Replacement of my transmission cooler lines.

[Clyde9]

From: denisondc  (Original Message)
Sent: 3/22/2008 9:42 AM


To start by quoting JUPP318 "I Know it sounds over-the-top but when I was in Drag Racing I used to make up Aeroquip hoses. Nasty job but once they are done.... So my Winnie now has nice braided stainless lines. I think they would put less strain on the radiator as I run them along the inside of the chassis rail so they are well supported.
Cheers Ian..."

I replaced my tranny cooler lines, and the short rubber hoses right at the radiator - after finding one of the metal lines had rusted enough to begin leaking. The short hoses looked cracked and feeble too.
The original metal (rusted) lines were 5/16th steel tubing, so I used 5/16th Bundy tubing, (aka brake line tubing in the U.S.) which is easy buy in auto parts places, in standard lengths, with flare nuts on them and double flares formed at the ends. That tubing is also easy to bend with the typical cheap tubing bender.
The two OEM rubber hoses had the proper tubing fittings swaged on them & are probably still available 'made-up". But I used two lengths of rubber tubing meant for transmission cooler lines, and a brass fitting at each end. Two of the 4 of them had a male tubing fitting with a 5/16" hose barb; the other two had a female tubing fitting with a 5/16th" hose barb. I used the small springy type of hose clamps that were on U.S. cars just before cars got fuel injection - the kind you expand by squeezing the tabs with pliers.
Its important to support the metal lines running back to the transmission. Not only so they don't have to be supported by the connection at the transmission, but so they cant rub against anything metal on the run back beside the motor and at the bell housing.
Later I added an auxiliary oil cooler when we were going to be towing a car behind us. I put it in series with the lines running from the transmission to the cooler in the radiator. I think the line coming from the front-most part of the 727 is the one for the oil being pumped up to the cooler. For that aux. oil cooler I didn't use flared connections. The special tubing for transmission coolers I just clamped onto the 5/16th" lines with hose clamps. I rechecked and re snugged the hose clamps a couple of times, a week or 2 after installing them.
It made my trans fluid run as much as 90 degrees cooler on long uphill climbs - even in 90°+ heat.
I had mounted it just below the radiator - so it had its own cool air flow, and didn't block the radiator at all.
In chilly weather I would cover the cooler with a sheet of cardboard. You don't want the transmission oil to be -cold- you want it warmed up enough to drive out any water vapor when the transmission is cooling down during damp nights.