Advice for fitting engine & gearbox to frame (2017)

Im currently rebuilding a Commando which has a 72 750 Combat engine and an early 73 850 Commando frame. The frame was recently straightened my Motoliner Maidstone and has been powdercoated black with the swinging arm and engine cradle. I have been busy getting the ancillary parts ready and have rebuilt the gearbox with new bearings, fitted new MK3 ISO bushes and adjusters and rebuilt the forks. I havent touched the engine as I have receipts for recent head work and the stack of previous MOT certificates suggest the mileage is approx 17k and engine appears in good condition.

I'm at the stage where I'm about to mount the engine & gearbox back into the frame and need some advise on the best way to proceed. I'm probably going to do this single handed and from what I have read this can be done with the engine lying on the drive side supported on wooden blocks. The frame can then be mounted on top and the ISO bolts attached.

I have a few questions about this approach which I hope others can answer:-
- does the gearbox need to be mounted to the cradle when fitting the frame or can the gearbox be mounted later?
- my engine already has the head fitted, is this likley to cause clearance issues or should it be removed ?
- are there any other issues to consider before I start?

All info welcome

The gearbox can be fitted later by rotating the cradle clockwise about the upper engine mounting bolt. This will expose the cutout in the bottom righthand corner of the RH side of the cradle allowing you to fit the gearbox in through the plate and twist clockwise into position. Do not forget to fit the spacer on the LH end of the top gearbox bolt.

I have found it easiest to install in this order (assuming you have the chassis up on a bike stand or lift table):

Assemble swingarm to transmission cradle.

Fit transmission cradle & swingarm to the frame with rear iso bolt.

Install transmission in it's cradle loosely.

Install oil filter & hoses.

Install horn onto battery tray loosely, set rear fender in place loosely, fit up battery tray with horn and snug everything up.

Install engine power unit with front mount already attached, with engine tilted forward, slip in front mount thru-bolt, tip tranny cradle back and lower the two assemblies together till the bolt holes line up, * * INSERT THIN LOWER REAR BOLT FIRST * * insert all other bolts, tighten all hardware.

Install top mount / head steady.

Adjust isolastic gaps.

Install primary inner case, clutch & primary drive, alternator.

Install engine timing cover if not already installed, install and static adjust ignition rotating assembly.

Install shocks, forks (slip thru headlight ears w/ o-rings per parts diagram, leave top caps loose), fit up wheel assemblies.

Pour fork oil into forks, install meter cups, tighten top caps.

Install tail light and front fender.

Install handlebars, hand controls, z-plates, footpegs & brakes pedal assy.

Install carbs & airbox or filters.

Install oil tank & connect all oil lines.

Install meters.

Install control & meter cables.

Install condensers & ballast resistors to coil mount frame; install coils, fit assembly onto frame.

Fit up headlight shell, install wiring harness, fit up and connect all remaining electrical components.

Install battery, test lights & ignition for spark, test brake light w/ both brakes.

Fit up gas tank, install petcocks, install fuel lines, secure gas tank.

Fit up and snug all drain plugs.

Fill oil tank; then SLOWLY pour 1/4 cup of oil in each rocker cap.

Add transmission oil till it dribbles out the level indicator hole.

Pour in primary chain oil to proper level.

Check everything over from front to back, set up a large fan in front of the engine, have a fire extinguisher handy, and connect your timing light.

Pour in about one gallon of gas, turn on both taps, tickle carbs then wipe dry with a shop towel. Let sit a minute, then check for leaks.

By this time, any oversight of oil line fitting task should show itself as oil dribbles. Address any issues.

Best to have a second set of eyes and hands at this point, if possible. Set up your viseo camera or smartphone camera if so inclined.

Start the bike, check for oil return in the oil tank filler neck with a flashlight. Check & adjust strobe timing as required.

If all appears correct, take it for a short test ride around the block, then re-check all fluid levels. If all good, grab a spark plug socket and a rag, don your helmet and get out on the road for a "plug chop". Adress carb settings as indicated by plug read.

TALLY HO!

Excellent advice Grand Paul, I will try it out and see how it works out.

I'm at the stage where I'm about to mount the engine & gearbox back into the frame and need some advise on the best way to proceed. I'm probably going to do this single handed and from what I have read this can be done with the engine lying on the drive side supported on wooden blocks. The frame can then be mounted on top and the ISO bolts attached.

I have a few questions about this approach which I hope others can answer:-
- does the gearbox need to be mounted to the cradle when fitting the frame or can the gearbox be mounted later?
- my engine already has the head fitted, is this likley to cause clearance issues or should it be removed ?
- are there any other issues to consider before I start?

Click to expand...

If the frame is bare, my preference is to mount the frame to engine and cradle (lying on its side). It is easier to wrangle a 26 lb frame than a 55-60 lb engine. The gearbox shell can be mounted later, but I find it easier to mount it first and usually empty.

Swingarm is mounted to the cradle after its installation.

I always have the head installed with this procedure.

If the front end or other assemblies are mounted to the frame, then this is not a preferred procedure.

Lifting a complete engine into the frame is a recipe for a slipped disc. +1 on Ron's method

Fitting the frame onto the complete power unit seems to be how it was done at Andover.

Wow! I have never seen those photos! Are they from a book or magazine?

For me, I find it easier to install the frame without the primary covers installed. Less chance of nicking a freshly painted frame or a polished primary cover. The factory guys were probably a lot more practiced at it. (Or didn't care about a few scratches).

Ron L said:

I'm at the stage where I'm about to mount the engine & gearbox back into the frame and need some advise on the best way to proceed. I'm probably going to do this single handed and from what I have read this can be done with the engine lying on the drive side supported on wooden blocks. The frame can then be mounted on top and the ISO bolts attached.

I have a few questions about this approach which I hope others can answer:-
- does the gearbox need to be mounted to the cradle when fitting the frame or can the gearbox be mounted later?
- my engine already has the head fitted, is this likley to cause clearance issues or should it be removed ?
- are there any other issues to consider before I start?

Click to expand...

If the frame is bare, my preference is to mount the frame to engine and cradle (lying on its side). It is easier to wrangle a 26 lb frame than a 55-60 lb engine. The gearbox shell can be mounted later, but I find it easier to mount it first and usually empty.

Swingarm is mounted to the cradle after its installation.

I always have the head installed with this procedure.

If the front end or other assemblies are mounted to the frame, then this is not a preferred procedure.

Click to expand...

Sounds like an excellent method.

Re the weight of a bare engine - From weighing the components Im coming up with right around 100 lbs with carbs .

Glen

Ron L said:

Wow! I have never seen those photos! Are they from a book or magazine?

Click to expand...

The first (linked) is from the Andover Norton website;
https://andover-norton.co.uk/en/service/

The second comes from a French magazine article
http://blog.wheels-and-waves.com/2009_0 ... chive.html

The third is in Norton Commando Super Profile by Jeff Clew;
https://www.amazon.com/Norton-Commando- ... 0854293353

Great pictures LAB, I'm going to try fitting the engine fitting this weekend, will report back progress.

Is that Dennis Poore sitting on the tea chest there, examining something. ?
Cigar in hand.....

Rohan said:

Is that Dennis Poore sitting on the tea chest there, examining something. ?
Cigar in hand.....

Click to expand...

The (Mike Jackson) photo caption reads; "Shaw Taylor, famous for his 'Police 5' series on ITV, visited the Norton factory at Andover for a Thames Television feature. Dennis Poore is seen in the foreground, seated on a conveniently-placed tea chest"

A front iso bracket? There is one on the bottom shelf of the trolley, maybe that is the reject pile and the good ones are in the bin on top?

Also looks like a tin of touch up black paint or maybe grease for iso assembly.

Thanks LAB.

That means that Thames Television have film of the assembly shop/production line,
and possibly even film of a bike being built up in the initial stages ?

Reviving this thread from 2017 to fine-tune assembly of the Commando from bare frame and assembled sub-assemblies. Most recommendations are either frame supported on lift (Norman White rebuild book) or fit frame to power unit.

Has anyone tried hanging their frame from the ceiling using 250lb strength adjustable straps and hooks? This would seem a useful way to orient the frame with ability to lift it up and down.

If you had a bad experience doing this I'd like to hear it! Thanks in advance.

If it is a bare frame I lay the engine / gearbox in the cradle on the its timing side with the front Isolastic unit removed then fit the frame over it.
A bit of rotating of the frame, rear Iso stud in then fit the front.
Easy even by yourself, why fight gravity or a balancing act (with a bare frame)

Edit as an in the present afterthought.

If the frame is new and shiny and has Vernier Isolastics most likely the end caps could be left off the rear unit which will give more clearance to the frame brackets.
Rear Iso stud in, front Iso unit in and pivot the cradle unit down (stud out stud in) to fit the rear Vernier caps and swing back up.

I put the engine / gearbox unit on something soft and suitable wooden blocks to set it level and secure.

Jdub said:

Reviving this thread from 2017 to fine-tune assembly of the Commando from bare frame and assembled sub-assemblies. Most recommendations are either frame supported on lift (Norman White rebuild book) or fit frame to power unit.

Has anyone tried hanging their frame from the ceiling using 250lb strength adjustable straps and hooks? This would seem a useful way to orient the frame with ability to lift it up and down.

If you had a bad experience doing this I'd like to hear it! Thanks in advance.

Click to expand...

My advice is unless you really know your rigging, use the tried and tested methods which have been well described.

gunnag said:

Im currently rebuilding a Commando which has a 72 750 Combat engine and an early 73 850 Commando frame. The frame was recently straightened my Motoliner Maidstone and has been powdercoated black with the swinging arm and engine cradle. I have been busy getting the ancillary parts ready and have rebuilt the gearbox with new bearings, fitted new MK3 ISO bushes and adjusters and rebuilt the forks. I havent touched the engine as I have receipts for recent head work and the stack of previous MOT certificates suggest the mileage is approx 17k and engine appears in good condition.

I'm at the stage where I'm about to mount the engine & gearbox back into the frame and need some advise on the best way to proceed. I'm probably going to do this single handed and from what I have read this can be done with the engine lying on the drive side supported on wooden blocks. The frame can then be mounted on top and the ISO bolts attached.

I have a few questions about this approach which I hope others can answer:-
- does the gearbox need to be mounted to the cradle when fitting the frame or can the gearbox be mounted later?
- my engine already has the head fitted, is this likley to cause clearance issues or should it be removed ?
- are there any other issues to consider before I start?

All info welcome

Click to expand...

Scroll down to September 30, 2021 to see how I do it here: https://www.gregmarsh.com/MC/Norton/CustomerCombatBuild.aspx

Very easy.

You said that the cradle and swingarm are powder coated. If they were not masked, you won't get the swingarm on or if you somehow do, it will leak. Make sure they will go together BEFORE putting the cradle in the bike - way harder to fix after.

I find it easier to build the engine in the frame. Yes, you need a lift and yes fitting the head is a bit fiddly but not nearly the ordeal it is made out to be.