Overfilling Transmission

[Old Smoky]

I have heard that it’s beneficial to overfill the Getrag by one quart. The added oil makes sense, but is this too much? Like in an engine, too much oil is a bad thing. Cavitation, and pressurization, are concerns I have with this. I would like to help my transmission last as long as it can, so I don't want to do anything that would reduce lubrication, or blow out seals. I know many have done this, but does anyone actually know if it helps? I would think that this has already been considered, and that I am worrying over nothing. It is about time to change the oil in it, so I need the facts. Also, what oil is recommended?



Mike

 

[JFitzgerald]

Mike, I've been doing this for the last two oil changes. I already had a very small leak from the trans, and it hasn't gotten worse, or better. The trans seems easier to shift. The trick is knowing your oil level after overfilling, so I installed a window. Take a look at this post. Others have had good results from doing this over a long period of time, and maybe they'll chime in.



I'd also consider adding a magnet and/or a Geno's filter while you're under there.



My manual says to use 5W30 synthetic, and I've been using Mobil 1. The manual also says it doesn't ever need to be changed.

 

[Old Smoky]

Thanks for the info JFitzgerald. I don't need to change the oil in the transmission? Well, that sure makes everything easy. Right Hopefully mine will shift a bit easier too. The window is a good idea.



How did you get the extra quart in? Did you have to remove the shift tower? That seems to be about the only way to do it.



Thanks

Mike

 

[JFitzgerald]

Yes, I removed the shifter. A little bit of a pain, but not bad. When I start to think it's a pain, I think about having to rebuild/replace the trans, and then it doesn't seem so bad. Another way to overfill that I read about was to add a couple nipples, an elbow and a cap to the fill/check hole on the trans. I just hate trying to pour oil in from below, so going in from the top is my preference.



A pair of beefy snap-ring pliers will help in removing/replacing the shifter, but it can be done without them.



I'm thinking Lil' Dog is one of the guys who has been overfilling his Getrag for many miles, and no problems.

 

[rwinslow]

My two cents worth: I have been overfilling by one quart for most of the life of the transmission. I have also been changing the oil in the transmission every 6 months. I originally used Mobil 1 5W-30 but have switched to Castrol Syntec 5W-50 for winter driving. (I like the Grp 3 Base Stock in the Castrol product better than the PAO Blend Base Stock in the Mobil 1 product for gear box application. ) During summer operations I use a non-sulfated EP gear lube at 75W-90 viscosity rating and over fill by one quart. This lube produces the smoothest shifting.



I have yet to perform a rebuild on the transmission. Seals are staying dry. Regularly tow 10,000 lbs over mountain passes, etc. Overfilling by one quart on this particular gear box will not result in churning or over-pressurization (the transmission vents out of the shift tower). You are correct in stating that overfilling of engine crankcases can result in significant lubricant issues, but not on this gear box.

 

[JBrookshire]

Just do it

Just do it and ask Questions later!!!! Not to be smat but I have had mine rebuilt once then out again gor a new imput shaft. That is when I did a search on GETRAG and find out the fill level is to low and had to spen 200$ more on it. The reason for the imput shaft was lack od lubercation. I used moble 1 syn in mine. I have nottice it is alot quiter and smoother. This will help you get that million miles out of that truck, at least that is what I am shooting for?????:-laf





Justin

 

[Old Smoky]

Well, it sure sounds like a worthwhile "mod". I should also change the oil in the front end, rear end, and transfer case while I'm at it. It’s been a while, and I can get it out of the way in one day. Are there any tricks with the other fluids?



Mike

 

[Tim1]

overfill

I liked the idea of an extra qt. of oil also. I did what was posted some time ago. I used a schedule 80 nipple and a 90 degree steel ell and a cap in the side of the fill hole. I ran the truck up a bank and scooted under and added the oil with a small hand held pump availble at any parts store to add the entra oil. The nipple goes in the hole in the gearbox. Don't use brass. I think it sounds better and it gave me piece of mind. Tim

 

[justduneit]

Hey, Timw:



I like your idea of the pipe nipple and ell - could you tell me what size you used? I'd like to make that mod on my Getrag so I can put an extra quart in it.



Thanks,

Keith

 

[justduneit]

Sorry, Tim1! I fat fingered your name -

Thanks again -

Keith

 

[rwinslow]

One thought for those of you adding a nipple, elbow, and cap to the side of the transmission. Be sure that this additional plumbing hardware is not vibrating excessively with the engine running. When the engine at idle, very carefully look at the nipple and elbow and make sure that the extra hardware is not vibrating like a tuning fork. Sometimes, when items like this are attached to the side of a gear box a resonant vibration condition will develop and the nipple, etc. will crack very quickly. I had this happen several years ago on an oil pressure sending unit on a Honda Civic - what a mess!



I like the ideas of the clear window on the side and the ability to add the extra lube through a location other than the shifter!

 

[Fast 1]

Don't forget you can always park the truck on a slant, then put the extra quart in the factory fill plug, without using a elbow / nipple.



If you have the clear inspection covers, mark them with a permanent marker where you would like to keep your oil level at. Then you will have an exact line for a referance. You can establish a factory fill level (which is to low) or the correct fill level which has one extra quart in it.



Of course the fastcoolers make it really easy to overfill, by using the top magnetic dip plug to top them off with. Normally I sell them in pairs, but I can sell a single one also. (Save you some money) Atleast you would have an easy way to overfill the transmission, and with the cover would let you see whats going on in their



The getrag uses 10 mm bolts instead of 3/8 " bolts. Make sure you get the 10 mm. ones for the getrags.



Geno's, Piers, Riley's, Engine Enterprises, ADT. AutoWurks. Huckstrorf, BlueChip, J&H Performance, Bluementhals, Consolidated Trans, Wildcat Diesel, Schields, Truck & Trailer works and others carry them. (Sorry if I forgot somebody. )



These vendors are the best



www.fastcoolers.com



Verlyn Fast

 

[Tim1]

pipe fittings

Hey Kieth, I'm not sure of the size right off hand,however it is just pipe, so pull the plug and run a tape across it. Be sure and use schedule 80 nipple for the strenght. This is simple to do and I really didn't check to see if I could get the extra oil in there without the parts when I had it on a slant. May go then you wouldn't need the parts. It is quietier now and that is a relief. Tim

 

[Old Smoky]

Well, I did it. I changed the fluids in the front and rear end, transmission, and transfer case. Some have said that they have noticed an improvement in shifting, etc. with an extra quart in the transmission, I noticed none. It remains difficult to shift into first and reverse, and I get a little "grind" shifting into third. It almost feels like the blocking ring is worn out on the third gear side of the 3-4 synchro. It’s not too bad, nothing to worry about for a while.

I can see why some have found other ways of adding the additional quart to the transmission than through the shifting tower. The shifter is not hard to remove, but getting that snap ring back in is a PITA. After fooling with it for a while I found a pretty good way to do it. But I think it only makes sense at 1:00am, when you’re tired and want to go to bed.



Mike

 

[Mgrant]

Hi

I found an easy way to overfill the transmission without taking the shifter out. This was a tip given to me by the dealer I got my truck from, take the top bolt off the PTO cover and pump in the oil through the hole, which is way above the fill hole. I used an old oiler pump can in my case, but any sort of pump with a hose or tip small enough to stick in the hole will work. Beats prying that shifter out and buying a six pack to con a friend in helping you put it back in. As far as any difference, I can tell mine was quiter, but I think that might have been due to the Energy Release antifriction additive I put in it. It will still clunk a gear now and then when cold, but double clutching will make it easier on it until the oil gets warm.



Mike

 

[Old Smoky]

Good idea, Mike. That sure sounds like it would be much easier. I will try that next time.



Mike

 

[Dale Reed]

I am trying your suggestion Mike. I pumped and pumped... before it started running out the bolt hole but only after I had added about 2. 5 qts. I assume this means that the transmission oil was too low.



Do you have an estimate about how much extra oil can be added by using your method? Thanks for the info. Dale

 

[RGT]

you should have only added an extra quart through hat hole, you should have checked the level at the normal fill plug prior to adding the extra quart... .

 

[Mgrant]

I'll second what rtrudeau said. One quart above normal level at the fill plug.



Mike

 

[Dale Reed]

Are you implying that I may have added too much oil? I have not driven the truck yet and can open the normal fill hole, drain the oil, then add a quart.



The transmission shifted OK before I added the oil, and it shifts OK now without the engine running. Very little evidence on the bottom of the transmission of a leak but maybe that is because it was so low.