R21 Gearbox cooler

I didn't get much of a responce over in the GTD section so I just started fabing up some parts. Here's some pictures.

The first one is the pump mount and then the next couple are with the pump mounted on it. You can see the filter also. I didn't use the flat mount that came with the pump. The two little sheet metal screws that hold the pump onto the mounting plate looked like they would last about 20 mins so I replaced it with a really cool clamp mount.

The next couple are of the cooler mount. This took a couple of tries but in the end what you see here is very stable and stiffened where I could see cracks might form. A little backyard engineering.

The last picture is where I pull the oil out of the box at the drain hole

I need to finish some more stuff tommorrow. I'll post some more pictures then.

I'm liking this Howard, keep it coming!

Howard,

I've been watching your thread on the GTD Forum anxiously. This is good stuff for me since I'll be doing nearly the same thing soon.

Thanks,
Lynn

Im putting a cooler on my R21T box as well. I havent decided on a place to mount the pump yet. The cooler is to one side of one radiator (lambo has 2). The air is ducted to go out via the engine bay.

My takeoff point for the oil is not in the oil drain hole but in a new hole I put in on the other half of the case. as the case is around 5mm thick, I needed more 'meat' to secure the output to. I welded a 3mm plate onto the back of the area of the hole and then run the NPT tap into that.
For the return, I done the same with the hole, eg: 3mm plate and tapped. My position for this was on the rear gearchange/5th gear cover. The inlet is aimed directly at the 5th gear, as this is the most stressed gear in the box. The theory is for the cool oil to run from one end of the box to the other.
I am currently looking at a place around the crownwheel area so I can spray cool oil directly onto the crownwheel (via a 't' junction from the pump).
The only other thing will be a temperature sender mounted in the differential area.

Here's a couple of shots from the top. I tried to keep all the hoses short so that there would be less weight on the fitting at the pump. The pump housing is a plastic composite material and so you need to be careful with the threaded ports.

You can see that the top of the gearbox has two return lines. One on the right returns right at the top of the ring gear. The other returns right onto 5th gear.

Here's a good picture of the back of the cooler mount. The webbing is added to give it rigidity and is also used as a mounting point for the brace.

The closeup is of the return to the ring-gear.

And the last one is a shot of the rear of the car. I tried to get it into the exaust air flow form the engine bay. After I get a temp gauge installed I'll see if I need cool air form under the car. If so then I will work out some ducting. There is such a low pressure area at the rear behind the spoiler that I am not sure which way the air flows in this area.

Looking good Howard....I too agree, feed 5th geat first then add the diff crownwheel spray as a second..rockonsmile

Howard,

Tape some 2"-3" pieces of brightly colored yarn along the edges of the vents and then have someone follow you and tell you what they are doing. It might even be interesting to have a taught piece of wire across the middle of the opening with the yarn tied to it. Sometimes the edge may cause atypical flow and the middle of the opening could be doing something quite different.

Lynn

Howard,

I was looking at all of the pictures to try to figure out how you have the reservoir tank plumbed in. Is it: bottom of tranny -> bottom of reservoir -> top of reservoir -> filter -> suction side of pump ?

Lynn

Lynn, the tank you see sort of above and right of the pump is the expansion tank overflow catch can. The tuffs idea is a good one, I have been meaning to do this at the rear of the car for a long time. Just so many things to do higher up the list.

Howard,

OK, its for the radiator. I've been kicking around the idea of a some sort of reservoir oil tank in the system for a couple of different reasons. The obvious one of more oil holding more heat, but also giving it somewhere to rest and let particulates fall out, perhaps aided by magnetics, in a location other than the transaxle itself. If located properly, it could also provide a very quick and easy way to monitor the oil level in the transaxle.

Lynn

Howard,
Super job!!
Where did you find that clamp/bracket combination? It looks considerably stronger than the clamps typicly supplied with pumps, filters, reservors etc.

If I am not mistaken, they are T clamps that can be ordered from most any aftermarket shop. If you are industrious you can go to a muffler shop and they should have some just laying around that you can get for NADA. Just have to make sure they are the right radius.

Bill

Lynn, I don't really think that more oil volume is necessary. The main thing is to keep it cool and get it to the high heat generating areas inside of the box itself.

If you only wanted to add more capacity then I would place a reservoir in position so that the full line in you new reservoir is the exact same height as the full line in the gearbox when it is topped off.

Then I would attach a hose, no less than -6 to the drain hole of the gearbox and run it to the bottom of the reservoir. Vent the top of the reservoir to the fill hole in the gearbox.

A fill cap could be added to the reservoir as well as a dipstick.

If you use a cooler/ spray system and pump then you will need seal the reservoir and plum it in series with the cooler. I would mount it below the full line in the gearbox. This will keep it full all the time without drain back issues. Draw oil from the reservoir through a filter then to the pump then through the cooler back to the gearbox via the spray system. Any added capacity will not effect the full line inside of the gearbox this way.

My gearbox has just at 1gal of oil in the system now. If I was to add a reservoir later I would think that about a 1/2 gal more would be about right. Any more and the reservoir starts to get fairly large.

I don't think a reservoir is necessary. You could use a remote engine oil filter as a system filter and gain a quart or so that way. I didn't do this because I was worried about whether or not the pump could pump through a engine oil filter. I used a simple screen in-line filter.

In the end room will dictate what you are able to do. Not much room back there down low like that.

Post pictures of what you come up with.

Those clamps are excess quantity work related donations. But you can call HRP at 866-851-7223 or Pegasus at 1-800-688-6946. They are the same type that are used on Accusump systems. They are smaller in diameter all though. Many sizes are available.

I had the back of the car off so I took a couple of more. Here's a good one of the port for 5th gear, and a better shot of the cooler mount without the bodywork in the way. Lastly a over all form the top showing the two return ports and their pluming.

First bit of data came in today. Outside air temp about 70F. Ran car down freeway about 15 mins at 75-85mph. Got off freeway and ran through Niles Canyon at relative slow speeds (traffic) for about 10 min. Oil temp in gearbox at this point without running pump yet aprox. 125F.

Turned off Niles and onto ------- canyon (testtrack) ran pretty hard for about 10mins in 2nd and 3rd gear. Engine speeds up to 6K a few times in second and 5K in third. Oil temp in gearbox now 180F ish. Ran pump/cooler for about 2 more mins at same pace. Oil temp in box down to about 160F.

At end of (test track) 5 min later Oil temp in gearbox remained at 160F ish.

It's really gonna take a long hard hot run to get above 225F or so. Not hot enough air temp yet to really see how good this works but it does work.

I should note that the temp sensor for GB oil is in drain hole fitting. I made a big "T" fitting that get good circulation around sensor as oil is pumped out of box. Sensor is selected when pump is on. Otherwise I use the gauge to read engine oil temp.

No leaks all well.

Hi Howard,
Just read up on your oil cooling project. Iam about to do the same to my UN1 4sd mated to a Nissan GTiR Turbo for Offroad racing buggy. What pump do you use as a oil transfer and can you recommend oils.
Regards Peter

This pump is sold by several different companys such as Mocal, Tilton, Wilwood, etc. You can get the Tilton version from Summit racing. I found a suplier in the midwest USA and it was $135 but that was a while ago. I can't find the name anymore either. The pump price ranges from $150-$200. They are all the same thing really, just different lables on the stickers. Everybody is using the same part and putting their name on it. Shop around.