rockwell oil

what oil is every one using in Rockwell transfer case.
Thanks in advance Greg

Crikey Greg, have you 'upgraded' the NP205 to a Rockwell ?

Original factory spec for the Rockwell is 90 grade but the smart money is on running ATF which has better high temp characteristics than mineral based oil and runs cooler anyway.

Deano

As it is hard to keep 80/90 gear oil in a Rockwell it would be nigh on impossible to keep ATF in there once there was any wear. ))

thanks for the reply deano it for 366

Peter and Sandra OKA 374 wrote: As it is hard to keep 80/90 gear oil in a Rockwell it would be nigh on impossible to keep ATF in there once there was any wear. ))

I dunno Pete, it's not unusual for a Rockwell to be running temps of 130 degrees C in hot conditions, I don't reckon 90 grade this hot would be much thicker than ATF

It's pretty common to run ATF in manual gearbox's under harsh conditions as its high temp attributes are better than 'normal' oils. My old Defenders had ATF from factory once upon a time and back in my old Bathurst racing (pit crew) days it was the manual gearbox lubricant of choice.

I had a chat with Oka Paul about this (TC lubricants) a couple of months ago and he noted that Reg Stirling the Rockwell Guru uses ATF in his rebuilt boxes.

Deano

Deano I used to run ATF in the rockwell too but keeping it in there was the problem, too much slop and wear even at 70k kms which was why I tossed the rockwell ASAP. Heat was big problem with it too but remember that once over about 120C ATF's service life is drastically shortened as well.
Don't get me started on the Spicer, the biggest problem with that though was that I had been driving auto 4wd's for the previous ten years and going back to a reverse pattern manual with lots of neutrals had knobs on it.
My 4wd ute runs ATF in the Borg Warner transfer case.

Fortunately #413's Rockwell is long gone and it was replaced with the NT HD150 transfer case. This might be a huge lump of steel weighing in at 150 Kg but it runs relatively cool compared to a Rockwell. I've put my hand on the TC under 'adverse' conditions and whilst I couldn't leave it there it wasn't nearly as hot as some Rockwells I've seen. I'd guess-timate around 60 C which is pretty good IMO. It runs SAE 30 the same as the NP205. Perhaps its doubled up bearings or its (from memory) approx. 4 litre oil capacity (Rockwell 2.5 litre) means it runs cooler. I've just finished rebuilding/upgrading a NP205 to go in which should be even more power loss efficient as well as much lighter (approx. 75 kg) than the HD150.

I drove an LT with a NP205 on 325/85R16's (38" tyres) from Adelaide to Melbourne a couple of years ago and was quite surprised how much more power it had when compared to my similar at the time Perkins powered Oka. Both were in good condition with the NP205 equipped Oka probably heavier than mine. The only difference was the TC and the difference was very noticeable.

I take your point Peter about the 'reverse' gate. After years of driving Land Rovers I'm afraid my brains programmed to a 'normal' gate and I still bugger up 1st and reverse if I'm not careful not to mention the occasional changing 'up' from 5th to 4th.

With the Spicer/Turner gearbox I changed to Castrol Syntans 75W85 (fully synthetic) several years ago and it made a considerable difference. No more cold weather/cold oil lockout and very good under hot conditions to boot. Not cheap at $25 a litre but worth every penny IMO.

FWIW my suggestion to Gregs mate would be to use Syntrans in both gearbox and TC with 1/2 a tube of Nulon 'smooth shift' oil treatment in the TC (other half in the rear diff if not LSD otherwise put it in the gearbox) as this is a very good anti friction additive which should make things run cooler. The reason I'd use Syntrans in the TC is that a/. it's fully synthetic so has very good temp characteristics b/. its quite 'thin' when compared to normal mineral 90 grade and c/. it's one less oil type you need to carry as spare.

Deano

We had various gearbox's around the farm that ran hot and the worst one was aRotax reduction drive gearbox on a Quicksilver aircraft. One circuit in that and you would burn your hand on it. I put a tube of Nulon gearbox treatment in with the oil and it only got warm after that. Same result with other gearboxes. This could be the answer for the Rockwell box. If the oil gets very hot the oil breaks down and then you get accelerated wear and failure.
George

Hi Greg,
The OKA manual specifies Castrol ST 90 to APIG1, 5MIL-L-2105B and holds 2.6 lts
If you go to Rockwell field service manual it states Mineral oil GL-1, S.A.E. 140 but it is an option to useGL-1, S.A.E. 90
These are all single weight oil recommended by the manufacturer and following on by OKA you could use anything you want but why would you unless you want to reduce the life of the T/case and or the seals.
Martyn

Hi All,
Just as a bit of info for those interested.
Automatic Transmission Fluid is really just hydraulic oil with some additives quiet a few actually and yes some G/boxes and diffs came out using ATF but they were designed that way and doesn't mean that all G/boxes or T/cases and Diffs can use it for long life go with what the manufactures state or as close as you can get preferably better rather than worse.
Here is an a indication of how temp will affect ATF and G/box.


So as you can see it can quickly damage the box and also seals.
Here is a pamphlet from Castrol explaining how this particular oil is designed for older G/boxes, T/cases which in particular have brass,bronze, copper and the additives in other oils can have a negative impact on yellow metal.

Sulphur/Phosphorus additives however have an unfavourable property: they can react aggressively towards bronze and copper. This can be disastrous for the synchromesh rings of a gearbox. Therefore it is not recommended to use in a gearbox unless the manufacturer allows this.
The Rockwell T/Case has brass bushes the rest is not but when they wear the noise you here is from the bushes and the oil leak is from the seals that have broken down because of the wrong oil.
The end result is the T/case gets a bad name where in fact it is the wrong oil put in, unknowingly of cause who would use the wrong oil on purpose.
If you cant get S.A.E. 140 then get 90 and use an additive like Nulon as suggested by George but check that it doesn't have Sulphur/Phosphorus in it.

Martyn

Hi Martin,

Thanks for the post, very interesting points you make and by the sounds seems like a reasonable solution. The only thing i would add to contradict just one of those points is not to blindly believe what the manufacturer recommends. The manufacturers don't always have the same intentions/design criteria in mind as the end user. Sometimes there are multiple political and/or cost based reasons why manufacturers use a particular design or method for doing things which is completely unproductive. I used to work in the car industry...

Cheers, al

Hi Alister,
Yes I dont disagree with you but not every one has the ability, experience or education to either see through or change what is done or recommended and have to put faith in the fact that if the manufacturer has recommended in this case oil then that is what is at least without any other firm facts the one to go with or at least a starting point.
OKA did recommend Castrol but that doesn't mean that that is the best its just that maybe they did a deal with Castrol and any other brand will do or even be better.
In these days with consumer law they cant give a false, misleading or totally wrong recommendation.
Martyn

mort wrote: Hi All,
Just as a bit of info for those interested.
Automatic Transmission Fluid is really just hydraulic oil with some additives quiet a few actually and yes some G/boxes and diffs came out using ATF but they were designed that way and doesn't mean that all G/boxes or T/cases and Diffs can use it for long life go with what the manufactures state or as close as you can get preferably better rather than worse.
Here is an a indication of how temp will affect ATF and G/box.

So as you can see it can quickly damage the box and also seals.
Here is a pamphlet from Castrol explaining how this particular oil is designed for older G/boxes, T/cases which in particular have brass,bronze, copper and the additives in other oils can have a negative impact on yellow metal.

File Attachment:

File Name: Castroloil.pdf
File Size:28 KB

Sulphur/Phosphorus additives however have an unfavourable property: they can react aggressively towards bronze and copper. This can be disastrous for the synchromesh rings of a gearbox. Therefore it is not recommended to use in a gearbox unless the manufacturer allows this.
The Rockwell T/Case has brass bushes the rest is not but when they wear the noise you here is from the bushes and the oil leak is from the seals that have broken down because of the wrong oil.
The end result is the T/case gets a bad name where in fact it is the wrong oil put in, unknowingly of cause who would use the wrong oil on purpose.
If you cant get S.A.E. 140 then get 90 and use an additive like Nulon as suggested by George but check that it doesn't have Sulphur/Phosphorus in it.

Martyn

What tempurature is your Rockwell running at?

Hi Holmz,
I dont know what mine runs at, I must check next time I go for a run which wont be till this virus runs its course.
It would be interesting to see what others have recorded
Martyn

............. What tempurature is your Rockwell running at?

The short answer here is 'too hot', and in central Australian summer conditions 'way too hot'

The Rockwell T221/223 (heavy duty variant) transfer case as fitted to the LT Oka is IMO very well described on the American 'Torque King 4X4' web site.

The Timken designed, Rockwell T221 transfer case was used in some 4X4 conversion applications prior to 1960. General Motors selected the T221 as the production transfer case for the new 1960, Chevy and GMC factory option 4X4 trucks. The T221 (223) is a 4 shaft 'clover leaf' design transfer case. The T221 design is reasonably strong, especially considering the low power engines it was coupled to, but by 1960, the T221 (Clover-leaf) design was obsolescent for the American market due in part to the advent of the Interstate highway system and the increasing long distance recreational use of pick-up trucks. The T221 generally runs hotter and is generally noisier than contemporary Dana and New Process transfer cases used in Dodge, Ford, IHC and Jeep full size trucks. The T221 was replaced by the New Process NP205 for the 1969 Blazer and all GM 1970 models with 4 speed or automatic transmissions.


So basically the end of an era in transfer case design. The earliest Rockwell T221 type or 'Clover-leaf' transfer cases I've found on line dates back to the 1940's. Within a few years the New Process NP205 transfer case was the transfer case of choice for all the 'Big Three' players in the American (world) market. ie. Chrysler, Ford and GM.

The 'Heavy Duty' version of the Rockwell 'clover-leaf' transfer case the T223 as fitted to the LT Oka continued on in various forms for several years in various IHC, Dodge and Ford F600 trucks and by the 1970's had generally been replaced with offerings from Dana, Chrysler (New Process) and others.

Moving right along, in the mid 1980's Oka was looking for a transfer case for the XT and unsurprisingly settled on the NP205 which was the transfer case of choice with production runs in the tens of thousands and the cost advantages this gives. The NP205's reputation for performance,reliability and adaptability to many situations made it the TC of choice globally. From airplane tugs to F trucks and Acco's to Oka's it did the job well
This isn't to say Oka didn't have issues with the NP205. Unfortunately Oka had chosen a TC input shaft used in an automatic transmission Dodge application which whilst fine in this non shock loading setup proved to be 'less than optimal' when used with a direct coupled manual transmission. Upgrading the input shaft solves this issue. IMO not really a TC issue but poor application/engineering on Oka's behalf.

Moving right along to the mid '90's Oka was looking to the LT 'upgrade' but unfortunately for Oka New Process/New Venture discontinued the NP205 after 30 years of production. Even though New process/New venture had manafactured 'several years' supply this was soon scooped up by various end users such as the IDF (Israeli Defence Force) which left Oka and no doubt others in 'a bit of a bind'.
"Back to the Future" the movie came out in 1985 and no doubt provided the inspiration for Oka to chose the obsolete Rockwell T223 Clover-leaf TC as its NP205 replacement
In all fairness Oka was caught between the proverbial 'Rock and a hard Place' and perhaps had no choice but to choose the lack lustre and 30 year obsolete Rockwell TC for the LT.

The Rockwell Clover-leaf TC is stolid performer, not flash and definitely not designed or intended to be used in high power/high torque or 'stressful' environment. It's a 70 year old design more suited to low power/low stress agricultural use. In the Oka if used in the southern (cooler) regions and not overly stressed will provide years of valiant service if maintained properly.

Which leads me to lubricants, the original spec Castrol 90 GL1 spec should IMO be avoided like the plague. This might have been OK in a low demand agricultural setting but fortunately lubricant technology has come a long way in the 70+ years since this TC was designed.
The GL (gear lube) 1 spec description as on Wikipedia ........................ "GL1 is the lowest level of performance and is only used in vintage transmissions. It is very similar to engine oil, having a very low additive content, but is available in much higher (thicker) viscosities to suit gearboxes with unsophisticated oil seals."
Considering the above it's worth noting that Chrysler specify for the NV4500 manual transmission (the one that nearly went into the LT and used in early manual NT Okas), current spec GL5 oils should NOT be used for the reasons Martyn outlined earlier but instead use GL4 spec oils.

From a practical viewpoint the heat generated by a Rockwell TC needs to be experienced to believe. In a hot central Australian environment this can be horrendous. In a bus variant/camper the internal temperature can be unbearable. I've experienced this and would definitely NOT recommend a Rockwell TC for use in a hot environment. Not (temperature wise) a problem in a cool environment but can be 'unlivable' in the hot centre.

Deano

I guess my point is that without knowing how hot it is leaves one doing a crap shoot.
If it is hot enough to light a smoke, or someone puts an IR gun on it, or a temp change sticker, then we would have something to go by.

I'll just assume that it is hotter than the hubs of hell.
And if that is the case, then wouldn't a cooler be a logical thing to add?

I would probably still use the fancy oil, but as Mort pointed out with the chart, running the oils at reasonable temps, is a story that is pretty old, and has been solved for the better part of a century.

Or is there some reason why a cooler cannot be run?

Adding an external cooler would be an excellent idea but it begs the question, has this been done before ? A fairly obvious response to a known issue but my trawling of US sites has not found any evidence of this.

Anecdotal evidence I've had related from experienced tour operators gives me a Rockwell TC temp of 130 degrees C (260+ degrees F) and from experience I'd believe this in a central Australian environment. No wonder the oil seals fail, it may be worthwhile to replace the standard seals with Viton ones for a better result. For an Alice Springs resident it may be worth having a chat with a local who has experience with a Rockwell TC equipped Oka in the centre

A cheaper/more practical response may be to run better lubricant. Both Motul and Redline make excellent lubricants which should do a way better job than the dinosaur GL1 standard originally specified, unfortunately both of these manufacturers offerings are 'niche' products here in Oz. IMO sticking to a GL4 spec would be a good move to avoid "additive contamination". GL2 & 3 are both obsolete standards. The previously mentioned Nulon additive is a proven friction reducer and may be effective here.

The obsolete Rockwell 4 shaft cloverleaf design and its many moving parts generate heaps of heat because of its inherent design. The three shaft NP205 with fewer moving parts is much more energy efficient but at the end of the day you've got the TC you've got.

Landrover owners use an aftermarket passive cooling fin extension cover fitted to the bottom of its LT230 TC along with increased oil capacity to address a similar issue. An external cooler with its additional capacity and passive 'thermo-syphon' type oil flow and better oil may address the issue but it may be more cost effective to ditch an ageing Rockwell TC and replace it with a NP205 depending on individual circumstance.

Deano

For the short period I kept the Rockwell in 374 you could feel the heat emanating from the transfer case under the truck when standing beside it after highway travel.
As Deano said it was never designed to be used in the Oka type application and is best removed.
When I was looking for an Oka I drove quite a few across all the eastern states and SA (cheap $40 airfares at the time) and every XT went better than the LT's and I was told at the time by old hands that the Rockwell was responsible for a 13% loss of power as it turned it into heat!

I already use redline

My thought was that the bung on the bottom for drainage, and the filler is at the top.
1) If there were temp sending units that fit in the bottom, then understanding the temperature would be easy.

2) If there were barbs that fit the top and bottom threads, then some hose, pump and small transmission cooler sized radiator could likely be relatively easily installed... and some combo where a temp sender, switched power the pump, could be somewhat elegant.

Dean and Kaye Howells wrote: ............. What tempurature is your Rockwell running at?

The short answer here is 'too hot', and in central Australian summer conditions 'way too hot'

...

From a practical viewpoint the heat generated by a Rockwell TC needs to be experienced to believe. In a hot central Australian environment this can be horrendous. In a bus variant/camper the internal temperature can be unbearable. I've experienced this and would definitely NOT recommend a Rockwell TC for use in a hot environment. Not (temperature wise) a problem in a cool environment but can be 'unlivable' in the hot centre.

Deano

That is a great yarn... just about everything was woven in there.

However I still do not know what an unbelievable temperature is in numerical form using F, C or Kelvin?
How can I believe it or not, if I do not exactly what it is?

[edit] I see now that 130C was mentioned a few posts back[/EDit]

And does one really need some other magical TC?
A few OKAs have been operated locally by tour companies, and those drivers are renowned for be pretty unsympathetic towards equipment. From memeroy most drivers came across from the DILLIGAF race team, so it is hard to believe that the Rockwells are like a grenade sans pin.

OP..
If it was mine I would just whack it full of Redline and change the fluid at a reasonable interval.
If it falls out, or grenades its guts across the corregations, then at that point consider chuckin in something better.
(IMHO)
Or find a spare Rocky, and have it in a box ready to ship.

They seem like they take a beat up session, but they usually finish the battle.