Lotus Elan

Rear transverse silencer box on S3

PostPost by: Pastapesto » Sun May 13, 2012 1:29 am

I am having a little trouble fitting my transverse stainless silencer into the recess below the boot on my early S3 coupe. Could anyone please help by posting some good photos showing how high it should fit, a side photo showing how far it sticks out at the back & also some clear pictures showing the two brackets that hold it into place. I have a new Double S silencer, two angled brackets (both look the same) and two straps that I need to cut to length. There are some existing holes in the boot floor but the brackets do not seem to fit nicely there and I did not want to go drilling yet more holes before I know if I have the correct brackets and a good idea of how tight it should be inside the recess. I have a feeling that the brackets I have are not the same as were originally on the car. What would be perfect would be to see an original box and brackets plus a rear photo so I can see how much of the silencer you can see from the rear of the car when looking from behind. Another point I'm a bit confused with is just how much of the left hand side of the box sticks out behind the l/h rear wheel. Seems a little too large for the recess IMHO. Has anyone else had similar problems? I think the earlier silencers with the entry and exit pipes on the same side probably fitted nicer but the new one I have has different entry & exit sides and perhaps this is why it is a little more bulky. I'm also a little concerned as to how hot it will get and if I will have issues with the heat and the paitwork, does anyone know if I will have any problems? I'm really struggling with this so I would appreciate any help please.

Thanks

Adam

p.s I realise that I ask a lot but I'm trying to get it as original as possible without drilling a lot of new holes and buggering it up :?
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PostPost by: jpt » Sun May 13, 2012 7:50 am

Tynemead completed a beautiful S3 restoration a while ago and then had it up for sale.
http://www.lotuselan.net/forums/elan-for-sale-f2/lotus-elan-fhc-take-look-t21856.html

Although the advertisement has disappeared it had some outstanding photos, and I have attached a couple below that show the muffler well.

Jon

P1070321_S3 FHC, 1967, Completed Car, Underneath, Rear View.jpg and
View from rear underneath

P1070376_S3 FHC, 1967, Completed Car, Left Rear Quarter View.jpg and
Left rear quarter view
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PostPost by: simonknee » Sun May 13, 2012 8:19 am

Can't give you any pictures at the present. Yet whilst my exhaust is custom made I think the hangers are original and they are pretty much on the same location as the photo provided by Jon.

What I can tell you is get it as close as possible. Just enough clearance to avoid it vibrating against the underfloor. You want as much ground clearance as possible. I have never had a paint issue in thousands of miles. The rear box doesn't get that hot.

What is really important in the fhc is a completely gas tight fit. The cabin is at a negative pressure - especially if you have the air-flow vents in the rear pillars. Any leakage under the car, from any join in the system, will get into the cabin. The boot seal is particularly important as is the gear gator. Modern fitters tend to use high temp silicone sealant which has the benefit of being resistant to vibration but I am not convinced by it. The stuff by Holts (gun gum etc) is rubbish. I currently use EAD5 by Hylomar which is OK but I once had a better type that was blue in colour but do not know the brand.

If you use U-clamps for originality then do not point the bolts down. Even at the y-pipe (though if you are after originality you have a cast manifold). This is back to the ground clearance issue. Basically if you ground any part of the system you will probably break the gas tight seal at a joint somewhere. In the fhc you will then proceed to poison yourself.

The box itself should fit inside the recess but the curve of the pipe might have to hang out a bit. Depends on how tight a radius the manufacturer managed.

Finally mount the box with as much of the tail pipe sticking out the back as possible. You want the exhaust gases as far away from the rear of the car as there are strange vortexes going on here that suck the air back in the car.

P.S. can you post pics of what you have?
Simon
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'69 +2 50/1370 (stolen '00)
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PostPost by: Pastapesto » Sun May 13, 2012 8:35 pm

Jon

Thanks for the photos of the Tynemead S3, I had forgotten those pics and they were really helpful.Thanks.

Simon.

Thank you for all the very helpful advice which I will use gladly. There were some very useful tips you have given me and I thank you again.

Well after spending all day trying to get the damn thing to fit inside the recess nicely with good ground clearance and with the pipe exiting the rear valance channel in the middle, I have now come to the conclusion that the box is about a half to three quarters of an inch too wide overall. The problem (IMHO) is in the semi circular bend on the left hand side of the box, it is just too wide. Not sure what I can do about it at the moment apart from reshaping the boot floor so it fits properly but as the car is all painted and looking nice it's very unlikely that I will be doing that. I will try and call the manufacturers (double S) tomorrow & see if they can help otherwise I may try to get another one from another exhaust manufacturer. It seems daft after having have done so much to the car that I will not be able to get the exhaust to fit properly or have it foul on the underside of the body.

Oh well, I supose nothing ever fits first time on an Elan without some major fettling, what was I thinking? :(

Has anybody else had trouble like this?

Adam
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PostPost by: mac5777 » Sun May 13, 2012 10:49 pm

Adam, I have a S3 coupe and my standard stain-less muffler would drag in driveways. A local muffler shop supplied a standard three hole muffler and sealed the out side end and used the intake and outlet as seen in the photo. That eliminated the pipe to the outside end and allowed the muffler to move forward closer to the axle where the pipe was and up giving an additional 2 inches of clearance. They welded attachment hangers to the muffler and use the original body attachment points. It was very reasonably priced and only took about 40 minutes. I applied a reflective foil insulation that was self-adhesive and protected the fiber-glass body from high temp. You can see that nothing is hanging down and has great clearance.
Simon has good advice.

Sarto
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PostPost by: Pastapesto » Mon May 14, 2012 12:10 am

Sarto
How are you, I hope you are well.
I think your tailpipe & box & the way it fits is the best I have seen. I also like the way it has been painted matt black to hide it even more.
My box would fit much better if it was about an inch shorter in width which would enable it to sit higher inside the recess and look a lot better too.
I will talk to the makers tomorrow and see if they can either shorten it or send me a better one that has been altered. They must be all made on a jig so they must all fit rather badly unless I am mistaken.
Failing that I will have one made up in a similar way to yours.
I will let you all know how I get on.

All the best

Adam
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