SP250 Exhaust Balance Pipe fitting

[Patersoncm]

I am having difficulty fitting a new exhaust balance pipe from David Manners on my 1960 A Series SP250. The pipe should run through the chassis cross bracing and meet up with the silencers. However it will not pass through the cross bracing (or line up with the silencers). The new balance pipe measures 525mm between the ends that meet with the silencers centre to centre. Whereas the silencers are 540mm centre to centre.

I have taken this up with DM and been advised that they have been selling balance pipes from the same supplier for some 30 years and all of the balance pipes in stock measure 525mm centre to centre. They are also not aware of any problems others have had and the solution for me is to cut the new balance pipe and intruduce a short flexible section (which is apparently done for automatic SP250's). They are however making further enquiries with their supplier.

Can any other members please advise the dimensions between the silencers (or balance) pipes and if the have had any similar problems?

Thanks

[Vortex O'Plinth]

I had a similar problem with a stainless system I bought from Bell Silencers of Swindon. There were minor fitting problems with the tailpipes as well as the 'H' pipe but Bell were very obliging in correcting parts to my patterns or dimensions.

I can't remember how short my balance pipe was - probably similar to yours - but this shows the small extension Bell let into it....

I suspect Bell and DM's supplier may well be working from the same patterns.

edit. I've just remembered I posted about this problem on the old forum - here - but it turns out my memory was wrong; the pipe was too long, not too short, so probably not a common pattern problem.

[V8 Junkie]

I have an A type and it is fitted with a stainless flexible it was on the car when I bought it maybe make enquiries ?

[Patersoncm]

Nick

Many thanks for positing the photograph (and useful link). It does look like you had the same problem with the balance pipes being some 15mm too close (hence the need for the short insert). DM are pursung with their suppliers.

Chris

[peterbee]

I have just removed an original mild steel David Manners exhaust system which I bought in the early eighties. The balance pipe inlet/outlet pipes measure 530mm c/c and the drop to allow it to pass under the gearbox is 1 3/8 inches - 35mm - and was a good fit. Have you checked that the silencers at both ends are centred on the holes in the X bracing? If they are not then the silencers will not be parallel to each other or the correct distance apart.

[Patersoncm]

Peter
Thanks for the message.
I can with some force push the balance pipe past the chassis cross bracing but it then fouls the short sections of chassis immediately before the silencers. An increase of circa 15mm would enable the balance pipe to pass cleanly though the chassis and align with the silencers. The silencers are I believe correctly fitted and there is no opportunity to adjust their location other than forcing the silencers to one side by pushing against the rubber bobbin mounts. Hopefully DM will come back with a solution when their supplier opens up. Other than that it will be a case of cutting the new balance pipe and introducing a new short section.
If many people are having the same problem it would be useful to get the suppliers to check their patterns.
Chris

[peterbee]

You can adjust the position of the silencers by first slotting the the holes in the support plate - Fig F1/14 in the service manual - and also by changing the bobbins. The height for these will depend on how well made the carrier plate/pipe clip -Fig F1/10 and 11 - are made. Get these right and your silencers will be correct ie centred and there should be no complication fitting the balance pipe the flexies or the tail pipes. I suggest you look at these options before butchering your new exhaust system

[Vortex O'Plinth]

You can adjust the position of the silencers by first slotting the the holes in the support plate - Fig F1/14 in the service manual - and also by changing the bobbins. The height for these will depend on how well made the carrier plate/pipe clip -Fig F1/10 and 11 - are made. Get these right and your silencers will be correct ie centred and there should be no complication fitting the balance pipe the flexies or the tail pipes. I suggest you look at these options before butchering your new exhaust system

I don't think the position of the silencers is Peter's problem. The tails of the balance pipe have to pass through the slots in the chassis cruciform - and preferably symmetrically since if they're not centred there's a good chance of them banging against the chassis under engine vibration. The exhaust system is best fitted from the front backwards, The downpipe flexible sections isolate the the rest of the system from engine motion and the position of the silencers is dictated by the balance pipe rather than the other way round.

If the centre distance of the balance pipe arms is not the same as that of the cruciform slots in the chassis the only solution is to modify the pipe.

[Patersoncm]

Nick
Spot on. The balance pipes will not pass through the slots in the chassis and will probably need to be modified.

[joewusa]

I have just removed an original mild steel David Manners exhaust system which I bought in the early eighties. The balance pipe inlet/outlet pipes measure 530mm c/c and the drop to allow it to pass under the gearbox is 1 3/8 inches - 35mm - and was a good fit. Have you checked that the silencers at both ends are centred on the holes in the X bracing? If they are not then the silencers will not be parallel to each other or the correct distance apart.

I am going to fabricate a balance "H" pipe assembly for my Dart and need some dimensions. I know the distance between the centerlines of 530MM (20 3/4") is correct for my car. I see you have 1 3/8" as the drop to pass under the gearbox. Since the engine and gearbox are out of the car I can't take the measurement. Is this drop center to center?
I also need the length of the two side pipes of the "H" and the distance the cross pipe is from either end of the side pieces.
Joe