Further to my earlier thread thanking Jonny for his help ... (long post alert) ...

On Saturday afternoon, I was pulling off J3 of the M5, breaking from the inside lane onto the slip road when a massive clunking started (from the front passenger side).

I immediately pulled over, on to the hard shoulder of the slip road and jumped out to see what was wrong. No fluids and nothing obviously loose.

I only had the Fiat jack / toolkit with me and, knowing that Jonny lived a mile or two from where I was, gave him a call to see if he was around and could bring a decent jack over.

Then noticed someone in the Ford Ka that was also sat on the slip road (about 20yds ahead of me) waving for me come over.

When I got there, I realised the woman was on her own and having a stroke Straight onto 999 to get an ambulance on its way, and then to try to make her more comfortable until it arrived ... she'd been at the side of the road for over half an hour

When Jonny pull up to the bottom of the slip road (about 200 yds ahead of me), all he could see was an ambulance and a couple of traffic officer Land Rovers. I think he initially wondered what had happened to me!

Anyway, the ambulance took the woman off to hospital, and I rolled the car down the the layby on the roundabout (by now about 1hr had passed).

Jonny and I then spent another hour trying to figure things out ... until we spotted the gearbox hanging about an inch off its mount. The bolt in the mount had sheared leaving about 10mm of stud poking out of the mounting

Knowing there wasn't a lot else he could help with, Jonny headed off and I called the AA telling them that I needed recovery and only a flat bed would do (knowing that a Transit VRS doesn't work with Coupe's).

45mins later, a Transit turns up

When he sees the Coupe, he immediately knows that a flatbed is needed ... so calls one. Its busy, so I'm told to expect anything up to 3hrs.

3hrs 10mins later the flatbed turns up and off we go back to my house (a 45min drive).

So after about 7hrs after breaking down, I get back home.

All three Vibratechnics mounts were replaced about a fortnight ago, and had about 500 miles on them. I'm therefore very suprised that the bolt running through the gearbox mount sheared in such a fashion.

I can only assume that the bolt was faulty/ flawed. I'll be giving Vibratechnics a call in the morning to seek their thoughts and advice.

That is worrying both the fact that the aa don't listen not really supprised but allso that the bolt has gone.
was it this long bolt sticking up

Dave - well done for helping the lady - wonder how long she would have been there if your car hadn't had a problem

However, I'm just a tad concerned at a failed Vibratechnic engine mount - clearly, I'm putting quite a bit of power through mine and I'm not famed for taking it easy

I think several people will be waiting for their explanation

No, Jef_uk ... it was the long bolt on the passenger gearbox mount that failed. This one ...



(I think your picture is the rear gearbox mount)

Yeah my one is the rear gear box mount.

I've spoken to Vibratechnics this morning, who are going to send out a new mount to me so that i can send the failed one back to them for analysis.

Hopefully the mount will be with me by Weds, and so they'll be looking at the failed one by the end of the week.

Keep us posted. I thought when fitting that the long bolt was a little bit too short where it screwed into the mount.

Crikey Dave!

As Nigel said - you deserve a pat on the back for helping the lady.

My car has developed an odd knocking noise from somewhere at the front (but think its more the drivers side). Hopefully its nothing to do with the vibra technics stuff, I'll check mine anyway

Chris

The first one i fitted i commented on the quality of the bolt being 'chinese' like in appearance = poor quality.

I think they are 8.8 grade, which should be stamped on the bolt.

Perhaps they need to supply the higher 10.9 Grade of bolt for the load they are under.

Alternatively, perhaps your mount wasnt torqued up/tigtened sufficiently creating higher load?

If we see more failures then the bolt is definately too weak for the job.

I had the front rhs gearbox one shear also not only on mine but on a customers.

Theres alot of weight and now increased shear force due to the reduction in rubber.

Mine i put down to the power i was running,but i have uprated all my bolts now.

The other coupe's mounts were fitted elsewhere by a specialist and 1 of the 13mm bolts was snapped just below the head and the big bolt had also sheared.
This was not down to fitment.
Luckily my earth strap took the load of the box but on the other it sheared this off and he was unable to start the vehicle after the failure.

Top quality mounts,great service and polite however bolts need attention though as Rog points out above.

Anyone know the dimesions off hand? I misplaced the two of mine for the rear gearbox mount so I'd like to replace them - might just do the others for piece of mind too. Also on the one that dave had fail, the original mount is keyed to the support bracket on the gearbox. I dont know if this could be ground off flat and a space fitted in place?

I have to say I'm concerned about the quality of the bolt that arrived with my rear gearbox mount. It looked rather cheap and nasty.

8.8 should be up to the job, I think the originals are 8.8. Most bolts that you can buy from DIY shops etc. are stamped up 8.8, although I don't think they are as something from an engineering merchant's will be far superior in quality strength for strength. Maybe were looking at a quality control issue with the bolts rather than the rating being wrong?

Has anyone had any trouble with the rear gearbox support? There are a couple of things I noticed that I think will need addressing before I fit it (only bolt issues, the mount looks very good).

edit: MattB, I think the two bolts that hold the rear gearbox mount on are m8 x 1.25. I'm unsure of the length though

JBT
Have you spoken to Vibratechnics about the two failures you've seen?
Do you know if either of your customers (whose cars they were) did?

I'm sure everyone understands what has happened ... but they do say a picture paints 1000 words ...


You can see the 10mm stub of remaining bolt sticking out of the mount.

Just out of interest Dave, what torque setting did you use to fit that bolt ?

No idea what torque was used, I'm afraid, Jim. I didn't fit any of the mounts.

Paul fitted them when he was fitting my new clutch. I'll ask him when I next speak to him.

Thanks for the PM for drawing me towards this thread. It is clear from the picture that the Bolt has failed and not the mount nor thread. Clearly it has reached beyond its tensile strength. This is obviously a major flaw in the design specification. I would like to apologise on behalf of VT and I will be on the phone with them tomorrow. Clearly the quickest fix would be to send out new bolts with a tensile rating of 12.9. I originally did query the use of 8.8 bolts for this application and was advised that this strength would be suitable. I would assume VT would want the broken mount back to investigate the failure properly, hopefully a recall will not be necessary but I will have to notify all those that has purchased.

Further to this if the bolt is failing because of excessive force (bending) in the Y & X direction then a 12.9 rating will not solve the problem but just delay it further. If it is failing due to the Z direction then the higher tensile strength will solve this issue. From the image supplied i cannot see any necking of the bolt which would be an indication of bending . Only VT will be able to find this out so I will wait for their verdict.

In the meantime until I have confirmation form VT can I ask if a moderator can post a sticky warning informing people of this situation as this can be potentially dangerous?

I will make this thread a sticky at the top of this section, as this is the most viewed area.

I would ask, however, that the "minute" you hear from V-T you let us know.

Be aware that we are in no way detracting from the product or inferring any failure on the part of the company concerned.

If the customer concerned wants to comment then its up to him.
My stock mounts kept working loose so i put the failure down to the torque i was running.
Mine sheared exactly the same as yours Dave.
Also tore my Cv boot as well.
I got some uprated bolts that were tested on lorry tailgates.
So you wont shear those.
Not cheap mind you.

As for Vibra technics,i was well impressed with the service and the time they took to send out such an order.
I would recommend them to anyone,fantastic product.
The bolts i would imagine were bought in for them and not manufactured in house.

The mounts were a fantastic price and im sure if a gb was organised for uprated bolts then no one would mind paying the additional for peace of mind.

VT has now received dave_t's bolt and are investigating the situation. I will post the news the moment I hear from them.

No they haven't! It's still on my car sat outside

Hopefully the VT replacement mount will be here today or tomorrow, and I'll get them changed over quickly, so that the failed mount (bolt) is with them late this week/ early next week.

Thank goodness I didn't fool around with my mounts, had been quite tempted...
Hope you all get it sorted ASAP !

John from Vibratechnics has just left, after driving some 90 miles (one way) and spending about an hour examining and removing my failed mount.

No conclusions at this stage; he has taken the mount away to examine it, to try to determine what the root cause was.

All I can say, at this point, is what fantastic customer service from Vibratechnics

They could have sent a replacement through the post, and waited for me to return the failed part (as was the original plan), but instead decided to get things moving quickly by coming here

They clearly know the effect of bad press and are doing their utmost to resolve the situation

Good to hear they are so customer-focussed

I eagerly await their findings

It's called Karma Dave, one good deed deserves another. Well done for looking after that lady

Told you they had it today you just didn't know it then .

LOL

John from Vibratechnics has called to give his first thoughts on what has happened.

It looks like the long bolt (the one that failed) has tightly bound against the bolt that comes down the same thread (from above) in the alloy boss.

This means that the mount on the gearbox wasn't held really tightly against the Vibratechnics mount (although it would seem to be as the long bolt would tighten no further).

The tiny amount of movement that this has enabled has then caused the long bolt to shear.

The effects of this movement can also be seen on the alloy boss, as there are slight indentations in the surface that touches the gearbox mount.

John believes that all that is needed is a washer on the top bolt to give the long bolt space to tighten fully.

He is going to talk to TuboJ in detail and pass this on ... and I'm sure J will correct anything I might have written in error above.

Vibratechnics are now planning the best way to move forward with washers, etc.

PROFESSIONAL ANALYSIS OF FAILURE:

“We have examined the break and the assembly and there is evidence that the 100mm bolt has contacted the 70mm bolt we fit through the insulator into the boss. This results in the assembly not being clamped together correctly as the bolt has bottomed out before the alloy boss has clamped onto the gearbox bracket - allowing a very small amount of flex on the bolt - which can cause fatigue and potentially a failure. This is further confirmed by 'fretting' on the mating face of the boss where it has been in contact with the gearbox bracket - if this was fully clamped there would be no movement and therefore no fretting. Thirdly we found that the broken bolt could not be removed from the boss until the 70mm bolt was loosened - then it could be turned easily - confirming that the 2 bolts were in contact.

This fatigue process has probably been accelerated on this car as it has been used on a trackday.

In anticipation that this may have been the cause of this failure the replacement part fitted to this car had a plain washer fitted under the head of the 70mm bolt to give an additional 2mm between the 2 bolts when they are tightened.

Obviously we were trying to get maximum thread engagement with the fasteners on this part but in this instance we need to reduce this slightly to ensure the lower bolt through the gearbox bracket is clamping the alloy boss to the bracket. Therefore we would propose that people who have fitted these take the precaution of installing a second washer under the head of the 100mm bolt. A standard M10 plain washer is 2mm thick and this will give adequate clearance between the 2 bolts and still have 15.5mm thread engagement.

In summary we now believe there is a potential problem of the lower bolt breaking and therefore suggest that all owners of cars fitted with our front gearbox mount take the precaution of removing the lower M10 X 100mm bolt and reinstalling with 2 washers under the head.”

SOLUTION:
For those that have already received their PGS mount in addition to the supplied 2mm washer. You need to add a further washer 1-2mm that will bring the long bolt down so it doesn’t contact the 70mm assembly bolt.



FUTURE MOUNTS:
To increase the diameter and length of the alloy boss and counterbore it to fit on the perimeter of the gearbox bracket to give a larger diameter mounting face.