Eldo Rear Drive Overheating - Mystery Solved

[Kiwi_Roy]

I replaced the rear drive on my Eldorado with one sourced on E-bay.
I thought at the time, this has zero backlash but it turned ok so I filled it with 90 weight gear oil with some molly additive and took it for a spin.
There was no noise or other bad symptoms but after a 10 mile run on the streets the drive was too hot to hold a hand on.
I'm assuming it is shimmed too tight, does that make sense?



Update
I just found this, looks tricky
http://www.guzzipower.com/RearDriveTear-Pete_R.html
http://www.guzzipower.com/RearDriveTear2-Pete_R.html

[Vasco DG]

Roy, be aware that the level plug was in the wrong spot on early 'Deep Sump' bevel boxes.

Sad news is that if it is an early box and you relied on the level plug the gears will be trash after ten miles.

Can you post up a Pic of the box from the side or just tell us if the level plug is in an indent in the casting or just flush with the back of the box? If it's in an indent it's in the wrong spot.

Either way if you want to drain it and stick it in a box I can have spook for you,

Pete

[Kiwi_Roy]

Thanks Pete,
                    I pulled the drive off again tonight - The bike is is a 72, this is from a later model

I found there is a little backlash between the pinion and crown wheel, as best as I can measure without a dial gauge the spline on the pinion will rock back and forth about 1 - 2 thou of an inch without moving the crown wheel.

Actually I think I may have screwed up and got something wrong when I installed the wheel I had to pull the axel through the box by about 1/8" and it sprang back about the same when I removed the nut.

I have a question about the pinion housing, looking along the shaft towards the rear it has a large flat at 12 o'clock and a smaller one at 7, does that sound right?    Showing large flat at 12

BTW I filled the box until oil ran out the plug, is that correct?



I also took a picture of the original 72 drive for comparason, this one had done 130,000 miles and is absolutely rooted, the pinion teeth have only about half the metal left and the crown wheel is not much better. First of all the housing showing the difference in the level plug, Pete confirmed this fill plug is in the wrong spot.

And a shot of the pristine gears that came out.


I reckon it must have sounded like a concrete mixer before you add water going down the road.

[Vasco DG]

Yah, the original is the one with the level plug in the wrong spot. The later one is the the first one but it's obviously had someone in it as the gaskets hanging out are a give away.

My guess is that whoever arsed about with it has the mesh wrong. If you run it as is it's going to trash the gears. What ratio does it have in it! Count the pinion teeth for me. Are there 8 or 7?

Pete

[Kiwi_Roy]

Pete,
        there are 8 teeth, same as the old one, the pinion has 570 engraved on it, I assume that's a serial No.
I will print out and study your paper on adjusting the mesh
This old girl is forcing me to learn more than I ever wanted to know on a variety of topics.
I was able to shim the gearbox after reading your dissertation on that topic.

BTW could you answer my question on the pinion housing, I note the old one has no flats, it seems like the
later version is something to promote oil circulation.
On a related topic the drive I borrowed pumped oil from the box to the universal area where it dripped out. Someone told me this was caused by the rear suspension struts being too short which let the driveshaft become flat instead of at an angle is that reasonable.

Thanks
Roy

[rodekyll]

The pinion holder is square as you say, but there is an index point for installing it.  If you look down the bore in the drive housing you can see a shoulder with two cutouts.  There are two flats in the sides of the bearing holder.  Align the flats to the cutouts.


Yes, if the swing arm is in a neutral-to-negative angle (rear higher then pivot point) you can have oil migrating up the drive shaft.  This can be an issue if you have short shocks, really worn springs, or a really heavy load on too light a shock.

[Idontwantapickle]

Roy,
That picture of the gears is fuzzy but from what I see those gears are shot. That is a bummer.
Hunter

[Kiwi_Roy]

, or a really heavy load on too light a shock.

David,
         Haha, are you trying to tell ne I'm overweight?
I didn't notice the flats inside, I will take another look

Hunter,
            That's the original gears, the ones in the replacement drive are fine (at the moment)
I don't know how the guy was riding it. I suspect it was low on oil at some time due to the overfill hole being to low as Pete pointed out, I will try to take a clearer picture of the damage, only about 50% of the metal remains.

[Idontwantapickle]

Hunter,
            That's the original gears, the ones in the replacement drive are fine (at the moment)
I don't know how the guy was riding it. I suspect it was low on oil at some time due to the overfill hole being to low as Pete pointed out, I will try to take a clearer picture of the damage, only about 50% of the metal remains.

Whew! That's good news! 

Hunter

[rodekyll]

Geez, Roy -- I'm a hefty 162#.  Everyone is a heavyweight compared to me.   

But I load my bike heavy for trips.  Much heavier than 2-up riding with average weight riders.  I have tipped the scales at the transfer station at 1200#, fully loaded, full of gas, and me aboard.  Without good rear suspension (mine varies) this is a formula for negative swing arm angle.  Going stop-to-stop on the swing arms is also hard on the u-joint.

[Kiwi_Roy]

Ok, as best I could in a hurry I checked the alignment, I pulled the crown wheel out and degreased it
Smeared the pinion with some sticky molly grease I have then assembled it all with the bolts nipped up.

I couldn't take a picture of the point of contact so I will try to describe it in text

Crown Wheel Teeth
   |------------------|<----tip of tooth
   |  ######## | <-----POC
   |  ######## |
   |____________| <---- Root of tooth
If anything the point of contact would have been slightly closer to the tip.

Looking down from the top the edge of the pinion aligned with the circumference of the crown wheel within a thou or two


Rodekyll,
            The pinion carrier was upside down, I see the cutouts you mentioned, thanks for that. 

I'm still wondering about the spring effect I saw on the axel, almost like it was pulled together under tension.           |
   

[rodekyll]

The tension is caused by the spacer in the rear drive unit not being correct (or missing), or a missing/incorrect spacer between the brake drum and axle (if it has one -- I don't remember).  If all the spacers are there and correct the springy thingy can't happen.

[Vasco DG]

The tension is caused by the spacer in the rear drive unit not being correct (or missing), or a missing/incorrect spacer between the brake drum and axle (if it has one -- I don't remember).  If all the spacers are there and correct the springy thingy can't happen.

Wot he sed! I can't remember the actual parts layout but if the swingarm is being pinched in something is missing. Maybe the wrong internal spacer in the BB?

Pete

[rodekyll]

You might get the tension problem fixed and discover the rear drive heat goes away.  If spacers are wrong you could be binding up all sorts of things.

[Kiwi_Roy]

Thank-you gentlemen
I will compare the dimension between the trashed drive and this one. It looks to me as though the part with the crownwheel fixed to it should be fully floating, I mean just held in place by the cogs pushing it outward.

As to the orientation of the pinion carrier, I strongly suspect the drive I borrowed had the flat on top also, I wonder if that was the reason it tended to spit oil out the universal area rather than lack of slope, to say the least the shaft was nicely lubed.
I have since returned the loaner box to its  rightful owner, I will ask him to confirm the orientation.
The original trashed drive had no such arrangement the housing is completely round with no flats or lube holes.

[smdl]

What is the normal expectation for heat coming from the rear drive?  Should it be cool enough to lay a hand on it and keep it there?  I'm now worrying about mine, as it seems to be very warm once I have been riding for a while.  I believe that I have the oil level right (340ml of gear oil, and 20ml of moly, as I recall), and that did seem to put the level above the level plug.  Maybe I'll take a picture and post it here.

Sorry to hijack, Roy!

Thanks,
Shaun

[Kiwi_Roy]

Shaun,
           I was wondering that last weekend a bunch of us went about 20 miles for coffee, I took the California II, there was a T3 and a 80 Lemans. All the boxes were just warm to the touch, you could keep your hand there.
After 10 miles I was unable to hold my hand on the one in question for more than about 10 seconds, that bike got left at home.

If you look back at the top I have posted pictures of the later drive with the correct overflow plug and below that the old style with the too low plug.

[Chuck in Indiana]

You might get the tension problem fixed and discover the rear drive heat goes away.  If spacers are wrong you could be binding up all sorts of things.

Absolutely..

[smdl]

Hi, Roy.

Thanks for the info.  I'll check it against my rear drive tonight.

This unit was rebuilt by Charley Cole, a few years ago, and seems to work fine, but I had it out for a u-joint change last weekend.  I was aware of the fill-level problem, so I measured out a total of 360ml, and then checked against the fill-level plug.  It immediately started pouring out when removed it, so I thought that was a good sign. However, as mentioned, it seemed very warm after about a 20 mile ride.  Unfortunately, I never thought to check it previously, so don't know if this is a new condition.

Thanks, again!

Shaun

[John A]

If you can touch a surface and keep your hand on it , it's about 185F or less. If you have to take your hand off right away,it's about 185F or more. I don't know what a healthy rear box runs at but the spring back is not right, is the axel spacer the same on both boxes? Also tighten the axel before snugging up the 4 mount bolts, according to the maintenance manual . Sometimes you can see the tracks of the original pinion orientation . there are some variations between boxes in the pinion bearings, there was a change to wider bearings but don't remember if it came with disc brake boxes or not.

[Peter from Sch'dy]

If you can touch a surface and keep your hand on it , it's about 185F or less. If you have to take your hand off, it's about 185F or more. I don't know what a healthy rear box runs at but the spring back is not right, is the axel spacer the same on both boxes? Also tighten the axel before snugging up the 4 mount bolts, according to the maintenance manual . Sometimes you can see the tracks of the original pinion orientation . there are some variations between boxes in the pinion bearings, there was a change to wider bearings but don't remember if it came with disc brake boxes or not.

Won't contradict but I measured the temp of the CARC oil through the fill port on my bike after 75 mile run and read 55deg.C.(131F) I could hold my hand on the outer case for about 15 seconds. Also, if there is spring back it could be improper sequence of assembly where the brake side axle pinch bolt tightened before axle nut has taken up all clearance between axle shoulder and brake backing plate and inner spacer. 

Best,
Peter

[John A]

I got that 185F thing from a old Dodge automatic transmission manual where the level would evidently fluctuate depending on the fluid temp and found it to be a fairly accurate way to judge the temp. For welders and machinists you get used to holding hot parts so take that into consideration . I did edit that post to read "take your hand off right away"

[Kiwi_Roy]

I took some careful measurements this evening, everything between the old and new drives seemed to be the same but when i married it up to the wheel I noticed some specs of aluminium inside the wheel. I found that the skirt of the drive had been rubbing on the wheel where the spokes attach, no wonder the drive housing got hot.


I checked the surface of the skirt in relation to the bearing stop in the drive.
The skirt on the new model drive is 3mm deeper than the old model, it goes into the wheel further.




Im not sure how I will resolve this yet, it's barely touching and only at a couple of spots so I think I will just fix a 16 gauge spacer to the bearing stop or the bearing.It needs to be fixed because you don't have access to the area once the wheel is slipped into the drive.

[John A]

That bearing stop just pushes out if you tap it with a punch from the axel nut side and easily swapped from one box to another if that helps

[Kiwi_Roy]

That bearing stop just pushes out if you tap it with a punch from the axel nut side and easily swapped from one box to another if that helps

Ok I might try that but I suspect they may be the same, I checked the measurement from the bearing stop to the back of the large bearing flange, same on both.
It's the bearing stop to the Skirt face that is different by 3mm.

Perhaps I can tap the stop out and put a thin shim between it and the case, on the other hand I can just fix a shim to the mating surface. It won't take much, after I dressed up the skirt with a file I was unable to get it to rub and it was only touching in a couple of spots.

[John A]

I would just make an axel spacer and leave the tube in place if it measures the same. There was a factory made spacer to move the wheel over for a little more clearance between tire and swingarm, used on early EV's so the idea has some merit. It just went on the axel if I remember it right.

[Kiwi_Roy]

John,
        I think it would be difficult to slip a loose spacer over the axel, you have to lift the wheel into the drive splines before inserting the axel so the shaft is unreachable. I'll figure something out.

[John A]

Really sticky grease or maybe glue might hold it in place until the axel is thru might work

[rodekyll]

I carry a 5mm shim for those on-the-trip tire changes where the same size tire is slightly fatter.  The shim goes between the wheel and the final drive.  I use sticky grease to hold it in place.  If it's a really hot day I might have to run a screwdriver through from the axle nut side to hold the shim while I push the axle through from the other side.  It's routine.

[ccoli]

I have spares of several size spacers I acquired trying to fit a Stone wheel into an EV. If you need a longer spacer ping me and I'll send you one.