Broken CSR Rear Upright - Any Experiences?

[Blue C7]

Would I be wrong in suggesting a careful cut either side down until close to the thread and then split the Ali from one side

[MarkTheGoose]

You would not... although, current Plan A, is to put a pair of bolts through the slots and then a plate across those bolts, so that I can effectively attach a long bar to the bottom of the black bit. It's then going upside down in the bench vice, which will grip the flats on the bit that goes through the wishbone...

Suspect that I might be back in a bit to ask how to reattach a vice to a broken workbench!

[Blue C7]

Sounds like a good plan A

[aerobod - near CYYC]

It looks to me like the failure was due to stress corrosion issues. If the boss area each side is 14x4mm, the total area taking the stress would be 224 square mm, which would have a yield strength of 6 tonnes for billet machined 6061 T6 aluminium (the most likely alloy used), which would be fine if the area is crack-free.

You can see two small cracks on the "good" side, which would be under severe bending stress due to the previous failure of the other side. Salt water corrosion mixed with stress could have caused the problems, always a problem in the aerospace industry.

I would say this is an area for annual inspection after cleaning away all surface corrosion and preferably spraying on a crack detection dye to reveal any cracks that corrosion could be penetrating into.

[MarkTheGoose]

Gosh - 6 tonnes! Ok, agreed, with no cracks, that's plenty, especially as there's 4 of those 224mm2 areas in total. Assuming having the part made is not silly money (I'm waiting on answers on that currently), I'm going to replace both sides, just to be on the safe side and then agreed, it's something to keep a close eye during future servicing

[aerobod - near CYYC]

Each side of one boss is 56 square mm, so 224 in total.

It seems a straight forward piece to machine for a competent machine shop with a CNC machine. For a greater safety margin the boss could be increased in thickness. It shouldn't take a competent drafter more than 30 mins to measure and create a CAD file to be used in the CNC machine. Material should cost about £5 for the 6061 T6 billet stock and about 2 hours of labour for the drafting, setup and machining time for a pair of components. Hopefully less than about £150 for the pair.

Assuming you can carefully remove and reuse the four pressed-in steel bushes, otherwise a bit more cost if they need to be manufactured, too.

[Doctor]

well done mark, good progress. 

[MarkTheGoose]

Thanks for clarification - I didn't do the maths! At £150 for the pair, I'm buying - I sort of expect twice that, once the 'Caterham CSR' markup has been applied! At the moment, I've only spoken to Chris at Redline and he's confirmed that there are none and is now checking leadtime & cost. Depending on what he says, I'll probably follow up Igor's suggestion to go and ask Titan as they originated it ...

The bush (they call it a 'top hat spacer' in the build supplement) came out of the broken one easily - tapped out with an 8mm socket as a drift. There's only one spacer on each side of the car, just where the threaded part of the bolt goes through the alloy.

[Wrightpayne]

I wonder why the tophat isnt the full depth of the aluminium - wouldnt the short tophat concentrate the loading?

 

[aerobod - near CYYC]

The tophat only seems to be there to give a firmer surface for the damper bushing to be pressed against, as opposed to indenting into the aluminium due to the small surface area. The nut and bolt faces have a larger surface area (especially if backed by a washer), so don't have the same indentation issue. One thing I would be sure of is that the damper bushing is a tight sliding fit between the two tophats, any play here will cause an over-stressing of the aluminium bosses when the bolt is tightened.

[Bob L]

From the picture would it be possible to use decent mole grips to perform removal.  

[bjw]

One thing I would be sure of is that the damper bushing is a tight sliding fit between the two tophats, any play here will cause an over-stressing of the aluminium bosses when the bolt is tightened.

That would be a horrible design. However, the diagram shows a split bush (15) at the bolt head boss rather than a top hat, which I would guess is free to slide in the boss to take up any minor variations in the damper bushing length ?

Cheers

[Hanns Per]

this is the bolt,  on the RHS side of the car the bolt head is showing to rear end and on the LHS the head facing to the front end,  if I am correct the split brass is the sliding side so it important to have it well lubricated that is does not get tight.

[Englishmaninwales]

#33

I wouldn't hold your breath waiting for Titan to help you out, their relationship with CC is watertight. I discovered this trying to get the K series dry sump pan re-manufactured about 6 years ago (when it was unavailable).

Malcolm

[Doctor]

I had an issue with the CSR oil swirl tower. Spoken to both parties, get it obvious to the level of embarasing and then CC made the order and Titan did the work. 

[MarkTheGoose]

Some new lessons learnt this morning. I decided to dismantle the good (right hand side) clevis as I'm increasingly thinking that I'm going to need it as the pattern for having a new part made. However, annoyingly, the final allen bolt didn't come out (everything else was a breeze) and instead, the impact driver just spun inside the bolt head. I did then try the great big mole grip, but the bolt is not for turning. You can see in the picture, that I was able to move the clevis with a spanner between it and the upright, so I suspect that the problem with the allen bolt is all about the thread being stuck in the upright. Not sure what to do next, I'm swaying between putting it all back together and leaving it alone (& working) or grinding the top off the allen bolt and then hoping I can get the remaining 'stud' out of the upright. Problem here is the upright is softer than the bolt and I'm really concerned about damaging it and having another larger more expensive part that's not available to buy!

This other picture shows the two bolts that go through the clevis & damper (not as shiny as yours Hanns Per!). Because my eyesight is poor, I hadn't actually realised that the first bolt I took out had two spacers stuck on it - I thought it was just a long head! As for your comments Hanns about keeping it lubricated, those spacers are properly corroded to the bolt.

The small bolt is the one that I did get out of the upright on the good/right side and shows clear signs of loctite

[elie boone]

To break the Loctite you could try to wack the head of the bolt with a hammer, wel with a chase inside the allen head of the bolt

[ScottR400D]

Could you weld a nut on to the head and remove it that way? If the thread in the upright is damaged you could always put a Keensert or similar in.

I see that CC say they have full upright kits in stock, including the part you need. I wonder if they'd split, but feel it's unlikely. They're pretty poor at making individual parts available if they think they can sell you a full kit for silly £, IME.

The earlier post about Titan is right too, again, IME. I got a set of RBTBs from them a few years ago, at much less than CC charge. (Same thing, just branded Titan). I've recently been told that they won't now supply them if they believe they're going on a 7, they refer you to CC. It's not really a surprise, CC and Titan appear to have similar attitudes to customer service.

 

[Wrightpayne]

I dont think Titan have poor customer service per say, Caterham have them locked into a contract so they can control supply / price of their parts.

[ScottR400D]

It was based on something I was told by one of the 'expert' transmission people. Apparently Titan were challenged as to why they continued to sell their LSD, with its family well known weaknesses, without properly addressing them. The answer was, supposedly, "so we can keep on selling you the rebuild kits!"

Hearsay, I know, but sort of fits in with my experience years ago with their oil pumps, which didn't seem to last long without a quite expensive rebuild.

[ScottR400D]

It was based on something I was told by one of the 'expert' transmission people. Apparently Titan were challenged as to why they continued to sell their LSD, with its family well known weaknesses, without properly addressing them. The answer was, supposedly, "so we can keep on selling you the rebuild kits!"

Hearsay, I know, but sort of fits in with my experience years ago with their oil pumps, which didn't seem to last long without a quite expensive rebuild.

[Englishmaninwales]

#44

Agreed. That killed any chance of a new pattern and remanufacture of the K dry sump pan without supply through CC. Interestingly, CC were not initially interested at all in this until they saw there was some demand and cashed in on the sale, significantly higher than the price I had achieved for similar numbers.

I see the K dry sump pan is now £775 incl tax !!!!!!!!

[Bricol]

If it's loctite, heat is the answer - but concentrated.  I have an induction heater specifically for such things - wrap the coil around the item in question and away it goes.  The suggestion of welding a nut (ie through the centre of the nut) is a good idea though.

If its corrosion - you might be looking at a bigger bolt or an insert when the existing one comes out with some or all of the internal thread stuck to it..

The skill in this sort of situation is knowing when to give up with DIY solutions and pay for an expert to do something so you can save the expensive bit.

[7 wonders of the world]

re the cap screw - clean it and pop a suitable nut over it and tack the nut the the cap screw with a MIG you can now get purchase, just be carefull not to shear it.

Vibration from a small hammer over a 10 min period with help as will a decent penetrant Plus Gas is my go to for seized items like this

 

[MarkTheGoose]

OK, a small step forwards today - in that I have more information. CC have finally heard back from Titan, who are delighted to make me a Damper Clevis (the black anodised bit in the CSR Upright assembly - which is £1,300). That's the end of the good news...

The not so good news. They want £675 + VAT and it will take 2 months. If I want the other bits, like spacers and top-hats, these are all a crazy "one off" price too! To be fair, part of the reason that CC hadn't shared this was because even they were shocked at the price and the lead time.

I'm back onto project "remove the good damper clevis and see if I can find somebody locally to make me one" ... James B has suggested a company in Warwick for me to try first...