Convert trans slipping

[gearman]

Well the convert with the belt drive almost left me stranded today.I noticed the other day that the link between rpm and speed was not as precise as before. Today after riding about three miles of stop and go the bike would only go walking speed even though the engine was revving up.I went about a mile this way running all the red lights I could, then the the trans started acting more normally so I did make it home.When I slowed to get back to my garage it was slipping again.I put it on the center stand and checked the tc oil. It was hot and looked somewhat dark cherry color.There was no emulsion and a magnet inserted to the bottom of the tank showed no metal debris.Of course I am thinking of the broken hex key problem,but I would think that in that case the tc would not work at all.My biggest dread is that a sprocket in my belt drive transmission has spun on its shaft.Ouch!It is 95 degrees outside today .Any ideas?

[bigbikerrick]

 Hey Gearman,let it run, on the centerstand with the atf tank open, and look inside to see if you see flow of atf into the tank. that would tell you the pump at least is circulating the fluid. also ,was the atf radiator hot? It would be nice to install a pressure gauge in the pressure line to see what you pressures are. I think if one of the "O" rings in the TC are bad it can cause those symptoms as well, without externally showing an atf leak.  Im sure Rodekyll, and a few of the other "convert gurus" will chime in soon with some better ideas.
If/ when you dis assemble it, please post some pics. i am interested in your belt drive setup, its been years since Ive seen an old pic!
Good Luck,
Rick.

[rodekyll]

The hex key is in the process of stripping.  It grabs, you go, it spins, you don't go and your fluid soon fails the stink test with all that implies.

The belt is not the problem.  Belt failure would be similar to running with the rear wheel in the air.  This is a straightforward failure to circulate fluid. 

I've been thinking about the t/c fluid in terms of a belt lately.  It doesn't do what oil does.  It does what a belt does.  As long as it goes 'round and 'round (circulates) to always present a 'fresh face' (metaphorically) to the fluid coupling, it works.  If it doesn't, the friction kills it just like it smokes a stalled v-belt.  That's different than lubricating oil that has to stick to work.  So any time friction happens the atf scorches and becomes ineffective.  Then it doesn't matter if the hex key is working or not.

Are you using the aviation fluid?

Have you installed a pressure gauge yet?

Any recent backfire/run out of gas episode?

[John in PA]

Tell me about the aviation ATF (??)  Is that desirable/recommended, or to be avoided?

[rodekyll]

It works.

[dsrdave]

+1 on the aviation fluid. 

[rodekyll]

I am running aviation hydraulic fluid in the trike with the torque converter coupled directly to the differential -- no clutch or gearbox.  Just a driveshaft sticking out of the torque converter and bolted to the diff.  I'm tipping the scales at about 1550# and cruise 70 when the road lets me.  I've got a couple thousand miles on it now on freeways, in town stop and go,, and 2ndary highway mountain passes.  It runs a nominal 10-20f above air temp and I touched 150f dialing the volume control up to 11 in a John-Day area mountain pass on a hot day.  I accelerate out of uphill hairpins and get mid 30s economy.  It makes a hydraulic coupling strong enough to shear crankshaft bolts.

I've done some other tinkering with my fluid system, but if aviation hydraulic fluid works for my extremely abusive needs, it will work for you.  Everyone who's dared try it says so, and I'm counting on it in a big way.

[gearman]

I am running aviation hydraulic fluid in the trike with the torque converter coupled directly to the differential -- no clutch or gearbox.  Just a driveshaft sticking out of the torque converter and bolted to the diff.  I'm tipping the scales at about 1550# and cruise 70 when the road lets me.  I've got a couple thousand miles on it now on freeways, in town stop and go,, and 2ndary highway mountain passes.  It runs a nominal 10-20f above air temp and I touched 150f dialing the volume control up to 11 in a John-Day area mountain pass on a hot day.  I accelerate out of uphill hairpins and get mid 30s economy.  It makes a hydraulic coupling strong enough to shear crankshaft bolts.

I've done some other tinkering with my fluid system, but if aviation hydraulic fluid works for my extremely abusive needs, it will work for you.  Everyone who's dared try it says so, and I'm counting on it in a big way.

I was reading about mineral based av.oil.Does it have a higher shear spec than atf? What brand and spec are you using?

[John in PA]

Dittos on Gearman's question.  Precisely what product do I look for if I want to replace the ATF with this exotic new fluid?   

[rodekyll]

I am using precisely this:

Phillips 66 X/C 5606A Aviation Hydraulic Fluid

Comes in a blue 1gal tin.  Someone said it was superseded by another number, but I've had no problem getting this at most of the general aviation airfields with a service station.  Look for the helicopter bay.  When you tell them why you want it the reactions can be entertaining.

[rodekyll]

GM -- it's a hi-vis, mineral oil-based product without friction modifiers or other stabilizers.  I don't know the other things you're asking -- I'm not an organic chemist.  Well, not the petroleum kind.

[gearman]

GM -- it's a hi-vis, mineral oil-based product without friction modifiers or other stabilizers.  I don't know the other things you're asking -- I'm not an organic chemist.  Well, not the petroleum kind.

Well , based on RK's diagnosis I tore apart my convert to get to the converter oil pump and hex  key.I was hoping to find some damage but it was in very good shape.I took the pump out, no easy task,and it looked and felt fine.Hmmmm? then  I took the pressure regulator valve apart and the only thing was the seat for the ball was a little imperfect.I don't want to put it back until I can test it.I want to put a gauge on the bike so I can see whats going on.How do you tap into the pressure side of the valve chest housing?Where can I get fittings to fit?To bbrick,I don't think I have a major o ring leak internally.When I did not see any obvious problem I decided to check into the belt drive trans.I took the fill plug and drain plugs out and used a new small vacuum cleaner to suck one hole and blow compressed air into the other hole.I was trying to make a whirlwind inside the housing and suck any debris out. I took the vac apart and there was no debris. I don't know is this is a valid test but it was the only way I could figure out how to test it without taking the tranny out.O f course the sprockets could be slipping on their shafts.Any ideas appreciated.

[rodekyll]

Cut the soft lin between the pump and the top bellhousing banjo.  Install a t and put the gauge there.

Check the parts the hex key joins.  Your next candidate for the key slipping is the drive bit inside the pump housing.  The female hex can get reamed.

What atf have you been using?  Mercon and type F is horrible for slipping and gets very hot.  Anything with friction modifiers will also slip.  I had assumed you were aleady using the hydraulic fluid when I said it was the key that is failing. 

Also - are you foaming at all?

[gearman]

Cut the soft lin between the pump and the top bellhousing banjo.  Install a t and put the gauge there.

Check the parts the hex key joins.  Your next candidate for the key slipping is the drive bit inside the pump housing.  The female hex can get reamed.

What atf have you been using?  Mercon and type F is horrible for slipping and gets very hot.  Anything with friction modifiers will also slip.  I had assumed you were aleady using the hydraulic fluid when I said it was the key that is failing. 

Also - are you foaming at all?

I think that I am using type f fluid.I did not notice foam but I did not check because the cap threads were too  tight. I ended up chasing the threads with a file in a lathe to make the cap easier to get off.Do you think the imperfect valve ball seat would make a difference?My converts never slipped before.Do you think the atf wore out?I was thinking of tapping into the valve chest with a copper line and guage. I want to test it on my bench and run the key with a drill. What do you think?

[rodekyll]

Your only high pressure line is the one I mentioned.  To run on the bench simply cap the end of that banjo with a mechanical gauge.

Yes, an imperfect seat or ball can reduce pressure.  I can change pressure ~3# by adding/subtracting washers behind the relief valve acorn nut.  I can also globally change pressure by adding shims between the spring and the acorn nut.  So even a little bit of leakage on the pressure relief can be a problem.  Don't do that sort of pressure shimming thing without a pressure gauge or you'll overpressure the system.

If you have been using type F fluid you may well have burnt the oil.  It runs too damn hot -- 80f hotter than av-fluid under the same conditions.  When I tested it in my Convert the slip was so bad my cooler was literally smoking within 30 miles and it wouldn't pull me up a residential street hill.  It is truly horrible stuff.

Is the fluid darker than new?  How does it smell?

[gearman]

Your only high pressure line is the one I mentioned.  To run on the bench simply cap the end of that banjo with a mechanical gauge.

Yes, an imperfect seat or ball can reduce pressure.  I can change pressure ~3# by adding/subtracting washers behind the relief valve acorn nut.  I can also globally change pressure by adding shims between the spring and the acorn nut.  So even a little bit of leakage on the pressure relief can be a problem.  Don't do that sort of pressure shimming thing without a pressure gauge or you'll overpressure the system.

If you have been using type F fluid you may well have burnt the oil.  It runs too damn hot -- 80f hotter than av-fluid under the same conditions.  When I tested it in my Convert the slip was so bad my cooler was literally smoking within 30 miles and it wouldn't pull me up a residential street hill.  It is truly horrible stuff.                                                                                        Yes the fluid is a little darker than new.I tapped the valve chest just below the smaller banjo bolt. 1/8 npt. I see some cute small oil filled guages on ebay.I was just looking for your thread where you stated the highest pressures you saw.They have 0-30 and 0- 60 psi. I am thinking 0-30 . What do you like?

Is the fluid darker than new?  How does it smell?

[rodekyll]

The book says pressure relief at 28#.  I find most are running lower probably due to an old spring in the pressure relief valve or maybe imperfect sealing on the ball.  My modified pressure can creep to 32# at high speeds, fluid cold.

[gearman]

I thought I would give an update to my tranny slip problem.  I made a test set up and determined that the pressure valve spring was way too weak. I made a mandrel to keep the spring straight in its bore and had a small extension on the end that went into the valve cap nut. I got it to run at 25-29 psi flat out.I changed the atf with new type f red stuff and the bike is running like its old self again.It was amazing how small changes in the spring length made a big difference in relief valve settings.

[mtiberio]

WHole thread and no one mentions his CLUTCH???

[gearman]

WHole thread and no one mentions his CLUTCH???

The clutch is dis abled. No throw out bearing, only the clutch pack. Thanks for the input.

[mtiberio]

if it isn't roll pinned, it could slip