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Commando Mk2A fork woes

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Commando Mk2A fork woes

Posted by mark_woodward at March 23. 2017

Hi chaps, I'm really struggling to remove the fork collars of the fork legs (the official manual calmly states "unscrew by hand, or if necessary use a strap wrench") - up to now they won't budge. I've cleaned the area where the caps screws into the lower legs and applied for lots of WD40 - no joy. I've applied a fair amount of heat and still they won't budge. The threaded areas are currently soaking in WD40 after being heated to try and open up the threads such that the oil can soak in. When I eventually manage to strip the legs I'll probably replace the seals etc. Do you guys have any tricks ref unscrewing the fork leg collars? They aren't left-hand thread or something are they?

These forks are proving to be a real pain. Three of the four mudguard retaining studs on the inside of the lower legs sheared off as I tried to remove the seized-up nuts. As I reported earlier, the drain screws are knackered.

All of this just so I could check/change the fork oil!!

Re: Commando Mk2A fork woes

Posted by john_holmes at March 23. 2017

Normal threads, stilsons will work but you can say goodbye to the seal holders as you will ruin the finish such as its is. I fit stainless replacements from RGM so do not bother what the originals look like as long as they come off.

Re: Commando Mk2A fork woes

Posted by ian_goodhall at March 23. 2017

You could try some proper penetrating oil. WD40 is thin but not penetrating oil per se.

Re: Commando Mk2A fork woes

Posted by jonathan_newton at March 23. 2017

Heat is always a worry as there are man made rubbers  in there.  But seeing its already done why not try one of  the "Freeezing" cans the plumbers use...   Focus on the Seal holder.... it may shrink away enough to break the  corrosive bond.  But soaking in penetrating oil  (for as week) and some hide mallet taps usually does the trick.

J

Re: Commando Mk2A fork woes

Posted by anthony_clayphon at March 23. 2017

Use PlusGas, it's much more effective than WD40.

Re: Commando Mk2A fork woes

Posted by philip_baker at March 23. 2017

I think that both the legs and the collars are aluminium and so will expand/contract equally under the effects of heat/cold. I have a large bench-mounted vice and I cut up an old inner tube to make a rubber collar for the fork collar then clamp it tightly in the vice upside down and use a long bar through the spindle hole of the fork leg. Nothing has defeated this method to date.

Phil

Re: Commando Mk2A fork woes

Posted by christopher_winsby at March 23. 2017

Long soak in Plus Gas, plenty of heat on Aluminium slider you should have to wear thick leather gloves, freezer spray on steel collar. Use strap wrench, Stilsons or take off fork leg and hold in vise. File flats on collar.

I held the collar in the bench vise and used a strap wrench on the slider having soaked in plus gas for a week and heated the slider as hot as I could get it with an electric heat gun.

You could try two Jubiliee clips opened and then  joined together around the collar then use strap wrench over the top.

Re: Commando Mk2A fork woes

Posted by james_fanning at March 24. 2017

Previously philip_baker wrote:

I think that both the legs and the collars are aluminium and so will expand/contract equally under the effects of heat/cold. I have a large bench-mounted vice and I cut up an old inner tube to make a rubber collar for the fork collar then clamp it tightly in the vice upside down and use a long bar through the spindle hole of the fork leg. Nothing has defeated this method to date.

Phil


Yes , used exactly this method to get my collars loose with exception of using two pieces of wood to protect the collar in the vice jaws. Long tommy bar through the wheel spindle hole , spit on hands , bit of grunt and away you go.

Re: Commando Mk2A fork woes

Posted by christopher_winsby at March 24. 2017

Previously james_fanning wrote:

Previously philip_baker wrote:

I think that both the legs and the collars are aluminium and so will expand/contract equally under the effects of heat/cold. I have a large bench-mounted vice and I cut up an old inner tube to make a rubber collar for the fork collar then clamp it tightly in the vice upside down and use a long bar through the spindle hole of the fork leg. Nothing has defeated this method to date.

Phil


Yes , used exactly this method to get my collars loose with exception of using two pieces of wood to protect the collar in the vice jaws. Long tommy bar through the wheel spindle hole , spit on hands , bit of grunt and away you go.

The sliders are Aluminium the collars steel. With heat holes expand and get larger. So if you have steel inside aluminium all you have to do is heat the aluminium up enough and the steel part will become loose.

Trouble is most people do not heat the part up enough. Forget damaging rubber parts. The fork sliders are the expensive parts, the rest probably need changing anyway.

Re: Commando Mk2A fork woes

Posted by mark_woodward at April 01. 2017

Thanks for the advice chaps but still no-go. I have applied Plus-Gas every day for a week so far and applied heat but neither will budge using 12" stilsons (the stilsons don't slip but even with hefty clouts with a hammer there's no movement (just scaring of the seal holders). It occurred to me to remove the entire fork legs and take them to a machine shop or similar but, guess what, the lower yoke pinch bolt heads have been virtually destroyed by the DPO and no allen key I have will grip. I've cleaned around the heads and will apply Plus Gas for a week (also in the split in the yoke fork hole to reach the screw thread (hopefully))and try again in a few days. The last resort would appear to be to use a Dremel cutting disk and get into the split in the yoke and cut through the pinch bolt  - I'm then left with the difficult job of removing the threaded inner remains of the bolt - all this just to check the fork oil! Any thoughts please?

Re: Commando Mk2A fork woes

Posted by ian_goodhall at April 01. 2017

If this is a Mk2A Commando with a disc brake then the pinch bolt should be a nut and bolt, it also shouldn't be an allen head. There is no thread in the alloy slider, just a plain hole. The earlier roadholder forks for the drum brake had a thread in and used a bolt threaded into the leg.

If there is no nut on the pinch-bolt then you have an older slider. If it does have a nut you could cut it in the middle and it should fall out.

 

Re: Commando Mk2A fork woes

Posted by john_holmes at April 01. 2017

The lower yoke pinch bolts are allen bolts on MK2a's, the slider is the bolt and nut not the lower yoke. The allen bolt will be 8.8 or similar so you will need a good drill to drill it out. I would use a carbide impregnated hacksaw blade to cut through the allen bolts and then drill out the threaded remains off the bike where you can apply more pressure.

Re: Commando Mk2A fork woes

Posted by christopher_winsby at April 01. 2017

Previously mark_woodward wrote:

Thanks for the advice chaps but still no-go. I have applied Plus-Gas every day for a week so far and applied heat but neither will budge using 12" stilsons (the stilsons don't slip but even with hefty clouts with a hammer there's no movement (just scaring of the seal holders). It occurred to me to remove the entire fork legs and take them to a machine shop or similar but, guess what, the lower yoke pinch bolt heads have been virtually destroyed by the DPO and no allen key I have will grip. I've cleaned around the heads and will apply Plus Gas for a week (also in the split in the yoke fork hole to reach the screw thread (hopefully))and try again in a few days. The last resort would appear to be to use a Dremel cutting disk and get into the split in the yoke and cut through the pinch bolt  - I'm then left with the difficult job of removing the threaded inner remains of the bolt - all this just to check the fork oil! Any thoughts please?

Allen bolt heads can be closed up with a dowel punch Then use an impact driver with socket and piece of Allen key

Can you remove top bolt's, clocks and top yoke then drop forks and bottom yoke out?

Re: Commando Mk2A fork woes

Posted by Martin Freeman at April 01. 2017

Dear Mark,

I read sympathise with your plight, havinfghad trouble with worn allen bolts myself. Solution to them is to sacrifice an allen key, hold it in and arc or mig weld -it won't slip then. If you need to remove forks to take elsewhere why not just undo the large nut under the yoke and split the yokes; I assume you already have top nuts off.

With regard to 12"" stillsons to undo collars, I would say you'll be lucky without a couple of foot of pipe on the handle!

regards Martin.

Nb if you only want to swap fork oil, then split yokes, tip it all upside down and you could empty and renew with correct volume.

Re: Commando Mk2A fork woes

Posted by ian_goodhall at April 01. 2017

Oops, I was thinking of axle pinchbolt at bottom of fork leg.

Ignore me.

Re: Commando Mk2A fork woes

Posted by mark_woodward at April 01. 2017

Allen bolt heads can be closed up with a dowel punch Then use an impact driver with socket and piece of Allen key

Can you remove top bolt's, clocks and top yoke then drop forks and bottom yoke out?

Hi Christopher - yes - I reckon you may have the answer (knowing my luck, other nuts etc. will be rusted up). I have very limited workshop facilities - no MIG/TIG/lathes etc. (it's just a garage) and the bike is now virtually immobile. I've thought that I may be able to  'create' a slightly larger allen keyhole in the stuck bolts with a Dremel and burrs etc. Nothing lost nothing gained .... I've got a nagging feeling that all this is going to end up expensive!

Thanks for the idea - it may be the only answer!

Re: Commando Mk2A fork woes

Posted by christopher_winsby at April 02. 2017

Previously mark_woodward wrote:

Allen bolt heads can be closed up with a dowel punch Then use an impact driver with socket and piece of Allen key

Can you remove top bolt's, clocks and top yoke then drop forks and bottom yoke out?

Hi Christopher - yes - I reckon you may have the answer (knowing my luck, other nuts etc. will be rusted up). I have very limited workshop facilities - no MIG/TIG/lathes etc. (it's just a garage) and the bike is now virtually immobile. I've thought that I may be able to  'create' a slightly larger allen keyhole in the stuck bolts with a Dremel and burrs etc. Nothing lost nothing gained .... I've got a nagging feeling that all this is going to end up expensive!

Thanks for the idea - it may be the only answer!

Trying to cheer you up- At least you can buy new Forks

My Norton I bought with an MOT and running turned into a nightmare and a Total rebuild. It took over a month to get stripped down.  Parts were priced so as to know what was cheaper to sacrifice.

Keep soaking in plus gas and heating. Impact drivers shock the threads disturbing  corrosion.

Your best bet is to first remove the Forks. Then give them a clean. Old Allen keys or hex bar can be brazed or welded to the yoke Allen bolts to remove them. With fork leg out you can tackle the sliders. Or take them to an engineering shop.

Before you go on price the cost of parts on Andover Norton site there is no point in paying more to repair an old part than a replacement costs.

Re: Commando Mk2A fork woes

Posted by mark_woodward at April 06. 2017

Hi chaps, thanks for the advice/sympathy so far. I've probably got through 1/4 can of Plus Gas and WD40 so far. To affect any sort of repair I've concluded that I must remove the whole fork and yoke assembly. I'm finding that virtually every nut, bolt and screw on the whole setup are chewed up, seized solid or jammed in some other way. I did manage to remove the large nut at the bottom of the main yoke spindle and I'm now trying to remove the fork legs with hammer blows to the top of the fork legs (protected with wooden blocks) - as shown in the'proper' workshop manual. One leg appears to be loosening up a bit - the headlamp bracket is now fairly loose - the other is still rather tight. The manual does say to 'slacken the lower yoke pinch bolts' but, guess what? they are chewed up and immovable as well. Looking at diagrams of the assembly I cannot see that it's strictly necessary to slacken them at this stage of the game. I'm hoping that when I can get the legs etc. on a bench I'll then be able to start fixing the numerous problems. Any thoughts please ?

Re: Commando Mk2A fork woes

Posted by john_holmes at April 06. 2017

If the large nut is off the only contact points are the stanchion top tapers in the top yoke and the stem in the bottom yoke, what should come out is 2 fork legs fixed in the bottom yoke.

Re: Commando Mk2A fork woes

Posted by christopher_winsby at April 06. 2017

Previously mark_woodward wrote:

Hi chaps, thanks for the advice/sympathy so far. I've probably got through 1/4 can of Plus Gas and WD40 so far. To affect any sort of repair I've concluded that I must remove the whole fork and yoke assembly. I'm finding that virtually every nut, bolt and screw on the whole setup are chewed up, seized solid or jammed in some other way. I did manage to remove the large nut at the bottom of the main yoke spindle and I'm now trying to remove the fork legs with hammer blows to the top of the fork legs (protected with wooden blocks) - as shown in the'proper' workshop manual. One leg appears to be loosening up a bit - the headlamp bracket is now fairly loose - the other is still rather tight. The manual does say to 'slacken the lower yoke pinch bolts' but, guess what? they are chewed up and immovable as well. Looking at diagrams of the assembly I cannot see that it's strictly necessary to slacken them at this stage of the game. I'm hoping that when I can get the legs etc. on a bench I'll then be able to start fixing the numerous problems. Any thoughts please ?

The Top yoke has a tapered fit where the fork stanchion fits. So having undone the fork tube top bolts  and disconnected damper rods You can then remove the Clock assembly removing instrument case from top yoke. You can now screw the top bolt back in so that the thread is engaged but the bolt is not clamping the top yoke.

Now you would slacken the bottom yoke pinch bolts and using a soft face mallet or hard wood and hammer tap the top bolt and remove the stanchion.

In reality you may have to accept that you will need to change the top bolts and after soaking the top with plus gas and  heating several times hit with a large hammer direct to let the shock transmit to the taper.

It the bottom yoke is still clamped when you try to free one side you are pulling on the other.

You still have a complete bike so have to be careful not to damage anything.

If top yoke is tight it may pay to remove the petrol tank and store out of harms way.

Re: Commando Mk2A fork woes

Posted by david_evans at April 06. 2017

Read the last post again Chris, the lower pinch bolts are damaged. I reckon cutting through the pinch bolts with a hacksaw and dealing with what is left once on the bench is the way ahead.

Re: Commando Mk2A fork woes

Posted by mark_woodward at April 06. 2017

Success!!! I thought about cutting through the lower yoke pinch bolts as mentioned by David but I thought I'd give them one more shot. I found an allen key that appeared to be about the right size (there was/is so little left of the heads that it was difficult to tell what size they actually are but I offered up the key and give it a good whack into the screw with a hammer and it lock in place solidly. I gave the key a few whacks to see if I could jolt the screw loose but no joy. I then got a two foot steel tube to extend the allen key, levered hard and 'crack' - a wonderful sound as the screw broke free. I thought that no way would I have the same luck with the other leg but, yes, it worked again! At this point I gave both fork leg tops a tap with a soft mallet and out they dropped. It goes to prove that Plus Gas and patience do sometimes pay off. Now the real fun (and hopefully, repairs) begin.

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