discussion on manual transmission cooling

[lostforawhile]

I was wanting to start a discussion on the benefits of cooling the manual transmission, I've been doing a lot of researching on this, and apparently it's pretty common on high performance cars, with the fifth gear issues, this may be a solution to two problems at one time, if someone is driving one of these cars to the grocery store, it's probably not needed, but many people here like to drive these cars hard, in that case the transmission is generating a fair amount of heat, put them on the track or at an autocross, and they really heat up, the solution is to circulate the oil through a filter and cooler and back to the transmission, the easiest way I can see to do this, is to drill and tap the center of the drain plug, for an AN adapter or a pipe thread adapter, and remove the fifth gear cover, and braze a fitting directly to it, this would allow oil to flow to an inline filter by gravity and into an electric pump, then be pumped through a cooler, and into the fifth gear cover, where it would flow back into the case, cooling the fifth gear in the process . I've been looking at pumps, and the main issue is the price, one solution I've seen mentioned numerous times, is to use a Holley red fuel pump, the pumps are supposed to be all metal inside, and only pull two amps, they run about 7 psi, lightweight small oil coolers are easy to find, and could be mounted in airflow, and the all metal inline filters are small and light weight, one thing that was a concern was using the pumps with heated oil, but I don't think the tranny oil will be hot enough to make a difference, the argument was using them to circulate engine oil to a turbo, that's much hotter then the transmission oil will ever get

here's a really interesting article dealing with inline pumps and some they offer, but at a very high price http://www.rbracing-rsr.com/oilsystems.htm

[MessyHonda]

the A20 trans has other weak points.


1. differential is likely to break before it overheats

2. no A20 engine is strong enough to even overheat a trans. it does not freight truck pulling lots of weight.

3. the more oil lines you have the more it can leak. if it leaks its worse than having no fluids at all

[stat1K]

done right i don't see a downside to this, done poorly i see many. however, while it's not the worst idea you've ever had i do believe it to be unnecessary. the issue with fifth gear is more of a design flaw coupled with neglect. as long as the transmission is filled and filled with the proper fluid there shouldn't be a problem.

now as for a racing application sure you could do this, but being that several honda guys race cars with much higher output and more expensive transmissions and still don't do this makes you wonder if it would ever really be necessary. very few times have i ever touched my transmission and it been hot to the touch. granted the fluid does get pretty warm, but again i don't feel it hot enough to matter.

[Dr_Snooz]

as long as the transmission is filled and filled with the proper fluid there shouldn't be a problem.


I agree. The fifth gear problems come from too little oil. Not too much heat.

[w261w261]

File this under "Don't fix it if ain't broke."

[stat1K]

File this under "Don't fix it if ain't broke."

it wouldn't be tim's car otherwise.

[Hauntd ca3]

i can see the point of cooling the gearbox oil if you were building a race car, but for a road car that might be used for autocross or even track days, its probably not worth it other than for just an exercise.
at a track day for example, you might be going hard for 15 or 20 minutes at a time. the oil might get warm, but not to the point of losing its protection qualities. and most track day guys just run a bit more oil in the gearbox or run a heavier weight of oil.

[lostforawhile]

the A20 trans has other weak points.


1. differential is likely to break before it overheats

2. no A20 engine is strong enough to even overheat a trans. it does not freight truck pulling lots of weight.

3. the more oil lines you have the more it can leak. if it leaks its worse than having no fluids at alleverything I build is AN, so I'm not too worried about leaks, a warning lamp if loss of pressure would warn of a major leak


done right i don't see a downside to this, done poorly i see many. however, while it's not the worst idea you've ever had i do believe it to be unnecessary. the issue with fifth gear is more of a design flaw coupled with neglect. as long as the transmission is filled and filled with the proper fluid there shouldn't be a problem.

now as for a racing application sure you could do this, but being that several honda guys race cars with much higher output and more expensive transmissions and still don't do this makes you wonder if it would ever really be necessary. very few times have i ever touched my transmission and it been hot to the touch. granted the fluid does get pretty warm, but again i don't feel it hot enough to matter. the idea wasn't just for heat, but to run the fluid through a filter, this would catch any debris that might be floating in the oil, a regular filter check might warn you of a problem before a major failure, if the oil was run back into the fifth gear cover, this would provide additional lubrication to that area, the cover would stay full of oil and the oil would have to flow back to the transmission through the fifth gear area. the pump I looked at is only 8 psi, so the gasket would contain it just fine


File this under "Don't fix it if ain't broke."
well right now it's just a discussion, but this may provide extra oil to that fifth gear area, which can fix a problem that already exists

[lostforawhile]

is the fifth gear cover just a flat gasket? I can't remember, mine is leaking slightly anyway, So I may remove it to see how this is set up in there, it's been a while.

[89T]

The fix to the 5th gear problem is to oversize the oil passage. done.

Where did I put that EASY button?

[lostforawhile]

The fix to the 5th gear problem is to oversize the oil passage. done.

Where did I put that EASY button?
like I said it's just a discussion right now, this is also to filter the oil, one of those aluminum inline filters that screw apart is perfect, they have a sintered bronze element, unscrew the filter from time to time, and check for debris

[carotman]

Honestly, before doing this, I would put a temp sensor in the transmission. As far as I know, no one ever did monitor the manual trans oil in a 3G.

If the oil never gets hot, there's no point in cooling it. If it does... well then cool it :D

[lostforawhile]

Honestly, before doing this, I would put a temp sensor in the transmission. As far as I know, no one ever did monitor the manual trans oil in a 3G.

If the oil never gets hot, there's no point in cooling it. If it does... well then cool it :D

,if it doesn't need cooling a simple circuit just to filter the oil would be useful, I plan on having mine rebuilt before the car goes back on the road, since it's off the road, it's the best time to do it, I can put it in the trunk of the Lincoln and take it to man trans in Tallahassee, Snooze also used them, very good very experienced re builders, once it's rebuilt I'm going to protect it. I need to search some info on tranny temps, most manual Honda transmissions will probably be very close, they all use the same basic parts, and are constructed about the same, not interchangeable, but the same basic type parts, most front wheel drive manuals are similar, so they should be the same or close enough for an idea, one thing to remember, you have the transmission and differential in one case, running the same oil, so they will get hotter then a manual in a rear wheel drive, with a separate differential, think of the combined heat of the transmission and rear end together,

[1813mdw]

i think the filter is a good idea for sure. many cars and trucks come w/ this factory. subaru's used to have them on pretty much every vehicle they made. they used regular oil filter/spindle setup, though i don't know how the trans fluid was circulated.

[lostforawhile]

the best answer i've been able to find on temp is the average manual runs about 90 degrees above the ambient temp, if it's a hundred degrees out, thats pretty hot, I would guess the hotter it gets out, the harder it is for the manual to get rid of heat, all of the heat they generate is removed by it transferring to the transmission case via the oil, and then heat transfer to the outside air, not very efficient, so the hotter it gets, the less temp difference there is for heat transfer. I think a small cooler with the pump operated with a temp switch would be very helpful. if you've ever put your hand on a differential in a rear wheel drive car, after a long drive, it's pretty hot, it's the same in a trans axle, but all that heat generated is inside of the case with the rest of the transmission. what got me thinking about this thread, is I've noticed how hot our manual lathes get at work, they aren't loaded nearly as much as the gears in a car, but they are basically the same inside, basic gears and linkages lubricated by splash. after running for a while they really heat up, whats happening in there is identical to the inside of a manual transmission, and it's not loaded nearly as much, Another thing to remember, is manuals generate very fine metal particles in normal use, these tend to form a paste with the oil, and get stuck in crevices and oil holes all through the gearbox, if they are removed as the transmission is operating this is going to help extend the life of the transmission

[MessyHonda]

are you rebuilding your transmission or are you going to do it to your 150+k mile trans?

im with alot of people here. if its not broke dont fix it. i know you will do it so go ahead and make it. remember to take lots of pics and paint it purple

[A18A]

i know you will do it so go ahead and make it. remember to take lots of pics and paint it purple

haha lol

[lostforawhile]

are you rebuilding your transmission or are you going to do it to your 150+k mile trans?

im with alot of people here. if its not broke dont fix it. i know you will do it so go ahead and make it. remember to take lots of pics and paint it purple

I was planning to have it rebuilt by man trans down in Tallahassee,it's got a lot of miles on it,

[MessyHonda]

how much driving will you be doing to make this project worth it? going up hill, pulling a load, racing, or just driving down the street because there is no gas money...honestly for me its easier to pull a 3/4 ratchet to pull the plug and fill it back up with honda mtf. like i said go for it and take lots of pictures

[lostforawhile]

how much driving will you be doing to make this project worth it? going up hill, pulling a load, racing, or just driving down the street because there is no gas money...honestly for me its easier to pull a 3/4 ratchet to pull the plug and fill it back up with honda mtf. like i said go for it and take lots of pictures
i do pull a trailer a lot, so that may make it worthwhile, the main thing is when I put the rebuilt transmission in, i'll know the oil will be filtered from day one, this really isn't that big of a deal for me to do, I may even have a small 12 volt oil pump somewhere in my stuff, al the lines,fittings etc, I already have them. I'm trying to have this on the road again within six to eight months, I have a lot of the major stuff figured out, and almost done, it's just a matter of finishing up one or two steps on each thing. for example, as soon as I can get my muffler packing and a piece of stainless tube, I can have my entire exhaust finished, same with the fuel system, i'm lacking one fitting to being able to finish it. Most stuff is at that stage, I try to work on it when I can, but I'm having to deal with a lot of BS at home too.

[1813mdw]

its hard to argue w/ the idea of filtering the fluid; a simple drain and fill will never get all the shavings and gunk that builds up. as for the "if it ain't broke don't fix it" mentallity, if that was the case everyone one this site would be driving completely stock 3gees w/ nothing but replacement parts. it will help add to the longevity of the trans that he drives in georgia(hot as hell) and tows a trailer with. no its not absolutly(spelling) needed, but neither is a lip or rims or...

[87roach]

If you pull a trailer a lot you should get another vehicle.

If you keep adding thing's to your car you'll never drive it.

[lostforawhile]

If you pull a trailer a lot you should get another vehicle.

If you keep adding thing's to your car you'll never drive it.

i've towed a small trailer for years, when this car is done, i'm going to build one of those mico trailers, basically a motorhome with just enough space for a couple of benches and a table that convert into a bed for two people, they are built on mini utility trailer frames, very light, and small, we are going to go around and visit members so this will be our tiny house on wheels, they have towed this type of trailer behind VW bugs for decades, and they had a lot less horsepower. My wife and I pack very light. I don't think it will be an issue, anything heavy will get towed behind the lincoln. this is pretty much the last thing i'm adding, i'm trying to finish up everything to get it rolling again

[87roach]

I get what you're saying about the trailer, I see them all the time in the summer on rods. They can be neat if done right, good luck.

[lostforawhile]

I get what you're saying about the trailer, I see them all the time in the summer on rods. They can be neat if done right, good luck.

I have tons of sheet aluminum put up, and all it is is a light weight wood frame in the shape of the trailer with aluminum over it, and sealed up, you can get the utility trailer kit from northern for just over 150, I even have some 14 inch alloys with tires that fit that pattern. I can go to the junkyard here and get motor home windows, interior stuff etc for nearly nothing. i"m setting a goal of not over 300 bucks to build the whole thing,

[MessyHonda]

ok i hope i just see your car running again...i also tried to make things complicated but now i just want a working car.

[lostforawhile]

ok i hope i just see your car running again...i also tried to make things complicated but now i just want a working car.
i've been getting a lot of stuff finished, there were times when I wasn't able to work on it for a long time