# How to determine fork travel (Rock Shox Judy)



## bryanus (Jun 1, 2008)

I picked up a couple old Judys and was wondering how to determine the amount of travel they have.

One is a '95 XC, but with Hardbody carts and Judd springs and the other is a '95 or '96 FSX with Speed Springs (yellow).

To my surprise, the XC has a longer A-C than the FSX does, perhaps due to the internals, which is why I'm here trying to figure out how much travel each of these forks has.

Bonus questions:

1) How can I tell if my damper carts are working?
2) Are Speed Springs and Judd Springs the same thing? What weight limit is "yellow"? What weight limit is "silver" (Judd springs).
3) If my carts have circlips, does that mean they are rebuildable?

Thanks!


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## Fillet-brazed (Jan 13, 2004)

to check travel with them together/intact you can unthread the springs from the top cap and measure how far it compresses. If you have them apart you can measure the amount the cartridge rod extends below the stanchion. You can also use this method (unthreading the top caps) to check if your dampers are damping. There isn't a lot of compression damping, but the rebound damping is noticable on a working cartridge. If you check your damper while apart and with them still in the stanchions, thread a bolt into the bottom to pull it back out as the rebound damping will make it a bit hard to pull it out when it's pushed all the way in. Hope that made sense.

Speed springs and Judd springs are from two dif brands, but could very well be the same thing... Not sure what the colors mean.

I have some NOS cartridges if interested.


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## Restricted (Jun 11, 2011)

I have Judy SL's from 1996 I think they have the same travel as the xc 60mm. The DH had 80mm.

Wait found this, Rock Shox Museum

1995 sees the introduction of the Judy series of shocks. All Judy shocks feature larger 28mm uppers, biaxial wrap around brace and a new forged aluminum crown. All Judy shocks use an MCU spring with a hydraulic damping cartridge. The entry level Judy XC weighs 2.9 lb and gives 50mm of travel. The SL model uses some titanium hardware and aluminum steerer tube to drop the weight to 2.7 lb while increasing travel to 63mm. The DH model is aimed at the downhill market and can be configured for 63 or 75mm of travel while weighing in at 3.1 lb. (all weights are projected weights).


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## Fillet-brazed (Jan 13, 2004)

Restricted said:


> I have Judy SL's from 1996 I think they have the same travel as the xc 60mm. The DH had 80mm.
> 
> Wait found this, Rock Shox Museum
> 
> 1995 sees the introduction of the Judy .


I thought it was 1996, but maybe not... Maybe that ad was late 95.


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## mechagouki (Nov 30, 2007)

The most common travel lengths (63mm and 80mm) are pretty easy to distinguish visually without dissasembly, the 80mm (or long travel :lol: ) is a longish fork, longer even I think than a modern F80 or SID (not 100% on that). Of course most of the better JUDYs can be travel adjusted by switching in different rods and dampers.

The early plastic dampers cannot be serviced, and it's unlikely you'll see one in working condition unless it's NOS. the later leaky aluminum ones can be refilled but will just leak again (in my experience) If you are going to ride these forks I recommend a Risse GEM, you can still but them brand new, I have one in my '97 SL and I love the way the fork feels.

Buy GEM cartridge here


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## bryanus (Jun 1, 2008)

Thanks for the input, guys. I'll have to take the legs off to get an accurate travel measurement...

re: Risse gem carts...do you only need one, plus a dummy leg? Are they rebuildable if they start leaking?



mechagouki said:


> The most common travel lengths (63mm and 80mm) are pretty easy to distinguish visually without dissasembly, the 80mm (or long travel :lol: ) is a longish fork, longer even I think than a modern F80 or SID (not 100% on that). Of course most of the better JUDYs can be travel adjusted by switching in different rods and dampers.
> 
> The early plastic dampers cannot be serviced, and it's unlikely you'll see one in working condition unless it's NOS. the later leaky aluminum ones can be refilled but will just leak again (in my experience) If you are going to ride these forks I recommend a Risse GEM, you can still but them brand new, I have one in my '97 SL and I love the way the fork feels.
> 
> Buy GEM cartridge here


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## Fillet-brazed (Jan 13, 2004)

bryanus said:


> Thanks for the input, guys. I'll have to take the legs off to get an accurate travel measurement...


No you don't. Unthread the top caps. Measure fully extended, then compress completely and measure again. Subract measurement number two from measurement one and there's your travel.



bryanus said:


> re: Risse gem carts...do you only need one, plus a dummy leg? Are they rebuildable if they start leaking?


Just one. You'd only need a new dummy side if you increase the travel... if you keep the travel the same or decrease it, the one that's in there will work.

I think the Gem cartridges are rebuildable, but I've never had one.


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## bryanus (Jun 1, 2008)

Interesting...but currently both sides have a damper and a spring in them. So if I got a Risse on one side, I would leave the other side with the existing damper and spring? That seems weird to me and I don't know why...haha



Fillet-brazed said:


> Just one. You'd only need a new dummy side if you increase the travel... if you keep the travel the same or decrease it, the one that's in there will work.
> 
> I think the Gem cartridges are rebuildable, but I've never had one.


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## Fillet-brazed (Jan 13, 2004)

bryanus said:


> Interesting...but currently both sides have a damper and a spring in them. So if I got a Risse on one side, I would leave the other side with the existing damper and spring? That seems weird to me and I don't know why...haha


So that must be a Judy DH then or one that was modified. I would guess the Gem cartridge for a non-DH Judy was meant to be ran with only one cartridge, but you'd have to read their literature to confirm. Maybe they had an offering that worked for the DH that used two cartridges.

Are your cartridges not working?


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## bryanus (Jun 1, 2008)

Interesting [again]...I've had maybe 10 of these old used Judys/FSX'/SLs over my relatively short VRC collecting "career" and I've never seen one with only one side of internals. They all had dual dampers and either springs or Englund air carts in them.

I haven't figured out if my carts are shot or not yet. I'll have to try your check above to determine that.


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## Fillet-brazed (Jan 13, 2004)

bryanus said:


> Interesting [again]...I've had maybe 10 of these old used Judys/FSX'/SLs over my relatively short VRC collecting "career" and I've never seen one with only one side of internals. They all had dual dampers and either springs or Englund air carts in them.
> 
> I haven't figured out if my carts are shot or not yet. I'll have to try your check above to determine that.


The only Judy (and I'm talking about 95-98 models) that had dual dampers was the red DH model. The FSX version also only had one damper. Of course you could put two cartridges in if you wanted, and that would be a better option when running coil springs since the elastomers they came with did have some inherent damping qualities to them. By '98 I think they had the type II spring kit which was roughly half coil and half elastomer if I recall correctly.


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## mechagouki (Nov 30, 2007)

Yup, type 2 did away with the awful 'Jax' system and used a 2" coil spring and a single elastomer in each leg for a more progressive feel.

I was under the impression that only the DH models had twin dampers, a second damper might be good with all-coil springs, but would add further weight to an already weighty conversion, unless you can find those lovely titanium speed springs of course.


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## JJY (Jun 6, 2004)

*Judy SHaft Lengths*

Bry,
If you tear the forks down to clean & lube them here is the info from my "unofficial cheat sheet" for cartridge shaft length:

186 mm. = 50 mm.travel
200 mm. = 60 mm travel
223 mm. = 72 mm. travel
226 mm. = 80 mm. travel

I don't have the measurement for the 63 mm. cartridge length but you can make a rough guess from the above information. I know the early SID axle to crown is (434mm. for 63 mm.) of travel and (451 mm.for 80 mm.) of travel, you can use that to get a quick estimate too. I have N.O.S. seals and a few cartridges... PM me if you need anything or help... -John Y.


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## bryanus (Jun 1, 2008)

You guys were right. I only have one damper in each leg. I guess I hadn't ever really bothered to pull out what I thought were the dampers (didn't have the right tool to remove the cir clips before). Anyway, pulled them out tonight and the right legs were dummy legs! I also confirmed that one of my dampers seems to be working as there is a noticeable amount of resistance when trying to extend it back out. My other fork wasn't so lucky; it's totally loose.

Thing is, once they were back together, I couldn't feel any difference between the two forks as far as the damping was concerned.

I also measured the stanchions as well as the exposed pistons of the dampers. Of course I should have written this down, but off the top of my head, the shorter A-C FSX was about 50mm travel and the XC was about 60mm. I can't remember exactly what the pistons measured at, but it was a bit more than what I got from the stanchion measurement method.

Based on this, I think I can surmise that my FSX is a 50mm fork and the XC is a 63mm.


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