Upgrading the swing arm? (2010)
- Thread starter Vulin
- Start date
- Status
- Joined
- Oct 19, 2005
- Messages
- 18,978
There's a bunch of ways to skin that cat, from just Norton's 850 box braced steel tube to off the shelf Al box type to customize your own for a mono shock. Tricky not to distort a DIY bracing, but certainly been done before just fine.
Tightens me groin and quickens my pulse to think of the conditions that test swing arm twisting/spring back. Here's a couple of teasers for ya.
R click- tag view image- to see it all.
RGM version on Ms Peel to diddle wheel in living room.
RGM more exposed outside.
A one in a row custom race version, as far as I know
Tightens me groin and quickens my pulse to think of the conditions that test swing arm twisting/spring back. Here's a couple of teasers for ya.
R click- tag view image- to see it all.
RGM version on Ms Peel to diddle wheel in living room.
RGM more exposed outside.
A one in a row custom race version, as far as I know
- Joined
- Nov 20, 2008
- Messages
- 1,362
Norton saw fit to improve the commando swing arm in 73 and again in 75 so if yours is earlier you could upgrade. Aluminum saves about 1.5LBs off stock which is unsprung weight. Replacement shocks are an easier improvement but do both if you can afford it. Most folks do the transmission cradle at the same time for another 1.5lbs - 2lbs. $aving.
- Joined
- Dec 30, 2003
- Messages
- 3,658
If you start stiffening the swing arm won't the stresses move to the frame, which isn't the latest technology either. So maybe get an aluminum twin spar frame with mono shock. Wait, now the problem is the antique engine and front forks and brakes and wheels. By the time improvements are complete the Commando has disappeared.
- Joined
- Oct 19, 2005
- Messages
- 18,978
Yoose guys can fuss and fiddle all's ya like to try to get better handling but its been so solved by triple links and tractor spring forks its unbelievable, even to me and I ain't found the end of it yet on the prior power on tap.
Goldie Locks has tasted the stiff solid mounted cycles and found them too rigid to take the tire conflicts in powered over leans, the rubber mounted Cdo is too darn flexy to take the powered over lean, but in between is just right, allows chassis to flex just enough to take out tire direction/traction conflicts and store it for as long as you want then unwrap in one motion w/o any rebounding ringing.
The isolastics also act to damper power pulses tire hysteria and like a 2nd road suspension for the chassis itself. Rear tire power loads and lumps bumps work on front isolastic with mono shock like rubber pivot at rear. Incredible handling delights, simply flabbergastlngly fabulous.
You want the ends of the bike to be light and rigid but somethings got's to give in either traction or chassis or both at once. There is road holding gold in that-there center hinge if the chassis can take it. The proof is ever other bike is trying to limit power or engine drag in turns, on or off road, pashaw, Peel seeks tire spin power to enter turns hotter and keep upping it all the way around.
Top link just takes out some wind buffet jiggles, front mostly just the front tire road texture following wobbles but the rear one tames the hinged floppy fish, on or off road thank goodness. Its only takes a few silly mm's to matter. Elites have some sideways give built in but not the damping features innate to Commandos.
Off the shelf Al boxed swing arms can set ya back at least $500, but what ya want to get out of life on two wheels before ya gone?
Goldie Locks has tasted the stiff solid mounted cycles and found them too rigid to take the tire conflicts in powered over leans, the rubber mounted Cdo is too darn flexy to take the powered over lean, but in between is just right, allows chassis to flex just enough to take out tire direction/traction conflicts and store it for as long as you want then unwrap in one motion w/o any rebounding ringing.
The isolastics also act to damper power pulses tire hysteria and like a 2nd road suspension for the chassis itself. Rear tire power loads and lumps bumps work on front isolastic with mono shock like rubber pivot at rear. Incredible handling delights, simply flabbergastlngly fabulous.
You want the ends of the bike to be light and rigid but somethings got's to give in either traction or chassis or both at once. There is road holding gold in that-there center hinge if the chassis can take it. The proof is ever other bike is trying to limit power or engine drag in turns, on or off road, pashaw, Peel seeks tire spin power to enter turns hotter and keep upping it all the way around.
Top link just takes out some wind buffet jiggles, front mostly just the front tire road texture following wobbles but the rear one tames the hinged floppy fish, on or off road thank goodness. Its only takes a few silly mm's to matter. Elites have some sideways give built in but not the damping features innate to Commandos.
Off the shelf Al boxed swing arms can set ya back at least $500, but what ya want to get out of life on two wheels before ya gone?
- Joined
- Oct 19, 2005
- Messages
- 18,978
850 boxed swingarm, spindle collars, Gerg Fuath's fork kit, RGM fork brace, REAR,
Font and top rod links [in order of effect], put in 2S cam and trim head or new pistons for near 10 CR and keep the smaller port head. May need steel flywheel to handle the zings and upgrade valve train to handle 7000+ rpm as no drop off to warn ya off.
Font and top rod links [in order of effect], put in 2S cam and trim head or new pistons for near 10 CR and keep the smaller port head. May need steel flywheel to handle the zings and upgrade valve train to handle 7000+ rpm as no drop off to warn ya off.
- Joined
- Oct 19, 2005
- Messages
- 18,978
i'd say a stronger swing arm is about the best upgrade you can do. w/o ever really needing too or even noticing it when ya do. Commando is a complex miss-mash of many things that can add up together for some sloppy/scary handling or even parts damaging.
I've got strong opinions now about what works for me and what to be aware of when riding a factory Commando or modern sports bike vs my Ms Peel special configured as I reviewed and relive inside about 24/7 since experiencing it.
A flexy swing arm will indeed add to handling upsets as it spring backs to lever through rear iso mount to front iso mount to slap it side-side which in turn wiggles the forks which in turn wiggles whole chassis back into swing arm ad infinium of non linear positive feedback until a floppy fish off edge of the dock.
Don't know what your are seeking nor what you think is wild riding so hard to say what to do first but everything adds up so swing arm as good a place as any to start. I upgraded my Combats to the 1st 850 type, just gusseted at front [+grease zerts], then later added collars, just in case they helped preserve things.
I absolutely did not know nothing about riding a bike that leaned or had any idea of what to expect when tearing Peel apart initially to fix leaks and finding major issues not yet in catastrophic failure - to end up with what I pretty much know and tested is way better handler than anything else out there in rather wide scope of conditions plus more comfortable for an old fart to appreciate while doing fun things on it a long time in a row.
For example of what it takes to bend the 750 swing arm, look close at my avatar rear tire profile, when the bulge got off centered .06 sec later and Combat rev'd to over 6800 the extra 2S 3rd piston power hit, it jerked instantly straight up then next instant slammed a high side off swing arm spring back action straight
sideways directly into ground on my R knee. Road fine hands off as normal but later could not get spindle out, mostly d/t rust and lipped wear but likely from this trauma too.
On the other hand on factory Trixie Combat, I stupidly tried to get out of dust cloud by passing a log trailer on the outside near ditch because feared to pass it through the blinding cloud to see any on coming in time - almost got past its cab when I saw road grader had left 2 ft high piles of rocks in my planned path and grader was in the road ahead with gap to get off ditch slope closing fast, nothing to lose I Nailed Trix to clear truck and weather vaned rear towards ditch bottom which put us into a flat tracker slide [no foot down] that almost got to a terrific low side till rear snagged sideways to fling a hi side that got it both back on road level and in front of truck but also aimed to just miss grader blade as space pinched between surprise car going a bit wide past grader. This harsh side load to swing arm tore out the RH shock rubber so shock came off to get idea of load.
After I fixed shock Trix still passed the axle fine and handled as good as any normal Cdo. But on 3rd week on her - deer took us down even harder, bike was jerked out from under sideways to twist in air then land on rear and hi side back up to land on me while I was in air out stretched like superman from speed of 1st ground impact flesh splash rebound. Bent forks so figured better check rear.
I never could get the spindle out so had to cut off swing arm. Took over 10 tons on hydraulic press to get spindle out of cradle.
If yours not a past constantly oiled 750 swing arm you too may find its spindle impossible trapped. I now think its a dis-service to future generations not to put grease zerts in as one can never tell what fate may sit the bike up another decade. My friend Wes has trapped spindle in his '71, rides fine until you press constant held sweepers then starts to jutter front to rear until slowing up.
It can still do fast lane switching with just a twitch in taking up slack though.
I've got strong opinions now about what works for me and what to be aware of when riding a factory Commando or modern sports bike vs my Ms Peel special configured as I reviewed and relive inside about 24/7 since experiencing it.
A flexy swing arm will indeed add to handling upsets as it spring backs to lever through rear iso mount to front iso mount to slap it side-side which in turn wiggles the forks which in turn wiggles whole chassis back into swing arm ad infinium of non linear positive feedback until a floppy fish off edge of the dock.
Don't know what your are seeking nor what you think is wild riding so hard to say what to do first but everything adds up so swing arm as good a place as any to start. I upgraded my Combats to the 1st 850 type, just gusseted at front [+grease zerts], then later added collars, just in case they helped preserve things.
I absolutely did not know nothing about riding a bike that leaned or had any idea of what to expect when tearing Peel apart initially to fix leaks and finding major issues not yet in catastrophic failure - to end up with what I pretty much know and tested is way better handler than anything else out there in rather wide scope of conditions plus more comfortable for an old fart to appreciate while doing fun things on it a long time in a row.
For example of what it takes to bend the 750 swing arm, look close at my avatar rear tire profile, when the bulge got off centered .06 sec later and Combat rev'd to over 6800 the extra 2S 3rd piston power hit, it jerked instantly straight up then next instant slammed a high side off swing arm spring back action straight
sideways directly into ground on my R knee. Road fine hands off as normal but later could not get spindle out, mostly d/t rust and lipped wear but likely from this trauma too.
On the other hand on factory Trixie Combat, I stupidly tried to get out of dust cloud by passing a log trailer on the outside near ditch because feared to pass it through the blinding cloud to see any on coming in time - almost got past its cab when I saw road grader had left 2 ft high piles of rocks in my planned path and grader was in the road ahead with gap to get off ditch slope closing fast, nothing to lose I Nailed Trix to clear truck and weather vaned rear towards ditch bottom which put us into a flat tracker slide [no foot down] that almost got to a terrific low side till rear snagged sideways to fling a hi side that got it both back on road level and in front of truck but also aimed to just miss grader blade as space pinched between surprise car going a bit wide past grader. This harsh side load to swing arm tore out the RH shock rubber so shock came off to get idea of load.
After I fixed shock Trix still passed the axle fine and handled as good as any normal Cdo. But on 3rd week on her - deer took us down even harder, bike was jerked out from under sideways to twist in air then land on rear and hi side back up to land on me while I was in air out stretched like superman from speed of 1st ground impact flesh splash rebound. Bent forks so figured better check rear.
I never could get the spindle out so had to cut off swing arm. Took over 10 tons on hydraulic press to get spindle out of cradle.
If yours not a past constantly oiled 750 swing arm you too may find its spindle impossible trapped. I now think its a dis-service to future generations not to put grease zerts in as one can never tell what fate may sit the bike up another decade. My friend Wes has trapped spindle in his '71, rides fine until you press constant held sweepers then starts to jutter front to rear until slowing up.
It can still do fast lane switching with just a twitch in taking up slack though.
grandpaul
VIP MEMBER
- Joined
- Jan 15, 2008
- Messages
- 13,243
Old thread, new addition to the conversation.
I got 2 of these box section swingarms from Kenny Dreer, the last of the VR880 stash as he was clearing house when he sold Norton to Stuart Garner.
They require a companion upgrade of the transmission cradle to accept steering bearings and a 1" diameter spindle in lieu of the small tube in the original setup. They provide you with slider block chain adjusters which do not alter the bike's geometry in the way that the eccentric adjusters do (slight, but noteworthy).
I got 2 of these box section swingarms from Kenny Dreer, the last of the VR880 stash as he was clearing house when he sold Norton to Stuart Garner.
They require a companion upgrade of the transmission cradle to accept steering bearings and a 1" diameter spindle in lieu of the small tube in the original setup. They provide you with slider block chain adjusters which do not alter the bike's geometry in the way that the eccentric adjusters do (slight, but noteworthy).
- Joined
- Apr 21, 2015
- Messages
- 322
Wonder how many owners have ever calculate the torsion constant and relative second moments of area to compare even steel swinging arms manufactured from round tube and recangular section tube?
Just a thought.
Just a thought.
- Joined
- Sep 18, 2014
- Messages
- 131
I think I'd spend my dough on some really nice rear shocks, like a set of Works or bare minimum a set of Hagons, add some front cartridge fork internals and that's probably the best bang for your buck beyond the swing arm. I rode my bike today with the factory 40 year old shocks and forks and really rang it's neck down my favorite back road, sure it was rough and the clutch slipping a bit but still better than some of my old clapped out dirt bikes.
I've got mods listed above ready to go on this winter. Like every other bike I've owned, you can't go wrong with putting money in the suspension shocks and forks are my favorite mod.
I've got mods listed above ready to go on this winter. Like every other bike I've owned, you can't go wrong with putting money in the suspension shocks and forks are my favorite mod.
- Status