Harley Fork Upgrade.

[muddy]

Last ride I took I noticed oil residue all over the tank, engine and frame of the bike. At first I thought it was slobber out of the breathers of the engine. However it's never done this before. So looking further i saw oil drips and runs on the front fender. So i felt up and the fork was leaking.

After seeing you have to disassemble it all anyway I decided to go with an upgrade and get Progressive Monotube Cartridges.





First drain the forks. To prevent a mess later.... ask me how I know.

Once off the bike you can put them in a vice. *Helpful tip if your clamping on delicate chrome, use a old inner tube to keep from damaging the chrome.





First you take out the bottom bolt. Then you can use the lower tube as a slide hammer to knock out the top bushing and seal. (I forgot the bolt and ended up wondering why I was getting nowhere and also cutting my finger (yes that finger) )




Next take the top slider cap off. (Keep in mind this is under slight pressure from the spring) then you can pull all the old parts out. Some of these parts will get reused with the new kit.







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[muddy]

After cleaning everything up time for reassembly We'll start with the lower slide bushing. As can be seen mine were in need of replacing.






The cartridge goes in next being sure to refuse your old top out spring (little one at the bottom). Progressive recommendation is one preload shim. From what I was reading on forums bigger guys like myself went with two and were happy with it. So I'm going with two. 






I didn't get a picture but you will also reuse your old bottom cap on the bottom of the cartridge rod. Then you can slide the bottom tube on and tighten the bolt to spec. (Add a little red loctite to these bolts)





Now time to install the top bushing, washer and seal. This can be done with a properly sized PVC pipe but for $12 I bought the correct 41mm driver.




Now once I get my oil and can fill the fork with the 5oz of 10 wt. And torque the top cap to spec. This is different then the factory spec. They'll be ready to go back on the bike. Think I'm going to polish them before that happens.





Unlike the factory setup the oil used with the Monotube kits is just for lubrication. The factory setup uses oil as a dampening agent. The difference in weight will change the rate of absorption and rebound.






The kit came with stickers. Don't forget to put them on your bike so everyone knows you have a race bike!





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[muddy]

While doing this job I was a little disappointed at the service provided by my local dealership. I've had it in for service at least once a year while in for inspection. But the blackness and smell of the oil it has never been changed before. I would think that should be something on their list to do with all the mileage service plans they have.

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[skfarmer]

thanks for the pics and story.

i know nothing of rebuilding shocks on bikes.

[muddy]

thanks for the pics and story.

i know nothing of rebuilding shocks on bikes.

I knew enough to be dangerous..... the rest I watched you tube

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[goodfellow]

Excellent Tim! Thank you for the great pics and the write-up. This is a great DIY post.

[stokester]

I did something similar to my '78 Beemer this last year using HyperPro springs.  In that style of fork there is a damper on the bottom that deteriorates over time and I found PVC spacers that were added by a previous owner to stiffen them.

Changing fork oil is one of those necessary maintenance items that is frequently neglected.  I usually change mine once a year depending on how much I rode that bike.  One of the things necessary with my new springs is that the quantity and weight of oil required changed.  Rather than use an amount of oil to be added the oil level distance to the top of the fork or "head space" is given.  This can be accomplished by a MotionPro tool which has a syringe and a graduated rod to get the proper level after adding and pumping the fork. 

The weight of fork oil is also be a big factor in handling and I learned that although they all have numbers like 10w, 20w there is no standard from brand to brand so you need to stick with one manufacturer to maintain or improve the ride. 

The addition of these springs and an improved top brace made a significant difference in my ride. 

Ride Safe