Tandem Gear Woes

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tatanab
Posts: 5033
Joined: 8 Feb 2007, 12:37pm

Re: Tandem Gear Woes

Post by tatanab »

Pete Cuthbert wrote: 19 Aug 2022, 2:11pmThere must be a better way than lying on one's back on the floor...
There is, especially when working on a gear mech. Haul the trike on its hindlegs and rest the saddle on the floor. Three points of contact, wheels and saddle, so it will not go anywhere, and the mucky bits are easy to get at.
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi All

Thanks Tatanab for your suggestion. So obvious that it never occurred to me, but given that this is a tandem perhaps I am excused. However, I do have a chain hoist in the garage and it was no trouble to get it standing up as you suggest.

IMG_20220819_Standing Tall.jpg

With that done it was simply a case of following Dr Bookers instructions. 1) Remove the M6 grub screw below the l/h bearing. No problem.

2) Remove the circlip on the left hand bearing. Ok, that bulge by the wheel must be the bearing, so it will be under that. Looks like the wheel will have to come off. Looks as if it is held on by a chain wheel bolt with a plastic skirt. Removed and now we have a hex shaft poking out through a hex hole in the wheel. What now?

IMG_20220820_Chain wheel extract.jpg

Spotted that the outer hole in the wheel is threaded rather like the hole in a crank. Grabbed my crank remover and it fitted. Quick as a flash and the l/h wheel was off. Back to the instructions. 2) Remove the circlip. Yes there is one and yes my long nose pliers look as if they will fit. They fit but they do nothing to remove the circlip. Remember that I have an unused pin spanner in the cupboard. Get it out of the packaging and then am disappointed to see that the pins are tiny and barely protrude from the surface. Cheered to spot that the pins are just M6 bolts with the ends turned down. Find a matched pair of M6 bolts, fire up the lathe and then turn the ends down to 2.5mm diameter for about 6mm. Fit them to the pin spanner and they fit. They also remove the circlip.

IMG_20220820_Circlip.jpg

Back to the instructions. 3) Pull out the axle and the freewheel and carrier will drop out. Grasp the axle and pull. No movement. Pull harder. Still no movement.

So here I am again back on the Forum seeking the advice of any kind person who knows the right trick. I wondered if I would need to take off the other wheel and axle and then use a rod and a mallet to drive out the problem axle. The trouble is that would only work if the driven axle goes right through the carrier. All suggestions gratefully received.

Regards

Pete
rjb
Posts: 7200
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Tandem Gear Woes

Post by rjb »

My freewheel carrier is held onto the left axle with an Allen bolt through the axle. Have you removed it? You may need a short Allen key to go around the bend as it were. :wink:
5 or 6 mm :wink:

Here's a photo I've just found on the interweb which may help you.
Longstaff block screw boss.jpg
Longstaff block screw boss.jpg (21.72 KiB) Viewed 339 times
From this blog.https://pedal-trikes.blogspot.com/2009/ ... moval.html

Good luck.
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
tatanab
Posts: 5033
Joined: 8 Feb 2007, 12:37pm

Re: Tandem Gear Woes

Post by tatanab »

As RJB says- have you removed the allen key golt at the freewheel end?

Pete Cuthbert wrote: 20 Aug 2022, 5:20pm Back to the instructions. 3) Pull out the axle and the freewheel and carrier will drop out. Grasp the axle and pull. No movement. Pull harder. Still no movement.
2 points -
1. On Longstaff axles there is a small allen key grub screw under the bearing housing. Loosen that. When refitting, don't do it up too tight because it could distort the bearing housing. Its purpose is only to prevent the bearing shell turning in the housing.
2. Refit the wheel so you have something you can clout with your hand to shock the shaft/bearing loose. Alternatively, make yourself a slide hammer by brazing a bottom bracket screw (M8x1) onto a bit of tube or something along which you can slide a weight or something. A slide hammer should not be needed because the Longstaff bearing housings are not a tight fit to the bearing, hence the allen key grub screw. I assume that the Cyclon has such grub screws, but I have been told in the past that the Cyclon axle is subtly different to the Longstaff axles I am used to. You can see an example of the little grub screw in the photo posted by RJB, just behind the gear hanger in that case.

EDIT
Link to Georges own instructions. This is for two wheel drive, so you can ignore the first half about removing the righthand whel and jump in at the second half. You will not need an extended allen key because yours is easier to get at. REMEMBER - this is for his usual axle, not the Cyclon, so there might be subtle differences. [urlhttps://www.tapatalk.com/groups/on3wheels/longs ... -t206.html][/url]
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi All

Thanks Tananab for the extra advice and the link to the Longstaff instructions. It is nice to know what the grub screws are for and I have found two and removed them.

This evening's progress, if that is the correct word, has been to reach the bolt in the end of the drive shaft which is effectively under the freewheel block. Not easy but could be done. With that out of the way the block and holder are free and floppy on the drive shaft. As earlier in the day the drive shaft still seems firmly in place.

By way of a diversion I thought it might be possible to take out the o/s undriven shaft and then tap out the drive shaft with a brass drift. I removed the bolt and the split washer plus the grub screw and then took off the other wheel. The circlip was much more difficult to shift this side and the pin spanner failed. Long nose pliers and a screwdrive did it this time. With a theoreticall free shaft a good heave should have got it out. Two good heaves convinced me that it was going nowhere just like its partner. It was clearly time to give up.

Thanks for the link to George's instructions. It is nice to have instructions and see it all drawn out. It has flgged to me a possible source of the current problem. The drawing shows four grub screws, i.e. two per half shaft. So far on the Cyclon I have only found two, one on each of the central bearings. I will have to look tomorrow and see if there are a couple more on the outside end bearings but in non-obvious places.

Thanks again for all your support.

Regards

Pete
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi All

I thought I had better post a progress report since there is some progress.

This morning I have done a grub screw hunt and finally found the remaining two under the back plate of the drum brakes. Fortunately, the back plate can be loosened without being removed giving just enough room to extract the grub screw.

IMG_20220821_Hidden grub screw.jpg

With that done, a sliding weight on the axle had it out in no time and finally the block and carrier were available.

With the carrier in the vice and the removal tool in the block I tried a good push with a spanner. There was, as expected, no movement. As a second thought I got out the Stiltson and tried that. All that produced was movement in the worktop suggesting that it is not quite as securely fixed to the wall as I had thought. Time for Plan B.

Both Plan A and Plan B need two M15 washers that are 2.5 mm thick or 1 M15 washer 5mm thick. Whilst I do have some 5mm steel in the scrap box I realised that I had never made a washer before and that it would have been much easier with a bit of round bar stock. It looked as if there was no suitable bar stock to be had so some M12 washers messed about a bit seemed the easiest solution. The first one has been bored out to 15mm and faced down to a little over 2.5mm. The next one will be done after this brew break. The spacer will go on the drive shaft rather than between the block and the carrier.

Looking forward to the re-assembly stage it has occurred to me that there will be a problem re-attaching the bolt that secures the block carrier on the end of the drive shaft. It was pretty difficult to reach originally but the addition of 5mm of washers will reduce the limited access further. I think that a possible solution is to remove the other axle and make a long reach allen key tool that will allow the carrier bolt to be screwed up from down the other axle tube. The second shaft's washer is slotted so it should be possible to put back the shaft with the bolt in place and then apply the slotted washer with long nose pliers or even tweezers. Tightening should be possible with a skinny spanner.

Regards

Pete
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi All

Having had so much useful help from you all it seemed only fair to bring you up to date.

The two spacer washers (4.89mm) were added to the drive shaft before the freewheel carrier and the drive axle re-assembled. The proposed long bar with an Allen key at the end was made and the fixing bolt was offerd up. First time I forgot the washer but second time remembered and used tweezers to slide it into the gap between the frame and the freewheel while feeding through the bolt down the other axle shaft. That secured the carrier to the drive axle. Some gentle tapping with a long bar down the other axle shaft bedded the inside bearing into place and the grubscrew was fixed. A gentle tap with a wooden drift at the other end bedded in the outside bearing sufficient to fit the circlip. Given the trouble that the circlips gave me initially I succumbed to buying a bottom of the range circlip plier set from Halfords. Clearly very cheaply made, but much more effctive than long nose pliers or my pin spanner in re-fitting the circlip.

The other axle was offered up with its end retaining bolt initially screwed in as that was small enough to go thought the bearing. With that poking out next to the freewheel it was possible to fit the split washer using tweezers and then a thin spanner to screw it up tight. The associted grub screw was replaced and then the other end sorted out and the grub screw fitted. Three cheers for circlip pliers! The drum brake backing plates were then re-secured and the wheels re-fitted. Overall a very satisfactory Sunday.

This morning I set about replcing the chain and fitting the Acrea RD M360 mech. Having swopped mechs many times this was not really a daunting task. With the tandem back on the axle stands it was soon set up and test began. Initially results were poor but adjusting the 'back and fore' screw (sorry I don't know its correct name) operation was improved. However it remained a 6 speed changer rather than the seven speed it was meant to be. With it adjusted to get to the largest sprocket I noticed that the chain looked as if it was a bit on the short side and could have done with a few more links.

IMG_20220822_Chain deficit.jpg

At the other end of the range the unobtainable top gear seemed a surprise. Looking at the position of the changer it was nicely aligned with the smallest sprocket but the chain showed no inclination to move across. Thus I wonder if the current problems may be due to a chain that is not quite long enough. Does anybody have any suggestions on this idea?

Many thanks for all the support.

Regards

Pete
rjb
Posts: 7200
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Tandem Gear Woes

Post by rjb »

Nice work there. The chain looks on the short side. A couple of extra links wouldn't go amiss. Can you get all the gears when using just the middle ring?
Is there any scope for fitting a shorter bottom bracket axle which would allow the chainset to move closer to the chainstays. This could improve your chainline. How does the chainline look currently.

Does your 5mm spacer leave sufficient of the hexagonal axle to engage the freewheel carrier. ?

BTW I like your man cave. I wish mine was as tidy and organised. :D
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi Everybody

Thanks RJB for your observations. Shifting to the middle chainwheel seems to make no difference although I had felt that it should. However, with a bit more slack in the chain things might be different. I have some spare links so that should not be a problem.

Looking at the chainset as currently fitted, it does seem reasonably close to the frame. As a test I have put a batten across the biggest ring and taken it as far back towards the rear sprockets as I can. That points to the middle of the gap between sprockets 2 and 3 counting from the outside. I assume, possibly incorrectly, that such a position should mean that the middle ring aligns (ish!) with the middle sprocket on the freewheel.

The hex section of the axle was not measured, but scaling from my photo I now think it was probably 3/4" or 20mm depending upon which system George was using. Thus the washer pair at approximately 5mm should have left 15mm of the hex shaft in the carrier body. I note that with the new set up the freewheel has a slight wobble which suggests that there might be a slight degree of taper in either the carrier body or the hex part of the shaft. I'm no engineer, but I would have thought that having 3/4 still engaged would do OK.

In my earlier post I commented that the smallest sprocket was 16.6mm from the face of the hanger bracket for the mech. Under the new set up that should theoretically be 11.7, but measured it turns out to be 13.1mm, subject of course to measurement error. It is possible that using the extended tool with the allen key through the other axle tube I have applied more torque than the cycle shop that fitted the replacement freewheel. I imagine that faffing with a shortened allen key in the gap between the freewheel and the end of the lay shaft would not guarantee a very tight fit.

Ah yes! The tidy ManCave. That came about because of the Downgrade. In the previous house my workshop area was at the back of a double garage and one of the car spaces. Plenty of room to be messy. Moving here there is enough space for a smallish car or my workshop. In addition, the movers placed all my kit in a sort of heap in the middle of the garage so it was a case of starting from scratch and going for the goal of a 'Tidy Workshop'. Setting up the shadow boards for the tools was fun but kept throwing up various embarassments. I made a rack for scredrivers thinking I must have about 8. When they were all finally gathered to gether the count was over 20... Since that early work I have moved from chaos to tidy but have not yet achieved organised. I can remember where most tools were in the former garage but have no idea where some things are now. The next plan for when I don't have things to fix, is to do an inventory on the computer. That way if I want a specific tool, I can just look it up and find where it is hidden (in theory!).

Thanks for the advice.

Best wishes

Pete
Pete Cuthbert
Posts: 21
Joined: 8 Aug 2021, 9:26pm

Re: Tandem Gear Woes

Post by Pete Cuthbert »

Hi All

It seems appropriate to finish off this thread by a unpdate of where the project is now.

With everything re-assembled the change remained poor. However, chatting with our garden designer, a keen mountain biker, led to him coming to examine the machine sitting on the axle stands. With the chain on the middle chain ring he too was surprised that the change was poor but then suggested adjustment of the fore-aft screw. That was adjusted and led to an improvement. We now had seven gears rather than six. The indexing was still a bit unreliable but at least the whole range was available. My bag of bike bits no longer has any chain ends so that will have to be left as a job to do when our Bike Expert return from holiday. I expect he will have some odd bits kicking about in the workshop.

Since then we have done one road test and the outcome was generally satisfactory. It feels as if, for the most part, that the indicated gear is the actual gear. Thus I think the time has come to stop messing about.

Thanks to everybody for your interest and support.

Regards

Pete
Jdsk
Posts: 24639
Joined: 5 Mar 2019, 5:42pm

Re: Tandem Gear Woes

Post by Jdsk »

I'm sorry that it isn't all perfect yet. It's been very interesting to follow the progress, and I'm sure that your discoveries will help someone sometime.

Thanks

Jonathan
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