New Exhaust System

[Roy Hudson]

Hi
I am looking at fitting a new mild steel exhaust system ( quite cheap at Moss Europe at the moment !! ) to my LE roadster and was wondering how difficult it might be to fit it myself , although I have very limited mechanical knowledge.
I do have a garage that I can use at my leisure and a decent toolkit.
I have gone for the mild steel because I want to keep as close to the original exhaust note as I can.
Any tips would be welcome

[Peter Cresswell]

Hi Roy,
There are 2 types of system for the MGB - the one piece system which includes the front pipes, and the 3 piece systems. both have advantages and disadvantages.
To start, remove the existing system by starting at the back and working forwards undoing the front pipes from the manifolds last. You will need to raise the car quite a lot (make sure it is secure before venturing underneath) particularly if the system is a 1 piece system, as it can be quite a struggle to get the front pipes out under the car if you don't. It is also easier to fit the new system if you have a new mounting kit. Make sure you get the correct one for the LE if this doesn't come with the system.
1 piece system. This can the easiest to fit and I've found is less likely to leak if you catch the centre box on speed humps! You will need a means of holding the system up to the bottom of the car - a trolley jack will often do the trick, or big blocks of wood. Start at the front and loosely attach the front pipes to the manifold using new sealing rings (with some exhaust sealant) and new nuts. Then move to the back of the car and offer the tail pipe up to the rear mounting, checking the centre box is siting in the groove of the cross member. When you are happy it is in the correct place loosely do up the fixings. Finally fit the centre bracket loosely, then check everything is in the correct place and then do up all the fixing tightly. The biggest problem you may encounter with the one piece system is that (edit - IF) it is slightly the wrong shape and correcting is difficult.
3 piece system. This can be difficult to get right as all the joins allow almost an infinite number of possibilities! If you can get your existing system off the car in one piece keep that as pattern, and try a dry run of the new system off the car comparing the shape of the new system to the old as you go. If you want to try to fit the new system a piece at a time then use a permanent marker so you know the relevant position of all the section. Alternatively you tighten all the section clamps just enough to keep the section together and then fit it in the same way as for the one piece system, remembering to tighten all the clamps when the system is finally attached to the car. If you do it a piece at a time fit the front pipes to the manifold first and tighten the nuts sufficiently to hold the pipes firmly. Then fit the next section, leaving the clamp to the front section loose, and the centre mounting loose, but supporting the system so far. Finally loosely fit the rear section making sure the silencer is tucked up as high as possible and the tail pipe is in the right place. You will probably have to twist the pipes around a bit to get a good fit (but this is the advantage of the 3 piece system!).

Getting the old nuts and bolts undone can be really troublesome, as they are likely to be rusted up. Give them all - especially the nuts that hold the front pipes to the exhaust manifold - a good dosing of WD40 or something similar several time is the days before you want to do the job.
It's a job that is more messy than difficult!

[Roy Hudson]

Thank you for your help Peter , much appreciated