Wrong Subframe Torque Settings - BOLTS OUT!

[Royalratch]

Dan Dan Dan...

In the Bentley manual it's got subframe anchor bolts listed as:

M10 @ 42Nm
M12 @ 77Nm

Section 13, page 47.

So it definitely seems I overtightened them by 60Nm! Jesus. I can't really blame the dude who replied first (maybe a little) as I should have confirmed the specs myself, very unlike me to just take someones word for it but I was in a hurry.


@B7, they are the same length as the originals I checked them against.

I haven't bought any tool for it yet but I will get whatever will do the job. This is a major ballache - one would be a pain but four...

[Royalratch]

Just got the subframe off (again ) and the rears have maybe 1.5 threads out and the fronts are flush with the chassis leg - the these holes are recessed quite a bit too. I'm gutted about this, I would have been driving about today if not for this.

Any kind of tool is going to be a bitch because the bolt has snapped off leaving an even surface - tough to get a pilot punch in let alone drill some kind of extractor in.

[Royalratch]

What about screwing in the new bolts - would they force the snapped thread out the top?

[DanThe]

Get somebody competent to drill a 5-6mm hole up the centre of the stud and use an extractor like the ones Rav posted

[beardymat]

aahh, this takes me back to replacing the front setup on my sport, thought i was being clever as i had a full new/ refurbed setup to just bolt on, four subframe bolts two bottom arm nuts two engine mount nuts and a couple of nut and bolts holding the rack on, ill pop that on in a couple of hours after work!!!

snapped the head off one of the subframe bolts flush with the frame, no problem ill drop the frame off and wind it out, subframe wouldnt budge as the bolt rusted to the inside of it, no problem ill just cut the corner off the frame, get that out of the way and spin the remains out of the leg, the bolt then snapped off flush with the chassis leg, no problem ill just drill it out and retap it, drill snaps in bolt lots of swearing, that is a problem, managed to pick out the broken piece of drill and finally sort it but the bolt was so tough to drill and tap out even though im sure theyre only 8.8`s not high tensile jobbies.

that was one long night.

Have they snapped flush with the chassis leg or with the subframe? its not clear.

[Brianmoooore]

If these are freshly fitted new bolts, not in a blind hole, they should be easy to wind out. We're not dealing with twenty years of rust here!

[Royalratch]

They are new bolts coated with Copper Anti-Seize.

So in theory they should be easy to get out but again, they were pushed in at 100Nm...

They are flush with the chassis leg - the subframe is off.

I'm going to get a quality easy out / drill out set and go to work on them. If I can get these out the car is essentially finished except for interior trim which is what makes this suck all the more...

[beardymat]

you should in theory be fine as theyre new and freshly lubed so should spin out fairly easily. sounds to me as if they have just snapped through being overtorqued, we had a memo a few years ago warning against using copperslip on wheel studs as this can cause overtorquing and the heads of the studs to pop off.

[DanThe]

you should in theory be fine as theyre new and freshly lubed so should spin out fairly easily. sounds to me as if they have just snapped through being overtorqued, we had a memo a few years ago warning against using copperslip on wheel studs as this can cause overtorquing and the heads of the studs to pop off.

I know someone who did this, the rear wheel came off on the motorway at 80mph

[Royalratch]

I think hammering in a sharp hard flathead screwdriver / chisel and then using it as a screwdriver will be route 1.

If not, something like these drill outs look promising.

https://www.frost.co.uk/item_Detail.asp ... %20of%204)

[ross_jsy]

I would say the problem here is the haynes book of lies.

When i was building my RS125, I went to bolt on the head, Haynes told me a figure I took as correct, a snapped head stud and a phone call to the company who bored out and ported my head confirmed that the Haynes manual was incorrect.

Turns out a lot of the torque figures and other general info for the RS was false. So I assume it to be the same for many Haynes manuals.

Bit of a joke really as they are so respected as a point of reference.

[Royalratch]

The Bentley manual is proper - I haven't looked din the Haynes manual for years.

If this was the USA, Haynes would be buying me a new chassis by now...

[ross_jsy]

On a side note; anyone know where I can get a Bentley manual from?

[Royalratch]

eBay, Amazon...

[irish320i]

What I normally do is drill a hole slightly smaller than a multi spline bit and hammer the bit in screw it out works well on vw steering column bolts so no reason it shouldn't work on your subframe bolts

ALan

[Royalratch]

I think it will be fine IF I can get a a drill into these bolts square in. If they are hi-tensile then I don't know how it will go...

[DanThe]

You still have the bolt heads which tell you the grade of steel.....

Just get on with it woman

[jbh]

are they sitting flush to the chassis? long shot but could you hold a nut on and weld through the center of it to catch the broken bolt then try unbolting it that way?

[Royalratch]

No welding gear and no time.

This has happened in the busiest week at work ever.

Plus its Arsenal Barça tonight...

[Brianmoooore]

You still have the bolt heads which tell you the grade of steel.....

I did ask that, part way down page 1 of this thread!

[mick_318is]

I would think as Brian also suggested earlier that a left handed drill bit should be first.

If you try this the stud that is left should just spin out when the drill bit catches.

As although you have overtightened the bolt now the head has snapped off the tension should be released on the remaining thread.

If not it will still drill a hole in the remaining stud which you can then use your easy out on.

[Royalratch]

You still have the bolt heads which tell you the grade of steel.....

I did ask that, part way down page 1 of this thread!

The bolts are inscribed with 'Verbus 10.5' I think...

I thought all structural bolts were hi-tensile.

[irish320i]

Cobalt drill bit will still drill if you use a bit of lube to keep the bit cooled

[beardymat]

You still have the bolt heads which tell you the grade of steel.....

I did ask that, part way down page 1 of this thread!

The bolts are inscribed with 'Verbus 10.5' I think...

I thought all structural bolts were hi-tensile.

yep, 10.5`s (or is it 10.9) are high tensile jobbies, explains why i spent over two hours of my life and several drill bits getting mine out, they will drill, just start small and go slow and hope the b@stard grabs and spins out. happy days

[Royalratch]

Oh man...

Got some damn expensive diamond and Carbide tipped bits, hopefully they'll help.

[ross_jsy]

And send the bill onto Haynes

[Royalratch]

I sent a horrific email to their customer services dept.

[jbh]

I sent a horrific email to their customer services dept.

would be interested in there response if you get one..

[gareth]

Oh man...

Got some damn expensive diamond and Carbide tipped bits, hopefully they'll help.

they're not masonry bits are they?

a carbide drill bit will drill a grade 10.9 bolt easily but they've very brittle so if you move the drill to much, they will snap off in the bolt... hours of fun to be had getting it out.

grade 10.9 isn't 'that' hard. some decent high speed steel (dormer etc, not el-cheapo) drill bits will make mincemeat of it. the stainless steel we use at work every day is harder than that. keep the drill speed relatively low and ensure there's enough pressure for it to cut (you're aiming for a continuous swarf thread) and nut chatter about as this will burn out the tip of the drill bit. oh and use some lube while drilling too.

the pressure on the threads will have been released so if they span in easily before the torquing stage, they should spin out as easily.

[Royalratch]

Was quite easy. Used a centre punch to locate some left spin Drill-Out bits and they basically dig their way in and spin the bolt out. Once I had a few threads showing I just unscrewed them by hand. Not sure if it would be so easy on 20 year old rusted seized bolts but they made mince meat of the hi-tensile M10's and looked unmarked after.

I highly recommend them.

Phew.

[jbh]

glad its worked out.

[beardymat]

just one question ratch, after the first one snapped why did you carry on and snap all the other three? surely even after the second you would be thinking WTF!

well done on getting them out though fella, must be a relief.

[e30topless]

nice one Ratch !

[Royalratch]

just one question ratch, after the first one snapped why did you carry on and snap all the other three? surely even after the second you would be thinking WTF!

well done on getting them out though fella, must be a relief.

LOL! I thought each one snapping was the Torque wrench signaling correct torque - it sounds exactly the same! Plus the frame only dropped when the last one snapped.

I feel like a new man.

[beardymat]

DOH! that explains it, ill bet you were stood there in disbelief with your mush wide open.