The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Billybream on 12.01. 2012 19:33

Title: Clutch centre removal
Post by: Billybream on 12.01. 2012 19:33
Early days of my Super Rocket restoration but already in trouble, I,m unable to remove the clutch centre on a 4 spring clutch, the centre is on a taper with key, tried the special puller with no success. The puller is soft and the 1" 24 threads are stripping, I have already cut the first few threads off the puller because they got damaged during the initial attempted removal and started again, using heat around the centre with still no joy, there is very little engagement via the puller within the clutch centre, I would estimate only 4 threads, the shop where I purchased the puller suggested hammer blow, which still has not worked, and I,m not keen to hammer any harder in fear of gear box casing damage. I have read on this forum welding the puller to the centre is an option for removal, but should the puller be hardened, if so, are they available. Any advice would be much appreciated. Thank you
Title: Re: Clutch centre removal
Post by: bsa-bill on 12.01. 2012 20:26
Think of a hammer as a precision tool, it's weight, direction of movement and speed as variables in the hands of a skilled user (you)
Screw the puller into the clutch centre until it is tight, then using your judgement select a hammer to suit the job, strike the end of the puller a sharp blow using the latent skill that you may not be aware you have.
When selecting a hammer think about what is your after generally too light a hammer will mark what you hit more than transfer force, too heavy will transfer force too far through the work
Title: Re: Clutch centre removal
Post by: beezermacc on 12.01. 2012 21:32
I have always had these problems with the 'correct' puller. Since wrecking a few pullers I have invested in a bearing puller designed to remove bearings from shafts. I don't know if you are familiar with these so here's a pic http://www.ldemporium.co.uk/pro-2pc-bearing-puller-set-p-462.html (http://www.ldemporium.co.uk/pro-2pc-bearing-puller-set-p-462.html). basically Its a circle of steel, chamfered in the middle and split so that it can be fitted around the bearing, clamped together then drawn off with the supplied bolt and saddle. The size I bought fits snugly in the recess about half way down the clutch adaptor. I've lent the tool out to quite a few other people who have all said it works brilliantly.  I would really recommend this over the chocolate tool often supplied by parts dealers. It helps to use a bit of heat as well. Don't be frightened of going for plenty of heat on the clutch centre adaptor. Never fails - I promise! here's another pic of the tool assembled http://www.ldemporium.co.uk/mini-bearing-puller-separator-set-p-86.html (http://www.ldemporium.co.uk/mini-bearing-puller-separator-set-p-86.html)
Title: Re: Clutch centre removal
Post by: paulo on 12.01. 2012 22:55
Have good experience with the use of a bearing puller as described above, worked great and for my clutch centre, required just a good tightning, no blowlamp *smile*.

Cheers, Paul.
Title: Re: Clutch centre removal
Post by: Hubie on 12.01. 2012 23:12
I had a similar problem and did not have a puller, a bit of wood against the end of the output shaft, a bit of thin bent steel behind the clutch centre and a sharp strike to the wood on the end of the shaft with a small amount of pressure on my home made lever and it was off with one strike!

Cheers,
Hubie.
Title: Re: Clutch centre removal
Post by: kiwipom on 13.01. 2012 02:59
hi guys/BSA-Bill, Your explanation of the versatilities of a hammer and its user is excellently put and i agree, you could say that you have hit the nail on the head,cheers,Bob
Title: Re: Clutch centre removal
Post by: Billybream on 13.01. 2012 07:41
Thanks for replies gents and advice, especially Beezermacc, will try for Bearing Puller, seems best method.
Title: Re: Clutch centre removal
Post by: beezermacc on 13.01. 2012 08:25
If the puller you buy has a fixed spike at the end of the centre withdrawing bolt you must use a pad between it and the gearbox mainshaft. Often the pullers are supplied with a detachable spike. If you allow the spike to enter the clutch pushrod tube you could risk bursting the end of the mainshaft open as quite a lot of force is required to remove the clutch adaptor, but it will be perfectly safe with a pad made from aluminium or soft iron. Let us know how you get on.
Title: Re: Clutch centre removal
Post by: BSA_54A10 on 14.01. 2012 15:43
Two points here.
1) get good quality tool steel pullers. If you can not get them in the UK then we have a nice chappie down here in SA that makes real nice tools.
2) although they are called pullers, they are not designed to "pull" the centers off.
ˇhey are designed to put a preload on to the center so when you strike the end of the "Puller" with a MALLET not a hammer the jolt will break it free.

However I have found that the magic tool is a rattle gun. The jerky shock application of torque to the nut works wonders and most times the centers will pop off with not much more than stiff finger tightness.
Title: Re: Clutch centre removal
Post by: BSA Patty on 14.01. 2012 16:39
glad somebody else has this problem,my 55 flash clutch centre was like this standard puller just stripped sd used my mate clives three leg claw puller both of us really tight precautions as discussed no joy so used my plumbers blowlamp to apply heat then a good whack on end of puller and of it came no damage so good luck.
Title: Clutch centre removal success
Post by: Billybream on 24.01. 2012 14:29
Finally removed the clutch centre, tried std BSA extractor, this failed, purchased bearing puller/splitter, but this failed as well, so welded std BSA extractor to clutch centre and used centre bolt together with light taps on and around centre and bingo she came off. There was no visible damage to the key or taper, just need to try and savage clutch centre.
Title: Re: Clutch centre removal
Post by: A10Boy on 24.01. 2012 16:39
I found that I could only get 2 or 3 threads of the puller into the center before it bound up, so I had to bore the internal of the puller to get some threads in there. Then it worked ok after a few sharp taps.
Title: Re: Clutch centre removal
Post by: alanp on 24.01. 2012 20:03
Hold it right there chaps!!!!
I went through this business of only being able to screw the extractor in a few threads and stripped them. I ended up welding the extractor to the clutch centre. The thing I found out later was that there are 2 slightly different thread tpi to contend with here. If you don't use one with the same tpi thread you are asking for trouble. It's not so easy to see the difference in the thread tpi by just peering into the clutch centre when it's on the bike. They look the same.
My supplier checked his stock and discovered that his personal extractor was correct for the 20 tpi I needed and all his stock were 26 tpi. He sent me his personal extractor. My memory says that the BSA centre needs 20 tpi and the Triumph clutch centre needs 26 tpi or vice versa, so check which clutch you're using and that your extractor matches it.
I now keep both tpi extractors in my kit
Title: Re: Clutch centre removal
Post by: jjbsa on 26.01. 2012 22:38
Two things:
The threads inside the 4 spring hub are 26 tpi and not 24.  I bought a puller sold to me for BSA use that had 24 tpi teeth and it would not go in more than a turn or so.  So I measered the pitch and turned up a 26 tpi one which went in and did the trick (even with loctite on the taper).  It also pays to put a steel button between the end of the mainshaft and the end of the bolt in the puller, this stops the end of the bolt marmalising itself.

Next, I would never advise anyone to hammer on the end of the puller or shaft.  The shock goes down the mainshaft and cracks the flange behind the bearing in the gearbox sandwich plate on the other end of the shaft!  I have had to get welding repairs done on such damage.
Title: Re: Clutch centre removal
Post by: K1100 on 22.03. 2013 20:00
I have read all of these postings because I am also stuck with a clutch centre I can't remove. The threads stripped on the first extractor twice. I cut off the first damaged section but can't cut off the second because there wouldn't be enough depth left on the extractor to clear the end of the mainshaft. I'm waiting for another extractor in tomorrow's post. I tried heat from a hot air gun but to no effect. I am wary about using the blowtorch but I suppose if I cut off the oil-soaked felt washer first to eliminate the fire risk there is not much else that can go wrong ....

I don't understand why using a hammer would help because it isn't on a taper, is it? I'd be grateful for guidance on that ....
Title: Re: Clutch centre removal
Post by: morris on 22.03. 2013 20:49
I use a slide hammer I constructed myself.
It consists of an offcut from a round bar of steel, about 2 inches of diameter and about 4 inches long, in which I drilled a 12.5 mm hole through the centre (ideally this should be done on a lathe to have the hole parallel, but if you're careful, it can be done in a vice with a handdrill)
I then pass a long M12 bolt (250mm) with a 50mm long thread, which I then screw in the extractor (my extractor has an M12 bolt hole). A couple of good blows has the clutch centre off in no time.
The reason why the thread from the extractor gets ripped off is that the short bolt provided with the extractor builds up the force to slowly, and acts on the weakest point, which is it's own thread.

By the way, the clutch centre is on a taper.
Title: Re: Clutch centre removal
Post by: muskrat on 22.03. 2013 20:50
G'day K1100. The shock of the blow does help. Quick heat fron a torch is better as the shaft doesn't have time to expand as well.
Cheers
Title: Re: Clutch centre removal
Post by: KiwiGF on 23.03. 2013 09:20
Any PO might also have done what i have done which is use loctite bearing retainer on the taper and heat makes that soft not too much heat maybe 200 deg c, i have the 6 spring clutch and it needs all the help it can get to stay in one piece and the keyway on the mainshafts are often not perfect mine certainly isnt so thats why i use the loctite

The bsa style extractor i bought from draganfly was not made in soft metal and has done job a afew times now,, the more years a centre is is on the harder it will be to free i guess

A tap on the puller is a good tip but not too hard as it could damage the ball races etc
Title: Re: Clutch centre removal
Post by: BSA_54A10 on 23.03. 2013 09:38
I have a full set of removers for BSA clutches.
There are 7 of them.
Most are CEI ( 26 tpi )
However one has 24 tpi and another is 20.
All of them will screw into the hub and bottom out with little more than heavy hand force.
If you can not screw the puller in till it either bottoms out or shoulders out then you are using the wrong puller.
The threads are all parallel .
Think of them like you would any nut & bolt.
If it only goes in 2 or 3 turns then you have mismatched threads ( or badly damaged threads )
The parts books all list the corrct puller by BSA part number and Lightning spares list their pullers also by BSA numbers with a description ( length, tpi & thread type )
Title: Re: Clutch centre removal
Post by: K1100 on 27.03. 2013 11:26
The thread has stripped on the second extractor. There is barely 3 mm to screw in to, which must be part of the problem. I have tried heating the clutch centre with my propane torch, I have tried a sharp smack on both sides of the centre while the extractor is tight, and I have tried a gentle smack on the end of the extractor nut. I don't have welding kit or contacts with welding kit so I am starting to feel low about this!

I have just re-read everyone's earlier suggestions and realise that I haven't tried a  bearing puller yet so I've ordered one of these.
Title: Re: Clutch centre removal
Post by: bsa-bill on 27.03. 2013 13:52
I bought a centre from someone (sorry can't recall) and returned it without trying it due to the lack of thread for the puller to engage similar to your problem K1100
as I recall there were barely two full threads, the seller took it back without problem, as I recall him saying he had never had a problem with them I wondered at the time if it was me, but the replacement I bought elsewhere had a lot more thread.
Looks like there's maybe a bad lot out there
Title: Re: Clutch centre removal
Post by: A10Boy on 27.03. 2013 15:12
Mine had the right thread etc, it just wasnt bored deep enough. Drilled it out 1/4 and it fits just right.
Title: Re: Clutch centre removal
Post by: BSA_54A10 on 28.03. 2013 07:02
It happens when some "evilbay expert" send a part they bought from another "evilbay crook " to a factory in India with 1000 Rupee and a note "make as many of these as you can ".
Another Evil bay b arron then sends one of these to China because Indian parts were too expensive.
Title: Re: Clutch centre removal
Post by: K1100 on 28.03. 2013 15:29
Well, it's off, using a bearing puller, and with the most almighty bang. It needed so much force that I was in a cold sweat when it eventually freed. There was no Loctite ....

In the picture is the bearing puller, £14 from RS, and the two clutch centre extractors. They are different, from different suppliers .... though I gave the same information for both. One is stamped MCA P127 and the other MCA P246. The threads on both stripped ... P127 is short because I sawed off the damaged thread section to try to use it again. I have tried to measure the tpi but there is not enough thread for me to do it ..... P127 seems to have more threads than P246. (i.e it is finer). P246 fitted better but there is so little thread inside the clutch centre that I think both were doomed to fail. Is it possible to get extractors made from properly hardened steel?

(PS Beezermac .... I couldn't find the mini-puller you suggested in stock anywhere. I am sure it would have been better and avoided the Big Bang)