Narrow Glide Fork spring size
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Intermediate
Joined: Nov 2021
Posts: 33
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From: Georgia
Narrow Glide Fork spring size
I have a 2002 883C sportster that has had the front forks lengthened at some point before I acquired the bike. It has an aftermarket frame that racks out the front forks more than normal. Riding the bike it feels like the front forks are just wore out. So, I want to rebuild the front forks, which are the narrow glide 39mm forks. My question is how do you determine the length to what they were lengthened to. Where do you measure from without fully disassembling the forks. I want to get new springs and whatever else I need to rebuild them. Online they have so many different lengths you can get. So I'm at a loss in determining the length to buy. I want to get all the needed parts ahead of time before I take the forks apart. Any help would be appreciative.
Stellar HDF Member
Joined: Feb 2013
Posts: 3,072
Likes: 1,727
From: Dallas, Texas
Sounds like a soft front end . . . bouncy and lots of nose dive braking. Change the fork oil to 10w is a good start. Save yer $$$ on a Fork Rebuild and/or springs. With the fork caps off (gotta have bike on a lift) pull out the spacers. Get the same diameter PVC tubing, measure and cut 2 1/2" longer spacers.Then Test Ride. This is a multiple step fix until ya get it where ya want it. Still too soft, make a longer spacer and Test Ride.
Looks like i took some notes when I disassembled my '02 883's front end. Stock assembled fork length (off my bike) was 32.75 in total length. The stock fork tubes (disassembled) were 25" long, though google is saying stock tube length is 24.25, it's in that neighborhood either way lol. Those measurements should help you figure out what the PO changed on your front end.
If someone put longer tubes in, they should have also added spacers to fix the preload. If your front end is diving, maybe they didn't add preload spacers? The stock springs could also have given out but I'm not certain how likely that is.
If someone put longer tubes in, they should have also added spacers to fix the preload. If your front end is diving, maybe they didn't add preload spacers? The stock springs could also have given out but I'm not certain how likely that is.
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Intermediate
Joined: Nov 2021
Posts: 33
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From: Georgia
It definitely does the nose dive when breaking. It gets kind of bouncy when on an uneven pavement, which made me think just wore out shocks. That was my thinking if on a regular vehicle. But the forks on a bike I haven't been into yet. Ill take the tops off and change the oil and just see how the springs look first. Play around with the spacers length until rides smooth.
On that note as I am kind of learning as I go on some of the things. So if one was to put longer fork tubes in versus stock ones. As the springs would go, would it be that the original springs are used with longer spacers to account for the longer tubes? Is this how having longer forks and the internals are done? Just out of curiosity.
I do appreciate the information on the front forks. I really started thinking of doing something with them as one day I was in a long curve in the road that was bumpy. That front end was all over the place, bouncing. With that and how the front dives when braking, it was time to address that issue before it bounced me off the road.
Thanks
Skeeter
On that note as I am kind of learning as I go on some of the things. So if one was to put longer fork tubes in versus stock ones. As the springs would go, would it be that the original springs are used with longer spacers to account for the longer tubes? Is this how having longer forks and the internals are done? Just out of curiosity.
I do appreciate the information on the front forks. I really started thinking of doing something with them as one day I was in a long curve in the road that was bumpy. That front end was all over the place, bouncing. With that and how the front dives when braking, it was time to address that issue before it bounced me off the road.
Thanks
Skeeter
Road Warrior
Joined: Sep 2016
Posts: 1,952
Likes: 903
From: South Florida (Ft Myers area)
I'm not supposed to be helpful, but I'll throw you a bone and maybe the trolls will stay away.
Looks like templeofdank gave you fork tube length information and chopper shops sell lengthened tubes in lengths starting with 24.25" +added length. Easiest way to see difference while still on the motorcycle would be to compare to a stock motorcycle and measure from the same point.
More rake and trail improves straight-line handling at the cost of handling in turns. So even at best, turns will not be great.
Motorcycle Rake, Trail and Offset Explained - MotoShark.com
Now the bad news (not really), there absolutely no way to know what someone did internally when they modified the forks, could be all kinds of things going on in there. Normally, the kits come with longer spacers, the ONLY way to know is to take them apart.
Hopefully, it was done like this....
As for fork oil....every brand is different (one brands 10w is not the same as another's 10w, etc.), pick a brand and stay with that when adjusting the viscosity, but here is a chart if you want to change around brands...
Comparative Oil Weights Table - Transmoto
You might read through this and get the entire motorcycle setup....Motorcycle Suspension Guide – Superbike-Coach – A Motorcycle Riding School in California
Heavier oil for more dampening, lighter for less. You can also play with the amount of oil, but I'll let you research all of that.
Looks like templeofdank gave you fork tube length information and chopper shops sell lengthened tubes in lengths starting with 24.25" +added length. Easiest way to see difference while still on the motorcycle would be to compare to a stock motorcycle and measure from the same point.
More rake and trail improves straight-line handling at the cost of handling in turns. So even at best, turns will not be great.
Motorcycle Rake, Trail and Offset Explained - MotoShark.com
Most choppers, baggers, and cruisers sport a bigger rake angle straight from production. Larger rakes facilitate high-speed stability, even at the expense of cornering abilities.
Hopefully, it was done like this....
As for fork oil....every brand is different (one brands 10w is not the same as another's 10w, etc.), pick a brand and stay with that when adjusting the viscosity, but here is a chart if you want to change around brands...
Comparative Oil Weights Table - Transmoto
You might read through this and get the entire motorcycle setup....Motorcycle Suspension Guide – Superbike-Coach – A Motorcycle Riding School in California
Heavier oil for more dampening, lighter for less. You can also play with the amount of oil, but I'll let you research all of that.
It definitely does the nose dive when breaking. It gets kind of bouncy when on an uneven pavement, which made me think just wore out shocks. That was my thinking if on a regular vehicle. But the forks on a bike I haven't been into yet. Ill take the tops off and change the oil and just see how the springs look first. Play around with the spacers length until rides smooth.
On that note as I am kind of learning as I go on some of the things. So if one was to put longer fork tubes in versus stock ones. As the springs would go, would it be that the original springs are used with longer spacers to account for the longer tubes? Is this how having longer forks and the internals are done? Just out of curiosity.
I do appreciate the information on the front forks. I really started thinking of doing something with them as one day I was in a long curve in the road that was bumpy. That front end was all over the place, bouncing. With that and how the front dives when braking, it was time to address that issue before it bounced me off the road.
Thanks
Skeeter
On that note as I am kind of learning as I go on some of the things. So if one was to put longer fork tubes in versus stock ones. As the springs would go, would it be that the original springs are used with longer spacers to account for the longer tubes? Is this how having longer forks and the internals are done? Just out of curiosity.
I do appreciate the information on the front forks. I really started thinking of doing something with them as one day I was in a long curve in the road that was bumpy. That front end was all over the place, bouncing. With that and how the front dives when braking, it was time to address that issue before it bounced me off the road.
Thanks
Skeeter
Video slw210 posted is a great summary on how to disassemble.
But yeah, it's going to be pretty darn tough to deduce what's going on with your forks without disassembling.
Thread Starter
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Intermediate
Joined: Nov 2021
Posts: 33
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From: Georgia
I do appreciate the information. One of these coming up weekends I'll do the dirty part and disassemble them. I'll see what I got once I'm in there. Ill post what I find once I get into it.
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Road Warrior
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From: South Florida (Ft Myers area)
Good looking ride. Looks well done, so it's a good possibility the extension was done proper.
Maybe try a fork brace.
You may just need to play with the fork oil wt and quantities, maybe just upgrade to cartridges or emulators/intiminators.
Maybe try a fork brace.
You may just need to play with the fork oil wt and quantities, maybe just upgrade to cartridges or emulators/intiminators.