v1000 Convert trans cooler swap / upgrade

[v8volveaux]

Does anyone have any experience swapping out the transmission cooler on a v1000 Convert? I have a larger cooler from a Triumph that's a near bolt-up swap that I'd like to try. The only difference (here it comes...) is the outlets on the Triumph would both be coming up from the bottom, whereas the Guzzi cooler has the left one on top, right one bottom. And yes, I know I'll be making hoses. Thank you very much for any help.

[rodekyll]

What do you want to know?

[fotoguzzi]

why do you need a larger cooler?

[v8volveaux]

I guess what I want to know is: With the stock unit having one outlet on top / one on bottom, if there is any thermosiphon action going on, or if the cooler works simply pressure in / pressure out, and the location of the outlets doesn't matter? It seems like a fairly straightforward affair, and I'm probably overthinking this. I just can't seem to find any info online -- specifically for Converts -- pertaining to coolers, so I wanted to ask this knowledgeable base first. Guzziology mentions that the hose pressures involved are around 30 psi, and since the cooler I'd be swapping in is an engine oil cooler, I think the cooler should be able to handle the pressure. I'm considering the swap because my old one has been repaired once already, is pretty beat up, and I have the Triumph cooler in hand.

[mtiberio]

the routing of the lines is probably due to aesthetics. if you are messing with oil tank mounting or custom oil tanks, then relative position matters. the original factory Eldorado based Convert test mule from 1972 had a tiny oil cooler, of a totally different design, with different routing. No issue obviously... (visable in lower left insert)



see the BIG hi-res picture here:
http://www.thisoldtractor.com/mg_images/convert_prototype_motorcyclist-1973-02.jpg

[v8volveaux]

Thank you very much. I think that pretty much answers my question.

[rodekyll]

The cooler is a very efficient design.  You can hit it with water at the gas station and watch your temperature drop 30º instantly.  I have never heard of a properly running 'vert that overheated its ATF. 

That said, there is a bit of voodoo in the placement of the various things that make up the atf loop.  Folks have tried moving the cooler and/or tank and had some odd and unexpected results, like foaming, t/c slipping and the atf migrating to the tank when the engine stops.  I've experienced some of that myself.  So be prepared for anything when you do the mod, and remember -- you can put it back to oem at any time.

Yes, in a perfect world you can peak pressure at ~30# when everything is cold and you're at highway speed. Pressure relief theoretically comes in at ~28, according to the book.  In reality you're going to idle hot at from no noticeable pressure-to-~12#, and at highway speed run 18-24#.  Temps with the oem cooler and MIL-H fluid seldom exceed 150ºf.  I did about 10 back-to-back 'rubber band' hole shots where I stalled my torque converter and then let go the brake for 1/4 mile times, and got the temp up to about 183ºf.  That's the hottest I've recorded for my 'vert's current configuration.  Normal operating temp in the summer is about 123ºf.  In the winter on my local roads I can't make the temp gauge register.

There is only one high pressure hose in the atf loop.  It is the one running from the pump to the side of the transmission.  Everything else is flow only.  Use a good quality hose, like Gates Transmission Cooler hose (yeah, they make a hose for this exact application).  It's good for high temperature. moderate pressure, and doesn't cost too much.

The hoses on the bike have swedged barb ends.  That means you can use your dremmel to cut the metal sleeves from around the hose ends, pull the metal fittings, and reuse them on the new hose (with proper hose clamps).  The fittings might be slightly large for US hose diameters.  Prior to fitting the ends, I put the hose end in boiling water for a minute or so to soften it.

Don't allow for sags and loops in the line and don't make tight bends.  Note the oem hose routing and try to follow it as much as possible keeping the sag and loop advice in mind.

If you are draining the fluid to do the mod, consider a full purge, with a refill of MIL-H-5606A (or its updated part#)  aviation hydraulic fluid instead of whatever you are now substituting for the OEM (and no longer available) DEXRON II.  I've done extensive testing and arrived at the MIL-H as the lowest temp/lowest slip/least foaming alternative to modern ATF formulas.  This is available at the hangars and flight service station of your local private airfield, many larger parts houses, and some have reported ordering through NAPA-type stores.

[mtiberio]

There is only one high pressure hose in the atf loop.  It is the one running from the pump to the side of the transmission.  Everything else is flow only.

all are positive pressure except the one from tank to pump which is suction... it needs to be special to prevent collapse, no?

[rodekyll]

No, the only pressurized hose is the one from the pump to the transmission.  The two returns are open on the tank end, so no pressure.  The intake from the tank (big hose on the tank's big lower banjo) is under suction, and although I've heard of collapses on it I have not experienced one.  The oem hose is wire-braid re-enforced for suction collapse.  I have replaced it with standard hose in the past with no bad consequences.  I don't have a problem doing that, but the hose I use is NOT reinforced and COULD possibly collapse under suction.  So while I say it works for me, I'm not recommending it for you.

atf flow:  tank outflow -> pump -> tranny in -> tranny out/cooler -> tank return
                                                                 -> tranny out -> tank return*


*this is the line from the bottom of the transmission.  It returns the fluid used to lubricate the t/c output shaft and bearing.

Hope this helps.

[v8volveaux]

Thank you very much for the additional info. How does one perform a "full purge?" I've got every hose off and it's drained, except for the torque converter I'm guessing. Might as well go for the full enchilada and new fluid.

[rodekyll]

After you replace the hoses pull the drain banjos, start the engine, and let it run till it's spraying mist.  Add a couple cups of the new stuff and let it run out x2.  That should be good enough.  Replace the banjos and start you fill with a pint.  Let it settle and add a little more until it comes up on the stick.  DO NOT FILL TO THE FULL MARK!!!  About halfway up with the engine idling should be good.

YMMV in a big way with the new cooler.  I can't tell you how much to fill it other than to let it settle in and watch the level on the stick.  I also can't tell you how the bike will react to the cooler.  Watch for foaming.  That would be the most obvious sign of trouble.

[bigbikerrick]

I just wanted to add that I also run the   MIL-H-5606A  aviation hydraulic fluid in mine, its the only fluid I have used since I got my bike 3 years ago, and have never experienced any fluid related problems at all.  After reading the extensive testing Rodekyll carried out while monitoring atf pressure as well as temps.  I was sold on the aviation fluid. It is a pure mineral oil with a pink dye for identification, but it has no friction modifiers, or any other additives.  I purchased mine from Aircraft Spruce Co. and had it shipped to my door.
 I also replaced all my hoses myself like RK mentioned, and flushed and cleaned out the system, when I first got the bike. My bike was well maintained by the previous owner, but it surprised me how much crap was in the bottom of the ATF tank.
Rick.

[v8volveaux]

Thank you everyone for the good advice. I'll be placing my order to Aircraft Spruce directly.