Pikey

I lifted most of this from some posts I put on THS he had similar issues, he's 6'4" it's a long way down to the bar from that height...Most peoples dead lift is way in front of their Squat until they are a very experienced powerlifter.

A really common mistake is to drive from the legs first ending up with the bar just beneath the knees with legs more or less straight and then a huge amount of strain is thrown onto your lumbers to finish.If you are ending up with legs straight and back bent try concentrating on moving the weight off the floor driving from your hips, pushing them through as the bar moves up – this puts your back in the right movement.

Do you use a power belt mate? If not give it a go the extra support around the stomach takes some strain of your lumbers?

Ps for once I know what I'm on about I was a powerlifter for years and once went for a world record attempt on the deadlift. I've also completed a BAWLA coaching course although years ago. If you are struggling with it big time I could come across to the good side of the M1 and take a look at your form sometime. ;-)
To try and talk through how to do the lift correctly

First thing is grip if you are power lifting training you’ll want to grip with knuckles over bar in one hand and knuckles under in the other , this limits the bars tendency to roll out of your grip. If you aren’t bothered about competition feel free to use straps and go for knuckles over the bar. I prefer a width just over shoulder width for a start let your arms relax at your sides standing straight and whatever width they centre at use that (neutral width), as you get into it you can try differing grips till you find your preference.

The next thing and probably more important is foot wear, you want flat footwear, boots or not is your choice, many power lifter use ballet shoes, myself I never got on with them preferring the ankle support from a lifting boot, Otomix bodybuilding boots are fine but running shoes are terrible. The reason foot wear is important is you should centre the weight over the middle of the foot and drive through the middle of the foot. If the weight is predominantly through the balls of your feet the weight will drift out in front causing way too much strain on your lower back, if the weight is mainly through your heels the weight will drag up your shins causing friction and grazing - ouch!. So running shoes all being equal would raise the heels and put the weight forward of ideal throwing undue stress on the lower back. Proper alignment will let the bar stay close to the body and allow the hips to come into play as soon as the bar comes over the knees.

So grip the bar, bar over the middle of your feet, tuck your back in with hips behind the bar shoulders over and slightly forward of the bar. Tense your core muscles (abs and lumbar prior to pulling the bar) Drive smoothly and slowly through the middle of your feet and at the same time slightly reducing the angle between your shoulder and vertical. The pull should be smooth and steady never snatched at or jerky and never fast. This should stop you ending up with the bar at your knees legs more or less straight etc. When the bar reaches your knees you should start to drive your hips up and in which will result in you standing upright holding the bar. Don’t rotate the shoulders back this is asking for injury.