How to attach this exhaust bracket back on?

[Bobton125]

Not a car but a road legal buggy. Exhaust bracket pictured below is supposed to be bolted directly to the soft alloy engine casing. The bolt snapped but I’m reluctant to put it back as the holes look very worn.

Any ideas how I can fix this so I can bolt to the engine casing again or where else I can fabricate a bracket to attach to?
I’m guessing it needs to be attached to the engine rather than frame due to the excessive engine movement it makes being a 1 pot.

(Sorry for the many pictures!)

[Bobton125]

This is what it used to look like

[CrutyRammers]

I had a similar casting (water pump) welded up at a local machine shop, though he did warn that castings don't always weld very well - but it was fine. So if you can get it off, that might be an option - weld up the holes and redrill, perhaps with a steel bushing in.

Otherwise, sometimes there are spare holes or studs available on the engine you might be able to repurpose. Or build a new hanger that attaches to the the existing engine mount bolts? Or maybe have the exhaust mounted to the frame, and use a flexible coupling between it and the engine?

[Bobton125]

Can’t be removed unless I remove the entire engine which is a ball ache.
Thanks

[catfishdb]

I would be tempted to use the "spare" upper unused hole. It hasn't been used and is not elongated.
The lower hole would still be used with a bit of an extension modification to the bracket.
The current two mounting holes only look to get more ovoid shaped until that lower one will wear through.

Arthur

[Bobton125]

Yeah I had the same thought about that spare unused hole at the top. Wasn’t sure for the bottom though,
What do you mean by extension modification on the lower hole?

[Bobton125]

catfishdb said:

I would be tempted to use the "spare" upper unused hole. It hasn't been used and is not elongated.
The lower hole would still be used with a bit of an extension modification to the bracket.
The current two mounting holes only look to get more ovoid shaped until that lower one will wear through.

Arthur

You would still use the lower hole even though it’s elongated that much?

[donkmeister]

I'm not a welder, but given there's a fair amount of meat around there to dissipate heat would someone who is handy with a TIG not be able to slowly and carefully fill the holes with weld without removing the casting? Then you can drill and refit original bracket (with a gently-pressed steel bushing to avoid the bolt vibrating the hole into an ovoid shape again).

Just to say again, not a welder myself so there could be good reasons why that wouldn't work.

[catfishdb]

Bobton125 said:

catfishdb said:

I would be tempted to use the "spare" upper unused hole. It hasn't been used and is not elongated.
The lower hole would still be used with a bit of an extension modification to the bracket.
The current two mounting holes only look to get more ovoid shaped until that lower one will wear through.

Arthur

You would still use the lower hole even though it’s elongated that much?

Well.....to be fair....my brain only started looking at options on where to begin. That top unused hole looks rather original and the same diameter. A good starting point to get a positive locate there. And yes the bottom one is not long for this world. I was ignoring that next step and the problems with it.

Not certain what the OP's abilities are but aluminum welding is not in my wheelhouse. I might even consider enlarging the lower hole (without touching that lower bit that is holding on for dear life) to get a bushing in there as more of a locate to help out with that new unused hole above.

Arthur

[Chris32345]

As other have said ideally that neds Tig welding to fill the hole in then redrilling a new hole doing it a little larger witha steel sleeve is a good shout I'd also have a small gap around the sleeve filled with polyurethane addssive to hopefully stop the bush wearing through the alloy again

[E-bmw]

It is one of those jobs that could be tackled in many ways dependent on budget/your abilities/your own equipment.

Personally, I would be:

Re-drilling & tapping the top hole to the next size up.

Getting the lower hole filled/welded up & tapped.

Then modify the bracket to find a way to fit some compliance between the casing & bracket, or the same is going to happen again & again.

[Bobton125]

E-bmw said:

It is one of those jobs that could be tackled in many ways dependent on budget/your abilities/your own equipment.

Personally, I would be:

Re-drilling & tapping the top hole to the next size up.

Getting the lower hole filled/welded up & tapped.

Then modify the bracket to find a way to fit some compliance between the casing & bracket, or the same is going to happen again & again.

Thanks, what would you suggest to have some compliance between casing and bracket?

[tapkaJohnD]

Bobton125 said:

Although a steel sleeve in a welded up and redrilled hole is perfectly viable, That doesn't address the problem, which appears to be from vibration in the exhaust system. The bracket that bolts onto the side of the transmission casing transmits that vibration and wears on the hole. Most modern exhaust systems avoid this problem by suspending the exhaust from rubber, via hooks on the chassis and exhaust, while that bracket is massive and rigid!

Just removing that diagonal brace would allow it to be more flexible, to absorb vibration, with perhaps a bobbin or other rubber support for the exhaust. I fear that without a rethink, this problem will just recur, possibly causing more damage to the transmission casing.

John

PS Ah! I see that others are thinking the same way! "Compliance" meaning elasticty. Compliance between bracket and casing has caused the wear. You need to keep the vibration away for those bolts, allow to be absorbed by rubber near the exhaust.

Edited by tapkaJohnD on Wednesday 18th May 10:00

[steveo3002]

for a cheap bodge i would jb weld in a sleeve

[littleredrooster]

Outside of the good suggestions for repair, I think it needs a bit of re-design to prevent a repeat.

From the pictures, it appears that the bracket is mounted solidly to the motor, the silencer is mounted solidly to the frame and there is little or no compliance between the two. In the meantime, the motor, being a single pot, wants to rattle everything to bits, which it pretty-much has done!

I would suggest some rubber hangers at one or both ends of a bracket between motor and silencer. I can't imagine that mounting the silencer flexibly would help to prolong its life, so the movement must be at the motor end not the silencer end. I'm thinking of something like early Minis used to hang their exhaust from - a rubber bobbin with a stud at each end. The pipe may also need a bit of flexi in it somewhere, too.

[CrutyRammers]

I don't see that having the bit attached to the engine rigidly attached is bad; good If anything as you don't want any movement at the manifold to head join. The exhaust will move with the engine. It has to.

It does need a flexi between that and anything mounted to the frame, however. If thats not already the case, then that would be the problem.

[Tyre Smoke]

CrutyRammers said:

I don't see that having the bit attached to the engine rigidly attached is bad; good If anything as you don't want any movement at the manifold to head join. The exhaust will move with the engine. It has to.

It does need a flexi between that and anything mounted to the frame, however. If thats not already the case, then that would be the problem.

This was my thinking. Surely when this is fixed (I'm in agreement about the top hole) surely some sort of rubber mounting would dampen the vibrations and stop it reoccurring?

[E-bmw]

Bobton125 said:

E-bmw said:

It is one of those jobs that could be tackled in many ways dependent on budget/your abilities/your own equipment.

Personally, I would be:

Re-drilling & tapping the top hole to the next size up.

Getting the lower hole filled/welded up & tapped.

Then modify the bracket to find a way to fit some compliance between the casing & bracket, or the same is going to happen again & again.

Thanks, what would you suggest to have some compliance between casing and bracket?

It is hard to say from what I can see, but you need to find a way of either putting flexibility/compliance at the exhaust hanger or the bracket/engine interface to stop the vibration causing the same again.

See if some kind of exhaust bush/hanger can be engineered at the exhaust or perhaps something like an engine mount at the other end.

Basically you need to use your imagination/googling & find something that you can either make/modify/buy to achieve the end result.

[tapkaJohnD]

There seems to be an infinite variety of flexible exhaust hangers:

Given the nature if this 'buggy' vehicle, I wonder if motorcycle mounts would be a good start for your search. https://www.bing.com/images/search?q=motorcycle%20...

John

[Cold]

It looks like someone has already snapped a seized stud/bolt in this part of the casing and attempted to drill it out.