Monday, August 11, 2008

HOWTO: (not) install Warn FWHs

Sunday afternoon I had set aside some time to swap the new Warn FWHs onto the Pathfinder. I'd been speaking to some other pathfinder owners who had done the conversion, and the general consensus was that it's an easy job, no longer than an hour and a half. I'd called into SuperCheap earlier in the day and picked up a pair of circlip pliers, and was ready to go.



I figured I'd best do the job in the carport, so that if any difficulties arose, the car could just sit where it was until it could be fixed, without needing to worry about it being out on the street half-dismantled. And yes, we'd remembered to move the Impreza out of the carport first, so it didn't get trapped in front.



Step 1 - Remove the plastic hub cap from the wheel.



Step 2 - Remove the cap over the end of the axle, and carefully remove the circlip from the axle.



Step 3 - Remove the nuts that are holding the drive flange onto the axle. This is what connects the axle to the wheel hub. We'll be replacing this with the new Free-Wheeling-Hubs, so that we can disconnect the hub from the axle. At the moment, you can see how the drive flange is simply bolted to the hub, and attached to the axle via the splines.



Step 4 - Remove the drive flange itself. You may need to give it a tap with a hammer to loosen it away from the wheel hub.



Here's a close up of the axle with the drive flange removed. You can easily see the splines on the axle that mesh with the flange/hubs to drive the wheel. You can also see the indent that held the circlip towards the end of the axle.



Step 6 - Remove the studs. The FHWs came with replacement (longer) studs to attach the hubs to the wheel hub assembly. To do this, we first need to remove the existing studs. The trick to this is to screw two nuts onto the stud, and tighten them together (IE, screw the inside nut out, and the outside nut in). Once you've got enough tension on the nuts themselves, you can unscrew the inside nut, and it will rotate the entire stud, and remove it. Once the stud is out, you can get a pair of spanners onto the two nuts and screw them apart, then remove them both from the stud.



Removing the studs was a time consuming process, but not overly difficult. The studs themselves came out easily once you cracked the seal they had with the hub. As you can see, I was working with the wheel still on. It would have been a lot easier and quicker to remove the wheel. As it happened, I scratched a bit of paint off the alloys when the spanner scraped along the wheel whilst removing a stud.



With the studs all removed, the wheel hub was looking very bare! It's still nice and clean in there though, which is a good sign. The studs themselves were nice and clean, and there was no surface rust to speak of.



Step 7 - Install the replacement studs. The photo above shows the new replacement stud (bottom) against the original studs. You can see it's quite a bit longer. You install the studs in exactly the opposite way to removing the old ones - screw two nuts onto one end, tighten together, and then screw the stud into the wheel hub.

The instructions with the FWHs stated to install the studs, then the hubs, washers and bolts, and tighten to between 18-25 ft.lb. torque. I assumed that this was the torque setting for the nuts. I figured then that I would need to torque the studs in slightly more than that, otherwise when I was tightening the nuts I would end up turning the stud instead.

So, I set my trusty torque wrench to 30ft.lb., and started to screw the stud in. Everything was going well, but it was getting very tight, and still my torque wrench hadn't hit it's setting.

Then, this happened:





The stud sheared off between the two nuts. Too much torque on the nuts, and it was easier for the metal stud to tear itself in two rather than tighten into the wheel hub any further.

So this was a problem.

I couldn't get another nut onto the stud, since there wasn't enough exposed thread left. So I couldn't remove the wrecked stud from the hub. It was no good leaving it there though, since there wasn't enough thread for a nut to attach to once the hub was installed.

I didn't want to proceed, since I didn't understand what I had done wrong, and didn't want to wreck another stud doing the same thing.

So, I called Jess' dad, Trev, who spent many a year as a mechanic. Instead of spending the afternoon watching the olympic cycling events, he threw some tools in the ute and came up to have a look.

After um-ing and ah-ing for a little while, we set about the following course of action:

Jack up car, and remove the wheel. This is when we found that whichever idiot had put the wheels on last had used a rattle gun with the torque turned all the way up. Between the two of us we got the wheel off, but there was one particular nut that we didn't think we were going to be able to get off at all without power tools. After abusing it for 5 minutes solid though, it started to budge. I've now made a mental note to undo the back wheel nuts this week and re-tighten, since i'd rather be busting my spleen in my garage on a nice level floor, instead of in the rain on the side of some dirt track somewhere.

Once the wheel was off, we were able to grab the stud with a pair of vice grips, and slowly undo it that way. It really was in very tight, and we're lucky that this worked.

With the stud out, we were able to have a look at how bad it was. It was only really missing about 10mm of thread depth. Trev was of the opinion that if we could repair the damage that we caused with the vice grips, that we might be able to use it still. So I set about cleaning the thread up with a set of taps and dies, and generally trying to make it look like a stud again.

Trev battled on with the rest of the studs, and in no time he had the 6 new studs installed into the hub. He explained that the torque settings were only there to cover the manufacturer's liability - IE, if they didn't specify a set torque, then some doofus would put them on finger tight, and then sue when the wheel came apart. He simply nipped them up with the ratchet until they were "tight, but not too tight", and we were almost done.

The FWH came apart, and the main body mounted onto the new studs very easily, and meshed with the axle spline perfectly. The lock-nuts that came with the FHW's to suit the new studs were again tightened up "nice and tight, but not too much", and the circlip was reinstalled on the end of the axle shaft. The top of the FWH's could then be lined up and installed back onto the wheel hub, and everything bolted together and given one last nip-up.

With the car still on the jack, we were able to verify that the hubs had been installed correctly, and were working properly. In 4x4 mode you could turn the hub and watch the axle shaft spin. Unlock the hubs, and the axle would stay still whilst the wheel hub turned.

So we bolted the wheels back onto the hub, took the car down off the jack, and started on the opposite side. The only concern we had with the driver's side was (apart from removing the jolly wheel!!) was that we re-used the damaged stud from earlier. I was able to clean up the thread with the dies, so we tried installing it "backwards" compared to the first time - IE, we screwed the newly-short side into the wheel hub. It went in nicely, and nipped up tight against the hub. Trev was happy with the depth of thread that it had to work with, so we then installed the remainder of the studs, and bolted the FWH on as normal.

So, from near disaster to completely finished. All I needed was a bit of disrespect for the instructions, and a hefty dose of experience to tell me that, despite what you'd first think, the studs/nuts/etc don't really need to be on *that* tight, and that even with a damaged stud, there'll be no problems whatsoever to be expected.

Time will tell, I suppose, but since Trev has been doing this for many years now, I'm inclined to believe him!

As it was now well after dark, we didn't bother to cut the centre caps, and just left them off the wheels entirely. I've got to pick up a replacement lock nut this week, since one of them still has half the stud inside it. But other than those two small jobs, it's all done!



Whilst it was a very easy job once you knew what you were doing, it wasn't really something a complete novice could attempt, not without a bit of guidance from someone mechanically minded. Luckily I was able to call Trev out on a Sunday afternoon at such short notice - others may not be so lucky! If you're contemplating doing similar work, by all means have a go at doing it yourself, but it would be a good idea to have someone with you to guide and make suggestions about what you should and shouldn't be doing.

For now, the Pathfinder's not moved from the garage yet, but I intend to take it for a drive this afternoon after work, just to make sure that everything still works, and to double check the tightness on all the nuts. We're now looking forward to some improved fuel economy figures in the near future!!!


EDIT - 13/9/2008 - UPDATE!!!

I have finished off the cosmetic side of the FWH upgrade, by cutting out the holes for the FWH's from the wheel centre caps. I drilled a pilot hole large enough to fit a jigsaw blade in, and then used a wood blade in the jigsaw to slowly work around the inside of the dark grey "Nissan" centre circle. Ended up with these lovely decorations:



The cut itself was reasonably rough, and I tidied it up with some rough sandpaper. Even though it's still not perfect, you can hardly tell without squatting down to inspect. As Stevie would say - Good from Far, Far from Good. One thing that I think I will need to keep an eye on is making sure that the void behind the cover is washed out well after going away, since with the large hole it could collect some lovely wet mud and hold it right up against the hubs, bolts, and rest of the wheel. This would be even more of a concern for those with steel wheels.

How it turned out:









I reckon it looks pretty good! From 3 feet away you don't even notice them, which is a good thing in my book! As for the driving of the car - it's definitely made the steering a lot lighter. As for economy, it's still to early to tell. Out of the past 4 weeks since I first started this, I've been away for two of them, and too busy at work this last one to even think about anything else! So hopefully we'll be able to get away some time soon, and that will give me a chance to see what difference they've made. In the meantime, we've fitted the roofrack, so I'll be happy if the gains from the FWH's offset the losses from the rack, and we come out with roughly the same economy as before.

Now, for that snorkel, and the lift, and the tow bar, and the tyres, and the... :)

Thanks!
Matto :)