Author Topic: Caravan bike questions  (Read 7513 times)

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Offline Patrick

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Caravan bike questions
« on: 28 Sep 2004 at 03:00 »
1. What quantity and grade of grease is the four-speed gearbox serviced with? There is a zerk fitting on top.
2. What is the purpose of the plunger/stem that floats from the top of the right side of the engine, just inboard of the generator. It extends/floats up about 3/4 inch when the engine is running?
3. I feel I have too much preload on the clutch cable...and need to disassemble and inspect the clutch. What is the procedure to remove the flywheel?
4. What does that zerk fitting service in the middle of the flywheel?
I am grateful for your help.

Here is some info I gleaned from Fulton's archives:

Douglas Chronology
from REF’s, “Eric Brockway” file, and “One Man Caravan” book and film.

1978, March   Insurance certificate
1980, June   Connecticut registration certificate
1982   From the film: bike observed to be operational. Tank and fenders painted gray. Aux fuel tank not attached.
1991, April   Membership card: REF, for London Douglas Motorcycle Club
1992   British Bike Magazine article: Fulton visited Bristol and arranged for restoration by LDMCC. Bike arrives in Bristol.
1992, May 7   Letter from Brockway: He’s annoyed with club. Bike won’t be completed in time for the ‘92 Cavalcade. Bike is sent to ‘the works’ at Kingswood.
1992, May 24   The Douglas Cavalcade occurs in Kingswood. Without GY1616.
1993, May 29   Bristol press releases: ‘Restored’ bike presented to REF. Work accomplished by apprentices from Allied-Signal Bendix at Douglas Road, Kingswood, Bristol, the bike’s birthplace.
1993, May   Douglas Cavalcade.(Undetermined if bike was operational)
1993   From Bernd Tesch’s forward to OMC: “Fulton aborted a trip to Germany on the restored bike. Clutch failure.
1993, Nov 23   REF letter to Brockway: “Where is GY1616 hiding?”
1993, Dec 9   Letter from Brockway: Bike is finally shipping. He feels guilty and embarrassed and let down by the ‘works personnel’s poor workmanship. The bike was then given to Don Brown to re-do. Eric mentions having a recent heart attack.
1993, Dec 23   REF letter to Brockway: “GY1616 is at the dock in NYC.”
1994, Jan 7   Letter from Brockway: “Don Brown should’ve had the bike from the beginning. He had business pressures and, ultimately, this bike, and others, had to be retrieved from his company. Thanks for Don’s vigilance. He found and fixed much on the bike following the Kingswood work. REF owes some money for out of pocket expenses. One pair of replaced bearings cost Ł175.
1994   Registration & insurance certificate. Connecticut
2004     Travis, Robert's son, asks me to resurrect it. I took delivery, from Connecticut, August 26.

Offline Doug

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Caravan bike questions
« Reply #1 on: 28 Sep 2004 at 05:17 »

Answering in the order you list:

1. The makers recommended Wakefeild's Casroleum or British Oil and Turpentine Co.'s Crimsangere, or Shell grease.  No much help today.  

I use standard wheel bearing grease, thinned a slight bit with 90W gear oil.  At 70F deg it should self-level in about five minutes after dragging your finger through it.  Straight grease will stay in the box better, but the sleeve gear lubrication is a bit marginal so I would rather have something a little thinner that has a better chance of getting in there and doing some good.  

As for how much, that is a very good question.  Douglas never did state a capacity in any of their prewar handbooks.  They just say it is best to add a little every 400-500 miles.  On straight grease you pretty near pack the box, and the gears cut trough through it.  On 'groil' you should only need to submerge the lay shaft.  You will not hurt it by over filling, and the excess will quickly find its way out!  It sort of seeks its own level.  If it is not leaking out the sleeve gear, you probably need to top it up!  

2. The plunger is the oil pressure tell-tale.  If it rises when the engine is running you have oil pressure.  If it does not, stop!

3. The clutch cable should have no preload; it should have a minimal amount of slack when the clutch is not in use.  If the cable is taunt you are loading the clutch throw-out ball thrust bearing all the time the engine is running, and it will not tolerate this.  Plus you are reducing the pressure on the clutch plate and inviting clutch slip.  Adjust cable so you have minimum 1/16 play.  If the clutch does not then lift fully and cleanly, you have other problems inside the clutch.  

To remove the flywheel, first remove the adjusting ring that applies pressure to the clutch springs.  This is the large chrome flange with hex in the center of the flywheel face.  This threads onto the flywheel nut proper (it with the zerk fitting).  If you are lucky, the flywheel will still have its extractor ring fitted.  This is a crenulated threaded ring that goes in the threaded hole and over the flywheel nut.  It serves two purposes.  Normally it is threaded tight in against the flywheel nut and acts as a jam nut to stop the flywheel nut from coming loose.  For extraction you back it off slightly (you will need to make a special spanner wrench, please do not use a hammer and punch or aluminum drift, you will distort the extractor ring and damage the threads in the flywheel).  Then loosen the flywheel nut, which has a flange the contacts the extractor ring.  Further backing off of the flywheel nut should draw the flywheel off of the taper.  Both nuts are right-hand thread.  The flywheel may be very tight on the taper (hopefully, or the taper may not be in very good shape from fretting.)  If it is tight a tap with a mallet around the rim (not a metal hammer and do not strike it very hard, the dish of the web is not very thick) should jar it loose.  The whole clutch assembly can then be withdrawn.  Beware when taking the clutch apart.  There are not many parts inside, but there are a lot of loose bearing balls and rollers that will fall out.  Lay down some newspaper to capture them all.  

4. The zerk fitting greases all those bearing balls and rollers that have scattered all over the floor because you forgot to put down some newspaper.  The center sleeve also slides on the hub of the flywheel to lift the clutch plate.  The grease is introduced via a groove down the flywheel nut thread and then through a diagonal drilling to the flywheel hub at the center of the clutch and works it way out under centrifugal force.  A slinger directs it out of the clutch and onto the chain but if you overdo greasing some will find its way onto the lining.  Some grease also works its way out the back end and lubricates the clutch throw out bearing.  It is because the clutch throw-out bearing only get what grease leaks out of the clutch, that you can not have the bearing loaded all the time.  It is not lubricated well enough to do this and will burn up.  A little shot of grease applied to the clutch often (every 400 miles) is best.  High temp grease would be an improvment.


The chronology is very interesting.  I was corresponding to Eric Brockway about that time, and amazingly in his long association with Douglas Motorcycle Ltd, and the London Douglas Motor Cycle Club he had never got around to reading "One Man Caravan".  I was about to send my copy over but he was able to borrow one closer to home and found it a good read.  The issues regarding the work done by Allied-Signal Bendix never got mentioned in the Douglas club magazine, but then that is not surprising.  They had hosted the club on occasion at the former factorty site, and they would not want to upset anyone.  

Hope the above helps,