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Fluid for J-Type Overdrive

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mgedit

mgedit

Jedi Knight
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New to the forum, and although I suspect this has been discussed before, I came up with little when I tried a search. I'm in the midst of converting my 73 TR6 to a j-type OD and have seen much discussion of what type of fluid to use. What is the experience of list members? Just about at the bench test stage and would appreciate any advice/input.

Cheers, Mike
 
In the midst of the same project. I was directed to Quantum Mechanics in Ct as John is considered the guru of Tr overdrives I believe. Interesting tech article on the site concerning a whole range of different fluids used and observations on pressure and operation. Give it a look( article is a few years old but I talked to John recently and info is still germaine)
Elysium
 
I have two J-types, one with Valvoline 20W50 racing (motor) oil (recommended by the west coast guru who rebuilt it for me); the other with Redline MT-90. Both seem to work fine.

With the J-type, I honestly don't think it much matters, as long as it can build the required pressure (which you should definitely check before installation). But they aren't all the same (and it's not even clear that John's supposed tests were done on a TR overdrive, as he mostly works on other marques).
 
John built my J-type and told me to use only 30wt Non Detergent motor oil. I happen to use Valvoline.
 
Thanks for the responses. There is certainly lots of discussion and different recommendations. I used Redline in my 4 speed and it works great although it does occassionally jump out of second on hard downshifts. I'm inclined to go with the racing oil or 30 non-detergent. Cheers, Mike
 
There is a lot of misinformation in John's reasoning for recommending non-detergent 30W oil.

There is nothing wrong with using 90W gear oil in an OD or non OD transmission. 90W gear oil has a very imlar viscosity compared to 30W motor oil. Gear oil and motor oil are rated differently and hence the reason for the different viscosity valves. John’s statement “…90 weight oil was so heavy…” just goes to prove that he does not understand the differences between motor oil and gear oil.

Detergents and bubbles are separate issues. Detergents are used to suspend soot within the oil. Detergent is different than soap, it won’t create bubbles. In an engine, if the oil level is too high, the crank could be partially submersed in oil and as it turns can entrain air into the oil, which will reduce the lubricating properties of the oil, hence the reason to not overfill the sump and the reason anti-foaming agents are added to motor. There is no mechanism within a gearbox to entrain air in the oil.

In terms of what type of oil SHOULD be used in an OD gearbox, why not look at the oil(s) recommended by the auto company that used more ODs than any other: Volvo. Volvo, who put over 400,000 OD units in the their cars specified everything from motor oil to gear oil and finally ATF, so obviously the OD unit is not particular.

Personally I use 75W90 synthetic GL5 gear oil in my Spitfire's J-type overdrive and my MGB's LH-type overdrive.
 
Mark Jones said:
There is nothing wrong with using 90W gear oil in an OD
Click to expand...
Depends on the OD ...
 
Quantumechanics rebuilt my J-type, and they will void the warranty if you use anything other than <span style="font-weight: bold">30-weight NON-DETERGENT oil</span> in it.

That's a pretty good reference, I'd say. Can't go wrong with 30-weight, non-detergent oil.
 
Regarding 30 wt non-detergent, a caution I'll add is don't do what I did. I had a tough time finding an actual non-detergent grade at the local store, so I wound up putting in a no-name 30 wt generic product. Big mistake. My A-type worked for about a month, then wound up having the symptom that it would not disengage. In my case, a clean up of the bypass valve, and switch to Valvoline 20W50 racing is working fine for me. Either way, make sure you buy a quality oil.
 
Yes, that's the one I have in my A-type. For that matter, its going in the engine next as I believe it has ZDDP but thats for another topic!
 
This is the one I've been using
https://www.valvoline.com/pages/products/product_detail.asp?product=94

At that time, it had more zinc than the VR1. However, it appears that they have increased zinc levels in the VR1, so I'd go with that today.

In gear oil terms, ZDDP functions as an "extreme pressure" additive that helps protect the thrust washers (a known weak point in the TR gearboxes); without the risk of increased corrosion on synchro rings as the EP additive used in some gears oils can.
 
30W ND in the Spitfire and Volvo (both have J-types). So far, no problems. Briggs & Stratton brand.
 
YUP!....Valvoline 30W(for the tranny & OD) is it!....All this talk about what to use as damper oil....Factory says 20W motor oil.
 
myspitfire said:
All this talk about what to use as damper oil....Factory says 20W motor oil.
Click to expand...
Or 5, or 40 ...
 
You may want to explore and rethink using it in your engine. Remember days of old? Nondetergent is a lot more susceptible to varnishing and sludge formation. Used to have to replace the oil every 1500 miles because it did not pick up and "hold" the dirt....

For the engine I would recommend a good Detergent...
 
Thanks to all who took the time to provide advice. One more followup question concerning differential fuild. While I have the transmission out I pulled the diff as well as the front seal is leaking. After I replace the 3 seals what fluid is recommended. GL4 90W as in the manual? Quick look locally suggests that all readily available are GL4-5 and 80W90. Can't find GL4 single viscosity. Any drawbacks to using oil with GL4-5 designation? Cheers, Mike
 
IMO, using multi-viscosity in the diff is no problem. GL4-5 may or may not be a problem, depending on what kind of extreme pressure additive it uses. Most conventional gear oils use a sulfur-based additive that can corrode the brass thrust washers used in TR diffs. Most synthetics, even GL5 synthetics, don't use this additive.

I've been using Valvoline full synthetic 75W90 GL5 for many years, and it's worked great for me. In fact, I credit it for extending the life of my TR3A diff, which was already well worn when I got the car over 150,000 miles ago.
https://www.valvoline.com/pages/products/product_detail.asp?product=58
 
Re: Fluid for J-Type Overdrive and NOW DIFF TO

Thanks again for the input. Found a local store that carries all the Valvoline products so getting what I need should be easy. Any other thoughts on diff fluid? Cheers, Mike
 
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