4 replies to this topic

[dschwartz1957]

In May 2013 I bought a '68 Mini Traveller Estate. The car is mostly original and has very little rust. The only major upgrade is the 998cc engine was replaced with a 1275cc engine which has a single HS4 carb. A previous owner also installed a very loud single box glass pack exhaust system.

 

The engine number is 12H159A / H175882.  I have been told this engine is probably from an early 70's Austin America or Austin 1300. The engine has the standard cast manifold and does not appear to have been upgraded in any other way.

 

In the interest of quieting down the beast, I decided to install a GEX155 Twin box exhaust, which is an original sytle exhaust for the Van/Estate. This is a single piece system which is cut in half to ship to the US, so the first order of business was to have the thing welded back together. I also bought a GEX9551 "Exhaust Fitting Kit, Stock Cast-Iron Manifold".

 

Removing the old exhaust was easy. It turns out the old system didn't use any clamps. Instead it had metal bars welded to the pipes which bolted to the transmission housing and two locations on the subframe. 

 

With an original style exhaust and the fitting kit I thought this would be an easy replacement job.Of course it was not. The first problem was the middle exhaust mounting block that bolts on to the front of the rear subframe didn't line up with the bolt holes in the subframe. The rubber block is also a bit too long and the bolt almost touches the spare tyre well. Bending the metal legs slightly made the holes line up, and pre-installing the centre strap and bolt solved the tire well problem.

 

The next problem was being short by one clamp. The fit kit came with a clamp for the rear but not the center or front. The exhaust system did have the gearbox clamp (GEX7526) but not the center clamp (GEX7052) which should have been supplied with the exhaust system. I figured a local auto parts store would have a univeral clamp that would work, so I decided to complete the installation.

 

With help from a friend I got the the exhaust system into position, loosely attached the rear clamp and improvised a center clamp. When I tried to attach the front downpipe clamp to the gearbox it came up several inches short. There was no bracket on the gearbox. Again I figured a local auto parts store would have a univeral part that would reach the gearbox.

 

Now the final problem. The diameter of the flange at the end of the downpipe was too small and kept dropping out of the manifold clamp, even when the clamp was completely tightened. The fit kit came with a two piece manifold clamp that was very hard to work with. The original clamp was two piece cast iron, and someone welded the bolts to one section making it much easier to work with. Even using the cast iron manifold clamp the downpipe still dropped out of the clamp. It seems the clamp was fully tightened against the manifold flange, but not against the downpipe flange. I compared the diameter of the downpipe flange on the new exhaust to the old exhaust, and the old flange is about 1/2 inch larger diameter. I have temporarily reinstalled the old exhaust so I can drive the car.

 

Now for my questions:

1. Did the cast manifold on non-Cooper 1275 engines (#12H159A from an Austin America or 1300) have a larger diameter exhaust manifold flange which requires a larger diameter downpipe flange?
    
2. Is a gearbox bracket required or recommended for a '68 Mini Traveller MkII? I thought these were only used on the early MkI cars with the rod change gearbox. If the braket is needed, what is the correct part number. I have seen three different brackets on the classic Mini parts websites (GEX7526, GEX7088 and GEX7053). I need a bracket that bolts to the GEX7053 front downpipe clamp when using a GEX155 Twin box exhaust.

 

I am open to other advice on how to fit the GEX155 exhaust to my car.

 

Thank you,

 

David Schwartz

Framingham, MA (near Boston)

USA

 

 

 

 

 

 

 

 

[Vipernoir]

All cast manifolds are essentially the same.
The fitting kit you reference has all the required bits in it to hang an exhaust.

 

As you're a member of NEMO, your best bet if you're struggling is to give Dave Black a shout.

[KernowCooper]

Something tells me some of the original early cast manifold clamps were a different size on the flanges ? top is larger that the bottom flange so if fitted upside down the downpipe would fall out, something worth checking on in case i got it wrong, long time since I saw one

[dschwartz1957]

My car has already had two visits to Dave Black's infamous "Barn" (to replace a front wheel bearing and a leaking rear main seal). I specifically asked Dave about replacing the exhaust system, and he told me the engine had a standard cast manifold. I also spoke with Dave after my exhaust system installation debacle and he suggested checking with the Mini parts dealer that sold me the exhaust.

 

As for the cast manifold clamp, the top and bottom did not appear to be different sizes. But then I wasn’t looking very closely. It may be worth removing the clamp and taking a closer look.

 

The new GEX7046 manifold clamp does look symmetrical, and the downpipe dropped out of that as well. Plus trying to attach the thing without the nuts and washers dropping off is next to impossible. Welding the bolts in place on the old cast clamp was a great idea.

[Vipernoir]

You have to make sure that the flange on the pipe is butted up hard to the manifold (I use a scissor jack) and the clamp is snugly around the two parts when nipping it up, or it will all fall off.