The accompanying PDF describes in detail with photos the approach that I successfully used to replace the gas springs in 4 Thule Hullavators (model 897xt).
I would be pleased to answer any relevant questions.
Donāt have one but good job you did on explaining
Well done! There are a number of examples of clever do-it-yourself thinking that went into that job. Best of all, you werenāt duped into thinking you needed to spend hundreds of dollars on āgenuine Thuleā replacement struts (I bet thereās nothing remotely āgenuineā about them anyway).
Oh, there are always more ways to skin a cat, and I just happened to remember that a few weeks ago I had to put a new wire-rope lifter on my garage door, and I used those aluminum sleeves for the first time. Not having any experience with how they worked (and obviously not wanting to buy a special tool), I just flattened them with a big hammer against an anvil, and then added some extra gripping insurance by hammering a flat-ended punch into a few locations along that line where you elected to indent the sleeve by pressing a nail against it. Hammering alone seemed to do the trick, though, with the sleeve being thoroughly molded to the wire rope after just a few whacks (using the āmediumā setting on my accurately calibrated hammer).
I simplified the procedure and replaced the original description with an updated description.
Excellent work, thank you. Iāve downloaded your PDF for future reference.
Nick
How can I get your pdf for hullavator piston replacement?
Tim
Hi Tim.
I posted a pdf complete with pictures along with my post of January 2018.
Please check with the site administrator as to its whereabouts and if it is no longer available Iāll try to find a copy and repost.
Let me know.
Canāt find pdf either.
Hello YakStan,
When I attempted to re-upload I received the following message: āSorry, the file you are trying to upload is not authorized (authorized extensions: jpg, jpeg, png, gif).ā
The PDF is about 1MB - can you send me an email address?
Hello again YakStan,
Try following the link below to another page (archived?) on the Paddling.com Forums site where I posted the details of gas spring replacement in JPG format - scroll down to April 2020.
Here is my story on refurbishing Hullavatorsā¦
Hullavator Summary
Drove for 3 hours to purchase two sets of Thule Hullavators for $300. Each set sells retail at $899 and the crossbars (included) sell for around $150 each including the foot mounts for a total value of around $1900.00. I knew there would be issues ahead of time as the current owner indicated they had belonged to a relative and sat unused for a couple of years. Additionally, the key to the locks was missing. I paid for Hullavators and brought them home.
Initial examination revealed the following:
1 Key for locks missing
2 End caps for crossbar feet missing
3 Crossbars were too short by 8 inches
4 Pivot hinge pins were missing
5 All four struts were completely worn out and needed to be replaced
The following actions were taken:
- Keys ordered and received ($28.00)
- End caps ordered and received ($60.00)
- Crossbars cut and extended ($150.00)
- Pivot hinge pins ordered and received ($68.00)
- Struts ordered, received and installed ($136.00)
Total expenditures: $442.00
Total investment: $742.00 (plus a few dollars for hose clamps, etc.)
By far, the most difficult part of the restoration was the removal and reinstallation of the struts. An online search revealed that Thule did not provide replacement struts, but required you to order the entire new arm assembly for $488 each (needed four). No way! This was the second time Thule provided less than adequate support for their products. I sent them an email a month ago asking if their crossbar āfootā assembly would fit a 2 inch round bar. It took them over two weeks to reply and they said it would not fit and I needed to buy an entire new crossbar support assembly. Upon receiving these crossbars, I discovered the 450 foot assembly clamped onto the 2 inch roll cage just fine!
The removal of the old struts (pressure fully discharged on all of them) was relatively easy. Unscrew the top piston rod (right had thread) with a pair of pliers, then unscrew the barrel end (also right hand thread) and remove. Note: If there is any pressure left in the piston or if you are not sure, drill a small hose in the barrel end to release any remaining pressure prior to removal
I contacted Gemini Manufacturing in Canada (they manufacture custom gas cylinders) and spoke with Henk, their Chief Engineer. They have manufactured struts for Hullavators in the past. I ordered four new struts for a total of $136 including shipping. They come with new threaded connectors at both ends. Just tell Henk you need gas cylinders for Hullavators and he will know exactly what you need. They were manufactured and shipping within two weeks.
Tools and materials required for strut replacement included:
10 SAE #6 stainless hose clamps
6 inches of 5/16 inch ID (inside diameter) fuel hose (lawn mower or small engine fuel hose)
Fine grit sand paper
One wire coat hanger (8 inches long with ends bent into a āVā) /___________
Two needle nose vice grips
Box cutter (for cutting fuel hose into 1 inch segments and splitting the entire length vertically)
Alcohol (or other cleaning solution) to clean the piston rod to obtain a better grip)
Once received, I utilized three SAE #6 stainless hose clamps, an 8 inch piece of wire coat hanger, 5/16 ID fuel hose (cut into 1 inch lengths) and some fine grit sandpaper to compress the cylinder and hold it in place while reinstalling. It was a fairly simple processā¦. - Remove the threaded connector from both ends of all struts and clean the pistons of all lubricant. (Note: re-lubricate after installation of new pistons). Put hose clamps around barrel and piston ā One hose clamp on the barrel end (with sandpaper used to grip the barrel). Bend each end of the 8 inch coat hanger into a āVā (to capture the hose clamp and prevent slipping when the cylinder is compressed and clamped). Insert one end of the coat hanger under the barrel clamp and tighten. Take a 1 inch piece of fuel hose and cut in open full length. Insert sandpaper into the hose with the sandy side used to grip the piston. Place on the piston at the barrel end. Place the two hose clamps over the fuel hose and end of the coat hanger and hand tighten both hose clamps.
- Compress piston into barrel to proper length (just short of reaching the upper piston connector when lower barrel is totally screwed in place ā about 6 Ā½ inches) and tighten hose clamps to hold. Others have used a floor jack and workbench to compress. I found that using the hitch on my boat trailer a convenient way to compress the gas cylinder. No protection was needed for the threads on either the barrel end or the piston end of the strut. Stand the piston upright under the boat trailer hitch and crank the hitch down until the strut is compressed to approximately 6 Ā½ inches from the barrel/piston connection to the threaded end of the piston. Tighten all hose clamps as tight as you can without stripping the hose clamp threads. Several tries were required to obtain the correct tightness. Crank the trailer hitch up and remove the strut. Monitor for a minute or two to insure it doesnāt slip open. I tried several times with a single hose clamp around the piston and could not get a good grip. Only when I went to the double hose clamp on the piston did it work.
- Turn the Hullavator assembly upside down and release the arm assembly. I rested the entire assembly on a wooden stool prior to clamping into the bench vice. Pull the arm assembly into a fully vertical position and clamp one side into a bench vice. This leaves the rest of the assembly resting on the stool and free to move up and down which will expand or retract the distance between the threaded connector and the threads on the piston. Screw lower barrel fully into connector at the release handle (right hand threads).
- Position piston threaded end at upper connector and screw Ā½ way in. Position the piston end of the strut near the threaded connector at the other end. By raising and lowering the main assembly, you can position the connector and piston properly. Screw the piston into the threaded connector about five turns (remember you are unscrewing the barrel end at the same time). Once both threaded ends are secure about half way in, release the bottom hose clamp on the piston (WHILE HOLDING THE MAIN ASSEMBLY FIRMLY IN PLACE ā YOU ARE RELEASING 120 POUNDS OF PISTON PRESSURE IN THIS STEP).
- While holding the lower assembly down (I sat on it), remove all hose clamps, fuel hose, sand paper and the coat hanger.
- Screw bottom barrel and top piston fully in place (simultaneously) using two needle nose vice grips. Clamp one vice grip onto the piston end near the threaded end of the piston. Using the other vice grip, screw the barrel end of the strut fully into the threaded connector. Then clamp the barrel end with the vice grip and screw the piston into its threaded connector at the other end with the other vice grip.
- Once this process is completed, slowly release the entire assembly and let it close upward toward the bench vice where the arm assembly is clamped. Release the vice and you are ready to install on the crossbar using the pivot pin!
Repeat the entire process three more times. (I had two sets of Hullavators)
Patience and determination are necessary ingredients in the process. It took me over a day to figure out the correct combination of sandpaper, fuel hose and clamping to secure the compressed piston. However, once that was figured out, all four gas struts were installed within two hours.
CAUTION: The most dangerous part of this entire process is the removal of the clamps, hose and coat hanger while holding down the entire assembly with your body weight. If either the piston or the barrel end somehow come loose from their threaded connectors, the piston will expand within the arm structure and you will have no way to compress it to remove it other than to drill a hole in the barrel and release the gas pressure which will, of course, destroy the strut and you will have to order a replacement. Additionally, your fingers are very much involved in this process. Be careful and be safe!
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Welcome, and thanks so much for posting your thorough and detailed instructions!
Are the gas struts you used provinding better lift capacity? My friend who si short and 69 years young is having issues lifting her 75 pound sea kayak and i was thinking i could replace the cas struts with stiffer ones.
Hi Sugata,
The replacement/new gas springs that I installed exert a force of 500 Newtons (112 pounds-force).
This strength was recommended by Henk at Gemini Manufacturing after he examined one of the used gas springs that I sent him. This strength nicely balance the weight of our 48lb (22kg) kayaks when lifting from the loading/down position.
I would suspect that a 75lb kayak would benefit from a stronger gas spring but I do not know what strength would be best. A stronger gas spring would also require the user to exert more force to cock (pull down) the empty Hullavator but this step uses ones body weight and so should be ok.
Be aware: to install a new gas spring it must be compressed to an appropriate length and (temporarily) held at that length for installation - there is considerable force involved and therefore the risk of personal injury. Always anticipate that the gas spring might unexpectedly de-compress (extend) before it is fixed in place so keep your hands out of the āline of fireā.
I understand that the original gas struts are only 40 pounds so 110 pounds would be a huge improvement.
I have owned two pairs of Hullavators that were used frequently and eventually had one of each pair fail - it happened in a short time period, I suspect that the gas simply starts leaking and is quickly gone.
Anyway, Henk of Gemini examined one of the springs that had not (yet) failed and reported that a replacement spring should have 112 pounds of force.
Donāt confuse this number with a lifting force of 112lbs.
I accepted Henkās assessment and replaced both the failed springs and their āmatesā with 112 pound gas springs. The result was Hullavators that lifted the same as when they were new.
So my experience is not consistent with the original gas springs exerting 40 pounds of force.
A thought occurred: your friend could buy a lighter kayak!
I strongly endorse the Delta line of kayaks - excellent construction and very good value. Our Delta 16ās are 16 feet long - surprise - and weigh 48 lbs.
Doesnāt the Thule limited lifetime warranty cover the gas springs for the original owner anymore?
Yes Thule will replace a Hullavator for the original owner if the gas spring fails.
Thule will not replace (just) the gas spring.
Now whoās going to discard an otherwise functional Hullavator without attempting a repair?
Not me!
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