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Panhard project - part 1

panhard engine

Quite a few of you will be aware that I have been talking (boring you) about a new car for some time and the form it will take changes with my underpants. (Well almost daily.)

So here it is … 3 wheels, Panhard engine, Guzzi 6-speed gearbox, clutch and starter motor, rear drive via Guzzi shaft, rear arm and bevel box. Possibly Panhard front suspension, all bodged into a Pembleton chassis. So there!

I can hear you shouting "WHY?"from here. Well, … because (I hope) I can.

I’ve started with the engine. "Why a Panhard engine?" you ask.

This illustration gives you an idea of the layout and history.

panhard engine

This is what I am starting with -an 850 Tigre engine from the 1960s. The oil filler, cooling turbine and cowlings have been removed.

panhard engine

Upon strip down, it soon became obvious that this engine had seen a hard life, as you will find out later.

Bare crankcase with iron rear main bearing carrier. Good news in a way. This was the final evolution of this engine - the PL 24 and the last car to carry the Panhard et Lavassor name, marking the end of one of the oldest names in motoring history.

The case has been rough-cleaned and inspected - all good. New main bearings although obsolete, were not difficult to find locally. There’s still some engineering to do on the case (more on that later) so the new bearings will not be fitted yet . Next job, remove studs.

pistons

Pistons, hmmm… They may be a tad worn. Half of the top ring had made an exit, stage left, through the exhaust valve. I did hear that BMW bike pistons can be used, so a trawl of interweb produced some "interesting" results. OK. Whatever you do, don’t Google "German pist on". Anyway, Wossner do some aftermarket high-spec, modern design pistons that may fit the bill, cheaper than OEM as well. These were sourced from Motoren Israel in Germany.

Some of these little engines have been over-bored to 1000 and even 1200cc. Standard bore is 85mm and BMW R series are available very close to that, so naturally I chose some R90 91mm pistons – bonus,they are 100 Grams each lighter than the originals.

The Original pin ran direct in the little end with no bush and is badly galled. The smaller replacement will allow the fitment of a bushing so the worn rod end is not a problem.

little end pin

Next the crankshaft. Play in the big end was evident. This would require pressing apart the assembly for inspection. Bad news, the roller bearings run directly on the crank pin and in the rod end. The crank-pin is shot. Worse news, the crank-pin is not replaceable, being forged in one with the web and main bearing. Both main bearings are good.

Both halves of the crankshaft are pressed into a central web and that press fit was loose, a common problem apparently. Where do I go from here? A visit to specialist roller bearing crank experts Alpha Bearings in Netherton, near Dudley, provided the answers.

  1. Grind both big end journals undersize.
  2. Make two new,hardened sleeves to suit and press them on.
  3. Make a new central web with correct interference fit to suit the re-ground pins.
  4. Grind to size and re-harden the big end of the con rod.
  5. Make new bearing cages and full width rollers to suit.
  6. Reduce the width of the little end and bush to suit the BMW piston and pin.
  7. Pop it all back together and here it is.
crankshaft and associated parts

Sounds simple enough but the precision required is absolute. This was not a cheap process but the final cost was just over half the price of a remanufactured standard crankshaft assembly from a marque specialist in Holland. The work took 18 months to complete. (There was a bit of a queue.)

Points of interest:

lower crankcase

The studs have been removed and here is the first test fit into the crankcase - only a very minor fettle to the case required and it’s in. I can now finalise the design of the new cylinder liner base detail.

The crankcase mouth will require machining to accommodate the larger cylinder liner.

cam shaft

Here is the camshaft, all good. A letter "S" on the end indicates this is the high output Tigre one. The camshaft gear is Celeron fibre. Although quiet running,these are prone to failure in service and this one has teeth missing. The crankshaft gear has chipped teeth and has been scoured by hard metal particles embedded in the Celeron. Replacements for both were obtained during our recent Retromobile Paris trip.

The camshaft is quite fat and has a large hole up the centre. This provides the main oil gallery from the front to the back of the engine.

cylinders

On to the cylinders. You will notice that they are "blind", the cylinder and head being cast in one piece. All the valve seats and guides require replacement, tricky at the best of times.

First, the old liner has to be removed. As this requires serious heat the part needs to be clean or the fumes will get you into trouble…… see Part 2.

I found this stuff from Screwfix. It says dilute 50/50 with water. Won’t that make it only half as good? Wear your PPE - its nasty.

DB Panhard 1954 LeMans car

That’s it for now.

Coming up in Part 2 of "From Crap to Scrap", Dave gets banned from the kitchen and proof that no matter how fast you juggle really hot things, you still get burnt.

I will leave you with this final picture of the DB Panhard 1954 LeMans car

Nice , well I think so.

Dave Parr


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