Transaxle oil cooler pumps Options

[pcar916]

Now there's some empirical data. John, what was the lash on those big R&P's and what was the diameter of the rings?

I just had my first R&P failure in the past 16 years and it was while I was pouring on the coals 120 miles from home. It acted strangely as well because up to 38 mph (GPS) it was completely quiet. Above that was very noisy. There were two broken pinion teeth adjacent to each other.

The regular noise variation told me the mesh area was moving as the speed went up, so perhaps the R&P got spread apart briefly by a broken tooth and the case got tweaked. When I put together another gear stack the diff carrier wouldn't preload with the same spacer/shim package.

I've cleaned up another case for the rebuild because although I don't see any cracks, Like you said John, I don't want to see this anymore, so the oiling system is required as far as I'm concerned. I'm convinced if I had one already this might not have happened.

[john rogers]

Good question about the oiling of gear assemblies and it applies to both a ship's reduction gears and our transmissions. In our case we start out with the splash lubrication only and by adding the squirters we increase the "splash" of oil on the most important areas, namely the R&P and gears. A side benefit is the cooling and when I was racing, I found that when trans temps got over 240 or so that shifting would get harder and harder, even with Swepco oil. The cooler kept the temps below 210 even when racing in Tecate MX in August. The bearings we have are sloppy when compared to the ones in a Navy reduction gears and in those cases the oil is pressure fed to the bearing and also splashed on the mesh area so everything gets it's share of oil.

The clearances of the R&P can change due to the flex of the side plate and I remember seeing several transmissions that had an aftermarket one that was much stiffer but I am not sure if they are still available any longer?

[pcar916]

Aftermarket (billet) side plates are available for the 915 but I don't remember seeing any for 914 boxes. I'm going to put on a late 915 side-plate on the early mag case diff section because it is truly stiffer with both extra webbing and made of aluminum instead of mag, but the early mag covers are just a slab.

I don't know if the billet side covers are worth the extra money for only 300hp and the associated torque. But I might want one when this engine gets tired and I tweak it a bit. I'm thinkin' 400 hp sounds nice "and will suffice" for at least an hour or two before I want more. I'm fortunate to have some extra cases (and stuff) lying about to build with so I can experiment... just need more time right?

[john rogers]

Well, for various HP ratings, Black Forest in San Diego and their race mechanic and at two other shops used this rule of thumb:

100 to 140 HP just keep the bushings and parts tight.

140 to 220 HP use a cooler and you could get 2 years of racing if you were careful.

220 to 300 HP use a cooler and rebuild at the end of the year for sure or sooner. Note a 915 can be used but over an average of 10 years of racing the total cost is nearly the same.

300 HP and up use a Turbo transmission especially if over 350 HP with a lube system. The 914 Bonneville car that had 850 HP used a Turbo 4 speed and cooler setup and never had transmission issues although it kept spinning out when the NO2 was cut in at 185 MPH or so!

[pcar916]

... 220 to 300 HP use a cooler and rebuild at the end of the year for sure or sooner... 300 HP and up use a Turbo transmission.

Well I'm out of the envelope by those guidelines and should have used a cooler since 1994! But after an upcoming hp upgrade on this 993 engine I do think about an inverted short-bellhousing G-50 since it bolts right up, and suck up the large axle/cv angle and the associated hp loss. But it's SO darned heavy and I have these others lying about that I already own. Regardless, I'll always have a cooler/filter system from this point on.

The 930 box is probably a smarter thing, it's just those four gears, marginal torque and technical tracks that worries me. But I suppose first gear is irrelevant anyway.

Haven't compared the two latter options but this is approaching OT for this thread. I haven't searched for the G-50/930 specific topic. On the cooler topic again...

I'll post pix of my cooler installation when I get it installed just to tidy up a bit.

The Tilton folks like to mount the pump after the cooler to keep the temps down in the pump-motor below 150F. Anyone experience priming problems using that configuration (with a check valve)? I'll be mounting my cooler with the fittings on top to keep the cooler circuit oil from going into the sump while turned off.

Thanks for all the thoughts in this thread! I've changed my design because of them.

[ottox914]

The location of the pump will make a difference. Gear drive pumps, like these: http://www.rbracing-rsr.com/oilsystems.htm need a gravity feed- they won't "pull" oil if the pump is located above the lowest point of the oil feed. The tildon style can be mounted above the trans if needed.

I switched from the tildon style to the RB gear pump for the scavenge pump on the turbo 914. Don't know if the tildon was bad or not, but liked the idea of the smaller and more powerful gear drive to be SURE there was no oil backing up into the turbo, as with the low mount of the turbo, there is no roof for a sump.

Just something to think about in the trans application.

[pcar916]

Gear drive pumps... need a gravity feed- they won't "pull" oil if the pump is located above the lowest point of the oil feed.

Now that's interesting. I thought all external-gear pd pumps were self priming (by definition) up to varying heights depending on the pump design. My check valve on the pump outlet will keep oil in the circuit anyway unless it leaks down but by this example since I'm pulling the oil out of the drain plug, I'd have to install the pump down at that level. Am I understanding you right?

[john rogers]

You are correct about the "gear" pump and they are all what we used to call positive displacement and as such as self priming. Some may have such loose clearances that they require priming to get started and they are done that way so they will not seize if the fluid is too cold or thick. One thing I found handy with the Tilton installed in the trunk was to empty the transmission I could disconnect the line at the outlet of the pump, run it through a line to a clean container. We would then filter the trans fluid and once the transmission was back in the car, use a suction line from the container through the filter back into the transmission. NO spills, puddles, etc and very handy.

[pcar916]

... We would then filter the trans fluid...

How often did you filter the fluid?
Did you also have an inline filter?
If you ran a torque biased diff rather than the LSD clutches would you filter less often?

I'm definitely looking forward to not crawling under the car to drain and fill the system after I've arrived at the proper fluid level.

[john rogers]

In the pictures I posted there is a bright red filter near the pump and it is a disk type that can be disassembled and cleaned as needed such as when a trans fails. That is the way Patrick set it up and the continuous filter may help prolong the internals life. One thing we did do was to look at the fluid with a very bright light for any microscopic "gold" which was an indication of a possible bearing failure.

I generally changed transmissions a couple times a year, short gear box (K-Q-V)for PIR, Button Willow and all the Mexico road races and long box (M-S-X) for Willow Springs and CA Speedway. This gave me a chance to check the fluid quite a lot.

[pcar916]

I thought I'd follow up with a summary of the approximate cooling system costs. This assumes you don't have any of this stuff lying about and that , instead of a diaphragm pump, you choose a mid-range gear pump with a catch can etc.

Pricing for hose fittings from Racer Wholesale Parts:
1. Cooler $ 90
2. Fan $ 70
3. Pump $275
4. Filter $ 75
5. Chk valve (1.2lb) $ 40
6. Fittings (-8AN) $308 (mandrel-bent except the vent system)
7. Hose (-8) $ 70
8. Catch can $ 70 (unless you make your own... I did)
9. Controller $ 30

Roughed out it'll be: $ 1,028

Someone out there is going to do this. For some reason I just can't get any new system into Penelope without spending $1,000. (IMG:style_emoticons/default/beerchug.gif)

[john rogers]

Did you give Patrick in Phoenix a call although the price may be higher now as I did mine a long time ago. I would imagine that the cost is 25% or more higher now now matter where you buy the stuff.

You can do some saving by installing in sections, I.E. pump, lines and nozzles first. The do the filter and cooler and it's ducting. Not sure what the "controller" is as I just wired mine to a switch and once I started rolling turned it on. I had a big blue light over it so I would see it and it was powered to run even if the engine was off. The pump can easily handle the cold Swepco so no worries. For a fan I used a small plastic housed axial boat bilge vent fan I bought at West Marine and they sell them on line. I ran when the pump did. Make sure to have a drain on the puke tank and some sort of filtered vent as race organizations want that type of setup. Remember you'll be running 4 qts of fluid instead of 3 so some will splash into the puke tank. Finally I don't think a check valve is needed as it all drains into the trans anyways so that will save a bit of $$$$ too.

But I have to say that after the setup, I never had a trans failure so it was worth it I think!

[pcar916]

I didn't give Patrick a call because I already have a lot of this stuff around now that I've been stockpiling over the last year or so. I'll just have to buy a little more hose, some more hose fittings and a few adapters. Then fab up the catch can and fittings for that circuit.

The controller is a pulse-width unit. Simple, reliable, and I don't have to throw off as much heat as a rheostat would. I figured I'd wire it in so that if I get too much cooling (return oil <160F) I can simply slow down the pump speed rather than break open the cooler ducting to blank-off some of it. If I always run the pump at full-bore I'll install a switch and use the controller for something else, like pushing the cockpit heat from my front oil cooler in the winter time. I use a 4 in bilge fan on my front heater system too. Good value that.

I am going to install the pump motor in moving air as it doesn't have it's own fan. Whether that turns out to be in the wheel well or upstream of the cooler fan housing I don't know yet. The specs on the pump read that it's top operating temp should be 150F.

Since the oil going through it will be hotter than that, there will be heat conducted from the pump housing into at least the output bearing and the lower half of the motor. Maybe that's overkill but I'm starting with a clean slate so it's easy to avoid that potential problem.

The reason for the valve was to avoid letting the pump lose it's prime. Even though it's self priming it makes me feel better. As to the extra oil, I thought it would be a potential leakage problem (i.e. output flange seals) if a lot of oil went back into the case.

[john rogers]

Generally those pumps can handle the gear oil temps we have with no issues. The extra quart of oil will not cause any leaks unless the input shaft seal is worn a lot and/or you park on a very steep downhill grade all the time. I never experienced any leaks or weeps during the years the system was installed. I would not worry about getting the temp too low unless you are racing in snow as the exhaust will keep everything back there toasty warm!

Patrick does sell a couple of handy transmission related items, one is an aluminum adapter that replaces the speedo drive and has a VDO sender matched to a temp guage. Another is an hi temp reversing wheel for the clutch cable which will never get soft or wear out. I used both items and they were very handy. I did have one of the factory wheels get smoochy in a race in Mexico and the cable came off and scared the hell out me as I thought I'd broke a trans or clutch!

[pcar916]

... or you park on a very steep downhill grade all the time.

... the exhaust will keep everything back there toasty warm!

... speedo drive and has a VDO sender matched to a temp guage.

Funny you should mention the grade. My driveway is extremely steep. But the input seal has never given me a problem.

That exhaust is always an issue. It's so close to my oil return hose that I'm sure I get a significant engine-oil heat jump. I put in an additional cooler (sandwich adapter) at the oil filter console behind number six.

I turned an aluminum, double o-ring plug to block off the speedo drive hole and considered putting a temp sender in it. But I though it might not give me the temp I really wanted which was in the R&P or main gear chambers. You think it would be close enough? It's an elegant place for one and easy to drill and tap.

[john rogers]

The temp setup Patrick sells uses the speedo hole. It seems the case transfers the heat pretty well and I have seen temps get to close to 300 degrees and that is when you have to be very careful with shifting as it gets harder.

[Randal]

I thought I'd follow up with a summary of the approximate cooling system costs. This assumes you don't have any of this stuff lying about and that , instead of a diaphragm pump, you choose a mid-range gear pump with a catch can etc.

Pricing for hose fittings from Racer Wholesale Parts:
1. Cooler $ 90
2. Fan $ 70
3. Pump $275
4. Filter $ 75
5. Chk valve (1.2lb) $ 40
6. Fittings (-8AN) $308 (mandrel-bent except the vent system)
7. Hose (-8) $ 70
8. Catch can $ 70 (unless you make your own... I did)
9. Controller $ 30

Roughed out it'll be: $ 1,028

Someone out there is going to do this. For some reason I just can't get any new system into Penelope without spending $1,000. (IMG:style_emoticons/default/beerchug.gif)

Thanks for the bill of materials!

What is the breakdown of the $308 and do you have any PICTURES of something similar?

It always blows me away what it takes in materials to put together racing stuff. (IMG:style_emoticons/default/wacko.gif)

[pcar916]

What is the breakdown of the $308 and do you have any PICTURES of something similar?

Here's a pic below, but some of the fittings, the Spal fan, and a catch-can and it's breather aren't shown. The breakdown is roughly this.

Hose fittings, hose, and adapters:
- 6 -8 mandrel-bent 90's
- 8 or 10 straight's
- 8 -8 adapters to 3/8 NPT
- 1 8 ft section of -8 hose
- 2 -6 straights
- 2 -6 mandrel-bent 90's
- 2 -6 adapters to 1/4 NPT

I'll probably add a couple of -8AN couplers since I found some other fittings I already have out there and the filter housing is already -8AN.

Notice that there is a -8 to 3/8NPT adapter fitted into the drain plug, which means there isn't a magnet in this system unless I want to attach one or two to the filter housing. I'm relying on the oil to carry the crud into the filter element. But I might also epoxy some strong neodymium magnets onto the case as well.

Everyone's gonna route their systems differently and the equipment will be different, so I wouldn't put to much stock in this list since it'll be specifically my install, but you're right. It's expensive, but it saves gearboxes.
Good luck.

[stewteral]

I thought I'd follow up with a summary of the approximate cooling system costs. This assumes you don't have any of this stuff lying about and that , instead of a diaphragm pump, you choose a mid-range gear pump with a catch can etc.

Pricing for hose fittings from Racer Wholesale Parts:
1. Cooler $ 90
2. Fan $ 70
3. Pump $275
4. Filter $ 75
5. Chk valve (1.2lb) $ 40
6. Fittings (-8AN) $308 (mandrel-bent except the vent system)
7. Hose (-8) $ 70
8. Catch can $ 70 (unless you make your own... I did)
9. Controller $ 30

Roughed out it'll be: $ 1,028

Someone out there is going to do this. For some reason I just can't get any new system into Penelope without spending $1,000. (IMG:style_emoticons/default/beerchug.gif)

Hey Pcar916,

I see that you have been working over the whole issue of trans cooling very diligently, but am left with ONE basic question: do you have empirical DATA so you KNOW your trans oil temp will run TOO HOT and that you MUST have an oil cooling system?

You could find, as I did, that all that extra hardware is just NOT necessary.

Best,
Terry

[ChrisFoley]

I'm planning on installing a trans cooler in my 1.8L race car if I ever resume racing at the National level.
I have no empirical data on which to base my decision - only experience.
What I do know is that shifting becomes more difficult the longer I'm on track.
To me, the most logical cause is transmission temperature.