Saturday 14th December
My left hand drill bits arrived in the week so I decided to make a start on drilling out the sheared bolts. Of the 3 front sub-frame mount ones, 2 were by the sills, so only one could be done without some other pre work.
As you can see in this pic it’s not possible to drill into the one next to the sill because of the folded over edge of the sill.
So I marked up where the drills chuck would be, cut into the sill with a junior hacksaw, and the folded the edge down with a pair of mole grips. It then looked like this.
I flattened off the end of the bolt with a file, marked the centre with a centre punch, and drilled a 2mm pilot hole. Next I used 3mm bit, then a 4mm bit until I got up-to 6mm. At no point did the left hand drill bits bite enough to undo the seized bolt. The final size before taping the M8 thread would be 6.8mm, but I had marked up slightly off centre. So I spent 20 minutes opening the hole up on thickest side with a needle file. But got called in for dinner before I was finished.
Sunday 15th December
Completed filing, ran the 6.8mm bit through and tapped a new thread. On the other side I had two to-do. Got started with the one closer to the centre of the car. Marked with centre punch, but this time used my cobalt drills, as they are a bit quicker, even if you do have to stop every few minutes and spray on some lubricant. Again I suffered from not quite getting dead centre.
I was just finishing this one when “Mr Maltby” and “BarryD” arrived.
We had a quick natter over a cup of tea, and then tried to lift the engine and gearbox off the sub-frame, but it was too heavy.
So we gave up and had a bit more of a natter. Looks like I will have to borrow an engine crane form somewhere after all. Thanks anyways boys!
For the second of the bolts next to the sill, I followed the same procedure as for the first, and all went well. In the end the one that should have been the easiest to get at was the one I was least pleased with. Looks like there are not enough good threads cut into the metal, so will have to follow CJJ’s new
“How to fix a damaged subframe thread”
how-to.
Next I moved on to removing the bolts from the Alloy buttress. One had already sheared when in a previous attempt, so I had been soaking the other in 3-in-1 penetrating oil all week. But it still sheared when I tried to undo it. Damn!
But anyway the engine mount could be lifted off, and I was presented by a thick layer of grot. Some of it was granular form and looked like salt.
(Sorry about the picture quality. Looked better on my phone honest)
I scrapped most of it off with a chisel (by hand without the use of a hammer!) and then clean up further with the drill and wire cup brush.
As both bolts had sheared I wasn’t sure what size they were, so I passed both M8 and M10 through one of the engine mount holes and decided they were probably M10.
The remainder of the sheared bolts were filed back flat and flush with the surface of the buttress, then centre punched. I wasn’t looking forward to drilling out steel bolts from softer aluminium, but I was able to use a pillar drill which is more accurate. There was a fair amount of fiddling because of the shape of the buttress. But starting with 2mm bit and working in 1mm increments I eventually got to the final 8.6mm drill prior to tapping the treads. With both done I decided to give it a quick clean up with the drill and cup brush. This was the result.
I think I will spray it with some lacquer to give it some protection before it goes back on. But it was the end of another days tinkering. Time to go in for food and