EB4 S2 Pro RTR shock rebound setup possible ?

[Dandare]

These are the shocks:

http://img.photobucket.com/albums/v515/DanAli/DSCN0761.jpg

I know how to set up the rebound but i just can't seem to set it at all with these kit shocks, eg if i set for 3/4 rebound & close them up i'll get 1/4 rebound only. If i put any more oil in the shaft won't compress fully. If i do seem to manage to get 1 or more set then after one day's racing if i re-check them all the rebound has gone & they'll be none though if i strip them they're still full of oil. These shocks don't have a bleed screw, foam compensator etc etc, just cheapo basic shocks, lol.

Is it simply because these are cheap rtr shocks or could i still be doing something wrong ?

Thanks.

[Dandare]

UPDATE:

Further experimenting shows the only way in which i can attain a degree of measured 'rebound' is to start by having them filled about 1/8" from the top with oil, resulting in zero rebound, then removing the cap time & time again, adding oil almost drop by drop & refittng the cap each time until i get approx 1/4 to 1/2 rebound. I do feel, however that this isn't true rebound but filling the shock a fraction short of too much oil meaning i get a small amount of 'bounce' due to the slight excess of oil rather than proper rebound.

weird !