Fork spring question(s)

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Mar 23, 2019 | 01:32 PM

Scootertrash60

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From: MN

Fork spring question(s)

OK, so I'll try to keep this as simple as possible.

I don't know much about suspension save for that it makes our rides more comfortable, so I want to try to learn some things about suspension, mainly the front for now.

I plan on putting a 49mm Wide Glide on my 85 Low Rider project, I would also like to lower it a bit. So my first questions are as follows:

Are the fork springs for all models all the same length and the difference in fork tube length is made up by different length damper tubes?

Or are the fork springs different lengths and stiffnesses between models?

Last edited by Scootertrash60; Mar 23, 2019 at 01:33 PM.

Mar 23, 2019 | 03:55 PM

misfitJason

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From: Florida

They can be different lengths and damping strengths. If you are talking across the Dyna line the difference is in spacer length until you talk about the lowrider s Models. They are a cartridge kit

Mar 24, 2019 | 07:18 AM

grbrown

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From: Bedford UK

If you are using a spring and damper-rod fork, I suggest you simply throw away the stock springs and install single-rate ones to match your weight. That will require cutting spacers (normally plastic tube) to set the sag just so. Also consider using Ricor Intiminators or aftermarket cartridges, to enhance ride quality. Check stock length of the 49mm forks against your current forks before lowering anything.

Mar 24, 2019 | 08:17 AM

Scootertrash60

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From: MN

After thinking this thru a bit more yesterday, I think I'm good on what I'll do.

The stock 35mm fork tube length on my 85 Low Rider is 25.5in (courtesy of Motorcycle Metal website)

I'm going from a stock 19in wheel to a 16in touring wheel, so that will drop the front approx 1.5 in, if I'm figuring correctly

I should be able to use stock 49mm Dyna Low Rider tubes , 25.5in (again from MM website). If I want to drop the front another 1/2in I can cut the spacer accordingly, I was wanting to drop the front 2in.

I will be using Fat Bob 49mm Triple trees, they have a slight built in factory rake.

I will be checking into the cartridge type internals, I've already researched the single rate springs for my weight and Ricor Intimidators will be used if I go with the single rate spring.

Last edited by Scootertrash60; Mar 24, 2019 at 08:28 AM.

Mar 24, 2019 | 09:15 AM

texashillcountry

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From: Haslet Texas

Quote:

Originally Posted by Scootertrash60

After thinking this thru a bit more yesterday, I think I'm good on what I'll do.

The stock 35mm fork tube length on my 85 Low Rider is 25.5in (courtesy of Motorcycle Metal website)

I'm going from a stock 19in wheel to a 16in touring wheel, so that will drop the front approx 1.5 in, if I'm figuring correctly

I should be able to use stock 49mm Dyna Low Rider tubes , 25.5in (again from MM website). If I want to drop the front another 1/2in I can cut the spacer accordingly, I was wanting to drop the front 2in.

I will be using Fat Bob 49mm Triple trees, they have a slight built in factory rake.

I will be checking into the cartridge type internals, I've already researched the single rate springs for my weight and Ricor Intimidators will be used if I go with the single rate spring.

I don't think you are.
IIRC both wheels should have about the same outer circumference once you put tires on them.

I could be wrong but I'd definitely find out for sure before you continue with your math.

Mar 24, 2019 | 09:50 AM

grbrown

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From: Bedford UK

texas is quite right, the difference in diameter is much closer, depending on the precise size of the front, which may be no more than around 1/2" larger in OD. Having messed with wheel sizes and suspension myself I recommend a dry build with entirely unmodified parts first, as that way you can measure what you actually have - not what you think you have! A little extra rake in the trees can make a significant difference in actual ride height at the front. By all means use the tyres you intend using, as they are fixed and final, so to speak.