10 replies to this topic

[nakered]

>
I thought i'll change the standard rubber bushes on the rear subframe to poly - simple enuff, seeing as the subframe is sitting on my workbench - no worries!

Front mounts (heelboard end) no trouble, even bought new trunnion pins, nice n shiny.
Rear mounts (the ones that bolt into the boot floor) started to unbolt, quite stiff at first then it happened.

The bolt sheared off from the pin - aargh!
Tried the other side - same thing happened, sheared off. it!!!

OK, no worries, got a good second hand one from a lovely forum member - started to dismantle the new subframe, got to the same mounts as previously and yep, you guessed it, the same two bolts sheared AGAIN!!
(even using heat on em, still sheared)

Has anyone got a foolproof way of getting these bushes off, without the bolts?

Thanx everyone!!

[Dan]

The pins welded to the subframe?

That sounds like incredible bad luck. I've never had one go but that's the second person who's been here in a week saying it's happened and to have it happen to both sides of two subframes is incredible. It could be the nyloc putting extra load on the pin (I've known nyloc nuts to shear really big bolts, they put loads of force on it they've been tight for a while) or it could be that the rubber bush has perished and bonded onto the pin inside and the washer outside. So when you turn the nut you're actually turning the bolt. Lots of plusgas and leave it a day or two is the only thing I can think of really.

[nakered]

I've read somewhere that you can drill out the pin, re-tap a new thread, and put in a new bolt. Dunno if thats safe/strong enuff, seems as though it may put a bit of stress on the pin - whats the opinion of others on this. Is there a better fix, or does it mean grinding off the welds on the subframe, and weld in a completely new pin. I just dunno what's best??

[Dan]

Last time this was asked I said that I think the only option is a new subby and I still believe that. Drilling and tapping what's there sounds like a recipe for disaster to me and welding on a new pin is all well and good but..
( A ) Where will you get one, they tend to come with subframes (but I suppose any good steel will do) and
( B ) Alignment is extremely important with subframe fittings. If you don't have BMHs subframe jig how will you know it's in the right place.

Maybe someone like Dave (Icklemini) knows of an easy and strong repair but I've never heard of one.

Edited by Dan, 29 April 2006 - 08:34 PM.

[philc]

Last time this was asked I said that I think the only option is a new subby and I still believe that. Drilling and tapping what's there sounds like a recipe for disaster to me and welding on a new pin is all well and good but..
( A ) Where will you get one, they tend to come with subframes (but I suppose any good steel will do) and
( B ) Alignment is extremely important with subframe fittings. If you don't have BMHs subframe jig how will you know it's in the right place.

Maybe someone like Dave (Icklemini) knows of an easy and strong repair but I've never heard of one.

i am still sorting my trunnon out, though the threaded part has snapped off it has left the part were the mount sit. this has some meat on it so it should be good to drill and tap if done properly with a good thread which is deap enough. surley this is about keeping the mount onto the subframe which in theory should do the job. i will let you know what happens.

[minidaves]

to snap them i would habe to say either your turning it the wrong way, or real bad luck, i dont htink i have ever snapped one and i've done proberly 50-60 subframe changes

as for repair if its onlt the studded part thats busted then i can see any reason why you cant tap (rethread) the pin out and wind in a piece id stud of good quaility the sone stud lock on the end and the refit. there is very little sideways force on these so cant see a problem.

dave

[nakered]

Well, i'm sort of going along with your theory minidaves - but i'm removing the complete pin (from within the subframe) - and getting a new pin made up from piece of high tensile steel, at a local engineering place.
I've managed to get one pin out fairly cleanly, only very minor trouble - ready for the new pin to be welded in.
I'll get some piccies up soon, just to show everyone what I mean!

[nakered]

Hello again, it's been some time, but i've finally got around to sorting this problem out!
I'll go through it all, stage by stage, complete with pictures!
(sticky subject p'raps?)


1. Using a hacksaw, cut off the sheared bolt (complete with sleeve) flush to the subframe.
2. Using a smaller diameter drill bit (I used a 3/16 bit - but something similar will do)
drill into the pin (at the end you have just sawn off) - about 10mm or so, it helps in the removal of the old pin.
3. Turning to a smaller drill bit, drill through this access hole, (see pic 1) to help break the weld from the pin and the subframe.

 New_Pin_05___lo.jpg   193.85K   14 downloads

4. Drill the weld out on the other end of the pin (see pic 2) take your time, and try not to remove too much metal from the subframe itself

 New_Pin_04___lo.jpg   152.85K   14 downloads

5. Using a drift (or something similar - I think I used an old screwdriver!) knock through the old pin from the sawn side, into the subframe side (if that makes sense!) after a wiggle the old pin (should) come out!
(see pic 3)

 New_Pin_02___lo.jpg   178.53K   5 downloads


6. I got a new pin (stainless steel) made up at a local engineering place, using these dimensions
(see pic 4)

 New_Pin_01___lo.jpg   111.72K   3 downloads

As you can see, the new pin has a threaded end on both sides - I was trying to get the new pin to bolt into the subframe instead of welding it in - but the nut would have placed the pin in slightly the wrong place (and we DON'T want that do we!) - so if anyone wants to get there own pin made up, just use the dimensions i've used, but just get a thread made onto the correct end only!

7. File out the hole you drilled (remember I used a 3/16 drill bit) - taken care to ensure that the new pin sits centrally.

8. Tap in the new pin, then all that you have to do is weld the pin to the subframe through that access hole, and weld the end of the pin where it comes through the other side!
(see pic 5)

 New_Pin_03___lo.jpg   189.5K   2 downloads

9. WALLAH! - jobs a goodun!

[Dave 1293]

Good job..

i've never heard of them shearing off there!! I've helped out with a fair few subframe changes and its normally the bolts that go into the heelboard that brake.

[philc]

well done looks like it will do the job you could start this as a business. i had the remainder of the trunnon drilled and tapped with a 10mm thread and 30mm deep, though i have not fitted it at the moment, i can't see any reason why it should not hold. so fingers crossed.

Attached Files

•  subframe_001.jpg   144.79K   4 downloads
•  subframe_002.jpg   140.31K   2 downloads

[nakered]

To anyone thinking of having a go at this fix, I have a second pin already made up (stainless steel) for sale.

It's gonna cost £12 plus p+p - it's a custom part, but if I get many offers, I can get em made up cheaper (bulk buy, the engineering company said)