Enough to do this, apparently....
[NOTE: Quick update to highlight that the bracket in question is on a Ricciardi (Australian 105-based sports car) - the mount in question is different to the stock 105 item because it allows for adjustment of the trailing arm, and because it is welded to the spaceframe rather than a tub).
(https://lh3.googleusercontent.com/-5267Ypa4d4M/VL9417qQIiI/AAAAAAAALIk/ouL8bDEtgLg/s640/2015%2520-%25201.jpg)
(https://lh4.googleusercontent.com/-h98vp6sza0E/VL9411KV4DI/AAAAAAAALIw/MDyp5zQVJ3A/s640/2015%2520-%25202.jpg)
Depends, how big is the driver?
Like most of life's problems this one can be solved by welding!
Looks like a bit of bracing wouldn't go astray there either, very minimalist mount design...
The trailing arms take the reaction force from braking/accelerating so the go through very cyclic loading
lucky you caught it when you did
Quote from: Colin Byrne on January 22, 2015, 07:44:02 PM
Like most of life's problems this one can be solved by welding!
Looks like a bit of bracing wouldn't go astray there either, very minimalist mount design...
The trailing arms take the reaction force from braking/accelerating so the go through very cyclic loading
lucky you caught it when you did
:) Yep, Hugh is going to improve the bracing during the repair. Will also apply the same improvement to the other TA and to "last" Ricciardi chassis that Monza are currently completing for another customer.
Interesting question of whether this was the result of cumulative wear and tear (car is 25 years old this year) or a particular incident (I did bottom the suspension out in the Winton paddock during the 6hr weekend).
Either way, really really glad that it didn't break at Broadford.
Been getting any brake hop in the rearend?
looks like a fatigue failure to me, is there any corrosion at the start of the cracked metal?
Quote from: Colin Byrne on January 23, 2015, 12:28:27 PM
looks like a fatigue failure to me, is there any corrosion at the start of the cracked metal?
I don't think so, but it's possible. Need to get the bulkhead panel out to get a really good look at it from the top.
Quote from: LaStregaNera on January 23, 2015, 12:07:32 PM
Been getting any brake hop in the rearend?
Interesting question - no, but now you mention it I was getting some judder and wheel skip accelerating out of the slow right hander at Broadford. I assumed it was the LSD locking/unlocking as the axle hit the anti-droop strap (which needs lengthening) and picked the inside wheel up a little.
Looks like fatigue over bad design....the mounting should have been made at least as strong in all stress directions as the stock 105 mount is, and should be attached to something of equal integrity......this one look like a nice pot-plant hanger, but maybe not a suspension anchor!
Perhaps a good case in point for why changes to club registration rules are being made.
Cheers,
Vin
Quote from: vin sharp on January 25, 2015, 08:03:00 AM
Looks like fatigue over bad design....the mounting should have been made at least as strong in all stress directions as the stock 105 mount is, and should be attached to something of equal integrity......this one look like a nice pot-plant hanger, but maybe not a suspension anchor!
Perhaps a good case in point for why changes to club registration rules are being made.
Cheers,
Vin
No argument that this is a weak point that should (and will be!) addressed, but I'm not sure more inspection of the design/implementation would have made a difference. This isn't a home-made modification, it's part of a chassis that was designed by experienced mechanical engineers to meet the ADRs circa 1990. Both the design and this physical chassis were engineer-inspected by road authorities and approved before the car was originally registered. This particular car has been on hoists in any number of workshops, and this design flaw has never been picked up.
I had thought that the changes to the permit rules were to weed out inappropriately modified or poorly maintained cars. Personally I welcome scrutiny of my car and suggestions to improve it - I certainly don't want to find myself heading into a wall (or worse, someone else's car) because of a mechanical failure - but if club inspections were to start questioning unmodified designs that are road-legal and ADR compliant, I can imagine there may be pushback from some quarters, and I'm not sure where the club would stand. Is it legally defensible to demand a higher/different standard for a club permit than for a standard registration?
I think this is a can of worms best left unopened for now to be honest.
For general info:
There are few mechanical components of vehicles that are only required to have physical testing for strength to be certified to the ADRs.
The ones that do are mainly ones related occupant protection: ADR 2/-- (Door latches and hinges), ADR 3/-- (Seats), ADR 4/-- (Seatbelts) etc....
Collision ADRs (69/--, 73/--) are measured with the resulting forces on an occupant (Crash test dummy): forces measured by load cells in the head, neck, legs etc.... How this is achieved is not specified (be it vehicle design through crumple zones, an airbag or blow up rubber duck etc).
ADR 62/-- (Mechanical connections between vehicles) include fatigue... These include the actual coupling components, towbars and drawbars that must be tested by cyclic testing (for fatigue) and/or static loading.
The design and safety of a vehicle outside the requirements of the ADRs (e.g. strength and durability) such as the chassis and suspension components are governed by the Australian Consumer Law (ACCC): Fit for purpose / Will or may cause injury for expected life and usage of the vehicle.
Modified, kit cars and ICVs get a bit greyer: This is where the authorities basically take a bit of a step back and let an Automotive Engineering Signatory decide what methodology they wish to use to certify a chassis design or modification. This may be as advanced as Finite Element Analysis, simpler such as comparison to existing design, or crude as: bigger is better! Whatever method they choose, they wear the risk of litigation if someone gets hurt (hence a requirement for rather expensive insurance that must be maintained by the engineer for several years should they cease certification work).
I agree with Vin. As an engineer, I say it is one piece one of B-grade auto design/manufacturing... A simple visual analysis of the force vectors on the mount shows the likely failure mode (which is what happened).
Quote from: LukeC on January 27, 2015, 01:50:46 PM
For general info:
...
Thanks - some useful detail :)
Quote from: LukeC on January 27, 2015, 01:50:46 PM
I agree with Vin. As an engineer, I say it is one piece one of B-grade auto design/manufacturing... A simple visual analysis of the force vectors on the mount shows the likely failure mode (which is what happened).
Indeed - I don't think anyone disagrees (certainly not me!). My point was that a lot of qualified people have looked at the design and the chassis over the last twenty five years and either not spotted that, or not believed it was a big enough problem to change it.
It will be changed now, on my car and on at least one other chassis, and part of the reason for posting this thread was so that other Ricciardi owners might find it if they do a search for Ricciardi material online.
On most production cars where problems like this show up, they are generally found in the same circumstances and then the shortcomings and alternative fixes can be worked through. At that point it becomes a check and fix as cars come in.
I don't think there is anything different in this case; yours probably being the first to show the problem. On inspection and with the failure in plain sight it is easy to see why it happened.
The main thing, as you say, is to now notify and or check with others of the model to avoid other failures.
These cars were Rick's (Hardy) pet project in his shed between court appearances......no nothing shifty, he was a sitting magistrate at the time!
I visited Rick at his house when the first couple were being made. I believe that under the SA regs at the time, not a lot of engineering certification had to be done because they used part of the original 105 firewall/front end which allowed a short cut to registration as an Alfa Romeo of whatever year the chassis number was.
Quote from: vin sharp on January 27, 2015, 08:40:27 PM
I visited Rick at his house when the first couple were being made. I believe that under the SA regs at the time, not a lot of engineering certification had to be done because they used part of the original 105 firewall/front end which allowed a short cut to registration as an Alfa Romeo of whatever year the chassis number was.
That would have been interesting! I've heard differing reports on whether Rick still has his car.
My info is the same - there was a registration short cut based on the amount of 105 chassis retained, but I'm not sure what that actually entailed. I've seen documents asserting that the design is ADR compliant for the late 80s/1990, but as Luke points out above, that might not mean a lot!
I know that there was an engineering report done for the overall design - I saw a copy a few years ago and it was certainly long, but I don't know how comprehensive/thorough it was. I recall looking through diagrams of the various chassis sections showing load in the various directions and calculations for the required strength, but I don't recall whether the suspension mount points were part of that. I've been trying to get my own copy of that document for some time.
Have been reading with interest and the replies.
Just my opinion,,
its not a 105 original front mount for a rear lower control arm.
The pictures show a 3 hole mount to lower or raise the arm,,which is not original,
Originally,a 105 has a single hole to mount the arm to the body.
The above car is a modified car with a modified suspension mount that is not a 105.
As Colin B says,,extra welding,especially above the modified bracket,,would have maybe been better.
The car is not a 105,,it does not have a factory pick up point part (3 hole mount),so I can not see what the fuss is all about.
This topic should be put in another area= modified cars ,so not to confuse Alfa 105 owners,or potential 105 owners about a problem that does not exist.
Quote from: giulia_veloce on January 28, 2015, 08:09:22 PM
Have been reading with interest and the replies.
Just my opinion,,
...
Sorry for the confusion - assumed people would realise from the pics and discussion that it's not purely a factory component. In fact that's what a lot of the discussion has been about :)
I've no objection if the admins feel there's a more appropriate part of the forum (Evan?), but there is quite a bit of discussion of heavily modified 105s here - Colin's panhard rod setup, TS conversions, etc.
I put it here because it's where the 105 experts are, and while this is not a standard component (or a standard car), it is mechanically a 105, with 105 rear suspension geometry and forces, so opinions from the 105 cognoscenti are useful and informative.
(btw, thanks again Rob for the 4.1 LSD I bought from you last year - makes a massive difference in this car).
All good tjb0274 ( forgot your name )
Was a good discussion,,but because its not a factory original part problem,I did not think it was relevant in this section with many not knowing what they were looking at,and confusing them.
The good thing is that you few Riccardi owners can discuss your problems and the many thousands of 105 owners can discuss theirs.
I suppose you were not aware it was not a factory mount.
Hugh and the Monza boys will make it a fun car for you.
Have seen a few vids of the Riccardi being driven spiritedly around race tracks in Victoria.
Looks like a good fun car,power to weight wise.
Glad the diff I supplied works well.
Just found a few more I had hidden.
Those 105 LSD can take a beating
You tube = alfa romeo junior zagato motorkhana to see how much fun the diff is.
Chats soon
Robert
Quoteut because its not a factory original part problem,I did not think it was relevant in this section
mmm, guess i better find somewhere else to post then
Rob, do you hang it with PSK from alfa BB much, think you too would really get along...
Easy up Colin. I was about six messages into reading this thread before I knew the discussion wasn't about a stock Alfa 105.
That's pretty unacceptable, in my view.
The OP should have made it obvious that it was a Riccardi and there would have been no problem discussing it here.
Perhaps tjb0274 can go back to edit that post to avoid misleading future readers?
Quote from: cjheath on January 29, 2015, 11:02:48 AM
The OP should have made it obvious that it was a Riccardi and there would have been no problem discussing it here.
Perhaps tjb0274 can go back to edit that post to avoid misleading future readers?
Fair point. Updated :)
I edited the original post, so the fact that this is a Ricciardi is in the title also as well as Tim's post update.
I think that's enough, there's not really another part of the forum for discussion of modified cars to go into and I'd rather not create more boards.
Scary picture. It's a good reminder to have a good inspection under your car on a regular basis, especially if used on the track.
QuoteEasy up Colin.
Yea fair enough, was a bit aggressive, I apologise
just getting a little tired of being told what is and what is not a 105 that's all
Quote from: Evan Bottcher on January 29, 2015, 02:18:43 PM
I edited the original post, so the fact that this is a Ricciardi is in the title also as well as Tim's post update.
I think that's enough, there's not really another part of the forum for discussion of modified cars to go into and I'd rather not create more boards.
Scary picture. It's a good reminder to have a good inspection under your car on a regular basis, especially if used on the track.
:) Thanks Evan! Yeah, it's definitely good to have a close look at everything before a run. It's also a bit of a reset for me driving wise. I've been driving the car harder and taking it closer and closer to my personal limits as a driver recently, and I think this is a good reminder to leave a bit more in reserve, stay off the kerbs, etc. I've posted PBs at the last couple of sprints, but at Broadford was definitely a little ragged and harder on the car than I should be.
Quote from: tjb0274 on January 29, 2015, 03:41:54 PM
... leave a bit more in reserve, stay off the kerbs, etc.
LOL - the only time I had significant subframe cracking in my 105 was after a kerb incident. It turns out that reversing out of a carpark in a quick U-turn can cause kerbs to appear that weren't there before... memories of when I was young and foolish (now I'm just foolish!).
Quote from: Colin Byrne on January 29, 2015, 09:51:57 AM
Quoteut because its not a factory original part problem,I did not think it was relevant in this section
mmm, guess i better find somewhere else to post then
Rob, do you hang it with PSK from alfa BB much, think you too would really get along...
Hi Colin..
There are many ways to answer your reply.
I will do it this way.
I have no problems with what you are doing with your modified Targa car.
I have no problems with anyone modifying any 105 or any car.
But I do have a problem with what was written about a faulty 105 part that was not original.
Be back soo= dinner on the table,,and I better think what I should write about your PSK remark
Back again,
Colin,,I think you are missing the point here.
And your PSK comment is way out of line.
Colin,,I read with interest what you are doing with your 105.
Great modifications you are doing to YOUR car.
Modifications that You like and suit You.
I have no problems with modified cars at all.
Those that know me,,and you obviously don't,,know how many cars I have modified over the years.
The original starting post said a problem with rear trailing arm mount failure.
For those of you out there that are wondering what all the fuss is,,,,,Go to the first pictures of this thread.
Yes,,a problem has occurred where the mount has cracked+ pulled away from the body.
The mount,,with 3 holes,,and bolted thru the middle hole,,is not an original 105 factory mounting.
So,,in my opinion,,and many others who know these cars,,there is NOT a 105 production road car problem,,The problem is a welded non original mount that was not adequate and caused a failure.
Have a look at it Colin.
What would you have done with this bracket.
Now it has failed,,it needs to be fixed.
But its not a 105 problem.
Now to the PSK bit.
Don't you ever classify me with another member that you might not agree with.
He has an opinion,and so do I
Many value my opinion,,cause of my background.
Many like me,and many might hate me,,but please don't put me in a PSK category.
Maybe you should find out who I am,,and how many cars I have modified + raced before you think I don't like modifications.
I modify cars all the time.
Colin,,keep up the great work with YOUR modifications and most importantly,,have funbuilding the car and raceing it.
I will wait to hear your response,and retract my association wIth PSK and his opinion responces
On a brighter note,,Get Smart is on TV.
99 never ages,and is still yummy,,IN MY OPINION.
Robert
Full retraction of the comment, as I said in previous post I realised it was a bit harsh and out of line like you said I don't yourself so was not an appropriate comment to make.
from my point of view it was very clear what the original post was about and I wrongly assumed that others did as well
All good Colin.
Its 10pm,,so go out in the garage and continue working on the 105 project and send us some more pictures.
Will be waiting for your opinion on the steering rack mod.
Hope its all positives.
We might even get some interesting responces from PSK.
Most of us wait in anticipation for the next update episode of = Colins Targa Car
On a brighter note,,we are all here as friends and enthusiasts and for fun.
Sometimes topics can be entertaining and responces ridiculous,,but hey,thats how it is.
Lets all enjoy our passion ( Cars) together,and discuss things in an interesting manner.
We all learn from our mistakes,and learn from each other.
Hey Tim!
I told you a can of worms would be opened! haha!
Divano Veloce
Post whatever you like
Makes good reading.
Standard,modified,race cars,,I like reading it.
But when a modified car or part fails,,it should not make other owners with standard cars, think they have a problem.
This thread became confusing to the new readers when the title got changed.
Quote from: Divano Veloce on February 02, 2015, 09:20:56 AM
But i dont think its acceleration/braking thats started the cracks. It looks to me like the trailing arm is twisting the bracket off the chassis. THis twisting along with the stress concentration at the top edge is the problem. The solution is to remove the stress concentration where the cracks originate by a simple redesign of the brackets.
What bushes do you have in the trailing arms?
Agreed on the bracket design. It's hard to know when the crack first started - the driver's side brackethas no discernible cracks. Could be from long-term cumulative stress (the chassis is 25 years old), or it could have been a specific high-stress incident - the axle was hopping under hard acceleration at Broadford, and I was hitting the curb hard through the esses.
The TA bushes are standard rubber items.
All good Divano Veloce.
As said before,,this thread became very confusing to many people and there were lots of opinions,,including mine.
Keep up the good work guys,,and the modifications.
Some mods are interesting.
Some make great reading.
And there will always be opinions.
Its pretty hard to see from the photo's, but the nut side looks like a weld quality problem. Once one side started to fail, the other side would follow due to increased loads.
Ordinary road loads are pretty easy to calculate, but that's not what causes problems. It will be impact loads from corrugations / potholes, etc that do the damage and these are nearly incalculable. Car companies use real world testing or rig testing based on data collected from real world driving for this.
The other thing that can cause loads sufficient for failure can occur at full suspension travel (ie full droop) if there is any misalignment of the linkages.
Simply re-welding it is not really adequate because of the fatigued parent metal and heat affected zone from the original weld. Either cut out a section and do it again, or re-weld the crack then add some gussets.
I think this thread has served its purpose, enlightened some, puzzled others, even an insult or two. Closing it now. Thanks!
Also: "Remember it's all just opinions"!