R75/5 oil Cooler

[Knifemaker]

I am thinking about adding oil coolers to my 1972 R75/5. I know they do not come with them. Can someone give me an idea about the procedure and installation on doing this and maybe some helpful hints on where to find the items necessary to do this.

[Boffin]

Many years ago I added an oil cooler to my R80/7. The kit used a modified oil filter holder that routed the oil out on flexible hoses to a cooler mounted at the front of the engine and back in again. I believe that this was a BMW factory mod kit, so they should be out there somewhere. It has the advantage of being a clean and easily reversible modification.

 

Andy

[Paul Mihalka]

Standard mod for a /5 was not a oil cooler but a deeper oil pan. Or by actually a new pan or a about 1" spacer to lower the stock pan. They have to come with a spacer to lower the oil pickup of the pump. About 1 quart more oil and if it is a new pan, more fins to cool.

[tallman]

Standard mod for a /5 was not a oil cooler but a deeper oil pan. Or by actually a new pan or a about 1" spacer to lower the stock pan. They have to come with a spacer to lower the oil pickup of the pump. About 1 quart more oil and if it is a new pan, more fins to cool.

 

 

Agreed.

 

I don't know I saw a cooler until the RT's.

My 1980 had one.

Trying to recall other's from the 70's but can't.

There may be a way but the pan is surely easier.

[moshe_levy]

Paul-

 

From reading Tom Cutter's posts on the subject on the Airhead list, I always thought the point of the deeper pan was to lower the oil level away from the crankshaft, thus reducing windage. It also serves to reduce oil temp by a couple of degrees, at most. By adding more oil to the lower pan, the windage issue is right back front and center again. As I understood it, you add the deeper pan but keep the oil level the SAME, at 2 quarts, for the mod to function properly.

 

 

 

First Q that nobody asked yet, is why the OP needs an oil cooler in the first place. Why is this being considered, exactly?

 

-MKL

[HairyCannonball]

Well, the spacer (Oil pan extension) I used back in the day had tubes running through it front to rear to cool the oil also. Came with a spacer for the oil pump pickup, and longer bolts. The drawback to a deeper sump is you either have to modify the crosstube on the centerstand ( lower it), or use a reynolds rideoff. Since I hated the reynolds rideoff stand, and the spacer really offered no improvement I took it off and have it stored away somewhere. I probably only ran it a couple hundred thousand miles on my /5. Probably sitting inside the pristine wixom trunk I have stored away, which is probably sitting in my basement next to the Vetter 4 fairing i had the audacity to put on my bike at one time

[moshe_levy]

Mmmmm. You could also simply use a centerstand from a later airhead that had the deep pan standard. Saves time from modifying a /5 stand.

 

-MKL

[HairyCannonball]

Mmmmm. You could also simply use a centerstand from a later airhead that had the deep pan standard. Saves time from modifying a /5 stand.

 

-MKL

 

Well, today you could, however back when I was using one of these pans, the /5 *was* a later model airhead

[HairyCannonball]

Actually, thinking about it it seems I might have tried that and there was some reason it didn't work. I believe /5, /6 centerstands were the same, but the /7 was different, and not just that the cross tube was lower. I might be very wrong about this as it was probably 15 years ago, but I seem to remember trying and it would have been to put a spare /6 stand on my '82R100RT. Then again maybe it didn't work because the cross tube fouled on the deeper oil pan on the RT. Hmmm. I dunno for sure now.

 

 

[Knifemaker]

The reason I was thinking about adding an oil cooler is because I am reducing the effective cooling ability of the motor by removing the rough pebbled motor surface and hand polishing the entire motor and transmission surface to a mirror finish.

[HairyCannonball]

Oh dear..Hearing this I feel like I do when I hear someone is going to cut up a pre '79 sportster frame..

[Huzband]

Oh dear..Hearing this I feel like I do when I hear someone is going to cut up a pre '79 sportster frame..

 

Wait'll you get a load of the springer front end.

[moshe_levy]

Bill-

 

First let's see if it's actually required, and then go through it. I think you may be overestimating the effect on cooling of what you're planning to do to that motor.

 

-MKL