On my channelled roadster I am running SoCal rear shocks. When the car sits it is 330mm (13.2 inches) eye to eye. With the shock out of the car at full extension it is 360mm(14.4in) So in my mind this shock has only 30mm or 1.2 inches of upward travel. Fully compressed the eye to eye is 240mm or 9.6 inches. With the shock I took off, the bolt that goes through the bottom is very tight on the bushing and I would think that if that is binding the shock is not getting any movement in the arc of travel.The rubber bushing has also split, at least on the outside and I can't get the bolt out yet to look at the rubber inside the lower mount. I think these shocks are a generic design for standard hot rods and because we are sitting so low maybe my upper mount should have been set higher to give more extension. I am running a SoCal transverse leaf in the rear. The rear is quite stiff and I think the ride could be improved with better shock ratings. I will be getting them both tested tomorrow as I wouldn't be surprised if they are damaged because of this setup. Any experts there that can give me some advice.
If your ride is "quite stiff" then a shock absorber will have a tough time doing much. It needs to be soft enough to travel more than 1"-1.5" to allow the shock to do it's thing. Sounds to me like you need to remove some leafs to make it softer, and go to a shorter shock OAL to allow the shock to have more travel. Binding on the bolt may create a problem, but hard to say without knowing the angle the shocks are mounted. The greater the angle, the more binding affects the shock. The more straight up the shock is, the less it matters.
Does the car settle when you get in?? Can you move the suspension by leaning on the car?? If not, you have way too much spring in the rear. This is VERY common on rods. The general rule that I use is 1/3 - 2/3; that is, 2/3 of shock travel in compression, 1/3 travel in rebound, at rest ready to run with driver and full load of fuel on board. Cosmo
A shock slightly out of alignment will eventually split the bushing as well as a shop that sees lots of dirt road. Something else that most people don't realize is that anything that is bushed should be lubed, a shock bushing without a sleeve needs it even more then a shock with a sleeved bushing.
Yes I think it may be too stiff. If I lean on the car it will not move at all and requires some effort pushing down to get any movement. On other advice I actually added a leaf recently thinking that it would cure the bottoming out occasionally. Now I think I will take out 2 leaves and put a spacer in to compensate because it will sit lower.Then look at shocks and maybe change them
I had the same problem with my delivery and I corrected it by going to a higher upper mount which gives the shock more travel.
Well I checked and I have 8 leaves in the rear spring. Took the shocks to an expert today and he said remove a couple of leaves at least. I can't really put a higher mount on the shock. If removing the spring leaves drops the car say 20mm that will then give me a softer ride and the shock won't be as far elongated (now it has only 30mm of upward travel) and give me a more balanced travel up and down. I have 2 higher holes in the diff bracket and I am using the lowest one at the moment. So how many leaves do I take out??? I will try for 2 and I guess it is trial and error. Which ones should come out first to give the softer ride? If taking a few leaves out lowers the car I can compensate with a taller block between the spring and cross member to lift it without affecting spring rate and then maybe use the higher bracket(20mm) to give the shock more travel. I also noted that there was no sleeve in the bottom rubbers and this had wrecked the rubbers. New rubbers with steel sleeves going in now.
The saga continues. Turns out that one shock was stuffed and not returning from compression stroke. I have 2 replacements and I am going to replace the bottom rubbers with the heavier duty plastic compound ones. After checking the spring I have at least 9 leaves maybe 10 including the shortest one at the top. The car is a light channelled glass body and carries about 65 litres of fuel plus me and maybe one other passenger.I can pull down on the rear cross member at the end of the rails and get a little suspension movement with the shocks off. Maybe 9/10 leaves is way too many for a light car. Any suggestions?
Stock Model A roadsters, as an example, had seven leaves in the rear. Try taking out two toward the middle.
It is a trial and error deal. Keep the main leaf and pull the next one. Then keep the next one in line and pull the one after that. Make sure you bevel the ends so the don't dig into each other. See how it ride after you do that. My roadster has, in the rear, the main leaf - the next leaf gone - the next leaf - the next one gone and a bunch of small leafs to make up the pack so it will tighten down with the bolts. I had the main leaf shortened twice because it would settle after a bit of time and extend the shackles out to far. Mine holds 20 gallons of fuel and weights a total of 2300 lbs. Good Luck
Pics of your shocks mounted would help greatly. On the travel length, there's probably a couple hundred different shock extenders available. A crafty fellow could make his own and correct any misalignment issues with one.
Generally, without shocks, you should be able to push it down fairly easily, get a gentle bounce, but not so much it bottoms out.
Ok looks like we have found the bugs. The bolts through the spring eyes were too tight and not letting the spring flex when we pulled down on the rear cross member. Now we have good bounce on the suspension without the shocks fitted.New shocks and I will be positioning them further up the lower bracket(maybe middle hole or even the top one).This will give me more upward travel on the shock and still retain plenty of downward for compression. Going to follow the advice from Cosmo in post 4 of one third up /two thirds down of shock travel. Will update after we go for a test drive late Monday.
I think Como's post was 2/3 in compression (wheels going up) and 1/3 in rebound (wheels going down). Of course I could be wrong, it's happened before...
Yes that is what I will be doing. I only had about 20mm of wheels going down(rebound?) as said above and plenty of compression(wheels up). So I can easily accommodate more rebound travel and not sacrifice compression travel.
....The bolts through the spring eyes were too tight and not letting the spring flex.... With a proper shackle this is impossible. However I have found some shackles that were wrong and your described condition occurred. The tech departments dangerous answer was to loosen up the nuts. The shackle's shoulder should be a touch longer than the bushing. The nuts can be tightened and the bushings perform as designed. but If the shoulder on the shackle is shorter, then tightening the nuts acts as a friction brake against the bushings shoulders and the shackles side plates.
Nothing wrong with slightly loosening the nuts IF the nuts are either castle nuts with cotter pin, or nylock nuts.
I bought a set of those shocks when I was down at the LA Roadster Show and installed them when I got home. The rubber bushings were very soft and a couple of them were not properly pressed far enough into the shock eye, compared to the Pete & Jake shocks I removed. I installed them, drove the car and ended up with a bushing split similar to yours. I have since installed larger washers on both sided of the rubber bushings, which seems to capture the bulge on the bushings better.
Have a look here - especially post 88 that explains the shackle shoulder issues. http://www.jalopyjournal.com/forum/threads/rant-save-your-money.863086/ This picture is SO VERY wrong on a few different levels. Don't build your car like this! The "if" part of your statement needs many caveats added to be correct. Letting suspension fasteners ride loose is not good design or advice and it is far far far from necessary.
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