Converting T20 swinging arm to needle rollers

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gammakeith
On the street
Posts: 22
Joined: Mon Dec 14, 2020 4:50 am
Country: United Kingdom
Suzuki 2-Strokes: 1966 T20

Converting T20 swinging arm to needle rollers

Post by gammakeith »

I had to resort to cutting my swinging arm spindle out of my T20 in order to remove the swinging arm as it was well stuck. The T20 uses a full length bearing/spacer tube so must be prone to the spindle seizing in the tube. Once the original sintered bronze bushes were driven out of the swinging arm it was obvious they had worn and were the cause of the play that I had. The bearing/spacer tube measured up as fairly unworn once I got brutal with a drift and blowtorch to get the remains of the wheel spindle out but was rusty internally. The “Suzuki” replacement bushes now come in plastic as this part is shared with some later bikes. Bearing/spacer tubes and swinging arm spindles are also no longer available so I converted to use needle rollers with all new parts as follows. Prices are Feb 2021 and in UK pounds;

1:Two 17mm (id) x 23mm (od) x 12mm (depth) needle rollers were pressed in each side. The fit was perfect with only a light clean on the swinging arm recesses. Cost £7.20 for 4 bearings.
2: A pit bike wheel spindle was used for the swinging arm spindle 12mm x 230mm. This was near perfect though the threads needed reducing by 5mm to improve the appearance. This obviously would not be needed if the original was fine. Cost £6.50.
3: Two IRT1225-2 Needle Roller Inner Races 12mm x 17mm x25.5mm were sourced from Simply Bearings UK. Each one spans the width of the two needle rollers on each side. Cost £9.89.
4: Steel tube 15.88mm od x 12.88mm id was sourced to make the central spacer tube and the two “top hat” spacers at the end. Two small pieces of plastic pipe were added to the central spacer tube to keep it roughly central in order to aid assembly. Cost £6.80 for 600mm.
5: Brass bar 30mm diameter was sourced to make the end caps to fill the gap to the outer race and to give the correct width of the swinging arm (the original bushes extended the swinging arm by 3mm each side). This was bored to 17mm so the inner races will pass through and then machined to width so it was a press fit in the swinging arm. The original caps were used along with some thicker o-rings I had in stock. Accordingly, I had to also machine a recess for the o ring to avoid this binding too hard with swinging arm rotation. Cost £12.20 for 150mm.

The total cost was £43 for materials plus a couple of hours of pretty unskilled lathe work. The longest time was spent carefully rubbing down the top hat washers so the end float of the whole assembly just vanished when the spindle bolt was tightened up.

Keith
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Alan H
World Superbike
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Joined: Thu Feb 16, 2012 11:50 am
Country: England
Suzuki 2-Strokes: 2 x GT550s GT750B, GS750B
Location: The Republic of South Yorkshire

Re: Converting T20 swinging arm to needle rollers

Post by Alan H »

Good work. Is there a grease nipple on the swing arm to ease maintenance?
Think of how stupid the average person is, then realise that half of them are more stupid than that.
gammakeith
On the street
Posts: 22
Joined: Mon Dec 14, 2020 4:50 am
Country: United Kingdom
Suzuki 2-Strokes: 1966 T20

Re: Converting T20 swinging arm to needle rollers

Post by gammakeith »

Not originally. I thought about adding them but they would struggle to get grease to the actual swinging arm spindle. Its probably much better to pull the spindle every few years and regrease properly.

Keith
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