Sunbeam's 1973 Fiat 125

[Sunbeam]

Flushed with the glow of success from obtaining legality for the first time in 15 years, I am acutely aware that there is more to do. My exhaust downpipe arrived. 

It came with an inch and 3/4 outlet and I need to make it 2.  Mark:

 

Chop. No going back…

Tack.

Beer.

[Sunbeam]

Did a bit more today between farm chores and ferrying kids around (to be fair it was for dirt drift karting which I enjoyed as much or more than the kids). First job was to grind off the bottom tacks so I could tweak the end of the pipe down a bit

 

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Then it was time to trim and hang the rest. This took a few goes. Main pipe section is ok

Over the diff is good:

The rear “muffler” hangs pretty good too, but could do with hanging a few mm lower which is just a small adjustment on the clamp

It’s the bit where the front pipe should slip into the first muffler that needs a tweak:

It surprises me how much just increasing the diameter of the pipe affects ground clearance. I have 105mm under the front of the first muffler. This is now the lowest point on the car. Also, the hand brake cable is quite close to the pipe- the bare steel bit, not the rubber sheath which will limit my ability to lift the muffler for more ground clearance. Is there a minimum clearance for cables that I need to be cognisant of for WOFs?

[Sunbeam]

I have gotten as far as I can go with what I have. I’m very happy with the downpipe I bought, the fit is perfect.  All the other joints are aligned now, but this leaves the tailpipe exiting at a 5 degree angle. This will be unfixable without tweaking some bends in the tubing. The lowest hanging part has 125mm ground clearance and it’s close to the rear axle so I’m happy with that. I also haven’t been able to avoid a very tight gap with the rear passenger footwell pressing in the floor. I have 4.5mm… is this too tight?

 

Also, every slip joint has a tiny leak!! I’ve run the engine and it sounds quite stout, a bit more bass but still with all the twinky rasp.

[Sunbeam]

I personally don’t like doing this on slip joints but beggars can’t be choosers.

 

Also I have new rubber hangers so I thought I’d accelerate the stretching process. Yes, that’s an old battery..

[Sunbeam]

Yes, 4.5mm is too close. It bangs the floor vigorously when traversing bumps. So I have undone everything again and extended the hook eyes I fabricated for the rubber straps and meddled with some angles and I now have about 10mm. Also, no leaks. Also also it might be a smidge loud. I know, I know but I’m closer to 50 than 40 nowadays and I have enough hearing loss from hundreds of hours in a Cessna 206. Don’t need to be more deaf.

[Sunbeam]

Been driving around some more. 2200-2800 rpm is punishing to cruise at. Transitioning through this band is fine and generally it makes bad-ass old car tunes. The rear muffler is a straight through bullet style and this needs to change, I think. I have a new problem with clearance though. The exhaust isn’t banging the floor anymore but now the rear axle housing is banging on the inverted U section. I think I need to ditch the slip joints and weld flanges in instead. This will give me some more wiggle room to play with angles before welding the flanges on. Also I may investigate adding another leaf or part leaf to the rear springs. They are so soft I can make the diff housing touch the bump stops (and exhaust)by pressing down firmly on the boot! Increasing ride height is not an option. 
Servo pic: 8.8 l/100km on this one. I was expecting 10-11 so call me pleasantly surprised.

[Sunbeam]

1000km post run in oil change time. 

 

Then I took it in for some surgery on the exhaust. I got sick of playing around with it so like a coward I farmed it out to a zorst wizard. There was much choppy chop and a quieter centre muffler was grafted in. Still sounds good but is now bearable to drive. Wizard made multiple angle adjustments to clear the diff and brake bias valve and torque arm.

 

One problem to report: Whiff of antifreeze when the heater is on. GROOOAAAN!! Looks like dash out in my future.