1LikesNEW AGAMA A8 BUGGGY
08-01-2010, 10:09 AM
#811
Tech Master
If I remember correctly the OD buggy used 17mm shocks. Maybe you could try those bladders out Jaz.
08-01-2010, 03:50 PM
#813
The original Z01B had mid bore shocks. The Team edition added 17mm big bores. The SG and Team Option now use 1mm inserts to lower the volume to 16mm.
08-01-2010, 03:57 PM
#814
Tech Master
Like I said the OD used to use 17mm shocks.
08-01-2010, 08:52 PM
#817
08-02-2010, 08:19 AM
#818
Tech Master
Greg Degani does another thing, he cuts the bladder inner out and uses is as an o-ring to seal the cap. Then glues a piece of foam to the cap and bleades out all the air bubbles like on an old rc10 shock with no bladder. He said it was a night and day difference on his Zcar after that mod. When I put the losi foam thing (or any peice of foam) it made my Agama susp feel a lot better. Before I tried that I did try the Hyper 9 bladder but it was even worse then the stock bladders. If you want to try this mod, I would use the Hyper 9 bladders as the o-ring because they fit the cap snug, while the stock bladders fit in loose.
There is nothing wrong with the stock bladders or shocks, it is just that the bigger bore the shocks are and more oil capacity, the more noticeable the bladder problem will be. Also with 17mm bodies, they hold more oil. The more oil there is, the more outside temps will affect the fluid viscosity.
http://www.twf8.ws/php/tip/shock.html
SILICONE SHOCK OIL AND TEMPERATURE
Although everybody thinks silicone oil is not affected by temperature, we can wake you up out of that dream.
When the same test is done @ 10 or @ 30 degrees Celsius we get other values!
Test result from our laboratory provid us with the following fist rule:
Below some examples.
Silicone shock oil measured in Centistokes at various tempratures in Degrees Celsius (Rheometer)
Shock oil temperature Losi 40 Trinity 40 Associated 40
5 754 688 747
10 677 622 685
15 605 555 598
20 539 492 536
25 501 467 502
30 455 420 456
35 409 377 410
40 373 345 375
45 345 320 346
50 319 294 319
Because of this, when you race in the morning or at night or winter, you will need completely different weight oil then in the hot summer day. Again with 17mm shocks this change will be more noticeable then with 13mm or smaller shocks that have way less oil in them.
08-02-2010, 11:25 AM
#819
No real race updates this weekend. I just ran a club race at a new track in Indiana called Race World Hobbies. I did go back to the stock springs and the car had better pack compared to my old setup. I did qualify in the A this time but I used it to try some different plugs, clutches and played with the tune a little bit. Nothing too exciting this weekend.
How was yours?
How was yours?
08-02-2010, 11:57 AM
#820
I don't think this is accurate. In a properly bled shock with no air in the oil below the bladder, the only way the bladder can collapse is when the shock shaft displaces the oil during shock compression. For the bladder to collapse immediately upon impact, before the piston starts to move, the oil in the shock would have to expand to take up the extra volume created by the collapsed bladder. We all know oil cannot be compressed nor can it expand. In fact, it is this property of the oil itself which prevents the bladder from collapsing as you describe.
It is my understanding that the actual problem with the air bladder in shocks is that it leads to inconsistency through a race. As the air temperature in the bladder increases so does the air pressure. This causes the rebound of the shock, and thus the handling of the vehicle, to change through a race. Therefore, by venting the air bladder this variable is removed. The foam is then substituted in lieu of the pressurized air to provide a more consistent rebound force.
If I am missing something, please let me know.
Also, great information in the link provided! That explains a lot with regard what I've been noticing with the Losi oils. I've always thought, for instance, that 40wt Losi oil feels a lot more than twice the viscosity of 20wt. The link explains it quite nicely.
08-02-2010, 02:20 PM
#821
Tech Master
Easy test. Take a shock off your car and hold it in your hand with the shock end on a table. Then push down as hard and fast as you can. You will feel a slight/quick pop before the shaft starts to move up into the body through the oil. That is the bladder collapsing. Air is easy to compress, oil is not.
The bladder is a soft rubber and just air behind it. When you try to force a shock piston in through the oil quickly, it is easier for the rubber gasket (bladder) to move up into the open air space then it is to force silicone oil through the small holes in the piston. The larger/more dome shapped the bladder is the more you will feel it. With the Hyper 9 bladder, it has a large air pocket. The Losi and Agama bladder is more flat so you feel that air gap under compression less. With a pice of foam or o-ring behind the bladder, it helps keep the bladder from moving/collapsing as much so the piston can't move the oil up and therefore forces the oil through the piston holes instead.
That is just my experience from all the different shocks I have felt over the last 23 years I have raced. I may be 100% wrong but that is what I feel and why I think using foam behind bladders is a good thing. The hole drilled in the cap is just to release the air pressure so the bladder does not get deformed or sucked up into the cap and stay there imo.
No war and everyone has their own ideas/feeling.
The bladder is a soft rubber and just air behind it. When you try to force a shock piston in through the oil quickly, it is easier for the rubber gasket (bladder) to move up into the open air space then it is to force silicone oil through the small holes in the piston. The larger/more dome shapped the bladder is the more you will feel it. With the Hyper 9 bladder, it has a large air pocket. The Losi and Agama bladder is more flat so you feel that air gap under compression less. With a pice of foam or o-ring behind the bladder, it helps keep the bladder from moving/collapsing as much so the piston can't move the oil up and therefore forces the oil through the piston holes instead.
That is just my experience from all the different shocks I have felt over the last 23 years I have raced. I may be 100% wrong but that is what I feel and why I think using foam behind bladders is a good thing. The hole drilled in the cap is just to release the air pressure so the bladder does not get deformed or sucked up into the cap and stay there imo.
No war and everyone has their own ideas/feeling.
08-02-2010, 02:24 PM
#822
Tech Master
So basically the theory is by using no bladder or putting a firm object behind the bladder (O-ring or foam), it will keep your car from bottoming out when landing as much. Therefore you can use thinner oil for small ruts and bumps and still land big jumps smoothly.
I went down 2.5 wt on my shocks after putting the foam in the cap and have no more bottoming out issues.
I went down 2.5 wt on my shocks after putting the foam in the cap and have no more bottoming out issues.
08-02-2010, 03:27 PM
#823
If anyone bought a set of the engine mount stiffeners and doens't use them, or have an extra set... I need them. Please PM. I am paypal ready
08-02-2010, 11:08 PM
#824
For the bladder to collapse immediately upon impact, before the piston starts to move, the oil in the shock would have to expand to take up the extra volume created by the collapsed bladder. We all know oil cannot be compressed nor can it expand. In fact, it is this property of the oil itself which prevents the bladder from collapsing as you describe.
You will feel a slight/quick pop before the shaft starts to move up into the body through the oil. That is the bladder collapsing. Air is easy to compress, oil is not.
The bladder is a soft rubber and just air behind it. When you try to force a shock piston in through the oil quickly, it is easier for the rubber gasket (bladder) to move up into the open air space then it is to force silicone oil through the small holes in the piston.
The bladder is a soft rubber and just air behind it. When you try to force a shock piston in through the oil quickly, it is easier for the rubber gasket (bladder) to move up into the open air space then it is to force silicone oil through the small holes in the piston.
If your theory is correct, than if you force the piston up fast enough to compress the bladder before an equal volume of oil passes through the piston holes. The space below the piston would have to decrease or air would have to leak in from the bottom seals. One scenario is impossible and the other is not desirable.
Regardless of what is correct though, the bottom line is it's suppose to make your shocks more consistent.