Sprocket choices

[ricochet]

I'll be needing to get new sprockets for my project and would like suggestions on tranny and rear sprocket choices.  Motor is a 73 stroked to 1200cc with dual plug heads and single fire dyna 2000i ingition.  S & S E carb. Andrews R5 cams.  Some Andrews gears in tranny.  Will be used on highway but not extreme MPH or long duration.  Looking for a moderate gearing choice.  I need to buy the 2 sprockets so now is the time.

What do you think guys?

ricochet

[nibroc]

51 and 22--leave room on chain for a 23

[ricochet]

Thanks.  Both seem to be readily available.  I may need some offset on the tranny sprocket once I get the rear centered.  Is this offset always accomplished with an offset sprocket or can spacer be used if not too much?  Not positive right now but think the rear tire is a 130/80-18 at 5.10 wide.

ricochet

[garyajaz]

i have from 18 to 23 in stock.  lol
last time i used a 20 was  town light to light racing.
very fun.
i now run a 23 .  mine is a 80 incher with tons of torque.
a 22 (as said above) will do you well.

[saltcaveminer]

like nibroc and garyajaz says.Salty

[ricochet]

What's the difference between the output sprocket for pre 79 versus 79 to 84? 

ricochet

[saltcaveminer]

sorry cant answer the question,but you might want to go to the truett and osborne web site and read the info regarding stroker final drive ratios etc.Salty

[ricochet]

This will get interesting as I get it all figured out.  Since I haven't got the engine back I'm putting another engine and tranny in the frame so I can mock up the rear sprockets and all.  Using a 60 spoke 18 x 3.5 wheel with a GT501 130/80-18 tire that's 5.10 wide in a regular swingarm.  The wheel hub is for 2000 and up bikes and is about 3/4 wider than the tire each side.  This all squeezes nicely within the swingarm including the rotor.  Depending on the allignment of the tranny sprocket to the rear may use a flat sprocket or even a dished one but backward so it's closer to the tire.  Trying to manage this via the rear sprocket versus using an offset sprocket up front.  From appearances it looks like I can adjust the front out a little with spacers before running out of threads on the mainshaft.  Is this reasonable?

ricochet

[saltcaveminer]

i think its best to keep the motor sprocket where it is and concentrate on the alignment from the tire to it.Salty

[ricochet]

Yea,  that's my plan.  The cases and tranny I'm using for mock-up are assembled rough.  There's slop in the mainshaft indicating missing a spacer or thrust washer on the inside of the case on the output shaft.  I imagine that all the slop is taken out of this by adjusting the thickness of those parts thereby moving the sprocket inward until the right side to side clearance is met.  Does this sound right?  I want to be close for front sprocket location as a reference.

Also,  how many links in Ironhead rear chain?

Thanks,

ricochet

[garyajaz]

"This all squeezes nicely within the swingarm including the rotor."  ??
rotor? 1973 dosent have a disc on back.
some other things are changed. if you put the 2000 wheel on a 1973 swing arm how you gonna anchor the brake?
i have a 1979 swing arm and stuff to put disc on back of my 1974.
just ride it so seldom havent put it on priorty list. good luck,,,post pix

p.s. was thinking you dont have a choice on sprockett size in back.  a 51 is riveted on (1973)
but you running a 2000 wheel.  would like to see the set up

[ricochet]

I'll have some pics next week after getting some time to work on layout etc.  Break anchor is easy as long as you're useing a bracket to the axle that keeps things alligned.  It's all 1 off stuff.  I can't say I've mounted a brake in a stock manner, ever.  Rigids, springers, girders, ... they all 1 off. 

FYI, the rear wheel takes a 3/4 axle so I'll need to make up something for the space between the axle and the slots in the swingarm axle plates.  I did manage to open up some nice chrome adjusters for the 3/4.  If I can find the pieces for the 5/8 axle maybe can open them up too.   Used a Unibit with maximum id of 3/4 and it worked slick.  Self alligning and cuts clean with no chatter or triagulation like when you open a hole with a big drill bit.

Later and thanks all,

ricochet

[ricochet]

Sorry, no pics.  Nothing to take yet, but.  I did some mocking up again with the wheel, sprocket and rotor on and find that the wheel hub is not centered to the wheel/tire.  On one side it sticks out beyond the tire about 3/8 where on the other it's 3/4.  So to best center the tire in the frame and allign the sprockets I had to flip the wheel assembly around from how it was.  This meant dismounting the tire and remounting.  Now I'm waiting on some sprocket bolts.   With things turned around the sprockets come nearly perfectly into allignment and there's equal room each side of the hub on the axle when the wheel/tire is centered in the frame.  The 3/8 should be adequate clearance for the chain to the tire,  probably be an 1/8th once mounted.  I had flipped the swingarm over so the tab (whatever that's for) and the brake anchor slot is on the left now.  There's also a threaded hole right where I might anchor the caliper.  Might even be able to use the anchor slot if I get creative.

ricochet

[ricochet]

Here's a couple of pics finally.    First is right side tight fit but aligns to front sprocket well.



Next is left side same story very tight but fits if I fashion some kind of caliper mount outboard of the swingarm as pictured.  This isn't bad but I might lop off the square end of the bracket to make it less obtrusive.  With a little creativity and some masaging of the bracket the shock mount will double as a sliding anchor.



Last is from the rear showing sprocket alignment.  Will be good to go with minor tweeking.



Still have to fine tune then get spacers.

ricochet

[adayrider]

Use a better camera and take more pics. Please.

[ricochet]

I have a good camera and the pics when initially posted viewed nice and clearly but something happened in the upload or reposting.  I spent the longest time trying to make them smaller too in photobucket and for some reason they're still too big.  I suck at this.  The pictures are great in any other medium.  What am I doing wrong?

On the subject at hand not going to go with that bracket method althought it would work.  Found enough room to squeeze a real simple bracket inside the swingarm where it should be if I make it out of 5/16 steel instead of the 1/2 thick aluminum you see.  I like the location of the caliper and the bracket needed is really small. 

ricochet

[saltcaveminer]

i was rereading some of the questions you had and i wanted to confirm your thought about the loose (endplay)in the tranny.shims are added to the inside on the mainshaft and countershaft to get things back to spec.i have never attempted converting a 73 swingarm to disc but i believe there have been successful conversions using like 79 to 81 swingarms and brake components.i also recall seeing in american iron a guy (dan)who adapted an early ironhead swingarm and it seemed to work well.i wish i could remember which issue(s).hope this info helps.Salty

[ricochet]

Thanks for the reply on the transmission alignment and sprocket question.  I've allowed myself a little bit of adjustment for when the real engine and sprocket go in.  Did see variations in dimentions of the new PBI sprocket versus the old one used for mock-up but will manage.  Also, it seemed to not want to slip on.  Is it supposed to be a press fit?  Just ordered a piece of 5/16 stainless for the bracket.  Only 3 x 8 piece needed that's how small it needs to be.  I do have a square tube swingarm that I scored but will save that for another ironhead on the back burner behind this back burner project.  That one has wider wheels and tires both front and back.

ricochet

[saltcaveminer]

i doubt that the sprocket is a press fit.it usually just bolts up.Salty

[ricochet]

The old sprocket is tight slip fit and it looks to be original.  I'll have to get down there closer for a look see and measure some stuff.  I wonder if there's a spline that is wider for orienting but couldn't see why.

Made the simple pattern for the bracket and am waiting on the piece of 5/16 stainless.   Seems 5/16 is not a very common bar stock thickness.

Working the front end in the mean time polishing the lowers and fitting the wheel bearings. 

ricochet

[saltcaveminer]

you might check out www.mcmaster.com they have 5/16 ss.Salty

[ricochet]

Didn't think of them.  Tried MSC and Grainger before going to this DiscountSteel.com.  Bracket is made up and ends up pretty neat fit tucked up tight below the swingarm left side casting.  I need to finish sand and polish what shows and make a block to attach to it that will serve as a sliding anchor in the slot in the casting.  Remember I flipped the swingarm over so this slot is on the left now .  There will be minimal grinding required on the lower webing of the casting to allow the bracket to float correctly when everything is clamped together with the axle.  This is so the bracket is straight and not cocked.

ricochet

[ricochet]

Testing  picture sizing out of photobucket:

[ricochet]

Slow progress.  Too many irons in the fire. Did manage to make the new bracket and here it's being test fit with caliper and spacer onto wheel assembly:





Things line up pretty well centered to the opening in the caliper but I may take a few thousands off the spacer to bring it in tighter still.

Then in order to squeeze the assembly into the swingarm I need to grind relief into the webing of the swingarm to allow freedom of movement for the bracket.



Finally need to make a block to attach to the bracket that will slide within the brake anchor slot.

ricochet

[ricochet]

Found this while looking back.  Never did show what the bracket looked like for the rear brake.  To recap this is using a disk brake within a round swingarm on a 73 frame as opposed to using the square swingarm and associated hardware.  Fits very nicely, tight but clean and certainly cleaner than my first attempt.  Here's the bracket including the anchor:





ricochet

[garyajaz]

looking good.
take pix of whole bike.

upside down swing arm..
got to love it...
.
like to see some one building old stuff instead of just ordering out of a catalog.

[ricochet]

I haven't got a pic of the whole bike but here's a recent one after stripping it down enough to place the frame over engine to bolt it in.  Finally at it again.  This has been a real back burner bike after my other pan project that is waiting for chrome.  By spring I should have 2 new rides.



Here's a poor pic but you can see the paint.  2004 tins.  Using 2006 front end and 60 spoke wheels.  Handlebars not shown but a nostalgic type that will go with the paint and theme somewhat.



ricochet