Vertical Link failed

[mikej]

We have a question from the Scimitar owners club regarding a failed "TR6" vertical link. As you can see from the picture, this one cracked below the top ball joint eye.

Not aware of this being a notable common failure mode on any TR model, does anyone have a better opinion we could pass on to them? Should the owner change both sides (I would!)?

Cheers,

Mike  

[RogerH]

Hi Mike,

he must change the other side as well. I would imagine that his car is in the 50 year old area.

The section of plain shank to the left of the fracture face looks either very corroded or very dirty. If it is corrosion then that is the stress raiser.

The dark mark in the red circle looks very corrosion like - I would suggest the crack started here and moved across the VL until it snapped at the far side where the face changes direction.

 

What hubs and stub axles do they use - these are also 50 years old

 

PS - theat black mark is on the underside of the 90' bend. Water could hold in there and generate the corrosion.

 

Roger

Edited February 24, 2020 by RogerH

[Waldi]

The picture is not very sharp, and even if it was, I find it difficult to do a good analysis.

The flat area, about 60%, looks smooth and was the first area that failed. Fatigue due to corrosion as Roger indicates or an old mechanical damage is my best guess. But high hardness from fabrication can be a (contributing) factor too. A minor defect can then act as a starting point.
The other smaller area looks like brittle appearance, and will have been the last bit to fail.

Waldi

[Drewmotty]

Top ball joint looks a bit “used” if it starts to seize it could put a big bending moment into the top of the vl. 

[Z320]

Hi,

this is rear or front?

Why not think about a DIY spare part / different construction?

Ciao, Marco

[RogerH]

Hi Marco,

front suspension   see item #20  https://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/steering-suspension/front-suspension/front-suspension-tr4a-1965-67.html

Not easy to fabricate at home.

Roger

[BlueTR3A-5EKT]

13 minutes ago, Z320 said:

Hi,

this is rear or front?

Why not think about a DIY spare part / different construction?

Ciao, Marco

Hi Marco,

Reliant Scimitar (and Sabre) models used TR front suspension.  There are a couple of odd balls but generally TR wishbones, trunnions, ball joints and vertical links fit the Scimitar, or Sabre.  
 

It was because of Reliant Spares needing the suspension parts we TR spares companies had a long lasting supply of factory original quality items.  As I recall it was through an intermediary in Coventry.

Hope that is of help you.

Cheers

Peter W

[Z320]

Hi Peter,

thanks for this information,

so this is the broken off angled top end of the vertical link?

I hope the driver has not been hurt, Mike, please tell hin our best wishes.

No DIY part there.

Ciao, Marco

[stuart]

I dont think Ive ever seen one break like that in service other than accident damage. Definitely worth changing both though.

Stuart.

[RogerH]

I think this is a valuable lesson in good house keeping.

The VL (left of picture) looks very dirty/corroded. And there are traces of rust around the area.

The rust suggests that the surface is not protected, or the protection has broken down.

Both rust and dirt retain moisture.  This is almost certainly the starter for the crack propagation (assuming it is not accident damage as Stuart pointed out)

Keep every thing clean and tidy and ensure the protective coat of paint or whatever is in good shape.

How is your powder coat paint finish. What disasters lay beneath !!! 

How are your steering rack rod ends that attach to the 'TRack Rod Ends'.  Clean I hope.

 

Roger

[ctc77965o]

Never seen this part break before.

[Rob Salisbury]

My brother had an almost identical breakage on the suspension of his Scimitar GTE around 5 years ago, we put it down to those wretched sleeping policemen, he was living in Central London at the time and could not go more than a couple of hundred yards before encountering yet another one.

Cheers Rob  

[stuart]

20 minutes ago, Rob Salisbury said:

My brother had an almost identical breakage on the suspension of his Scimitar GTE around 5 years ago, we put it down to those wretched sleeping policemen, he was living in Central London at the time and could not go more than a couple of hundred yards before encountering yet another one.

Cheers Rob  

By the sounds of it as that another failure on a Scimitar its more likely that the loading on them is far more than on a TR, exceeding its design limit.

Stuart.

[Bfg]

20 hours ago, RogerH said:

he must change the other side as well. I would imagine that his car is in the 50 year old area.

"he must"  ..strong words.! 

Do I understand you are suggesting changing any and all structural part on any fifty year old car ?  ..where does that end - the chassis, the body mounts, the bulkhead and B-post, the rear deck ?  ..surely not everything on the car,  but perhaps for a rear light lens (..as long as it's not scratched) !  

When I had a Scimitar a few years back - I never heard of this, so clearly it was not a common failing.  A previous owner of that particular car may simply have curbed one wheel many years ago, and still it's taken all these years to fail, or else a piece of slag was caught in the inner corner during the part's forging from new.   Personally, I see no reason to condemn serviceable parts just because of their age.   And I'm very sure most of us wouldn't want to swap our TR for a new model Tianjin made Volkswagen.(..or whatever)  "just because" it's not new. 

[Tom Fremont]

I had one fail on my TR4 in circa 1974 but that was a couple of weeks after sliding into a curb at high speed while racing a 356B on the highway ( a box truck lost a load of cardboard and the entire cohort behind it locked up their brakes ). It broke off just above the trunnion as I was tooling along at 30 MPH; the wheel got stuffed into the arch and stopped the car in a 30 ft. skid.

 

Tom

[BlueTR3A-5EKT]

I'd agree that TR suspension parts are condition monitored not hard time components that are time limited. 

Hard time component is one that is time limited rather replace on failure or that should last the life of the vehicle.

Cheers

Peter W

[RogerH]

Hi BFG & Peter,

over the last couple of years too many rear hub stub axles have snapped off. They may have been kerb'd they may not - we simply do not know.

What we do know is that during the past 50 years anything could have happened.

If you lose a rear hub you also lose the wheel - ooops , not good.

The Vertical Link along with any steering/brake part you should also consider the age of these items especially if they lead a rusty/dirty life.

I appreciate that your comment about where it ends (chassis etc) is in jest I hope)

But if you believe I am being over the top then please do not drive near me.

 

Roger

 

[Tom Fremont]

In a related matter, I bought CD8315L with a reversed upper A-arm trunnion which lent it much negative camber on the LH side. I took it to a chassis shop who gave it back to me with neutral camber and I drove it another 20 years that way, including X-country to California where it served as my daily driver for a year before driving back to Ohio. At a certain point I realized the chassis shop had simply heated up the link until soft and bent it to get the camber out. Not knowing about the offset on the upper trunnion I eventually decided to fit an un-bent link and try to repair the issue properly. Only then did I discover the offset, informed the shop and they switched it round, much relieved that great force would not be needed. That was ~ 24 years ago. 

IMO considerable violence would be need to break one of these, and as we've all twigged by now the fracture could be delayed for some time.

Tom

[Motorsport Mickey]

2 hours ago, Bfg said:

"he must"  ..strong words.! 

Do I understand you are suggesting changing any and all structural part on any fifty year old car ?  ..where does that end - the chassis, the body mounts, the bulkhead and B-post, the rear deck ?  ..surely not everything on the car,  but perhaps for a rear light lens (..as long as it's not scratched) !  

When I had a Scimitar a few years back - I never heard of this, so clearly it was not a common failing.  A previous owner of that particular car may simply have curbed one wheel many years ago, and still it's taken all these years to fail, or else a piece of slag was caught in the inner corner during the part's forging from new.   Personally, I see no reason to condemn serviceable parts just because of their age.   And I'm very sure most of us wouldn't want to swap our TR for a new model Tianjin made Volkswagen.(..or whatever)  "just because" it's not new. 

Up to every owner what he does with his car BUT...TRs have often lead interesting lives.

"Race on Sunday go to work on Monday" was the selling mantra which tempted young (ish) people (men mostly) into buying a TR when they were THE car to enjoy club or even national motorsport (race or rally) at a high level back in the 1950s and 60s especially. A change of wheels and tyres and Sundays fun was assured, and then change the wheels and tyres and drive it home (often) ready for the Monday rush hour trip to work. That means your TR which you now polish and treat with reference may well have a secret past. It could well have been kerbed (more than once) doing it on right hand and then left hand corners evens out the added camber on both sides...now it matches !

The earlier TRs especially are well renowned for being robust, with their "ladder type" box chassis and cart (rigid) axles at the rear they stand decades of rusting internally with hardly any original paint protection, but as the design changed onto the more sophisticated IRS cars from 4a onwards the "Innsbruck" design rear end (shared with saloons Triumph 2.5 and Stags amongst them) has shown to be a little more delicate. At 50 years plus old these parts on the highly stressed parts of the car (includes front hubs and stub axles also) are slowly dying from old age. Unknown violence and just hard work with repeated flexing operations and the application of modern tyres and compound mixes giving increased grip levels are stressing these components up to and beyond the limits to failure. Go ask a BMW design engineer if he thinks ANY of the current models would be safe on these components in 50 years time and he would go pale. 

Have a look at 2 rear hub failures shown here, fitted upon a Stag they were obtained from one of the specialists after they had been "refurbished" by them. After 3 months this happened to one 

 

 

And then this happened to the other

 

This owner was lucky, neither of these failures which caused wheel losses to happen caused the car to become inverted...but it has happened to TR owners, we tend to drive them like "Jehovah" ...ie furiously, a bit different from a Stag driven by a Nun wearing slippers ? The operation of splitting these hubs for a new rear hub bearing fitment vey likely caused the problem, a 20 ton press and heating up is often the only way to get them apart, and their venerable age probably did the rest. No...crack testing would unlikely find these faults (RogerH is de man on this, that's why we listen to him), a lifetime of non destructive testing trying to keep various planes safe has given him a keen understanding upon what is possible and what could be missed.

No Pete, we wouldn't want to change all of our cars components, but given that a serious accident could be the result if these let go sometimes a change onto new components is very much a good decision.

Mick Richards 

Edited February 25, 2020 by Motorsport Mickey

[Waldi]

My take on this is that age in itself does not deteriorate steel parts on our cars, either made from bar, castings or forgings.

A bit of background:

Many (many) varying loads, and especially reversing loads can introduce fatigue. But a variation in loads in itself is not an issue, as long as allowable (localized) stresses are not exceeded. The Smiths-curves show this, google it. Here you can see a component can fail at a much lower stress level that for a normal continuous applied stress (load).

The allowable stresses reduce with increase of the number of cycles, but typically for over 100.000.000 cycles does not reduce further, below is an example.

If the stresses are below a threshold, which is material specific, fatigue will not occur, also not after millions of cycles, as you can see.

But:
Slight surface damage, either from wear or corrosion or an occasional overload change this completely. Now very localised peak stresses can appear, and suddenly fatigue failure can occur on a component that would otherwise not be susceptible to fatigue.

The moral is:

If you have had an accident, or hit a curb stone etc, safety critical components are best inspected. But there are no clear guidelines (not from me at least).

If you see damage on say a stub axle: replace it. Even a scratch can be the initiator, if located in a higher stressed area.

What did I do:

During my restoration I visually inspected my VL’s after cleaning and grit-blasting, and found that sufficient when I did that. If I would do this again, I would use more advanced techniques which are used common in several industries. But I’m not going to replace them.

My front stub axles I simply replaced with new items from a trusted supplied, that was a no-brainer for me

My old rear hubs are still on the car, but on my list for an upgrade later. I simply have not decided if I will go the full route (CV’s including other type diff), or just CV axles or just new hubs. Too many issues with any of these solutions are reported on this forum. I don’t want to be disappointed after spending a lot of cash.

Regards,

Waldi

[ianc]

Mick describes the design of the suspension of the IRS cars from 4A onwards as "more sophisticated".

Hmmm - not the description I would use.

Without any doubt, more complicated, but, as we started to discover from the mid-1970s onwards, prone to numerous failures.

First, the suspension brackets at the front pulled out of the chassis.  Then similar things happened with the semi-trailing arms and the differential.

More recently, the drive shafts and hubs are failing.

OK, Triumph's people might not have expected the cars to survive this long, but I cannot accept that as an excuse for such bad design and the failures.

Thank goodness for the tough, unsophisticated and long-lasting TR2-TR4 beasts.

Ian Cornish

[BlueTR3A-5EKT]

Topic Drift.

There is a bit of conversation about the ultimate strength of the Girling rear axle.  Notably the hub bearing being carried on the shaft rather than hub mounted in bearing that is carried on the axle tube.

To this the TR7 5 speed axle (derived from Rover SD1 axle) is probably a stronger unit.

Discuss.

Peter W

 

[stuart]

19 minutes ago, BlueTR3A-5EKT said:

Topic Drift.

There is a bit of conversation about the ultimate strength of the Girling rear axle.  Notably the hub bearing being carried on the shaft rather than hub mounted in bearing that is carried on the axle tube.

To this the TR7 5 speed axle (derived from Rover SD1 axle) is probably a stronger unit.

Discuss.

Peter W

 

I believe one of the American racers has a solution to that with a redesigned axle end.

Stuart.

[RogerH]

19 hours ago, Rob Salisbury said:

My brother had an almost identical breakage on the suspension of his Scimitar GTE around 5 years ago, we put it down to those wretched sleeping policemen, he was living in Central London at the time and could not go more than a couple of hundred yards before encountering yet another one.

Cheers Rob  

Looking at where the crack started (black mark with red circle in pic above) riding up onto a sleeping policeman would not cause the break. 

This would compress the inner radius at the top of the VL

It would need the suspension to fall completely down (wheels in the air) and then stop suddenly with the top arm on the turret to cause the crack. 

How fast was your brother going over them.

Possibly a very seized top ball joint may give enough bending stress when the VL is moving upwards.

 

Roger 

[Bfg]

Adding a little context .. from the original post  < here >

This suspension was on a 2.8ltr Middlebridge Scimitar with a kerb weight of 1226 kg (2703 lbs),  with a different weight distribution from that of the TR6  @ 1130kgs (2491 lbs), or the TR4 @ 966 kgs (2130 lbs).         Disclaimer.. these arbitrary 'internet' kerb weight figures are most likely not so very accurate but they might be a consideration re. front suspension loads.

Original Post - Quote :     ... "just exited a roundabout not even up to 30 when it broke. Got the car off the main road in reverse - did not like going forward.  I have never heard of one failing either - threads wearing away yes"  ... "Trunnion was a little tight but I have had worse and the upper ball joint was not seized - plenty of grease in it" ... "No sign of corrosion on the surfaces"  ..."I have no idea what may have happened to the car prior to me buying it 8 years and 17,000 miles ago and the car now has 308,200 on the clock."

 

 

Edited February 26, 2020 by Bfg