joint
« Reply #15 on: July 10, 2015, 16:30:55 »
Like this!:
   

ACOCArch

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« Reply #16 on: July 20, 2015, 02:20:45 »
Quote
Originally posted by nikbj68
   
Like this!:
   [img]
   Sorry I don't have any specific information but, from memory, AC Cars (Labinsky era) introduced a modification to cure a problem similar to this.
   
   I strongly recommend you investigate this further before taking metal off what is a highly stressed and safety critical component.

ACOCArch

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« Reply #17 on: July 21, 2015, 17:52:47 »
quote:
I strongly recommend you investigate this further......

   Further to my earlier post David Hescroff, a long standing ACOC Member who does not subscribe to the Forum, has agreed to the following being posted on this thread.
   
   David had a similar failure on a late model Ace which, in his case, occured when reversing on lock.
   AC Cars had already modified his early model Ace to prevent the problem, and supplied the parts free of charge to fix his later car.
   
   David's recollection is that there was a recall at the time, his later car having slipped through the net.
   
   David's advice is to contact Neil Fisher at Redline. Neil is understood to know of the problem and the correct solution.
   
   I would add, from an engineer's standpoint, that all Brooklands Ace owners should have their cars checked as a matter of urgency.
   
   As not every owner subscribes to the Forum, the Ace Registrar may also consider it prudent to inform owners in writing

Adrian_S

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« Reply #18 on: July 21, 2015, 18:31:53 »
Many thanks ACOCArch this is wise advice. I have some more pictures to add this one being the stock Transit ball joint, pre machining
   
   

Adrian_S

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« Reply #19 on: July 21, 2015, 18:56:48 »
Here is a picture of the post machined article as supplied by Redline
   
   

Adrian_S

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« Reply #20 on: July 21, 2015, 19:09:00 »
And here are some pictures of the fitment on the hub carrier. The proximity of the hole to the upright section won't allow a nyloc nut above, hence the need for a pinch bolt arrangement.
   
   
   
   
   
   I spoke with Neil Fisher whom confirmed that my car has the recall fitment and that this design had been adequately SVA crash tested to be fit for purpose. However, he did concede that the steering geometry was such that, under full lock the wheel angle was very acute, and could exert undue force on the lower ball joint. I hit the pot hole quite hard and it's not unknown for other vehicles to suffer suspension damage in this way. However, I am looking into ways of restoring strength to the ball joint and would greatly value any suggestions.

Nev

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« Reply #21 on: July 21, 2015, 23:16:14 »
Very interesting info, I appreciate the effort to put it up on here. Has anyone managed to fit end-stops to reduce the lock on the steering?

ACOCArch

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« Reply #22 on: July 22, 2015, 02:49:56 »
quote:
Has anyone managed to fit end-stops to reduce the lock on the steering?

   Fitting rack end stops might reduce stresses at the extremes of lock, but not for potholes! Another possibility is that there is not sufficient articulation in the joint at the combined extremes of steering lock and full suspension travel.
   
   The broken parts may have fatigued for a while, with the pothole the last straw. Examination of the broken part by a metallurgist would quickly determine the failure mode. A workshop check of articulation at the extremes would resolve that issue.
   
   The AC 3000ME has end stops on the steering rack. These were a homogolated AC Cars Ltd design to modify the Triumph rack fitted to the car. The idea has stood the test of time (33 yrs on my car).
   
   If rack end stops are the answer for the Ace, strictly speaking they should be approved for the car. The 3000ME stops would almost certainly not fit the Ace rack. However, if a competent engineer wishes to take up the idea I would be pleased to supply the AC Cars 3000ME drawing, on a strictly advisory understanding, as one basis for a design which might be suitable for the Ace.

Wally

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« Reply #23 on: July 25, 2015, 00:26:58 »
quote:
Originally posted by Nev
   
Very interesting info, I appreciate the effort to put it up on here. Has anyone managed to fit end-stops to reduce the lock on the steering?
   

   
   Quote from the Rack Thread below
   From what I remember we fitted a rack from a VOLVO 740 ID No. 34003798, the only thing we had to alter was putting spacers on either rack end (behind the rubber gaiters)to stop it turning as far when on full lock.
   
   All we did was put a collar with the same outer diameter as the outer diameter of the knuckle joint, and with an inner diameter being a tight fit onto the rack, and then re-fit the knuckle joint. Obviuosly we did this on both sides. The thickness of the spacer then limits the lock as the spacer instead of the knucke joint comes up against the outer rack housing when on full lock. I can't remember just how thick these were but at a guess they would be around 25 to 30mm.
   
   Wally

Adrian_S

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« Reply #24 on: July 28, 2015, 06:47:41 »
Thanks Wally can you remember the material you used for the spacers, nylon perhaps or aluminium? I have the old Volvo 740 rack to experiment on. Your help really invaluable, thanks!

Wally

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« Reply #25 on: July 28, 2015, 10:29:31 »
We used mild steel but only because as we had a piece that was almost correct size, we just trimmed it slightly and cut it in two.
   
   Wally

Adrian_S

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« Reply #26 on: August 16, 2015, 21:25:35 »
I've discussed ball joint designs with some other Ace owners and discovered that earlier Brooklands Aces were fitted with a different modification to the transit stock ball joint. I've had some more ball joints machined to emulate this design shown here on the right
   
   This design continues to use a parallel machined shank but now features a scalloped slot along one side to accommodate the pinch bolt (rather than a groove machined around the whole circumference). Here are the two machined ball joints ready to fit
   
   This design leaves a lot more metal in place and should, theoretically, be much stronger. My CNC shop achieved a smooth finish and ensured all edges were radiussed, to avoid any stress cracks developing. According to another owner, in excess of 90k miles were achieved on this design. I'll have these fitted as soon as possible and look forward to reporting back! Now to machine some rack end stops to Wally's description.....

Max Allan

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« Reply #27 on: August 19, 2015, 00:45:19 »
Adrian - the slot instead of circular groove is far better idea, although the failure you experienced wasn’t at the groove, but lower down. I guess another solution would be to machine the hub carrier to same taper as ball joint (should be sufficient meat available not to weaken carrier), but retain pinch bolt as means of securing joint in place. Out of interest what was the cost of removing taper from transit ball joints?
   
   As Wally says the stops are nothing more complex than spacers fitted behind the tie rod knuckle joints of sufficient thickness to restrict rack travel so on full lock tyres don’t rub against inner wing valance. You can use steel, aluminium, plastic - whatever comes to hand. The spacers can be fitted as washers (cheap and easy to make) by removing the knuckle joints or made in two halves with screws holding the halves together (lot more expensive!) if you don’t want to remove said joints.