Any thoughts on how to save this subframe -- two tower bolts have sheared off and even an easiout won't shift them. Is it possible to dril them right out and put some bolts through from the underside and weld them up to stop them turning on assembly? -- any help greatly appreciated as otherwise the frame is in reasonable shape and has all the usual strengthening welding already done. Thanks
Steve Shield

Myself i would soak it with WD40 or diesel for a few hours,may help.I have never had any joy with easyouts,try a old torx bit,hammer it into the hole you have drilled,then heat it up,does not have to be 'red' hot,dont try to unscrew it,but wind it in,as the threads on the other end of the stud will be covered in rust;if that idea fails,i would then weld a nut on the underside
good luck

What a pest I suppose you could do as you suggest - mine have studs in them and I guess yours are the same but I can see that it might be a problem retapping the holes so I can't see anything wrong with welding bolts in as long as they don't interfere with the suspension cone.

don't weld if possible .. look for a helicoil kit and use studs in the helicoils .. leaves you with more possibilities later without compromise ..

Yep - that's a better idea.

The one on the left of the photo. The hole drilled in it is obviously way off centre so drilling it out is going to be a bu@@er. Try drilling with the current size drill until you are beyond the thread in the subframe. Then increase the drill size until you break through the bolt at the thin side and start touching the threads on the subframe. That might allow the bolt to collapse a little and unscrew without having damaged the subframe threads too much.

The other one - looks like the hole is fairly central. Assuming that's the case then increasing the drill size gradually will get you to the core size of the bolt and the threads can be picked out of the subframe with a sharp scriber. Done carefully you can get the thread from the bolt to come out looking like a coil spring.

Penetrating fluids and heat before you start might mean the things start turning whilst you are drilling and mean you only need to go partway with all these steps and preserve the subframe threads.

Depending on how much damage you end up doing to the threads will give you a way forwards - helicoil would be the first step. Then a clinch nut and finally weld something.

It does look like someone has been st those towers with a welder already though.... Is the rest of the subframe good enough to go through the pain or would it be better to get another one?

Iain

Drill them out and tap them the next size up. Doesn't need to be the 5/16 UNC (iirc) that they came from the factory. M10 would do the job nicely.

Thanks for all the ideas guys -- I've just taken on a contract so workshop actitives are a but curtailled -- I'll try the carefull drilling approach first and then if it needs it helicoils. The relatively awful welding -- I was/still am a bit out of practice -- is as per the rally "books" with a seam around the tower tops and reinforcement plates on the tie bar mounts. We used to do this on our MInicross cars -- it didn't look pretty on them either!
Regards,
Steve

There is another way, though the drilling attempt may have made it impossible. I have a fair bit of experience removing broken studs and bolts from motor-cycle cylinder heads, A Series blocks and from at least one Mini front sub-frame. My method is to drill a hole, about 4 or 5 mm diameter, in a six inch length of 3mm by 25mm mild steel. Place this carefully over the bust stud, mig weld through so that the stud remnant and m/s bar are joined, and tap the bar in the appropriate direction. It works! I think the heat generated by the welding helps loosen the rusty bond, and the length of bar exerts considerable torque. Be careful not to weld the stud to whatever it is stuck in - not a problem if it is in aluminium alloy or cast iron, but may be more likely in a mild steel subframe.

I think the original size is 3/8UNF so about 9.5mm. M10 therefore should be do-able so long as you only just clean the old bolt out of the hole with the drill.

From memory people used to stick A-Series cylinder head studs in them to make re-fitting the subframe easier.

Iain

Some form of stud sounds like a great idea -- at least then you could treat the part in the engine compartment to lashings of grease etc to ensure it didn't corrode solid. Also it would help align the subframe for assembly to the chassis.
Steve

I just drilled mine out and welded in some new nuts, job done and was used for many years, did it both on the coupe and on many a mini