UPDATE: SAFETY ISSUE - potential front suspension failure - Rose Jointed Dampers

[EFA]

I have just discovered that Caterham have indeed revised the spec of the bolt holding to bottom end of the front dampers to the wishbone since early 1999 when I purchased the bolts securing this fixing on my car.

 

The bolt which failed on my car (the head was missing, so i could not check the spec) was not a high tensile bolt. I have determined this as the bolt on the other front damper is an ordinary steel bolt as well.

 

The repolacement bolts are a 12.9 high tensile.

 

 

The simple way to check whihc bolts you have is by the size of the hex key required to undo:

 

7/32" means you have low tnesile steel bolts - these are what have failed with my car and its rose jointed dampers.

 

1/4" is the hex ley dia for the 12.9 bolts which are high tensile and thus far less likley to fail.

 

 

 

Fat Arn

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[captain chaos]

Cheers Arnie,

I replaced these bolts just 6 weeks ago and so will assume I have the improved bolt.

What springs are/were (pre-curboro' hype) you running on the front.

 

you should have seen Richard Inces' car at oulton on Sat. Dedion tube broke at the ear after about 8 laps. The car had come from the back to lead in that time aswell!

[CHRIS CLARK]

I thought that Jason K was ahead all the time; yes,no?

 

I do believe that Richards style of driving is somewhat 'enthusiastic' with kerbs being all part of the track. This I'm sure lead to the somewhat premature failure. Difficult to know for sure though.

[EFA]

I've broken a few ears on kerbs before. Only when the ears are shimmed with washers though. Unsafe practice this IMHO.

 

Gary, to be sure just check the head size.

 

Fat Arn

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[felix.klauser]

Interesting. The bolts that came with my widetrack upgrade purchased a few months ago are the 7/32" variety, as are the ones that came off the car. I have several of the 1/4" variety from the hardware included as part of a side impact bar purchased a year ago. They also differ in that the 1/4" bolts have knurled sides to the head whereas the 7/32" are smooth.

[Richard Ince]

Arnie

Different sort of kerbs! Your type are normally next to a pavement.tongue.gif

[gordon wilson]

I bought a set of bolts from Caterham last week and having just checked they are the 7/32" heads - Arnie, who did you get this information from - presumably someone at Caterham??

 

This on top of having found that a set of radius arm bolts bought at the same time are too short..........

 

Gordon

[felix.klauser]

This info is a little suspect; 12.9 refers to a metric bolt grade while these are UNF bolts.

[EFA]

Several bolt suppliers have confirmed that the HT version of this bolt size have a 1/4" hex head, whereas the ordinary version is 7/32.

 

Caterham (technical at Darford) also told me they have changed all thier suspension bolts to HT "recently" They told me 12.9 and I also thought this was a metric std. The bolts I found in the correct size used a US standard for the HT rating called "1960 series" which is similar to a 12.9 in material properties.

 

The knurling pattern on the side of a hex bolt normally determines thread type, but I am not sure of the various definitions.

 

Those without a knurling I guess could be cheapie imports???

 

Richard, I'm not taking the bait!

 

Fat Arn

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Edited by - fat arnie on 28 Apr 2002 21:13:06

[Chelspeed]

Mine take 7/32 in allen keys and they're a couple of years old, I'm running rose jointed dampers too so I'm interested.

 

But I've never come across two different types of allen screws, both the same thread, but with two different heads to take two different size allen keys. I'm not convinced that a 1/4 in allen key could be physically fitted inside the head, you couldn't fit a bigger head or it wouldn't fit inside the recessed head on the wishbone.

 

I'll be down South West Fasteners tomorrow for a chat.

[EFA]

Graham,

 

It does and I have all the tech data to support. Trust me!

 

The head dia is only around .03" larger and still easily fits in the hole on my wishbones.

 

I think the head to dia inconsistancy is down to English vs. US standards.

 

Fat Arn

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[tony pashley]

I would assume that the 7/32 versus 1/4 key size difference helps identify the two types of Caterham supplied bolt, but not a hard and fast rule for all bolt supplies.

 

Re the 'anomly' - I've had stainless caphead screws in 5/16 UNC (for exhaust manifold) come in both 7/32 and 1/4 key size, so it can be done. There are one or two larger imperial sizes that routinely turn up were hex bolt and nut of the same size have different AF sizes. Very confusing.

 

Now when we get on to metric, we have European and Japanese thread pitches... oh forget it...

[captain chaos]

When I first ordered my replacements they were out of stock. I asked about getting them elsewhere and Tony in parts told me I could not do this as they were special manufacture for caterham. They were special in that the head's are turned down so that they will fit into the holes in the wishbone.

Does this info help?

[Chelspeed]

That would certainly explain the lack of knurling on the bolt head.

 

No doubt they're also out of stock at the moment due to a lot of worried Blat Chatters.

[felix.klauser]

I can confirm what Graham's implying; the heads of the knurled head bolts don't fit into the recesses in the lower wishbones. They would if they were turned down a bit though.