One week after having a broken driveshaft and the vibra technics rear gearbox mount replaced, the three bolts holding the front gearbox mount to the chassis snapped. I'm now wondering if it would be worthwhile upgrading all of the engine and gearbox mount bolts from 8.8 to 10.9 steel to cope from the extra stress they seem to be under at this power level.

Anyone else done similar, have experience of this or able to tell me if it's a good or bad idea given the whole 'brittleness' thing...

Cheers!

...and it turns out the thread has gone on the gearbox. New gearbox... again...

Now

Tonight

Tomorrow

Monday

Won't a thread insert work?

One thread has pulled on my front box mount.
After trying to remove the long single bolt first, the head sheared clean off, I'm going to replace the whole mount and bolts.

Sorry I seem to be a bit behind events.
I have all 3 of the VT fast road mounts.
The rear and o/s seem ok but i`m dubious about the n/s.

The bolts supplied to retain the mount to chassis leg are very poor quality 8.8 grade as supplied to the shop fitting industry. I`ve seen plenty of these bolts, when opening a box of 1000 the trick is to find a few without duff threads to do the racking job. One of the bolts supplied had a duff thread.
The main bolt looks like 12.9 grade as self colour, I didn`t note prior to fitting.
There are 2 small set screws holding the sandwich together, these look like they may be 10.9 but may be 8.8.
Point is the mount is not ride on but suspension and we are all running at considerable upgrade.
I see no downside to using 10.9 where one can, downside of 12.9 is often only self colour.

Did you have any further problems,Trappy/nissansteve?

I've had issues with the bolts supplied with the N/S VT mounts so I don't use them and swap them for better quality.

Thank-you for the input. Fiat seem to use 10.9 with fine pitch on the car for suspension/running gear although I haven`t managed to see the head clearly of the o/s mount bolts.
Not determined the finish of the standard bolts for sure to replicate, I might send one to the plating supplies. Just seems like heavy/quality zinc, they last really well. My Ti just for show/build till the originals redone.
Plenty of the bolts I have encountered were non-original so I have filtered, shame about the original clips too as they seem like stainless?

"and can we confirm that?"

Yup, I just pulled an original o/s bolt and it is 10 grade so i`m off shopping.