i kept snapped gearbox bolts about every week or two (the bolts the hold the mount to the floor) and eventuall i have found a bolt that will hold up alright, but not it has snapped the acsual mount. just wondering if anyone has had this problem in their datto and what they did to over come it, also im wondering if the box mount on a 120y would be the same as the one i have on my a14 with the a14 box...??? whats the best way to go about getting rid of this problem. i have a feeling the mount might have been custom made

Is the hardware you are using of the correct grade? I usually use grade 8 or 9 hardware, or whatever the replacement parts come with. Is it possible that the engine and tranny are shifting, but you only are noticing the broken bolts on the tranny mount...

I think you must have some serious problems somewhere else. There is no way that a standard mount would give way. The rubber part of the mount would break first. You could turn the car over and hang it upside down from the crossmember, Its strong enough. Look at your engine mounts or maybe the pillars on the front crossmember. I'v had the right one collapse. olboy

Somethings wrong -- and it's not the grade of the bolt. The angle of the transmission may be incorrect. Make sure the transmission is sitting level, and not up or down a little in the back (which will create vibrations).

i think it must be a custom mount because there is not rubber bit that car brake or anything. the box seems to be on the right angle and isnt off to one side or anything. ill take a photo of the gearbox mount tomorrow. engine mounts seems fine

That's why it keeps breaking -- it doesn't have the rubber part. Without that the mount needs to be magnitudes of order stronger.

Get the stock transmission mount from a B310, then create a flat-plate crossmember to bolt it up. As a bonus it won't transmit vibrations into the car either.

perfect, ill give it a go, thanks mate, i tried putting a suspension bush on one of the bolts a few weeks ago hahah and that seemed to work a bit better so it does make sence. thanks

Here is how the stock mount goes:


stock 4-speed mount

Here are 5-speed adapters. The flat plates need a long bolt with spacers.



5-speed adapter mount



5-speed adapter mount



B310 mount



5-speed adapter mount

Here's some that don't need spacers and long bolts:


5-speed adapter mount



5-speed adapter mount