StumpHunters Cycling and MTB page

The I-drive system was introduced by GT in 1999 with much publicity and fan fare but in the initial year was a bit of a let down for GT. Initial bikes were tooted as being heavy and unreliable, those who bought them disagreed as the I-drive itself is really simple and easy to look after (if you need to) and the bikes in the first year were under specified for the price range that they where placed in ....... oh sorry this is supposed to be a article about working on I-drives :-)

This piece is optional but REMOVE the chain, it will make putting the thing back together far easier, just trust me on this one please.
The First thing that you have to do with the I-drive is remove the none drive side crank (check out the BB and Chainset article if you need help) but don't get to carried away and remove the drive side crank as you don't need to.
Doted around the I-drive unit on the side that you have just removed the crank from are three locking nuts, remove these
All the I-drive is really is a cylinder inside another cylinder with flanges on the end to hold it in place (and bearings to help it rotate and seals to keep the crap out) so in order to get the internal cylinder out you need to remove one of the flanges .... does this make sense. If you look at the I-drive on the side that you have removed the crank from, you will see lots of little holes, the idea is that you get a pin spanner and twist this end off, me I just insert a Allen key and shove :-).Just loosen this end as the I-drive cannot be removed yet, I'm just making thinks easier for later
Now you have to remove the rear shock, this is to give you enough clearance to remove the dogbone.
At each end of the Dog bone is an bolt remove these and the remove the dogbone.
Now it's time to remove the flange and boy will you be glad that you followed step 4.
The Drive side should now just simply pull out and you will have the internals of your I-drive bear to the world,take note of how it comes to pieces as you have to put it back together again, and you will either be going, 'god I wish I had done this earlier' or 'all this effort and it didn't need doing'

At this point you will have a the I-drive internals attached to the drive side crank and the, the main job now is the clean it right out, you will probably find that dead center of the I-drive casing (the bit on the bike) is full of crap (this is ok because if you look there is a hole that stuff supposed to fall through) was this out first as it will make cleaning easier.
Take the bearings out and clean them, making sure that you noted which round they come out of the I-drive. Make sure that the bearings have not rusted and that they are all there and that they rotate .... if they are damaged you will need to get new ones
make sure that all the rubber seals are clean and not damaged (there is one either side of each set of bearings)
Once you have it all clean it's time to put it all back together again

The I-drive is right in the thick if things, if you ride heavy muddy routes the I-drive is going to take a hammering, make sure that you use a good quality water resistant grease. The I-drive takes about the same amount of abuse as you wheel hubs so treat it as well (if you don't look after you hubs start).
Make sure that the inner seals are in place
Insert both bearing braces (make sure that they are the right way around and run freely) and grease apply a coat of grease into the cup of the bearing brace
Insert the Main body of the I drive make sure that you do not knock the inner seals and bearings out of place as you do so
Screw in the none drive side of the Idrive (The locking cap) until tight, at this point it is best to give the cap a couple of LIGHT knocks with a soft hammer in order to make sure that the grease is not stopping things bedding home correctly
Put the Dog bone back into place and locktight the bolts that hold the dogbone in place
Replace the shock
Line up the threaded holes in the I-drive (none drive side side) with the little inserts on the I-drive, if they do not line move the locking cap until they do
Locktight the locking nuts into place
Put he crank on and you should be all done, do for a little ride to make sure that everything is in place and running smoothly

Some of the things that can/do go wrong are that the shock is not in place correctly, to check that this I place my hand on the back wheel and lift the saddle (make sure your saddle is tight) if there is any play in the bushings you will feel it.
Another favorite is the bushings in the dog bone go, you can usually feel this one my holding the locking nuts in the rips of your fingers and try to move them, if they move you dog bone bushing have either gone or the nuts that hold it in place are not in place correctly (you should also be able to feel the dogbone move about if you hold it with the tips of your fingers)

GT's, I - Drive