7 replies to this topic

[goat64]

1976 850 Mark 3, no mods.

 

Metallic mechanical knocking since rusty silencer replaced few years ago with standard replacement (Minispares GEX177 EXHAUST SYSTEM WITH TWIN BOX FOR SALOON SMALL BORE).

 

Fitted by a local garage , who claimed to be mini enthusiasts.

 

 

Since then, the middle section has been knocking against the gear selector box which sits directly inder the gear stick in the central "tunnel" running front to back under floor.

 

It only happens when engine is wibrating a bit at idel / low revs, e.g. when just pulling away from stationary.

 

On investigation, the middle section of te silencer is a few millimetres away from the gear slector housing, so slight movement makes it knock on the housing.

 

A total of 4 proper garages with qulaified mechanics have accepted my cash over the lasst 3 years to play with it and try and do something, with no result.

 

It may be a clue, perhaps, but the silncer seems to be hanging too low in the middle. I know minis have small clearance anyway, but the distance from 1t muffler box to road is barely 3" (less than the width of my iphone8, for thise of you working in metric !)). It had been known to scrape on speed bumps in our local supermarket car park.

 

None of our local exhaust specialist fracnhises will even look at it, when I tell them it is 40+ years old.

 

I'm loathed to part with more cash for mechanics to look at it, as all the 4 I tried came highly recommended and did very little, so need to try and realign it myself..

 

I can't find any pics of what it SHOULD look like, but pretty sure it shouldn't be touching the gear selector housing, and should be an inch or 2 higher.

 

I feel sure it is just a missing cotton reel rubber mount or clamp somewhere, but in absence of anything to compare with (stupidly I didn't think to take pics of old rusty one before entrusting to qualified mechanics), not sure where to start. Can't ell from verious scematics what mounts / bushes are needed.

 

SO.....

 

1) has anyone got an 850 (is a 1000cc the same?) with original silencer set up (small bore, 2 muffler boxes) who is willing to send some pics / measure clearance from pipe to seletor housing , and clearance of muffler-to-road, and maybe pics of the mounting / bushes fitted. This would hopefully give me a clue as to what is wrong with mine, and where to start tinkering.

 

2) can anyone recommend someone local (sussex) who might actually be able to adjust / bend / realign it properly. I am very dissillusioned with the local garages. I'm sure they mean well , and try to fix the problem, but without actually fixing the problem. Well, 1 of them managed to lift the silencer another 1/2" for extra road clearance, but not change in knocking.  Most have not seen a car older than 7 years in their professional careers, and even the one I trust most (old car enthusiast couldn't fix it !

 

I am happy to try and take some pics if needed, but I have no room to jack car in garage and our usual area for worrking on it is still 8" deep mud!

 

Thankls for any pointers / tips / advice.

[lsto]

As far as I know they only have a metal bracket on the gearbox, a square rubber mount on the rear subframe and the two bobbins just above the tailpipe.
I'll be honest every exhaust I have ever bought has been a poor fit and always required some adjustments. My current 998 has an RC40 and I ended up binning the brackets that came with it and made my own because it hit gear selector and also was hard up against the rear valance. Unfortunately it was a case of trial and error until I could get it where I was happy. On my old cooper I fitted a sportex system and that was terrible too. Sorry I'm not much help but I feel your pain.

[Shooter63]

Are you sure the exhaust is hitting on the gear selector, normally the first box sits well back from that. What I have had a problem with is the first box hitting the threads of the bolts that hold the seat belt on. I changed these out for shorter ones and that seemed to cure the problem.

Shooter

[coopertaz]

they may have put rear section too far onto front pipe, usually very close to handbrake connection plate where front and rear cable join under the car. is the sxhaust attached to the rear subframe front mount. also check engine mountings and stabiliser bushes for wear

[Cooperman]

The problem is probably the exhaust hitting the seat belt bolts. I have had this several times and the solution is to cut off a bit of the bolts where they project through the trapped nut plate.

If that doesn't give clearance you just need a big crow bar!

[goat64]

Thanks to all.

 

I'm pretty sure it's the gear lever selector housing impinging, but will double check the seat belt bolts again.

It's definitely bashing on the front bit of pipe  - the bit from engine to 1st muffler box.

The worn engine mounts and stabiliser bushes is also a distinct possibilty as they are 50 year sold, as far as I know !

I think there is only 1 bobbin bush at tail pipe end mount, which may be contributing too.

It feel slike it needs bending, just an inch or so, around the selector housing.

 

It will probably turn out to be several different things, which is why no single garage has been able to (i.e "could be bothered to") do a proper fix.

 

We have just had our 1st 48 hour rain-free period since Christmas here (Sussex), so hopefully will be able to get it outside and jack it up soon. I will report back if 

[goat64]

.....(pressed post too early).....report back if and when I can fix it.

[goat64]

Finally got round to addressing knocking silencer...

Very awkward to get at , even up on 4 jackstands.

It was definitely knock on gear changer housing in the central tunnel, not seat belt mounting bolts.

I loosened all the fxining points:

• exhaiust manifold to downpipe.
• bracket at rear of gearbox/engine block.
• U-clamp at junction of front and rear sections (2-section RC40 GEX177 from Minispares).
• Bracket to front of rear subframe.
• Bracket to rear of rear subframe.

Very little "wriggle room" apparent even with eveything loosened off.

Starting at back, I slid the bracket as far towards the rear of the car over the silencer pipe.

Did the same at the next bracket (at front of rear subframe).At this site, the pipe is anled, which means the further towards the rear of the car you can slide the bracket round the pipe, the more the pipe is pushed towards teh driver's side of the car, away from the gear change housing.

There was no useful mvt at U-clamp (joint) or rear of gearbox.

 

With the  2 "slidable" brackets positioned as above (as far as possible towards the rear of the car on the pipe), the clearance from pipe to gear chaneg housing is now 12mm (1/2" if you are as old as I am !) - a big improvement over the 2-3 mm it was.

 

My only concern is that the 2 rear brackets are "doing a  lot of work", as they are now "pushing" the silencer forward / outward (toward driver's side), so the silencer is under a little compression / tension now. It certainly feels quite solid now, which may not necessarily be a good thing!  If the brackets give up under repeat stressing, I will replace with some customized brackets, now I know what is needed.

 

Tightened up all the clamps (starting at rear). Clearance still good.

 

Ran engine: small blow at manifold clamp cured by tightening up the pinch bolt a bit (pinch bolt type, not cast iron type). I'm loathed to tghten any more than is just needed to seal leak, as I think it is very easy to snap pinch bolts which are not necessarily "in-lilne" when tightened (like the pinch bolt clmap at base of distributor).

There was also a barely detectable leak (can feel it , just, but not hear it) at the U-clamp securing front and rear section, which wass NOT improved by tightening U-clamp as much as I dare. If this bothers me in future, I think a bandage or some gun gum and retighten the clamp over it would fix it.

 

AND the result of all this.....

NO RATTLE now , no impingement of pipe on gear change housing.

Engine sounds sweet as a sweet thing, with extra honey, sugar and maple syrup  on top

 

The clamps / brackets are all very non-standard, looking NOTHING like the minispares bracket kit. If I have further / recurrent problems, I will invest in the proper fixing / bracket kit, or try and make my own, as suggested by "Isto".

 

All took me (an un-qualified occasional DIY-er) a couple of hours, most of which I was struggling to find a half-tolerable position under the care with very little groumd clearance.

 

So, why have 4 qualified (?) , not to mention expensive (£60-£100 per hour) , garage mechanics NOT fixed this problem when asked / paid??

Which brings me back to my other Q in the OP: anyone know (and TRUST) any "proper" mechanics in Sussex area who might actually be ineterested in fixing stuff rather than just taking money and not fixing stuff????  I have no problem handing over bits of my pension for a proper, quality job by someone who cares, but struggling to build up much trust for our locals (sussex borders)..

 

Next problem: split pot joint gaiter: beyond me. I shall have to trust local garage for this. I shall let you know how it goes, hopefully to "big up" the local garage for excellence of work. We can but hope !