P500 Failed pinion joint replacement

[GreatNorth]

Our P520 has had a disconcerting rattle/clunking sounds at certain speeds coming from the rear final drive area since new. We never could find anything wrong looking/feeling/listening, but did not take anything apart. My kids walked home yesterday, and we definitely have a failed pinion joint. Drive shaft runs right up to the hub rear brake is mounted on, but that hub and brake disc don't move at all. In 2 wheel drive, there's no effort to move, and in 4x4 we get a 1 wheel spin up front (both until one slips). One wheel drive doesn't get far in winter!

Here shop manual shows what it'll look like with boot off (if nothing were mashed):

I found a couple threads where others had this failure:

• Rear Propeller Shaft and Pinion Joint Connection GONE BAD
• Rear Final Gear box internal clunking noise. - This one really resonates with our experience of hearing noise coming from the back, followed (a couple years later in our case, though noise got much more noticeable very recently) with pinion joint failure.

Looking at shop manual, it looks like this part is what we need to get to and replace. Anything else we should order to go with it?

It looks like it may be possible to remove rear final drive mounting bolts and shift things enough to remove u-joint from transmission output connection and then pull it out of pinion joint.

I'm not sure if we can do this in place, or if we'll have to remove the rear drive shafts from final drive and take it right out.

My shop is the great outdoors which is cold & snowy at this time of year in the north (similar latitude as Wrangle, AK, but further inland where it tends to be chillier). Dealers are 10 h drive away (in either direction). Any tips from anyone who's replaced one of these?

 

[Admin]

 

[Buggyman]

Our P520 has had a disconcerting rattle/clunking sounds at certain speeds coming from the rear final drive area since new. We never could find anything wrong looking/feeling/listening, but did not take anything apart. My kids walked home yesterday, and we definitely have a failed pinion joint. Drive shaft runs right up to the hub rear brake is mounted on, but that hub and brake disc don't move at all. In 2 wheel drive, there's no effort to move, and in 4x4 we get a 1 wheel spin up front (both until one slips). One wheel drive doesn't get far in winter!
View attachment 415777

Here shop manual shows what it'll look like with boot off (if nothing were mashed):
View attachment 415778

I found a couple threads where others had this failure:

• Rear Propeller Shaft and Pinion Joint Connection GONE BAD
• Rear Final Gear box internal clunking noise. - This one really resonates with our experience of hearing noise coming from the back, followed (a couple years later in our case, though noise got much more noticeable very recently) with pinion joint failure.

Looking at shop manual, it looks like this part is what we need to get to and replace. Anything else we should order to go with it?
View attachment 415776

It looks like it may be possible to remove rear final drive mounting bolts and shift things enough to remove u-joint from transmission output connection and then pull it out of pinion joint.
View attachment 415779
View attachment 415780
I'm not sure if we can do this in place, or if we'll have to remove the rear drive shafts from final drive and take it right out.
View attachment 415781
My shop is the great outdoors which is cold & snowy at this time of year in the north (similar latitude as Wrangle, AK, but further inland where it tends to be chillier). Dealers are 10 h drive away (in either direction). Any tips from anyone who's replaced one of these?

Sorry to hear about the break down. hopefully one of the wizards will be able to answer your ?

 

[NTCPrezJB]

Our P520 has had a disconcerting rattle/clunking sounds at certain speeds coming from the rear final drive area since new. We never could find anything wrong looking/feeling/listening, but did not take anything apart. My kids walked home yesterday, and we definitely have a failed pinion joint. Drive shaft runs right up to the hub rear brake is mounted on, but that hub and brake disc don't move at all. In 2 wheel drive, there's no effort to move, and in 4x4 we get a 1 wheel spin up front (both until one slips). One wheel drive doesn't get far in winter!
View attachment 415777

Here shop manual shows what it'll look like with boot off (if nothing were mashed):
View attachment 415778

I found a couple threads where others had this failure:

• Rear Propeller Shaft and Pinion Joint Connection GONE BAD
• Rear Final Gear box internal clunking noise. - This one really resonates with our experience of hearing noise coming from the back, followed (a couple years later in our case, though noise got much more noticeable very recently) with pinion joint failure.

Looking at shop manual, it looks like this part is what we need to get to and replace. Anything else we should order to go with it?
View attachment 415776

It looks like it may be possible to remove rear final drive mounting bolts and shift things enough to remove u-joint from transmission output connection and then pull it out of pinion joint.
View attachment 415779
View attachment 415780
I'm not sure if we can do this in place, or if we'll have to remove the rear drive shafts from final drive and take it right out.
View attachment 415781
My shop is the great outdoors which is cold & snowy at this time of year in the north (similar latitude as Wrangle, AK, but further inland where it tends to be chillier). Dealers are 10 h drive away (in either direction). Any tips from anyone who's replaced one of these?

First one I’ve heard for that particular failure on here. Sounds like it will be a bit of a project. Hopefully you don’t have any trouble getting the parts for the repair.

 

[906UP]

You're on the right track on how to remove the rear drive shaft. I would recommend pulling the bolts on the front diff as well and sliding it forward about an inch before your start on the rear. If you don't the main output shaft in the engine will get pushed back from the spring pressure of the front driveshaft and roll the seal on the front cover of the engine......ask me how I know

 

[GreatNorth]

You're on the right track on how to remove the rear drive shaft. I would recommend pulling the bolts on the front diff as well and sliding it forward about an inch before your start on the rear. If you don't the main output shaft in the engine will get pushed back from the spring pressure of the front driveshaft and roll the seal on the front cover of the engine......ask me how I know

Thanks for the tip @906UP! This is the kind of on-the-job learning I'm happy to avoid in our luxurious outdoor "shop" and 1-2 week wait for parts shipping.

 

[GreatNorth]

We had a warm (just over freezing) day and it's all apart. Definitely needs a new pinion joint and prop shaft. I didn't end up loosening the front final drive, but was also careful not to add force pulling rear drive shaft away from engine (clamped vice-grips to shaft, then pried against vice-grips to get u-joint off). If I were doing this again, I'd do it in this order:

1. Remove any aftermarket receiver from back for easier access (likely necessary for future steps anyway).
2. Block up rear end. Could drain rear final drive oil, but can also do after removal like I did (doesn't leak out axle holes unless you really tip it).
3. Remove both back tires.
4. Remove rear knuckles and rear axles (stopper rings should be replaced). Pry on 2 sides between axles and final drive to easily pop axles out, support and keep axles straight while removing from final drive to avoid damaging oil seals.
5. Remove 2 rear brake caliper mounting bolts (these should be replaced). There's a hose that looks like it's in the way of upper one, but deep socket slipped onto bolt past hose alright.
6. Pull large & small o-rings securing dust boot between prop shaft and final drive off boot and pull boot back onto shaft.
7. Remove rear brake disc (5 hex bolts should be replaced). It's now possible to wiggle disk and caliper around enough to free caliper from disc and set it on frame toward passenger side. No need to disconnect brake line or parking brake cable.
8. Disconnect breather tube from final drive.
9. Remove 3 final drive mounting bolts (lock nuts should be replaced).
10. Pull final drive & pinion joint off prop shaft (should be really easy).
11. Clamp vice-grips onto prop shaft on rearward side of u-joint (big boot on shaft), and then pry prop shaft out of u-joint. I found a large pliers wrench adjusted to size so it wouldn't slip over u-joint shoulder was the perfect size to pop this off easily--pried on both sides at once with the 2 sides of jaw, and jaw thickness was right to fit between u-joint shoulder and vice-grips that where placed back a bit due to prop shaft sloping down to smaller size from u-joint.
12. Remove pinion joint from final drive, using pipe wrench to hold largest diameter of pinion joint and impact with 22 mm socket to remove pinion lock nut. Pull out carefully to avoid damaging dual oil seals (though Honda tech suggested replacing both after removing pinion joint).

 

[GreatNorth]

Is the pinion joint supposed to be packed with a moly grease (say 3-5% moly) or moly paste (~60%)? The failed one doesn't seem to have anything greasy--just powder. I'd guess there was some moly in the ground up metal, but no sign of grease.

Here you can see the greasy end of propeller shaft pulled out of u-joint vs. powdery end that was in pinion joint.

There was grease in the dust boot, between it and outside of pinion joint as well as between it and the dust seal that goes in groove in shaft at left side of dust seal in picture above. Dust seal is in installed position in picture above.

A closer look at worn propeller shaft end:

The shape of these teeth explains why the kids had better luck backing up than going forwards when it suddenly quit going:

Hard to get good pictures inside pinion joint--a bunch of this metal powder fell out when I took out the luck nut with impact.

The teeth in pinion joint were still full height at both ends, but chewed way down where they meshed with the splines on propeller shaft.

This doesn't seem like something that should fail at 3700 km / 450 h. The dust boot is original, was in place, was never touched before, and nothing looks dirty inside-aside from metal shavings. Could this have been assembled dry? Or did the grease just disappear in the metal powder? What could have caused this kind of carnage?

 

[GreatNorth]

Neither Honda tech I talked to (two Canadian dealers) has seen one of these rear pinion joints fail. I asked what this should be packed with as service manual says "Apply 5 – 8 g of molybdenum disulfide grease to the pinion joint splines," and also uses the same terminology for the grease to go on o-rings, etc, while one tech suggested Honda's MH77 moly paste. After some back and forth, tech suggested packing the pinion joint with their MH77 moly paste and use grease with 3+% moly for lubricating shaft seal o-rings, etc. The lubrication section of manual shows this:

This seems to me to suggest a moly grease for all--more like what seemed to be on the splines at end of propeller shaft that was in u-joint:

What do you use on splines? Is MH77 the right stuff? Or should I use moly grease like the CAT Extreme Application Arctic (5% moly) I use on a CTL?

 

[Splorin]

Good job by you! Does make you wonder if it was properly lubed to begin with. Any evidence of leaking around boot? Built during lax Wuhan days?????

 

[GreatNorth]

It doesn't look like anything leaked around boot. Grease in boot looked clean, just no sign of grease in joint itself. It was built in 3/21 if I'm reading sticker correctly. And assembled with zero grease in dump box pivots (not a serious issue, but a significant source of squeaks) as well as a loose bolt or two I found on initial inspection.

 

[GreatNorth]

Some more pictures. Before starting disassembly:

After pulling back dust boot, disk, and caliper. As you can see, there is grease in boot and on the surfaces it's on, just not much past it going into pinion joint:

Rear final drive and pinion joint removed:

Prop shaft end that was in pinion joint as it looked immediately after slipping rear final drive and pinion joint off it:

 

[DRZRon1]

Neither Honda tech I talked to (two Canadian dealers) has seen one of these rear pinion joints fail. I asked what this should be packed with as service manual says "Apply 5 – 8 g of molybdenum disulfide grease to the pinion joint splines," and also uses the same terminology for the grease to go on o-rings, etc, while one tech suggested Honda's MH77 moly paste. After some back and forth, tech suggested packing the pinion joint with their MH77 moly paste and use grease with 3+% moly for lubricating shaft seal o-rings, etc. The lubrication section of manual shows this:
View attachment 417494
This seems to me to suggest a moly grease for all--more like what seemed to be on the splines at end of propeller shaft that was in u-joint:
View attachment 417496
What do you use on splines? Is MH77 the right stuff? Or should I use moly grease like the CAT Extreme Application Arctic (5% moly) I use on a CTL?

I use bel ray waterproof grease for all that kinda stuff - non-moly - may be breaking a rule, just kinda slob it all up good.

 

[GreatNorth]

Picked up parts at the post office today. New prop shaft and pinion joint teethe fit nice and snug with just a little play.

The new teethe are missing the nice sawtooth shape the old ones had. Think that'll be alright? 😄

Here's the new one with better focus. Prop shaft comes only as an assembly with boot, boot rings (o-rings), spring, and o-ring for end that goes in u-joint.

I'm still trying to decide on Honda Moly 77 Grease vs. CAT Extreme Application Arctic 5% moly grease to go in pinion joint. Either is probably fine. I think OEM assembly may have been dry, or at least close too it. Otherwise I'd expect to find at least some wet grease stuck to the sides inside old pinion joint outside area where teethe meshed.

 

[GreatNorth]

It's all back together as of last weekend. While pipe wrench on largest rim of pinion joint and impact worked great to remove pinion lock nut and pinion joint from rear final drive, pipe wrench and torque wrench for reinstall did not. We struggled with it for a while before putting on the brake disc and sticking a 1/4" extension through a disc hole that lines up (barely) with a mounting bolt hole in the final drive. This made it easy. We held the extension straight for less stress on things while torquing the pinion lock nut to 80 ft-lb.

We used the old brake disc bolts just snug for this as we thought we'd be taking it off again to install final drive in frame, based on the way we'd pulled it out.

However, we ended up going ahead with torquing it in with new bolts as shop manual suggested installing brake disc before reinstalling final drive. This does work if you tip it just right on the way back into the frame.

We ended up using the Honda Molly 77 Grease in the pinion joint. Given tube says it's 75 g and was half full of air, we probably used more than 5-8 g specified in shop manual, but I can't see that being a problem in this application.

Lots of molly:

We used the CAT Extreme Application Arctic (5% molybdenum) grease everywhere else that required grease (u-joint and drive shaft splines, o-rings, seals).

It took a bit of wiggling things around to figure out how to get the brake caliper onto the already mounted disk with cables still attached to brake caliper, but there's just enough room to do it without too much fuss. Overall assembly went smooth. The hardest part was (unsuccessfully) trying to hold the pinion joint by its outer rim while torquing the pinion lock nut inside it. Jamming it via brake disc is the way to go.

I didn't take any pictures, but we did replace the dual oil seals behind the pinion joint as well. It was harder than expected to get a screw into them, but roofing screws eventually threaded in and worked to pull them out. Might be faster to drill a tiny pilot hole through the metal backing of the seal, then insert a screw. After lightly greasing bore and rim of new seals, firm press on both sides of seal with thumbs was enough to place the new ones.

The P520 still has plenty of squeaks and rattles, but the occasional disconcerting clunk is gone now.

 

[Jerryg]

What caused the failure? Seems odd.

 

[GreatNorth]

Yeah it does; doesn't seem like something that should fail for a long time, and almost no one--including two dealers I talked to--has encountered a failed one. We had occasional clunking from the back since new or close to it and looked externally trying to find something and never did. It got worse toward the end till it quit turning the rear final drive and we tore it apart to find this. I almost want to say it was assembled dry (like the dump box hinges), but it does seem there was at least some moly in all the metal flakes in the pinion joint.