wraggy78

Hi guys I have a my99 type r and is crunching in 4th and sometimes in 5th.
I thought I had sorted it by changing oil but after a long time it has come back.
I am mechanically minded as im an engineer but not done any major work on a car.
Im tempted to have a go myself as I know the majority of the cost is labour.
Is this a job that could be done on the drive ? its not my everyday car so no rush to do it in a weekend.
Also if it is where can I find the synchro's and is there anything else that should be changed while I have it in bits???
I really need to get this done so if anyone has any information It would be greatly appreciated !
Thanks in advance