Transmission filter return line install for a '70 model central oil tank

Joined
Apr 27, 2015
Messages
1,659
Country flag
In the never ending saga to have more modifications on my 70 commando than anyone, I added a transmission filter to my return oil line. It was a simple project who's details were recommended by Jim Comstock as a alternative to adding the late model filter kit parts...

Parts:
NAPA Automatic Transmission Filter - In-Line Part #: ATP 18721
https://www.napaonline.com/en/p/ATP18721




Premolded hose- https://www.retromotioninnovations.com/products/3-8universalmolded




I also made a curved bracket that fastened to the lower central oil tank bolts. I fixed the filter in place with some rubber to cushion the filter and 2 zip ties. The hose is 3/8" internal and I just muscled it onto the oil junction fitting and the oil tank fitting. The molded hose alone has all the bends needed to do the job.


Here's the timing side:

P1010419.JPG


and here's the primary side view. I still need to trim back the rubber sticking out on this side.

P1010420.JPG


The smooth line in front of the filter is my crank case breather lines from my dual breather set up... The clamps are the double tooth Mcmaster-carr clamps. The molded braided hose is rated for 125* C, which should be good enough.


*Obviously my commando is not spotless nor free from any scraped paint, dirt, nor the occasional oily or rusty nut and bolt. This post is to share the modification and archive an easy way to add an oil and magnetic filter to an early model commando with the central oil tank. (thanks as always to Jim)
 
Last edited:
Joined
Sep 5, 2015
Messages
9
Country flag
I really like this idea of using the transmission filter instead of mounting an oil filter head somewhere. I am going to look into this. Your air filter is squashed. They do make a filter that fits into that space. I had the same problem and found the other filter and got rid of the crushed one. I used the same sintered brass filter on my Honda CB 750 and the thing stalled out on me from lack of fuel. Took it off.
 
Last edited:

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
13,317
Country flag
I ran one for a few years. For reasons I can’t recall i reverted back to a cartridge type.

Squeezed mine in here...

21E6FAA6-5A9E-4981-8ADE-D58E102158DB.jpeg
 
Joined
Apr 27, 2015
Messages
1,659
Country flag
I really like this idea of using the transmission filter instead of mounting an oil filter head somewhere. I am going to look into this. Your air filter is squashed. They do make a filter that fits into that space. I had the same problem and found the other filter and got rid of the crushed one. I used the same sintered brass filter on my Honda CB 750 and the thing stalled out on me from lack of fuel. Took it off.
The air filter is not crushed, just bent up from handling. With the central oil tank I had to "muscle" the air filter into place because there is only exactly enough space for the filter body in the space between the carbs and central oil tank once the rubber boots of the filter slip over the carb body intakes. The bike runs well so the mangled air filter wire seems to have no effect except to make my bike more "ratty" looking... which doesn't bother me at all.

.
 
Joined
Jan 5, 2019
Messages
1,794
Country flag
I would really love to try that filter setup.... First I have to figure where to move my after market horn to because that nest belongs to it. There's only so much room on a Commando for all these pretty trinkets..... I can tell you where the horn isn't going though.
 

DogT

VIP MEMBER
Joined
Jan 20, 2009
Messages
7,236
Country flag
I dunno. I put the new filter on the cradle, it seems to work fine, and I still use the original ham can filter. But I do have a modified breather from the central oil tank which I won't get into at the moment. I'm partial to original look.
 
Joined
May 5, 2017
Messages
278
Country flag
In the never ending saga to have more modifications on my 70 commando than anyone, I added a transmission filter to my return oil line. It was a simple project who's details were recommended by Jim Comstock as a alternative to adding the late model filter kit parts...

Parts:
NAPA Automatic Transmission Filter - In-Line Part #: ATP 18721
https://www.napaonline.com/en/p/ATP18721



snipped
I'd like to ask you to cut that filter open when you do your next oil change. I ask because ATF is considerably thinner than 20W-50 or straight 40 weight motor oil. Check to see if the filter element is deformed by the more viscous fluid. I really like ATP products. I ask for them by name when working on customers vehicles. Jim has probably already researched this and verified that the filter will hold up. That oil hose is perfect!
 
Joined
Sep 5, 2015
Messages
9
Country flag
The air filter is not crushed, just bent up from handling. With the central oil tank I had to "muscle" the air filter into place because there is only exactly enough space for the filter body in the space between the carbs and central oil tank once the rubber boots of the filter slip over the carb body intakes. The bike runs well so the mangled air filter wire seems to have no effect except to make my bike more "ratty" looking... which doesn't bother me at all.

.
Yes I know the exact filter you are referring to. I put my Amals back on so I am probably going to put on a proper one. They have come a long way in 10 years !
 
Top