Temprature of the rear drive (loop)

[garbln]

I have a question for the loopframe guys.
I have a 70 Ambo I bought as a pile of parts, and have managed restore it and get it running.  I think it's sweet bike but I have one concern.  The rear drive runs pretty hot, by that I mean I can't hold my hand on the case more than a few seconds after a ride.  I have had the thing open to replace the seals and the gears look perfect but I didn't check anything else while in there.  I figured that when I got it it had maybe 40K on it and the gears looked perfect so it must be set right.   I'm beginning to think maybe those are new gears and there not set right.  Or do these old gear cases just run a bit hot?  Or do I take it off and give it to my local Guzzi Guru to work his magic on?

Gary

[rodekyll]

I'd think that's unusual heat.

[Triple Jim]

It seems to me  that the rear drive on my Mille gets just about that hot after a long ride at highway speeds.  I can touch it, but it's not comfortable to hold my hand on it.

[pete roper]

Sounds like it to me too. While the early loop bevelboxes only hold about 3ml of oil they also only produce about 5hp and they loose 95% of that in the driveline on a good day! There shouldn't be enough heat there to boil an egg! Never mind burn your hand!

Whip the box off, pull the pinion carrier and have a real good squizz at the gears.

[Kiwi_Roy]

I had that problem with mine, I had a later version of the box.
It was the box rubbing on the wheel that caused the heating.
I forget what I did to fix it, I think I must have added a shim, I can check.

When you pull the wheel off look for signs of rubbing.

[Antietam Classic Cycle]

They do run *very* hot, even when shimmed correctly. That's why I change the gear oil with the engine oil (very often).

[lucky phil]

I have a question for the loopframe guys.
I have a 70 Ambo I bought as a pile of parts, and have managed restore it and get it running.  I think it's sweet bike but I have one concern.  The rear drive runs pretty hot, by that I mean I can't hold my hand on the case more than a few seconds after a ride.  I have had the thing open to replace the seals and the gears look perfect but I didn't check anything else while in there.  I figured that when I got it it had maybe 40K on it and the gears looked perfect so it must be set right.   I'm beginning to think maybe those are new gears and there not set right.  Or do these old gear cases just run a bit hot?  Or do I take it off and give it to my local Guzzi Guru to work his magic on?

Gary

So that would mean its running at around 70-75 deg C. which isn't hot enough to damage anything but I don't know whats typical.

Ciao

[TOMB]

I had the same problem years ago . Same issues HEAT. Switched to Mobil 1 Syn Heat problem solved ,try the syn before you tear the Diff apart chasing a problem that cam be solved with the proper lub

TOMB

[bigbikerrick]

My 73 eldo has the gearcase with the sump on the bottom, I assume thats what you have. Once when I replaced the big seal, I drove the seal too deep in the carrier, and it was rubbing on the bearing, I think, but  I guess the added friction,it  caused made the housing run real hot. You could not pace your palm on it after a short run up to highway speeds. my seal was the expensive viton one, and surprisingly, it was not permanently damaged, I carefully popped it out, and re inserted it, using a bit of contact cement type gasket "glue", and was careful not to drive it too deep upon re install.Afterwards, all was "Cool" !   
I hope it helps,
Rick.

[Moto]

I have a question for the loopframe guys.
I have a 70 Ambo I bought as a pile of parts, and have managed restore it and get it running.  I think it's sweet bike but I have one concern.  The rear drive runs pretty hot, by that I mean I can't hold my hand on the case more than a few seconds after a ride. 

Gary

Not to sound like snake oil salesman, but have you put moly into the oil? It should reduce the heat. Guzzi seems not to have recommended it until the Eldorado, but the reason they did may have had something to do with the performance of the rear drive on the previous production series, the Ambassador!

[Dofin]

I have a cheap infrared temp gauge I bought from harbor freight and checked my rear wheel drive, it runs  from 145deg F  to 155 deg f according to how much weight I have on my 2015 V7 Stone.  I also get about 155 deg F on my honda PC800 rear drive.

If you are concerned spend a few bucks for the gauge.

[acogoff]

     This thread got me thinking about this also and got out the infrared gun and after a 50 mile ride at 80F ambient the rear drive reads 143F up front reading on the rear of the steel swing arm itself. On the aluminum above the pinion it was 137F. I also found that it was 137F above the carrier bearing at the front of the swing arm. Forgot to mention this is on my T3 that has about 25K miles since new pinion bearings so they should be broken in and about 50K miles on ring and pinion gears.

[Triple Jim]

IR thermometers can read very low on bright aluminum or other metal surfaces.  When I have to read one, I put a spot of black spray paint on.  It comes off easily with mineral spirits if you don't let it dry more than a few minutes.  I suppose black tape would be pretty good, but I haven't compared it to paint.

[rodekyll]

A good IR gun has the ability to compensate for the type of surface it's reading.  I have one where you dial in the substance and it adjusts the readout.

[Triple Jim]

A good IR gun has the ability to compensate for the type of surface it's reading.  I have one where you dial in the substance and it adjusts the readout.

Well, a fancy one has the ability.  Simple can be good.