Rebuild Curnutt Gas Shocks

Has anyone got the info for rebuilding the later Curnutt Gas shocks? I have copies of the early rebuild info, but not for the later gas charged units.



What do you need to know?

Well, I followed the links to Oregon Trail's web page where he has some nice vintage Hondas and the 2 pages on how to rebuild your vintage Curnutt shocks. Problem is that this is the same information that I have from the early years. I have copies of Charlie's rebuild sheets for the early non-gas shocks, but I never got any copies of the info for the later inverted gas-shocks. both of my pairs of Curnutts are the later style. I need to know what kind of pressure he ran and what fluid level. I can probably design a pressurized chamber to close them up inside of but it would be nice to have some information on pressure etc.. Heck, a picture of what someone else built for rebuilds would even help, but lacking one I can design and assemble one.

I have had Curnutts on my twinshock vintage bikes for about 34 years now. I do know that one or more of them is ready for new seals and repressure/rebuild.



Back in the day, they mixed ATF and diesel fuel (for real). I would use Mobil One ATF. The fill procedure is as follows:

• Fill and bleed the dampers.

• Screw down the seal head until seated, then back off one half of a turn.

• With the damper shafts facing upward, push the rods until bottomed (the oil should come out of the threads.

• Seat the seal heads.

• Place the dampers in boiling water; the shaft should raise about 2 inches.

• Loosen the seal heads and push the shafts down again.

• Charge with 100 PSI nitrogen. The charge tool has an oring on the seal head and one on the body. Loosen the seal head and let the pressure equalize, then tighten.

Thanks, I will build up a charge tool. The Mobile 1 sounds like a good modern upgrade. I guess that inserting the body in the boiling water expands the fluid to the same kind of level that it will see during operation.


That's right. On the standard shocks, the bleed was refered to a 3/4' bleed. That ment that you pushed the shafts down to 3/4" from bottomed after the hot water treatment, then tightened the seal head. When they cooled, they have pressure in them. It feels like 15 or 20 PSI. I built a set form my son's PW 50 about ten years ago, they still have pressure. Still going strong after 5 kids had out grown the bike. Properly tuned, they work as well as anything modern.

Charlie developed some mountain bike shocks that are on Foes and some other high end MBs that are pretty trick.

Take Care

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