Performance Fork Rebuild
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From: poway
I assume this is a 17 FXDB. I've not set one up but if you are getting 2 inches more travel, I'd go with lighter springs. You may want to check on coil bind since the original forks are set up for only 4 inches of travel. IIRC the springs springs for the fatter tubes are shorter and have a long spacer.
As far as holes in the bottom of the tubes go. IIRC RT recommends 6 5/16 holes. If the holes are larger say 3/8 inch, the area would be close to the 6 5/16 holes. 0.382 would be exact..
With 2 inches more travel, you should be able to set the compression valve spring on the emulator lighter and possibly go to lighter oil for rebound.
As far as holes in the bottom of the tubes go. IIRC RT recommends 6 5/16 holes. If the holes are larger say 3/8 inch, the area would be close to the 6 5/16 holes. 0.382 would be exact..
With 2 inches more travel, you should be able to set the compression valve spring on the emulator lighter and possibly go to lighter oil for rebound.
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From: Unreconstructed
I assume this is a 17 FXDB. I've not set one up but if you are getting 2 inches more travel, I'd go with lighter springs. You may want to check on coil bind since the original forks are set up for only 4 inches of travel. IIRC the springs springs for the fatter tubes are shorter and have a long spacer.
As far as holes in the bottom of the tubes go. IIRC RT recommends 6 5/16 holes. If the holes are larger say 3/8 inch, the area would be close to the 6 5/16 holes. 0.382 would be exact..
With 2 inches more travel, you should be able to set the compression valve spring on the emulator lighter and possibly go to lighter oil for rebound.
As far as holes in the bottom of the tubes go. IIRC RT recommends 6 5/16 holes. If the holes are larger say 3/8 inch, the area would be close to the 6 5/16 holes. 0.382 would be exact..
With 2 inches more travel, you should be able to set the compression valve spring on the emulator lighter and possibly go to lighter oil for rebound.
Well, one question down. Just spoke directly to RaceTech (don't know why I didn't call before) and they confirmed 165mm of oil and 25mm preload. And your reasoning behind fewer holes makes sense to me but I'd really love someone who's installed them to chime in.
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From: Nor Cal
That "someone" would have to be someone installing Emulators AND the TrackerDie +2 dampers pre-drilled for Emulators ... Otherwise people would just drill whatever the instructions called for (whether it be on a stock damper or an aftermarket that isn't pre-drilled)
John CC and Max offered sound advice ... understand the Theory and it's easy to Calc ... "Trust the Science"
Max, It looks like those Springs have a "Min. Travel" (their Heading Name) of 170mm (6.693") and I'll also mention that most people using those +2 dampers are using them to raise the bike, Not for more travel ... although ramifications always have to be contended with
Think of Coil Bind as a Fork Tube Stop without any Hydraulic "Slow-down" (oil lock)
.
John CC and Max offered sound advice ... understand the Theory and it's easy to Calc ... "Trust the Science"
Max, It looks like those Springs have a "Min. Travel" (their Heading Name) of 170mm (6.693") and I'll also mention that most people using those +2 dampers are using them to raise the bike, Not for more travel ... although ramifications always have to be contended with
Think of Coil Bind as a Fork Tube Stop without any Hydraulic "Slow-down" (oil lock)
.
Last edited by multihdrdr; Mar 7, 2022 at 12:40 PM.
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From: Unreconstructed
That "someone" would have to be someone installing Emulators AND the TrackerDie +2 dampers pre-drilled for Emulators ... Otherwise people would just drill whatever the instructions called for (whether it be on a stock damper or an aftermarket that isn't pre-drilled)
John CC and Max offered sound advice ... understand the Theory and it's easy to Calc.
Max, It looks like those Springs have a "Min. Travel" (their Heading Name) of 170mm (6.693") and I'll also mention that most people using those +2 dampers are using them to raise the bike, Not for more travel ... although ramifications always have to be contended with
John CC and Max offered sound advice ... understand the Theory and it's easy to Calc.
Max, It looks like those Springs have a "Min. Travel" (their Heading Name) of 170mm (6.693") and I'll also mention that most people using those +2 dampers are using them to raise the bike, Not for more travel ... although ramifications always have to be contended with
For the record, I think @Max Headflow is right. Why would Cory over at TrackerDie sell these dampers as pre-drilled if they were wrong? The dampers I received match what's online so they're not defective either. The evidence points to the fact that they're right...I just want to do more than just due diligence.
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From: poway
Max, It looks like those Springs have a "Min. Travel" (their Heading Name) of 170mm (6.693") and I'll also mention that most people using those +2 dampers are using them to raise the bike, Not for more travel ... although ramifications always have to be contended with
Think of Coil Bind as a Fork Tube Stop without any Hydraulic "Slow-down" (oil lock)
Think of Coil Bind as a Fork Tube Stop without any Hydraulic "Slow-down" (oil lock)
I'm not sure where you got the full travel spec (RT?) but it sounds reasonable..
OK So with damper rods only, there will be 6 inches of travel and with 25mm of preload, that would be about, 7 inches of compression.. The bottoming cones will cut the full travel but I'd say there is a potential for coil bind. Springs don't like to be run there..
With 1.0 springs, the OP may not ever bottom the front forks unless he try's to jump 13 buses.
A 1.0kg/mm spring is roughly 56 lb / inch.
So with 1 inch preload (roughly 25mm), there is roughly 112 lbs force (2 springs). At full collapse 6 in there is roughly 784 lbs but only 560 if only 4 inches of travel is used. Maybe it would be better to use a lighter spring so that the compressed length is closer to 560 and use some more of that travel. Then you get back into increasing the coil bind issue.
I know tho,, Most just want to know what to set the suspension to and forget about the details.
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From: New Hampsha
If you're using racetech springs then I'd go with the racetech numbers. I may have misinterpreted something earlier. Are you using stanchion tubes that are 2" longer? If so, and if Racetech did not take that into consideration, then you should add 2" to your preload spacers and measure the oil level from the top of the longer tubes, but use their measurement. Not perfect, but probably as close as you're going to get.
If, on the other hand, the damper tubes themselves are 2" longer then they're going to raise the bottom of the spring 2" in which case you probably want to reduce the preload by the same 2". The problem then is that when the fork extends the additional 2" the spring may completely unload. You should probably confirm that when you fully extend the fork there's still some preload on the spring.
With the addition of the emulators, the 25mm spacer and the cap, you're probably right up against the 2" additional travel. but, then, you've moved the bottom of the spring up 2", so it all sort of cancels out and you should be good.
Max is correct, though; with the additional travel now you have to worry about coil bind on compression.
If, on the other hand, the damper tubes themselves are 2" longer then they're going to raise the bottom of the spring 2" in which case you probably want to reduce the preload by the same 2". The problem then is that when the fork extends the additional 2" the spring may completely unload. You should probably confirm that when you fully extend the fork there's still some preload on the spring.
With the addition of the emulators, the 25mm spacer and the cap, you're probably right up against the 2" additional travel. but, then, you've moved the bottom of the spring up 2", so it all sort of cancels out and you should be good.
Max is correct, though; with the additional travel now you have to worry about coil bind on compression.
Last edited by John CC; Mar 7, 2022 at 08:03 PM.
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From: Nor Cal
Btw, what are you including in your 4" travel measurement? ... "effective" travel? ... it's not total physical travel
.
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From: Unreconstructed
If you're using racetech springs then I'd go with the racetech numbers. I may have misinterpreted something earlier. Are you using stanchion tubes that are 2" longer? If so, and if Racetech did not take that into consideration, then you should add 2" to your preload spacers and measure the oil level from the top of the longer tubes, but use their measurement. Not perfect, but probably as close as you're going to get.
If, on the other hand, the damper tubes themselves are 2" longer then they're going to raise the bottom of the spring 2" in which case you probably want to reduce the preload by the same 2". The problem then is that when the fork extends the additional 2" the spring may completely unload. You should probably confirm that when you fully extend the fork there's still some preload on the spring.
With the addition of the emulators, the 25mm spacer and the cap, you're probably right up against the 2" additional travel. but, then, you've moved the bottom of the spring up 2", so it all sort of cancels out and you should be good.
Max is correct, though; with the additional travel now you have to worry about coil bind on compression.
If, on the other hand, the damper tubes themselves are 2" longer then they're going to raise the bottom of the spring 2" in which case you probably want to reduce the preload by the same 2". The problem then is that when the fork extends the additional 2" the spring may completely unload. You should probably confirm that when you fully extend the fork there's still some preload on the spring.
With the addition of the emulators, the 25mm spacer and the cap, you're probably right up against the 2" additional travel. but, then, you've moved the bottom of the spring up 2", so it all sort of cancels out and you should be good.
Max is correct, though; with the additional travel now you have to worry about coil bind on compression.
Now, if I can just get another opinion on the damper holes.@Max Headflow suggestion about hole sizes being equal makes sense, however, does placement matter also? The RT specification for hole size AND placement are pretty specific.
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From: New Hampsha
What is the diameter and number they recommend, and what is the diameter and number you have? I don't think placement is important from a functional standpoint. Maybe structural or just aesthetics. The point is just to make sure they are not limiting the flow when the emulators are calling for more.
Last edited by John CC; Mar 8, 2022 at 12:29 PM.
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From: Unreconstructed
What is the diameter and number they recommend, and what is the diameter and number you have? I don't think placement is important from a functional standpoint. Maybe structural or just aesthetics. The point is just to make sure they are not limiting the flow when the emulators are calling for more.
The TrackerDie tube has 4, 1/4" holes, 2nd image below.
