Connecting 5/16 OD steel trans line to 11/16 OD rubber hose

Many years ago the previous owner had a transmission cooler installed. The steel 5/16 OD transmission lines were connected to 11/16 inch OD rubber lines, one to the transmission cooler inlet I believe, and one outlet from the rad, back to the transmission. The rubber lines are slid onto the steel line ( which is cut with no flare). Two hose clamps separated by a few inches hold the line on. There is trans fluid leaking from this setup. Can anyway suggest a better configuration for these lines. All the lines are currently held with hose clamps. The trans cooler is in series with the integral radiator transmission cooler Thanks.

 

I ran mine independent of the radiator. that way I'm not trying to cool fluid that is already 180-195*. also another plus is the radiator isn't trying to cool transmission fluid.
in this pic you can see my transmission cooler mounted behind the rear bumper (top right).
I ran hydraulic hose from transmission to cooler then back to transmission. the hydraulic hose can handle the heat better than reg. rubber hose. the connections at the transmission are short transmission hard lines w/flare, the cooler has AN fittings.
that cooler had a fan of it's own (switched on power) but it kept the fluid too cool . without the fan fluid temps are 170*.
that's about 5* below recommended min. operating temp of 175* .
the hottest I've seen it (heat gun) was on a hot day, running it hard...... I checked it at the return line at the transmission and it was 182*.
this system has been on my...C-4...AOD...and now on my 700R4, no problems so far (12-15 years).

 

Compression fittings.

 

Use tube nuts to connect to a hose barb of the appropriate size(will require flaring of the steel line and a flare-to-barb adapter fitting)

 

Thanks everyone, so I can do a single flare on the 5/16 steel tube, ( not forgetting to put the nut over top), connect it to a AN 6 fitting with a barb fitting to the 11/16 OD line with a hose clamp over top. I don’t think I’ll get fancier than that.

 

After having no luck in town I ordered up two these 5/16 compression by 3/8” barb fittings. Price is CDN dollars. One good thing is I don’t have to put a flare in the 5/16 steel line. There is a show and shine this Wednesday so I’ll just tighten the clamps and try not to drip fluid on the road.

 

Get good hose too, so many people put regular fuel hose on the trans lines. It works but not the best solution. If you get a good push lock hose youllbe good to go. Parker, Gates and Contitech (formerly Goodyear) all have a good push lock that has the pressure and temp rating plus they are A rated for oil inside and out.

 

Good luck.

 

I installed the Derale brand compression fittings on the 5/16 OD steel transmission lines. The hose went to onto the 3/8 “ barb fitting, secured with a hose clamp. No leaks so far. The installed shot is also in my Maverick/Comet Projects page under 73 LDO 302. I’ve got clean up the oil pan.