Exhaust rear pipe clearance

[Andrew S]

The rear offside exhaust pipe has always been very close to one side of the cross member as it travels through the hole. This has always caused a noise under acceleration and deceleration. I replaced the bushes etc on the hanger recently and refitted by wedging a piece of wood in the hole of the cross member on the side that it was closest too before tightening everything up. My first attempt was excellent, with no vibration under load but there was just an exhaust resonance at 30mph and 60mph which you could drive through. Thought I would have another go at realigning and now its back to how it was. The positive thing is, I know what is causing it.

As you look from the back at the offside cross member, the pipe is pulled towards the diff and when tail pipes are fitted, upwards.

I have just removed the tailpipes, and the pipe section that runs across the diff and the pipe sits perfectly square in the cross member hole and when its also in the hanger, although not bolted up tightly.

Put it all back together again and there is an instant pull to the left

My tailpipe hangers appear to be in the right place and I am now wondering if the intermediate pipe GEX 1435 is too short of the wrong shape. Its stainless so I cant really bend it.

Tempted to buy a mild steel intermediate pipe so that I can bend when fitted

I know that I can tighten up the hanger but when everything including tailpipes are fitted, there is a lot of tension there and has always been there.

Has anyone had a bad intermediate pipe that is too short or badly shaped?

And why is the exhaust bracket and hanger so close to the handbrake cable tube as I must have about 1/8 gap, if that when bolted up.

Any advice or suggestions much appreciated

Andrew

[jleyton]

Hi Andrew,

I'm afraid I haven't got an answer for you but I just hope I may be able to give you a little moral support !!

As I removed the front pipes to drop my sump I noticed that both silencers were in pretty poor condition so I decided to renew the complete system - a decision made easier when a kind contributor on here offered me a stainless steel system (just minus front pipes) that had only been on a car for 100 miles or so. I bought a pair of new front pipes and, with all my engine and suspension work done, it was 'just' a case of fitting this nearly new system.

I won't bore you with the details but I spent two, annoying and frustrating days sorting it, and that was despite the fact that I'd renewed the whole rear hanger arrangement on my original system about six months ago.

But the thing is, I got there in the end and I'm sure you will. My old intermediate pipes and the tail pipes weren't in too bad condition and, if it helps you at all, you'd be welcome to have them however as the new ones aren't a stupid price then I guess you'd be better off with that, but if I can help then just let me know.

So, sorry I can't suggest an answer but good luck with it

Cheers

Julian

Ps I agree with you about the exhaust hanger and the handbrake cable tube - they are amazingly close

[Andrew S]

Thanks Julian for your support and I can see that playing around with it may cure the problem but thought I would ask in case there was something obvious or known.

Did you have a lot of tension in the pipes and did you get rid of it. When I say tension, I mean for example, did you claim up the hangers so they wouldn't move and then bend the pipes to suit the next joint and so on? I just feel that any tension in the system gets transmitted through the car.

I may have another play with it tomorrow as she is still on stands and accessible and more importantly, in the warm. The only good thing was starting her up without the back pipes on and to be honest, it was a lot quieter than I expected even revving her up.

Thanks again

Andrew

[jleyton]

Hi Andrew,

I know exactly what you mean about tension and I totally agree with you. More by luck than skill, I think I managed to avoid getting any in mine.

I had the front pipes tightened to the manifolds as I reckoned that that was a fixed 'datum' point. Then, from there backwards I put each pipe loosely into its respective bracket and only had to juggle slightly to get a 'natural' run. I didn't have to bend anything. Obviously because of the shape of the intermediate pipes, rotating them gives a fair range of movement.

The major problem I had was that the silencers didn't go far enough on to the front pipes and so were sitting about an inch or so too far backwards which then, of course, put the intermediate pipes in the wrong position. In the end I managed to get a pair of very large G clamps on the balance pipe and on the gearbox cross member and put that under pressure. Then with repeated, but judicious, application of the realigning tool (aka hard rubber hammer), I eventually got the two silencers to move forward to their correct position. From then on it was relatively simple.

I think one of the key things is to have a pretty loose joint between each bit of pipe and the next so that you can easily manoeuvere each pipe section as required. In fact I slightly opened up a couple of the outer female joints so that they'd be easier to move and then tightened up with the proper original type of clamp - not the 'U' bend type.

I don't think there's a magic answer - just dogged perseverance !!

One thing I noticed is that I had two different type of mountings for the hangers in front of the rear subframe. One type had a metal tube through which the bolt ran. Although this would have been easier to fit than the fiddly pure rubber two piece one, I can't help thinking that the metal to metal contact would have given problems so I stuck with the rubber type (I hope this makes some sort of garbled sense !)

Anyway, good luck - still don't think I've been much help I'm afraid

Cheers

Julian

[elvimto]

Andrew,
Its stainless so I cant really bend it.
should make no difference stainless can be heated up and bent, I had to tweak the stainless system on my car from the front all the way to the rear. The PO had an exhaust shop install the system it did not fit well. If you have the gear to do it ie welding torch it bends quite easy, I did mine of the car.

Good luck Stuart

[AlanD]

Hi lads,
FWIW, i found if you fit from back to front, then fasten and tighten from front to back once its all fitted, making sure the silencers are on the right way round, my stainless system fitted really well, it was second hand and i took it off the stag that was scrapped. i had to turn parts of the exhaust to fit, IE the sections that go through the chassis, it took a while for me to realize that i had to turn them to keep them away from it.

hope this helps a little

[Andrew S]

Thanks Julian and Stuart

Interesting comment Julian on Obviously because of the shape of the intermediate pipes, rotating them gives a fair range of movement. Maybe the nearside pipe needs to be twisted which may allow the piping to go more towards the offside and the tailpipes will still fit OK.

I think before I go any further, I am going to look under another Stag and see what angles of twist each intermediate pipe has and make that my model to start with. Bending with heat is an option as long as I get it right. It feels at the moment that I need more of an angle on the intermediate pipe on the offside so that the pipe can be pulled towards the tailpipes without reducing the clearance on the cross member hole. At the moment, the pipe runs straight through the cross member nice and squarely and its only when I put the tail pipe on, it goes off centre.

Thanks again guys
Andrew

[jleyton]

Just one thought Andrew,

I've got two tailpipes and the mounting hooks are in different places on them

As your system is ok until you fit tailpipe, I wonder if the mounting hooks might be in the wrong place on yours?

Cheers

Julian

[Andrew S]

Interesting point and to make things worse, I have just welded 2 of them back on as they broke off the tailpipe and they are stainless. This has been caused by the tension over a long period. Will look into this, thanks

[chrisn]

At the front end of the system, check that the gearbox is sitting on its mountings correctly, and that these are not twisted to one side at all. I had this problem, traced to the offside engine mounting being fractionally further forward than it should have been. This amounted to the thickness of the mounting plate ie about 2mm. Doesn't sound much but it then throws out the system at the point you describe.

[Andrew S]

Thanks Chris, will have a look

[Andrew S]

I have been playing with the pipes again today and still cant get rid of the tension I have between where the offside pipe goes through the cross member and the intermediate pipe connecting to the tail pipes. It would appear that the angle of the pipe going through the cross member is incorrect.

Decided to copy the image off an ebay old stock item and photograph mine and compare angles. The below is what I have found with point 'A' being the focal point. I have drawn straight lines where the straights appear and projected the line to generate angles. Looking at my pipe compared to a new one being sold, at point 'A' there is a 5 degree difference.

Once again, the pipe comes through the cross member centrally and its only when I bend the pipe to the nearside to meet and fit the tailpipe, the pipe fowls the cross member.

Any comments greatly appreciated and maybe this is my problem and the pipe need bending.

Thanks
Andrew

Exhaust pipe.jpg

[jleyton]

Hi Andrew,

I don't know if this would be any help to you but you are welcome to have my old pipe, just for the postage cost. It's in reasonably good condition - it's a mild steel one. I don't think I even posess a protractor so I've got no idea how to work out the angles on it !!

Cheers

Julian

[Andrew S]

Thanks Julian for your kind offer much appreciated, but I think I am going to explore having it bent being that its stainless. There is a company called Pipecraft who actually make up exhaust in stainless and I can get there in half an hour and I think what I am going to do is to fit the system loosely and take the car down there and see what they suggest with a view to either the pipe being bent or a spacer put in on the straight that runs parallel to the boot floor.

The problem is, I am due to have the rear valance repainted and the boot floor cleaned off and re-undersealed and so don't want to fit it all now finally as it will all have to come off again.

The last couple of days has been more focused on why it wont fit nicely and why there is so much tension in the system. i mean, why do we have 3 chunky tailpipe hangers, why so heavy that surely transmits exhaust through the body shell when under tension.

My aim is to get the exhaust hanging without any tension so that all I have to do is lift the tailpipe section and just secure it with soft rubber hangers. I may be bashing my heard against the wall trying this.

Thanks again Julian for your kind offer

Regards

Andrew

[jbuckl]

Was there a useful way around this?

The intermediate hangers are a pita, anyone used the polybush & stainless kits?

My cars exhaust is now 24 years old, and won't be long before it's replaced.

I wondered if anyone has photos of an improved intermediate hanger set up?

Does anyone supply the silencers with the heatshield?