Weight distribution

The vehicle I'm building is looking quite nose heavy (i.e. the front springs are a couple of inches more compressed than the rears at the moment; I've still got about 250kg to add to the rear but there's more stuff to go on the front too).

Anyone got experience of how weight distribution affects off-road ability? I'm really worried that it's just going to dig in at the front the first time it sees mud.

what are you building

+1 what are you building.

You might need to get the axle weights weighed and alter the front rear spring rates.

But yes weight distribution will have an impact on an off road. Some pros and cons.

I'm building a cab-forward bobtail - build thread here: https://www.landyzone.co.uk/land-rover/frankentruck-lives.324682/
The front springs are softer than the rear (110) springs but not by a great deal. With hindsight, I should have located the spare wheel mounts just forward of the rear wheels rather than just aft of the front ones. Hindsight is a wonderful thing. The fuel tank is hugely robust and carries 100l of fuel, and will live behind the rear axle, but there aren't many other heavy things for the back end. At the moment I'm minded to accept it, for want of other options, raise the front with stiffer springs / spacers, and go to flotation tyres if it proves prone to sinking in.

A tip from a Jag suspension designer that I know is to talk to either John Eales http://jemotorworks.co.uk/, or Bowler http://www.bowlermotorsport.com/ as the two best at the game, who I'm sure would be happy to help - given the charitable nature of the project.

Bowler are a good shout - at least one of their team follows the project on Facebook.

Is there any difference between front and rear springs on a Discovery or 90, other than the rate? Fitting some of these uprated Disco rear springs:
http://www.paddockspares.com/da4204-britpart-hd-yellow-coil-springs-pair-rear-300-340lbs-inch.html
would raise the spring rate from 230lb/in to 300lb/in which might be more appropriate given the higher load.

I'm not a 90 or Disco expert, but on 110s the free lengths and diameters are different. I've spoken to a few spring manufacturers and not been too depressed by their small order pricing, and again, you might find them amenable to charity/pr.