Checking Axle and Gearbox Fluid Levels

[Vulture]

Gentlemen

 

Last week due to my inexperience with my GMC CCKW 352 I misjudged how the suspension would handle a particular rubber sleeping policeman, and went over it a bit fast. The old girl was mighty offended (believe me I will be crawling over them in future), and the front diff in particular, which proceeded to blow a good teaspoon full of fluid out of the breather

 

Weather and time permitting, either this weekend or the next, I intended to check the fluid levels of all the Axles and Gearboxes (in fact I'm thinking of changing all the oils entirely). Your wise counsel is sought on the following questions:

 

Question 1. Do I check the levels after a run, or when the truck is cold ?

 

Question 2. What in your experience is the best method / tool you use for topping up ? My brother has recommended I purchase a syringe from Halfords, but before going this route thought I’d sound you out.

 

Question 3. Is there any particular tool you favour for undoing the square nuts concerned ?

 

Kind regards to all

 

Ian

Edited September 22, 2011 by Vulture
Sorting out formating

[deadline]

You need a free copy of the TM9-801 located here: http://www.tm9-801.com/tm9-801/index.php

 

The capacity of the axle depends on its type (split or banjo).

 

Fill it to the level of the plug.

 

The specific TM page is http://www.tm9-801.com/searchTM9/tm9_pages/157.pdf

[Scammell4199]

Hi Vulture,

 

1. I'd check levels when its cold, because if its not quite upto level, you need to poke your finger in there to find out what level its at and you don't want to do that with hot oil! If you're going to replace the oil always drain the old out when hot so you can be sure of getting as much of it out as possible.

2. I have a large syringe for filling through oil plugs that are on a vertical plane.

3. Any open ended spanner that fits will do. If you're doing a GMC i would have thought you need A/F spanners for all the fixings etc, but for rough cast oil plugs just use anything that fits snuggly.

 

Hope that helps, Richard

[deadline]

When the US Army switched from 140wt to 90wt gear oils there was a *huge* 'fight' as to the proper level.

 

The oil level can rise almost an half an inch (1-2cm) when 'hot' due to expansion and air in the fluid. So you don't want to CHECK it when hot, but about 30 min after driving.

 

Also, you don't want to check it 'cold' because if you rotate the ring gear due to wheel movement, a significant amount of cold oil will 'cling' (due to the oils viscosity) and show a very low reading.

[Vulture]

 

When the US Army switched from 140wt to 90wt gear oils there was a *huge* 'fight' as to the proper level. The oil level can rise almost an half an inch (1-2cm) when 'hot' due to expansion and air in the fluid. So you don't want to CHECK it when hot, but about 30 min after driving.Also, you don't want to check it 'cold' because if you rotate the ring gear due to wheel movement, a significant amount of cold oil will 'cling' (due to the oils viscosity) and show a very low reading.

Deadline, thanks for your advise, I'll make sure I follow it. Cheers Vulture

[Toolman]

Hello

 

I have purchased this, although I must admit I haven't used it yet.

 

http://www.machinemart.co.uk/shop/product/details/cgg500-500cc-oil-suction-gun

 

Machine mart have plenty of "oil transfer" tools, just look in the following section:

 

http://www.machinemart.co.uk/shop/search/filter/lubrication-fuel-transfer-equipment/type/any/module/shopcategory/page/1

 

MT

[Vulture]

 

HelloI have purchased this, although I must admit I haven't used it yet.http://www.machinemart.co.uk/shop/product/details/cgg500-500cc-oil-suction-gunMachine mart have plenty of "oil transfer" tools, just look in the following section:http://www.machinemart.co.uk/shop/search/filter/lubrication-fuel-transfer-equipment/type/any/module/shopcategory/page/1MT

Toolman, that Oil suction gun looks excellent. Thanks for the link :-)

[deadline]

You can read about the hub-bub in the January and February 1943 issues of Army Motors.

 

Both are available here:

 

http://www.tm9-801.com/ArmyMotors/index.php

[Vulture]

You can read about the hub-bub in the January and February 1943 issues of Army Motors.

 

Both are available here:

 

http://www.tm9-801.com/ArmyMotors/index.php

 

 

Deadline

 

I see what you mean ! They were getting quite excited about it at the time.

 

Vulture

[Vulture]

Guys, a supplemental question on the subject of Axle and Gearbox Fluids, what type of oils are you using ? I've had this Gear Oil 80W/90 GL4 from Halfords recommended as fit-for-purpose Link. Thoughts ?

 

Kind regards to all

 

Vulture

[Degsy]

I wouldn't use that stuff, what you need is a straight 90 not EP. A good oil would be Morris's, they do one which a lot of people on here use and which I have used for years. From memory I think it is called AG90 but you would have to check on that unless someone else can confirm.

[Vulture]

I wouldn't use that stuff, what you need is a straight 90 not EP. A good oil would be Morris's, they do one which a lot of people on here use and which I have used for years. From memory I think it is called AG90 but you would have to check on that unless someone else can confirm.

 

Degsy

 

Thanks for the recommendation. Checking their web site Morris Lubricants do this AG90 Gear Oil Link

 

Cheers

 

Vulture

[Degsy]

You're welcome.

[Rover8FFR]

This is a previous thread to help you.

 

Clive's PDF is very useful for lubrication :cool2:

 

http://hmvf.co.uk/forumvb/showthread.php?30192-oil-application&highlight=oil+application

[Vulture]

This is a previous thread to help you.

 

Clive's PDF is very useful for lubrication :cool2:

 

http://hmvf.co.uk/forumvb/showthread.php?30192-oil-application&highlight=oil+application

 

Thanks for that link, it makes interesting reading

[deadline]

In a differential GL5 is completely acceptable. Its also completely acceptable in a manual transmission.

 

If had this discussion plenty of times and can debunk many of the misconceptions:

 

GL5 is NOT GL4 with additives. GL5 is a completely new oil.

GL5 WILL NOT affect yellow metal in a transmission if it has the MT1 spec (GL5-MT-1 or some combination).

GL5 WITHOUT the MT1 specification WILL NOT AFFECT yellow metal in a manual transmission. The sulpher compounds will not activate unless there is water AND the running temp of the oil reaches 250F or more. Since water boils off at 212F you have to have a significant amount of water or other, much larger issues.

 

My 1966 (nay, ANY US Military M35) has been running GL5 in the differentials and transmission (5 speed, synchronous) for AT LEAST 20 years. The Lubrication order changed in the 1980's superseding GL1 (which basically straight mineral oil with anti foaming agents) so every M35a2/a3 you see on the road has had GL5 in it... ever hear of any massive issues with them? Nope.

 

GL5 is easier to find, and since it more common its generally cheaper.

 

I have had 90wt GL5 in my jeep for 8 years (tranny/trans/diffs) with absolutely no issues.

 

Use what you like... but don't be concerned with GL5 blowing up your drive-line.. its just not happening.

[JonP]

For a jimmy your going to be pumping forever with laser oil pumps and syringes. Go the whole hog and buy 25ltr containers with a humoungous oil transfer pump. This is what I use for the GMC and also the jeep:

 

http://www.lubetechshop.co.uk/advanced_search_result.php?keywords=GL4&osCsid=q22ep60ir56n5nbeqh1bgcrop6&search.x=0&search.y=0

 

http://www.lubetechshop.co.uk/product_info.php?cPath=65&products_id=202

 

For the sake of £38 its not worth messing around with anything smaller... believe I changed three diffs on the truck very quickly... I have the small laser oil pump that I used to use for the jeep.. ended up with a crinked neck and aching back with all the pumping

 

Its EP90 (extreme pressure) and GL-4 (so no need to worry about compatibility with metals... I had the GL5/4 dilemma and researched it quite a bit... decided to use GL-4 to be safe)

 

Btw I intend to use this oil in the diffs and the gearboxes for both the truck and the jeep... I seem to recall from my research notes that it is okay to use (hypoid blah blah blah... would have to dig out my notes to give you more detail).. certainly the conclusion I reached but don't quote me on it.

 

Certainly I was scared off from GL-5... especially for old vehicles. And GL-4 is easily obtainable so why not stick with it

 

Jon

[deadline]

GL-4 has stayed around longer in Europe than in the US. It is available in the US, but most likely you will find GL-5/MT-1.

 

The main issue is how the syncho gears work. Not sure if you know so a brief overview:

 

The brass synchro keeps the input/output shafts spinning at relatively the same speed by friction. The tranny lube provides a protective buffer but still allows enough friction to occur to keep both shafts spinning... that's what allows you change gears without double clutching or grinding. Syncho's are wear components and will wear out. They are not needed to operate the transmission, but they do make shifting much easier.

 

GL-5 includes a LOT of sulfur. Like zinc (in engine oil) it is a friction reducer.

 

WAY BACK when GL-5 first came out there was an issue with the sulfur turning into an acid and eating yellow metal (well, actually the copper which brass is made of) and when they looked into it the culprit was the sulfur. BUT two things have to happen before the sulfur turns into an acid. You need water (a little) and heat. A lot. The magic number for the heat is 250F. Below that temp the sulfur remains basically inert. It cannot combine with water to make the acid to eat the gears.

 

So, why do you get so many differing manufacturers opinions with respect to GL-5 oil? First, most of the vehicles that POSSIBLY might be affected are older models and they simply don't want to deal with the possible liability of it. Not from the acid issue, but from everyone that has a tranny problem who changes from GL-4 to GL-5 will believe that anything that goes wrong is a manufactures defect and will complain. Another is that they don't want to generate the paperwork to make it an 'approved' change. So basically businesses see no benefit to spending all that money to 'approve' the GL-5 oil.

 

Again, the single, largest, best example of what I can point to and prove my point is the US Army M35a2. These trucks were built in the 1960s and are still in use today. Originally they were specified to run GL-1 oil in the drive-line (diffs and tranny/transfer)

 

If you look back at LO9-2320-209-12-1 (30 April, 1983) it superceedes LO-2320-209-12 (1971) and LO-2320-209-12/1 (1976) and specifies MIL-L-2104 as the lubricating oil. This is the first specification for GL-5. That's 1983.

 

If you follow the long list of specifications and updates it brings you to SAE J2360 as the performance tests for M35a2 lube oil. Here's what J2360 is:

 

"The gear lubricants covered by this standard exceed American Petroleum Institute (API) Service Classification API GL-5 and are intended for hypoid type, automotive gear units, operating under conditions of high-speed/shock load and low-speed/high-torque."

 

http://standards.sae.org/wip/j2360/

 

That's from the SAE's own web site.

 

So, here is DOCUMENTED PROOF that since 1983 M35a2/3 have have GL-5 in them (and they have synchronized manual transmissions - aka yellow metal) and they are running FINE.

 

 

My 1966 M35a2.... GL-5 in her since 1983. Runs fine.

Edited April 19, 2012 by deadline

[Vulture]

Guys

 

Thanks for taking your time to give me your thoughts on the best oil for the Gearbox and Diffs. Much appreciated. JonP, that is a serious pump arrangement !

 

Kind regards to all

 

Vulture