Rock Shox Quadra rebuild CHEAP - done

[Indyjps]

I have a 94 trek 930 with rock shox quadra 10 forks, theyre dead so its been sitting for some time. My buddys teen son was looking for a trail rider to keep at their cabin. Guess what pops up, '94 trek 930. Exact match to my bike with a bit smaller frame. It was meant to be. The rock shox on the second bike have a little life but not much.

 

[Indyjps]

After watching videos on how to rebuild rock shox, the elastomers are what goes bad, other than corrosion and grit.

If youre not familiar, elastomers are 3/4" urethane bar stock. After pulling one out, Its a purple floppy solid rod 6" long. Thats for quadra rock shox, judy rock shox have stacks of shorter elastomers so you can tune the ride ( different design with tubular elastomers that slide over a rod and remove as a pack). Replacement elastomers are $55. WHOA.

I considered rigging some springs. But there no dampening, maybe a spring and rubber combo......

I started learning about PUR polyurethane specifications.

Found this handy little chart. Shore A spec (middle) is the one we'll look at. Shore A is the closest thing to durometer I can find for this material.

 

[Indyjps]

Found this on amazon. $11 for 48" of 3/4 diameter shipped to my door.

Amazon didnt know Shore A spec on the bar.
I looked up the manufacturer, small parts inc, and by checking their manufactuer number againt some Shote A data they had. The Shore A is in the manufacturer number.

 

[Indyjps]

Gonna rebuild one of the rock shox with Shore A 60, PUR polyurethane bar in place of the elastomers. From the chart above, 70 is car tire rubber, 40 is pencil eraser.
We'll see how it rides. If i dont like it I can move up or down durometer (shore A #) or cut the bar in half and go harder or softer to tune the suspension.

 

[RustyGold]

Definitely report back on this...I have a couple Girvin forks and Pro-flex frames that I was wanting to run elastomers on...but, I can always find something more interesting to spend $55 on than chunks of poly .

Jason

 

[HuffnPuff]

That's great. I rescued some Manitou 2 forks a while back and spend the $75Au to get new rubbers. If I had known this ....

 

[Indyjps]

Took some digging around to find the info....and its still untested. Rock Shox was not in the new plastic development world, had to be an off the shelf item.

 

[Indyjps]

Sorry about going absent. Bought a couple trucks at an asset auction, took a while to get them picked up.

Original elastomer is purple, New is yellow. New is a little larger diameter but fits in the tube and end caps fine. Seems to be the same durometer from finger nail test and finger bend test - not real scientific.
Original was 6 1/16, cut the new material to 6 1/4, just cause it seemed like a good idea.

I need to make a long 5mm hex extension before i can tear these down.
Interested to see if adding length and new elastomer makes these ride well, i can always cut a 6 1/2 or 6 3/4 piece. Have plenty of material.

I can practice on friends kids bike fork rebuild since hes about 130 lbs, see how stiff they are and adjust for my fork rebuild to carry more....um...mass.

 

[RustyGold]

 

[Indyjps]

Got a chance to finish this up today and ride.
New PUR rod at 6 1/4 feels great. Took that inch or so of deadness out of the top of travel that rock shox get.
Ill likely go 6 1/2 on mine for a little more stiffness.

The bike itself is great, looks like all original parts, everything cleaned up and tuned up well.
Its a bit small for me, but brought back some memories.

Need to pull my trek 930 off the shelf and go thru it. Shox are figured out, the rest is wear.

 

[George W]

How did you cut the PUR rods? I have a 95 930 SHX. Thanks.

 

[Grant]

Putting gummy bears instead of elastomers inside my Rock Shox.

 

[Indyjps]

How did you cut the PUR rods? I have a 95 930 SHX. Thanks.

Razor knife for drywall

 

[Indyjps]

Circling back here, got an IM asking questions.

After going thru this rebuild, I think many specs of the PUR rod could be used. I chose the spec that i thought would give the best results, based on info I could find for comparison. If that specific spec is not available, find the right diameter and give it a try. Its somewhat tubeable with length of the rod.
This is not a specialty material specific to rock shox or the bike world, these PUR bars are used all thru manufacturing industry in various diameters. Dont get gouged on price.