Corse I rear suspension failure

[hollytree]

LuckY I took today to check things over before driving to Stoneleigh tomorrow.
Rear right upper wishbone rear weld has failed/ripper.
The front mount weld is also damaged and allows the mounting tube to move left to right.
This allows the wheel twists and the damper spring then makes contact with the wishbone. Obviously the toe in goes all over the shop.
Anyone haD similar problems and how did they fix them?
Anyone know a good mobile welder in St Albans as engine will have to come out?
Anyone know any dimensions so I can make sure any welding is back in the right position.
Craig said something about beefing up Corse I rear mounts but I assume mine had been done?

Thanks
Steve9579

[turbonutter]

Yet another corse I failiure....

This has been covered a few times on here, or the old site. Yours has not been modified, See below how my chassis was modified by Arthur before I bought the car, as it failed 8 years ago..

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I am not saying that this is the best way to do it, but this has worked for 8 years, including a few with the turbo engine... I did have to re-do one side, as when the strengthening had been done, the pivot tube was in my opinion not corectly aligned. I dont have any dimensions, but the tube should be parallel to & in line with the lower chassis rail, so horizontal & pointing straight forwards

[hollytree]

Neil
Thanks.
Just need to find someone to do it, a I can't weld!!
Regards
Steve

[hollytree]

Neil
I will buy some steel and start making plates like yours. What thickness please?
Ta
Steve

[Strat Fan]

Here's a couple of pics of one I did about 8 years ago. I used an extra tube to brace the bracket & then filleted it inside & out with 3mm plates. This was on a Thema 8.32/Ferrari version of the chassis.
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[hollytree]

Here's a couple of pics of one I did about 8 years ago. I used an extra tube to brace the bracket & then filleted it inside & out with 3mm plates. This was on a Thema 8.32/Ferrari version of the chassis.

Craig
Thanks
As I am taking the engine out, should I switch to one of your cable gear change setups?. Do you do 5 speed to fit the Corse tub?

Regards
Steve

[mariner]

Hi,

Slightly worrying to read this thread having just driven to and from Stoneleigh but after a quick check this morning found no problems with my car.
Another project now added to the list - will probably be much easier to modify and beef up in some way before any breakage.
Hopefully fabricate something with engine in with a view to improving at a later date next time engine out.

rgds Bob

[john]

Bob, surely you've heard about this problem before?
Steve, that is worrying with so little use.
It looks as if the box section has actually torn from the photo. Is that correct?

[hollytree]

Bob, surely you've heard about this problem before?
Steve, that is worrying with so little use.
It looks as if the box section has actually torn from the photo. Is that correct?

The weld on the tube section has completely torn away from the tube. This allows the wishbone tube to rotate and this has torn the weld out of the box section. The white line is the shiny bare metal from engine side.

9588
750 miles total.

[mariner]

Bob, surely you've heard about this problem before?
Steve, that is worrying with so little use.
It looks as if the box section has actually torn from the photo. Is that correct?

Hi John,

No not heard about this before other than knowing about Neil's/Arthur's which I had obviously wrongly thought was a one off problem.
Never mind there seem to be a few ways to rectify it especially as mine isn't broken yet.

rgds Bob

[john]

Right, so it looks like the top forward wishbone mount has failed and that has allowed the wishbone to twist backwards and in so doing that has torn the corner of the square tube as the weld has broken away.
If you intend to follow the advice here I would not rip the engine out just yet as you need to ensure that the extra plates, tubes or whatever you add in do not foul anything. Particularly at the gearbox side as the box is very close to the frame.
It goes without saying that you will mod both sides of the chassis while you are at it?

[john]

I'm surprised that you were unaware of this Bob.
It happened to Dave Carson's car while both Hugh and Dave were out playing in it, although allegedly they hit something hard to initiate it. But other early Corse I cars have also had to be modded. Neil/Arthur's car included but also Tony Aylot/Jan Leach's car and the other V reg Corse which was rallied from time to time. The guys name escapes me now, (Richard somebody??), but he modded his rear frame completely to allow the rear of the cradle to be removable.
This was the driving force for the mods which were carried out to strengthen the whole back end and make all the wishbone mounts double shear, as well as to allow eas fitment of the 24valve engines and exhausts. This coincided with moving the chassis production to CAGED at Frome, but only one chassis was built there to the correct modded drawings.
Sadly Steve's chassis was the last built at Skipton where there was, perhaps, some "inertia" to change and something of a disinterested attitude brought about by Lionel's insistence that they were charging too much!

[Bernard]

John

was it Richard Gibbons ??........ that name rings a bell with me..... a Red car with yellow inset around the front indicators and white wheels.........

only have this photo from Abingdon 2001

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[john]

That's the fella Phil. Well done. Yes, the rear of that car had been radically reworked.

[hollytree]

Right, so it looks like the top forward wishbone mount has failed and that has allowed the wishbone to twist backwards and in so doing that has torn the corner of the square tube as the weld has broken away.
If you intend to follow the advice here I would not rip the engine out just yet as you need to ensure that the extra plates, tubes or whatever you add in do not foul anything. Particularly at the gearbox side as the box is very close to the frame.
It goes without saying that you will mod both sides of the chassis while you are at it?

John
I have taken plenty of photos, and I think the mod that Craig posted will work. I think the engine needs to come out to do the repairs correctly as access is difficult.
I may also take the opportunity to convert to a cable gear change if Craig tells me I am suitable!

Steve

[john]

Yes, I understand that you will need to take the engine out eventually to gain full access for the welding. It's just a cautionary note to say don't do it straight away until you are sure everything fits together.
Craig's gear change will undoubtedly work well on your set up. I fitted one to Frederics Corse without difficulty. That was an S chassis but no significant differences to yours I can think of for gear change purposes. It's cable after all. A degree of flexibility is in built!

[turbonutter]

John
I have taken plenty of photos, and I think the mod that Craig posted will work. I think the engine needs to come out to do the repairs correctly as access is difficult.
I may also take the opportunity to convert to a cable gear change if Craig tells me I am suitable!

Steve

Whats the reason to change to a cable gear change, the corse rod change I had on my alfa box was one of the best I have used....

[hollytree]

Looks like mine is a hybrid mongrel stage of design
It seems I have the additional tube support that Craig suggested I get welded in to match what he did (see above), but mine has not been filleted, nor does my bracket drop from the higher diagonal tube thus mine does not get the extended lever with a mid span brace.
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[john]

That's probably not a bad way of putting it. Clearly Craig's pictures show a better solution which is probably the best you will get without completely remaking the rear of the cradle to the last incarnation.
I'd take the advice of the Project Binky boys and carry out, as they call it, a CAD exercise. Cardboard aided design!
Your photo of the left hand side shows how close the gearbox casing is to that wishbone mount. The nut is hidden behind part of the casing.

[NoCorseChris]

The weld on the tube section has completely torn away from the tube. This allows the wishbone tube to rotate and this has torn the weld out of the box section. The white line is the shiny bare metal from engine side.

9588
750 miles total.

The mod looks OK-ish. Not ideal though as it's still in single shear but certainly better with it than without it, but it was let down by zero penetration on that weld by the look of it. Given the situation, reworking what you have there already to copy Craig's solution looks like the best way forward. You should be able to do that pretty easily once the damage to the right side has been resolved as you already know it will clear OK.

Could even consider a combination of that and Neil's solution for a proper belt & braces job.

Tim Page had his car modded after we spotted the same flaw. Sadly, the guys that did it took two stabs as the gearbox fouled their first effort.

Still amazes me that either Steve and/or Hugh let that go - seems so out of character. :(

[hollytree]

3 hours, engine and gearbox out

steve

[john]

I think Steve's input had ceased by the time the Corse moved on to Alfa specific engine cradles, although it seems the rear suspension on the Corse I was always a work in progress.

[Strat Fan]

The first I chassis was the Honda version, this was the Gary Midwinter rally car that later moved on to Bernie Roonie. This was a Litton product, The first Ferrari based I chassis was also manufactured by Litton for Hugh Carson which is the yellow chassis seen in the Italian Super Cars guide. Darkspeed's Honda I was also a Litton era chassis.
The Alfa based rear cradle was developed by Hugh Carson & his brother David in circa 1992/3 around the same time that Neil fitted the 3.0 12v into his S chassis. Steve by this time was long gone so in reality probably never saw any of the Litton I chassis cars make it onto the road let alone have time to witness any failures.
CAE ceased trading in 1999 so again very few of the cars they produced would have done enough miles to show the limitations of the design.
The Ferrari & Honda cradles were lower which in turn made the offending hanging bracket less remote and less susceptible to leverage issues. The Alfa cradle was a lot higher which made the wishbone bracket very long & susceptible to fatigue.
Steve (Hollytree's) chassis has had an additional tube fitted but it is still too remote relative to the bracket & the second error in this case is that the bracket is not carried through to the upper tube for additional strength, the quality of the welding must be brought into question in this case aswell as the limitations in the design.
David May ran a couple of simple bolt in braces which prevented the fatigue issue from raising its head. Bob has a similar brace across the rear of the top wishbone mounts which can only help, a simple triangulated bolt in brace to the forward mount would also be a huge benefit.

[NoCorseChris]

Thanks for the extra info chaps.

It is easy to see problems with the benefit of hindsight isn't it. It's not as if chassis cracks on kit cars are unheard of either. Some big names in the business have suffered from that over the years.

Absolutely it's fixable, just somewhat of a shock to discover on ones own car I imagine!

[john]

Exactly as I understood the situation.
As I found it the production of the later I chassis left much to be desired and was a stark contrast to S chassis production.
I say this because there was a full set of drawings for the S. Properly drawn with full material specs and every engineering detail. All were notated as drawn by SG.
There was also some continuity in production.
The Alfa I chassis drawings were never complete, sparse in detail and dimensions and most fabrication was done from detail contained in a red hardback notebook at the fabrication shop. This had been passed down from the S chassis fabricator.
Sporadic production cannot have helped either as lack of continuity meant that critical dimensions and details may well have been missed. Development would also suffer, naturally.
Couple all this with a complete disinterest at the fabrication shop who really did have better and profitable things to do, and no wonder that things went wrong.

[GrahamH]

Exactly as I understood the situation. As I found it the production of the later I chassis left much to be desired and was a stark contrast to S chassis production. I say this because there was a full set of drawings for the S. Properly drawn with full material specs and every engineering detail. All were notated as drawn by SG. There was also some continuity in production. The Alfa I chassis drawings were never complete, sparse in detail and dimensions and most fabrication was done from detail contained in a red hardback notebook at the fabrication shop. This had been passed down from the S chassis fabricator. Sporadic production cannot have helped either as lack of continuity meant that critical dimensions and details may well have been missed. Development would also suffer, naturally. Couple all this with a complete disinterest at the fabrication shop who really did have better and profitable things to do, and no wonder that things went wrong.


Bad design in my view , poor understanding of loads and load paths , pretty shocking . Lucky it's easily fixable and hopefully before anyone has a major off.

[john]

Indeed. One of Carroll Smiths mantras was "Never ever put a load into the middle of a tube". And that is pretty much what was done there.

[mariner]

Hi,

Finally got around to hopefully sorting this potential problem on my car.
Made a simple bolt in bracket which runs diagonally from the front wishbone bolt back to the rear chassis.
Fairly straightforward for me having previously modified the rear chassis there was already an attachment point I could use.
When the engine was last out I had replaced the long diagonal tube with two shorter ones to give more room for the exhaust and at the same time fitted a brace across the car between the rear wishbone bolts.

rgds Bob


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