Clunk clunk
For some time I had been fighting a really annoying problem that I just couldn’t seem to correct. It seems a lot of people on this platform have this same issue that goes misdiagnosed and they end up replacing parts like me trying to fix the problem. I have never really been the kind of person that just throws parts at a problem unless I’m pretty sure I have verified the issue. In this particular case it may have just been a combination of problems and this was the final fix to eliminate it. The issue I’m referring to is the dreaded clunking you get in the AWD models when taking off or slowing down. Basically when the drivetrain loads or unloads itself.
I originally thought the issue was coming from the rear of the car, So I dropped the rear diff and checked the backlash. I found no issues so I buttoned it all back up, threw in some shockproof heavy and continued to look. The next obvious step was the driveshaft. The carrier bearings are known to cause issues as the bearing itself is just floating on a rubber hollow donut that wears down and allows the shaft to bang around. I could feel some slop so I went and filled the hollow donuts with polyurethane which stiffened them right up. Still didn’t solve the problem. So let’s move on to the transfer case. Pulled it off and started looking it over and that’s where I noticed the problems.
I guess in my rush of building the car I never bothered to inspect the transmission or the transfer case like I should have as I would have noticed the issues right off the bat. The clunking I was feeling was being caused by the wear on the teeth of not only the transmission output shaft, but the transfer case spool was also shot.
The shaft and spool splines should be well defined cones so that when they are connected there is zero play between the shaft and the spool. In my case the splines were missing an edge completely on the cone, both the shaft and the spool. This allows the shaft and the spool movement which was causing the clunking as the splines were bouncing off of each other when the car was loading and unloading the drivetrain. So basically the spool in the transfer case and the output shaft both have to be replaced.
The output shaft is probably the bigger pain to get out but it can actually be done without pulling the entire transmission. Remove the end case from the trans which takes some prying since the input shaft is press fit into the end case bearing, but it will come off. I also found that the intermediate shaft end bearing was toast and fell apart the second I got the end case off. Not about to go into that pain in the ass of getting that replaced… With the end case off you need to knock in the steel pins of the center differential which is the far left shaft. It’s the round can looking thing with a bearing on the end. Once those pins are knocked in far enough the end cover comes off. The problem is the reverse gear is overlapping it enough that it won’t come off. You can stick a pry bar into the intermediate shaft and pry it up and out of the way far enough to get the end case off. From there just pull out the output shaft.
I decided to go with the output shaft and input spool kit offered by Ninja Performance. I have no need for the hardened 300m shaft as I was never shooting for a power goal where I would need it. So the OEM spec shaft and spool were fine. The tricky part is the input spool as the bearing and gear are pressed onto the spool which requires a 40+ ton press to do properly. I only have a 20 ton press so I sent the spool off to ninja Performance to have them do the pressing portion on their end and ship it all back to me ready to be dropped back in.
I got the spool and shaft back from them within about a week or so “This was all prior to his cancer diagnosis” and slapped everything back together, pretty much the reverse of how it came out. The input spool does need to be shimmed to ensure that the gears are mating properly. You can find all of that information in the manuals linked at the top of the page.
