87 replies to this topic

[fezzasus]

From memory the S1 hub arrangement puts the bolt under double shear. Would be interesting to see how many S1 failures there have been vs. S2/Vx220

[siztenboots]

imo, the bolts for the double shear bracket are feeble

[fezzasus]

Size isn't everything, if the shear stress is removed you can use a smaller cross sectional area bolt.

 

the EP GT hubs are also under double shear.

[slindborg]

ZOMG call watchdog!!!

[Bootdog]

Size isn't everything, if the shear stress is removed you can use a smaller cross sectional area bolt.

 

the EP GT hubs are also under double shear.

 

Tom I assume these are hubs you're referring to: http://www.elisepart...t-s2-rear-pair/

- Good to see these are available (albeit not cheap ...), do you know if they fit onto VXs?

[fezzasus]

 

Size isn't everything, if the shear stress is removed you can use a smaller cross sectional area bolt.

 

the EP GT hubs are also under double shear.

 

Tom I assume these are hubs you're referring to: http://www.elisepart...t-s2-rear-pair/

- Good to see these are available (albeit not cheap ...), do you know if they fit onto VXs?

 

 

Yup, Mike ran them on his time attack car.

[mbes2]

http://www.nitron.co...ar-toe-link-kit

[YvoTuk]

I would like to add some things to the thread before people jump to conclusions.

 

Our toe link kit including the choice of fasteners is based on calculations and simulations which have been performed and signed of by professionals in the automotive suspension area.

The people involved have a track record of designing various cars, ranging from performance cars to SUV's etc.

 

The choice of an 8.8 bolt is because a lower grade bolt is less brittle than any high grade bolt. For instance on high energy impacts, a 12.9 bolt will snap much quicker than a 10.9 and a 10.9 will snap much quicker than a 8.8.

The general consencus is you'd rather want a bolt to bend rather than snap.

There is a properly large margin in what the bolt should be able to cope with and what the car can generate during normal use (based on a race car running full slicks!)

 

Besides the theoretical part of this, the kits have been tested on several race cars.

Our most important test has been during the 24hr of Dubai and 24hr of Barcelona events. These tests have shown no issues at all. (the car has been pulled apart after every event to properly check every part.)

 

The motorsport kit is a spin-off from our original kit. It uses different rod ens (NMB) and as it's specifically designed for racing applications, the kit is shipped with 10.9 fasteners as well as a spare set of fasteners. Every kit comes with instructions which explicitly ask for a spanner check before every outing.

 

We've meanwhile sold over 1500 toe link kits. I don't expect to see or hear from every issue as people don't always get back to us but we've never seen a trend in bolts snapping or anything which would point at an oversight in the design.

 

Double shear would be great (and better) for this application but with standard uprights it would be a bit of a challenge as there simply is no way to attach anything to them properly.

 

In general, when people drive their cars through potholes or slide the rear wheels at a curb etc. there will be high force impacts. These will eventually destroy every single shear bolt.

Now, I don't think one should be worried as in 'these bolts snap all the time', I think that's also quite clear when you look at practice with over 1500 toe links and no specific issues.

 

The one thing I've never understood is why Lotus (but in fact no manufacturers) never describe proper check ups in their service schedules.

I would (and I do) take the bolts out of the toe link kit every year and just check them. When they look ok I put them back in, when they look marked or of course if they would be bent I replace them.

I've never seen any garage who does this at a service. It's something you've got to ask for specifically.

 

Oh and as mentioned by the OP.. using correct torque is the first step to prevent failures.

I'll keep an eye on how this develops and will stay in touch with the OP, we do of course want to know what's happening out there

 

 

[siztenboots]

the problem with 10.9/12.9 and zinc coating is hydrogen embrittlement

[slindborg]

CAT bolts unless they are over 10.9

 

Rolled threads, passive as hell, strong (my friend saw one go through a gearbox to be reused again while all the teeth were missing from the old box )

[FLD]

the problem with 10.9/12.9 and zinc coating is hydrogen embrittlement

 

That should only be a problem if they aren't plated correctly.

[JG]

Yeahthat.

Or avoid zinc coating all together like i do on the HCB kit (of which there has never been a failure as far as I know in 300 sets)

[Winstar]

I'll add my 2p worth those failures are both fatigue failures you can see the crack initiation point before the brittle fracture occurs to shear the bolt. This would lead me to one of the following conclusions. Either: - the joint is poorly designed meaning the bolt experiences a cyclic force most likely in bending, is this why Lotus changed to the conical seat in the turbo? has the outer joint failed with a conical seat - there is insufficient clamp force in the bolt meaning load is transferred to it rather than the joint. This could be due to the nyloc loosening due to vibration or simply the design of the joint requires a higher grade to ensure enough clamp force. The reason to go to a 10.9 or 12.9 is about getting enough clamp force, the joint should be designed so that the shock impacts are not taken by the bolt but by the joint.

[WrightStuff]

For a car that is tracked on semis then, and may ride the occasional kerb  , am I better off using 8.8 bolts or 10.9, 12.9 ?

Would I have to hit something pretty heavily going sideways for the the brittleness of the higher grade bolts to be a factor ?

 

 

 

 

 

[Nev]

...of which there has never been a failure as far as I know in 300 sets)

 

FYI:  I've had one of your HCBs fail. It occurred going though a pothole that also bent a rear wheel, so it was an exceptional/understandable failure IMO. The bolt that failed was approx. 1.5 years old and had been tightened up with a torque wrench by a friend (an old owner on here) and also double checked by me.  

Edited by Nev, 03 July 2014 - 12:31 PM.

[siztenboots]

going to raise the defcon level

[Andrew aka Stuwy]

 

 

 

Video, in-car:

 

 

 

 

 

great control

 

[Rusty789]

All this talk of failures is almost making me scared to drive the car!

[JG]

 

...of which there has never been a failure as far as I know in 300 sets)

 

FYI:  I've had one of your HCBs fail. It occurred going though a pothole that also bent a rear wheel, so it was an exceptional/understandable failure IMO. The bolt that failed was approx. 1.5 years old and had been tightened up with a torque wrench by a friend (an old owner on here) and also double checked by me.  

 

 

Thanks for the feedback

 

Shall I send you another set?

[Rusty789]

James, a little off topic but Mango Motorsport is down? Have you stopped or is it broken?