Rear End Equaliser/Compensator Spring Assembly

I have just puchased myself a 69 Beetle as a basis for a beach buggy project and I have noticed that the equaliser spring assembly has been removed by one the previous owners. My understanding is that VW only installed it on a few type one models. My question is what exactly does the equaliser spring do and is it an essential peice of equipment that I need to think about reinstalling?

[ Edited on 12/5/2007 by sdat ]

I just bought one of these, but haven't installed it yet. I believe that it helps stop the swing arms from tucking in.

Is this what you mean?

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=150114931365

What do others think?
Cheers
Dave

[ Edited on 13-5-2007 by challenger ]

[ Edited on 13-5-2007 by challenger ]