Gas Assist Lift Cylinder

For those of you who have ever thought of using these and have researched it, the big question comes down to what pressures do I use? Since many parts houses will not take returns on these, it becomes very important. On my car, I just put two cylinders on the front and two on the rear. They are mounted within 8" of the pivot point. I found that two 20lb cylinders were perfect for the front clip. I can easily lift it with one finger and where ever I stop, it sit exactly there. On the rear, I started with two 35lb cylinders which were entirely too weak. I put two 60lb cylinders on it and it is much better. Not as well controlled as the front, but certainly acceptable as it will drop slowly over the last ten degrees before closing. 80lb cylinders might work, but I am going to stick with the 60lb assists for now. As to length, as long as you stay within the distance of the pivot I mentioned and keep the cylinders near vertical, you should be able to play with length and mouting points and stroke of the cylinders to get the range of motion you need.

Lynn,

Where did you purchase yours. Also do you have photos of front and back?

Thanks,

Having owned many Porsches with gas lifts front and back they do lose their power over time, and were not cheap to replace. I would think that Porsche would use good ones and they are actually needed to hold the two lids open. The GT40 does not have that requirement so IMHO stainless cables are preferable and also far more authentic. Regards

I thought of using gas struts, but was advised against it by a few guys who know about fibreglass - apparently, the continuous pressure of the strut (presumably in the closed position) can distort the clips unless they bear onto steel re-inforced sections.

My current thoughts are to make up simple solid struts (2 for front, 2 for rear) which latch onto mounting rings on the chassis in the "up" position, & hinge back to clip into retainers under each clip in the "down" position.

During the build process, I have had each clip restrained by a simple bit of rope in the "over-centre" position. Twice now, I have accidently bumped the front clip & had it go back over centre & crash down - partially responsible for my developing expertise in fibreglass repairs !!

I can see the same sort of risk with any type of cable/webbing restrainer, particularly with the car sitting on display with the clips open & being hit by a sudden gust of wind from the front or rear. Hence my rigid locking struts idea. Half inch Aly tube should do the job, but it is proving to be a challenge to find a suitable small latch clip for the end of these tubes (I had in mind, a small version of the fitting used on the ends of spinnaker poles on yachts, but all the ones I have seen so far are way too big). I'll keep thinking & looking.

Kind Regards,

Peter D. /ubbthreads/images/graemlins/cool.gif

Peter,

You might try a removeable ball and socket joint, maybe a throttle cable/carb connector,
on either end of a threaded tube. Small, simple to remove/store, and all that's permanently attached are the two little ball studs, one on the chassis, and one on the clip.
They should stand up to a fair amount of wind, if used in pairs.
For all of the leadfooting that I've done in my lifetime, I've never seen
one of these connectors fail!


Bill

I too looked at using struts - it seemed the way to go. But after the clips were installed and the SS cables were fit I must admit this is much better than the struts. The clips go to a point and from there on they just easily go to full open and stay there. The clips are easy - one person can lift with no problem. Critical issue is the connection points for the cabels.

Jay, I agree, I too wanted gas struts and then after I intalled the cable I never pursude the gas shocks. The simplicity of the cable is all I needed.

Hersh /ubbthreads/images/graemlins/smile.gif

Hersh. Way to go. As a commentator on the British Open Golf said "Be careful if you have an easy shot don't try a hard one". Regards

I had a 1968 Corvette that had a nice locking strut for keeping the hood locked in the open position. It might be of interest if you want to check it out.

Jim Seisser

Well all, I now have the rear clip working as I wanted it to work. The 35lb struts were to weak and once the clip got passed 45º it was pretty much in free fall. I tried 60lb struts and they made almost no difference, although they did make opening the rear clip much easier.

I ended up with two 120lb struts. These fully arrest the closure and there is now no danger of a gust of wind or some idiot pushing the rear clip closed and having it fall to the normal position. This is my biggest problem with using catch straps as most do: they offer no resistance or protection from and inadvertant closure. Now, applying this much pressure led to a new problem. I had a 11/32 ball on a bolt plate on the partition that forms the inner wheel well. When the rear clip was hanging on the struts and as one pushed the clip closed, these rather thin fiberglass partitions flexed a great deal as did the bolt plate. To correct this, I ran a piece of 2"X 1/8" flat bar from near the top of the partition, downwards to and butting up against the plate that is the pivot point (4" X 4" X 1/8" steel). I bolted this on using 4 pairs of 1/4" bolts and drilled 4 holes (spaced at 1" increments) to receive a 11/32" ball with a 5/16" stud. This did the trick! Now the rear clip is very easy to open and close and there is no danger of it accidently slamming shut.

(One should consider that the base of my struts are only located around 6" laterally from the pivot point. If you have more arm, you might be able to get by with 80lb or lesser struts- these were the next strength down from the 120s in the lengths I was looking at.)

Regards,
Lynn

Lynn,
Can you post a picture of your installation?

Chuck

Chuck,

You're from Sedona, AZ then? Lucky guy, I loved Sedona the one time I visited there. I'll never forget landing on top of the butte at the muni. airport! Take off was a breeze having 2k+ ft. as soon as you hit the end of the runway.

I am unbelievably busy right now, but I'll get some pics as soon as I am able.

Regards,
Lynn