Author Topic: New project 1937 aero 600 (Read 6069 times)

Red · « **Reply #50 on:** 15 Apr 2023 at 09:33 »

Neil

On the front brake the operating rod is fitted with what Douglas called a spring box. Is this fitted on your bike. Without the spring box there is a good possibility that the brake will not free off completely. See link below. I had to make one for my son's Aero for the same reason.

Roy

https://www.douglasmotorcycles.net/index.php?topic=6194.msg23211;topicseen#msg23211

Tazmantic · « **Reply #51 on:** 15 Apr 2023 at 19:25 »

Thanks Roy I had noticed that most 600 had a steel rod and mine does not so looks like another part I need to make

neither of my 250s have this rod so yet more wrong with my bike.

Neil

Tazmantic · « **Reply #52 on:** 16 Apr 2023 at 19:48 »

So having a better look at the drawing I presume the cable adjuster goes in the top of the spring box? Also does the ID of the spring fit over the adjuster?

Neil

Doug · « **Reply #53 on:** 17 Apr 2023 at 06:19 »

The cable adjuster projects into the spring box. The spring does fit over the adjuster thread, and abuts the shoulder in the brake rod.

A picture of the top of the brake rod:

-Doug

Tazmantic · « **Reply #54 on:** 17 Apr 2023 at 09:32 »

Thanks Doug that’s great should the 250 have the same?

Neil

Red · « **Reply #55 on:** 17 Apr 2023 at 11:05 »

Hi Neil

If you look at page 17 of the numerical parts list yes ALL the Aero models were fitted with the same front barke arrangement. There are a few minor changes to the 1937 bikes (model F) when straight pull levers were fitted, but the spring box was still used - part numbers 5299 and 18421 and operating rod C/11437.

Roy

Tazmantic · « **Reply #56 on:** 17 Apr 2023 at 13:54 »

Thanks Roy, everydays a school day as they say so looks like I need to make 3 sets

and that’s why there are 2 different return springs listed for front and rear brakes I was thinking they meant the ones in the drum on the brake band, so I presume the one listed for the rear (11350) is the one on the brake pedal?

Neil

Tazmantic · « **Reply #57 on:** 17 Apr 2023 at 21:07 »

Sorry another thought does anyone one know the spring size? Length and wire gauge?

Neil

Red · « **Reply #58 on:** 18 Apr 2023 at 09:43 »

Hi Neil

I think this is the one I purchased from Feked.

Roy

Tazmantic · « **Reply #59 on:** 18 Apr 2023 at 12:29 »

Cheers Roy, I did find that one earlier and wondered if that might be it. Appreciate the help again.

Neil

Tazmantic · « **Reply #60 on:** 18 Apr 2023 at 19:47 »

So springs and some bar ordered did you make the lower rod out of 3/16 and what clevis fork did you use?

Neil

Red · « **Reply #61 on:** 19 Apr 2023 at 08:43 »

Hi Neil

Yes I just copied the dimensions Chris provided so I used 3/16 inch rod. The fork was made out of a small block of steel with plenty of cutting and filling. I don't know whether you could buy anything similar. Others may have better ideas.

Tazmantic · « **Reply #62 on:** 22 Apr 2023 at 20:09 »

Cheers Roy, my metal didn’t turn up so made some bolts to hold the gearbox today as last owner thought 3 threads was ok….not original and probably the wrong thread but match the thread in the box and should work ok so that will do for me

Neil

Tazmantic · « **Reply #63 on:** 07 May 2023 at 15:28 »

Well here’s my attempt hopefully it will work

Neil

Red · « **Reply #64 on:** 07 May 2023 at 16:42 »

Hi Neil

Looks good

Tazmantic · « **Reply #65 on:** 07 May 2023 at 22:52 »

Cheers, hope it works

Tazmantic · « **Reply #66 on:** 15 May 2023 at 18:34 »

So with everything I’ve found decided that the “refurbed engine” needed a once over just to check and yep that’s just as bad as the rest of the bike, I personally wouldn’t let the bloke who built this engine pump my tyres up

loose nuts and bolts and spacers missing not to mention all the wrong nuts and bolts anyway main question is what implications does the aluminium being broken out on the engine case main bearing timing gears side (pic attached) has anyone run an engine like this? Will it cause major issues?

Neil

cardan · « **Reply #67 on:** 16 May 2023 at 06:46 »

Hi Neil,

That doesn't look too good, but maybe it's not as bad as it looks.

I wonder how it happened - knocking the end of the housing out is a difficult thing to do with an ordinary engine malfunction? Perhaps it was done on the bench trying to get the bearing out?

To trust the engine you need to know that the bearing is properly seated in the crankcase. There's very little end thrust when the engine is running, so the missing alloy is not a problem provided there is a rim on which to seat the outer bearing shell. There might be more oil than usual blowing into the timing chest through the bearing, which may or may not be a problem. Hard to say without running the engine and seeing if your right foot is drenched in oil on the maiden ride!

If the bearing looks securely seated in the case, and the crank end float is withing tolerance, you could run the engine and see what happens. Probably the proper thing to do (aghh) is to strip the engine entirely and have a proper look?

I empathise.

Leon

eddie · « **Reply #68 on:** 16 May 2023 at 07:45 »

Neil,
To add to what Leon has said - there should be little or no force on the timing side bearing if the engine is properly assembled. In fact the only end thrust on the crank is in the opposite direction, when operating the clutch!

Regards,
Eddie.

Doug · « **Reply #69 on:** 16 May 2023 at 15:02 »

Some of the Douglas models had cam spindles drilled from the rear for a passage for oil mist from the crank chamber proper to lubricate the cam bushings. I cannot remember offhand if the Aero models still had this, but they probably did. So a loss of 'back pressure' venting into the timing chest might reduce the amount of lubrication forced through the passages. On the other hand the increase of oil mist getting through due to the missing crankcase wall will mean more oil vapor swirling around in the timing chest. From there it would have to work its way into the bushings. It also means more oil for the scavenge pump to deal with.

Structurally it is not that big a deal, so long as there are no loose bits ready to fall off and jam the works and no cracks that might propagate. It looks like there is enough there to locate the bearing. A snap ring would suffice.

Replacing the end wall can be done, but it is a rather involved machining process of making an insert (usually steel) to replace the bearing bore and face. The attached images are of a 1931 350cc crankcase, during a period when Douglas was using a timed breather and so the presence of the end wall is important to the function.

I would say leave it be, while it is not ideal it is not a show stopper.

-Doug

Tazmantic · « **Reply #70 on:** 16 May 2023 at 20:18 »

Thanks for all the reply’s guys and information I’ve added a few more pics to show what it’s like now I’ve stripped it down for you to look at I was hoping it was just the disc that was broken and what this might cause but think the pics say it all. I do have some other cases but none match and I’m not sure what year/cc they are from as the bearing disc are different and the mag mountings are different if I wanted to use the l/h case that’s fitted at the moment, also the bearings are not tight on the crank they slip on quite easy

think I might need a new engine or just sell as it’s just one issue after another.

Neil

Tazmantic · « **Reply #71 on:** 16 May 2023 at 20:21 »

These are the cases I have, the first is the current one to show the mag difference, any ideas what the other 2 are??

Neil

eddie · « **Reply #72 on:** 17 May 2023 at 07:42 »

I reckon that bearing housing damage was caused by a ham-fisted owner with a club hammer trying to shift a stubborn flywheel!

Regards,
Eddie.

Tazmantic · « **Reply #73 on:** 17 May 2023 at 08:49 »

Hi Eddie, it’s a bit of a mess for sure but after a sleepless night thinking about it I thought maybe I could buy a bearing with a metal seal on one side but they don’t seem to be available (that’s if I’m searching the correct bearings 25x62x12 (98305)) so I’ve decided my only option for the time being is to fit the bearing with retainer (though it’s not loose in the case but to just make sure) and machine up a thin disc to cover the bearing on the timing side and be held in by the gear. Won’t stop all the oil mist but might reduce it significantly… machining the case out and inserting a metal sleeve like Doug said would be the better option but not sure my machines or me are up to that job.

Neil

eddie · « **Reply #74 on:** 17 May 2023 at 09:09 »

Neil,
Another option would be to machine the crankcase back to the face the bearing sits against, and somewhat larger (68mm?). Then turn up an alloy washer to replicate the damaged bit of the casting, and get it laser welded into place. Laser Welding is not cheap, but it hardly imparts any heat into the casting, so doesn't cause any distortion. A couple of our Surrey/Hants members have resorted to laser welding for repairs and have been very impressed with the results. One was a modification to a magdyno end plate to make it marry up to a Speed Special crankcase - the other was a repair to a cracked Sunbeam S7 rocker cover.

Hope this is of some help,
Regards,
Eddie.

Dads bike · « **Reply #75 on:** 18 May 2023 at 10:32 »

Morning Neil
Sorry I have had little input to your posts, my attention has been directed elsewhere unfortunately.
Let me try to answer your latest questions.

Leaving the 250 & 350cc machines to one side. What You have in your latest pictures, is one of each, of the three 5/600cc Aero engine types produced, do you have the flywheel side, this has the engine No stamp on it.

Picture 1 with the cast magneto stand, this is the correct casing for your 1937 machine, this crankcase type would be prefixed 6P for 1937 and 6Q for 1938

Picture 2 this engine type dates to the later 1936 Aero period, it has a separate removable magneto stand, and was the first of the longer crankshaft models it only came in the 600cc variant and the engine No was prefixed 6M.
In your picture there are two holes drilled in the casing at the back of the main bearing housing, this is another bodge someone has done to allow them to punch the bearing out.

Picture 3 this is the early 1936 engine type and was used for both the 500cc units and the 600cc units and would be prefixed 5L or 6L, again with the removable magneto platform, however this crankcase with the crescent moon shaped oilway at the back of the main bearing
accommodates the shorter crankshaft type. The shaped oilway allowed more oil vapour to the additional components of the shorter crankshaft ie the extra parts for the oil pump drive and the Dynamo drive.

Your comments around the crankshaft fit.ie it’s loose within the bearing.
The two main bearings are shrink fits into the crankcases housing and therefore tight on the outer race, assembly of the unit is allowed by the crankshaft being a push/sliding fit into the inner race. Crankshaft end float is set with thrust shims on the flywheel end of the crankshaft and with the correct size of gasket between the crankcase half’s, look for 6thou of an inch end float when fully assembled.

The damage to your crank case looks like some buffoon has attempted to take the crankshaft out without removing the oil pump drive and timing gears as there is still a slight step at the back of the bearing, ie it’s all gone inwards rather than outwards.
I agree with Eddy, the way to fix would be to let in a thin ally washer shaped piece.

Note that all the crank cases are all matched pairs, stamped on the case under the front cylinder so if you do go along the line of mix and match you may have to do a little alignment work.

The timing chest main bearing is SKF 6105 with the dimensions you stated with a CH3 clearance and 05 to the outer race.
Steve

Tazmantic · « **Reply #76 on:** 19 May 2023 at 07:21 »

Thanks for all the replies guys I do really appreciate it, I do have 2 flywheel side cases (pics attached) one is the original engine but was removed as the mountings are corroded (I thought one of the timing side cases was a match but not) I also have a 500 flywheel side case but that doesn’t match either of the timing side cases either

.

The ally washer idea is definitely a plan or a steel cup insert but there are other issues with this case (one mounting lug bodged, one barrel stud bigger, all timing cover bolts drilled out bigger) so I’m wondering if it’s worth doing or trying to find replacement cases even though the previous owner went to the hassle of changing the engine number with the dvla.

My idea was as I’ve found a slightly thinner bearing for the timing side was to make a thin ally washer to put in behind the bearing to act like the original case and stop the oil mist but I am really struggling to part off a thin enough washer as it keeps wandering off (expect it’s my equipment) so another plan is needed.

Cheers Neil

Tazmantic · « **Reply #77 on:** 20 May 2023 at 12:44 »

So here’s a couple of pics of the bodge I mean precision fix, a thin steel washer, slightly cupped to miss the inner race and original bearing used, so will just need to check the end float. So a couple more questions I presume the bearing on the flywheel side should be self aligning the one that was fitted is fixed and also I’m going to probably strip the crank down and make sure that is all okay as the bolts that hold the crank together on one side you can see the end on the other. It’s quite sub flush so I’m not sure what’s going on there also I’ve attached a picture showing the conrods should the slots be at the top or the bottom as one is top and one is bottom and also should that hole be in there.

Cheers Neil

Tazmantic · « **Reply #78 on:** 22 May 2023 at 17:56 »

Stripped crank today bolts were different lengths also managed to get it apart by holding the web and tapping the bolt so now think I probably need a new crank as well. Con rods look ok and crank pins might just be acceptable though all the rollers did fall out of the cage on one big end the other stayed together. Last pics are how far I could push the crank back together by hand….

Neil

Tazmantic · « **Reply #79 on:** 24 May 2023 at 10:16 »

So I think this crank is going to have to do but would like to replace a few parts namely (and I hope these are the right bits)

18471 crank pin bush
18523 set screw (securing webs)
16832 locking washer for screw

Are any of these parts available as I’ve looked on the spares list and all I can find is the lock washer but it doesn’t list one for Aero just EW T6 and S6

Neil