Mountain Biking - XT M740 or XT M770

Here is the story...

I just bought a full suspension frame and I am currently missing the following to complete my build:

Crankset & BB (sorta)
Rear Dérailleur
Shifter Pods
Cassette

I currently have a hardtail and I am going to make it a single speed after my full suspension is build up. The hardtail currently has a set of complete XT 8spd system (M740). A friend mine suggested to buy complete new parts on my new full suspension instead of transferring my 8spd system over is it is old. I am considering if I should do that or just or buy new parts. He said I might run into problems later if I use the 8spd.

If new parts, I am going for complete 2008 Shimano XT M770 Series. It will cost $500 tax included for crankset, bottom bracket, rear dérailleur, cassette, and shifter pods.

Of course budget is an issue here. But $500 isn't too much and I am debating if I should go with new parts or use old parts. I also have an old RaceFace Turbine LP which I can put on my new bike. But my new XT purchase must be in bulk (including the crankset) at that price or is a no deal at all.

What do you guys think...all new or go with old parts?

Here is the story...

I just bought a full suspension frame and I am currently missing the following to complete my build:

Crankset & BB (sorta)
Rear Dérailleur
Shifter Pods
Cassette

I currently have a hardtail and I am going to make it a single speed after my full suspension is build up. The hardtail currently has a set of complete XT 8spd system (M740). A friend mine suggested to buy complete new parts on my new full suspension instead of transferring my 8spd system over is it is old. I am considering if I should do that or just or buy new parts. He said I might run into problems later if I use the 8spd.

If new parts, I am going for complete 2008 Shimano XT M770 Series. It will cost $500 tax included for crankset, bottom bracket, rear dérailleur, cassette, and shifter pods.

Of course budget is an issue here. But $500 isn't too much and I am debating if I should go with new parts or use old parts. I also have an old RaceFace Turbine LP which I can put on my new bike. But my new XT purchase must be in bulk (including the crankset) at that price or is a no deal at all.

What do you guys think...all new or go with old parts?

I built up a new suspension frame two years ago because I had been riding the same hardtail for so long. I went for all new 9 speed XT stuff for the FS build and have not regretted it. Kind of during the same time period I had been gathering up some new, some used 8 speed stuff to redo the hardtail (I love my steel Parkpre) because I had hung on to a 7 speed system for so long and THAT was ridiculous to keep replacing stuff. I had all 8 sp stuff except I had bought a new 9sp XT crank with which I was going to use a nine speed chain with the whole works. I just got to thinking about having to try to replace the 8 sp stuff in the future- and I just said screw it. Turned the HT into a nine speed and things are right with the world again.

Unless you just gotta have 8 speed, do what your friend said and build new 9 speed, I agree with him.
No issues, no unavailable parts, now you have new parts, now you have what most serious MTB people have.

I built up a new suspension frame two years ago because I had been riding the same hardtail for so long. I went for all new 9 speed XT stuff for the FS build and have not regretted it. Kind of during the same time period I had been gathering up some new, some used 8 speed stuff to redo the hardtail (I love my steel Parkpre) because I had hung on to a 7 speed system for so long and THAT was ridiculous to keep replacing stuff. I had all 8 sp stuff except I had bought a new 9sp XT crank with which I was going to use a nine speed chain with the whole works. I just got to thinking about having to try to replace the 8 sp stuff in the future- and I just said screw it. Turned the HT into a nine speed and things are right with the world again.

Unless you just gotta have 8 speed, do what your friend said and build new 9 speed, I agree with him.
No issues, no unavailable parts, now you have new parts, now you have what most serious MTB people have.

Thanks for the advice. Its not a must that I want 8 speed. I have no problem riding 9spd with that closer gear ratio. I am going to make my hardtail a single speed so I will have my 8 spd stuff left behind hanging on the wall. In that case, I am thinking if I should buy a new 9 spd on the FS and leave the usable 8 spd on the wall or just move that 8 spd over and don't bother changing until the 8spd falls apart (which should last quite a long time). My hardtail is going to be single speed as soon as I start changing things. There is no doubt about that.

I don't get where people is going with the 'hard to find replacement' for 8 speed system. What will you need to replace besides chain and cassette on a normal riding? Unless you crash and break your shifter pods, that is a different story. My 8 spd is XTR and that M900 has served me 4000 miles and still going strong. Current running 8 speed PC-89 chain. Those are the only two piece that can go wrong and I am sure the chain is the first one that will screw me over. You think I still have a chance finding another PC-89 around?

Thanks for the advice. Its not a must that I want 8 speed. I have no problem riding 9spd with that closer gear ratio. I am going to make my hardtail a single speed so I will have my 8 spd stuff left behind hanging on the wall. In that case, I am thinking if I should buy a new 9 spd on the FS and leave the usable 8 spd on the wall or just move that 8 spd over and don't bother changing until the 8spd falls apart (which should last quite a long time). My hardtail is going to be single speed as soon as I start changing things. There is no doubt about that.

I don't get where people is going with the 'hard to find replacement' for 8 speed system. What will you need to replace besides chain and cassette on a normal riding? Unless you crash and break your shifter pods, that is a different story. My 8 spd is XTR and that M900 has served me 4000 miles and still going strong. Current running 8 speed PC-89 chain. Those are the only two piece that can go wrong and I am sure the chain is the first one that will screw me over. You think I still have a chance finding another PC-89 around?

You really DO make an excellent point, though, it's not like 8 speed parts are totally unavailable. And yes, all it is is shifters, chain, and cassette in difference to 9 speed. Jeeze, ya know it's probably not that big of a deal, either way could work fine. Who can say that 8 speed is a mistake, just a little harder to replace.

EDIT: Also' really not a bad idea to 'use up' the 8 speed stuff. Use it till ya just can't do anything with it anymore.