Porsche G50 Info

[Chris Martino]

Hey Bill - when did you get your 40 on the road? I have my 40 coming mid September and I will be using my G50 03 box mated to my 289. Have you made many upgrades to your G50 and if so what did you find was/has been the best solution to the "limitations" of the torque issues/strength of the unit?

Any info would be great! Roger at PHII has been a fantastic help answering all of my inquiries and I feel I haven't given him due credit for all of his help so - thanks Roger!! I will send as much business your way as I can - you guys definately deserve it.

Chris

 

[Bill Bayard]

Chris,

My car's been on the road since April of '02. When I bought my gearbox, I had it stripped, rebuilt, and a Quaife LSD added. I had a problem with an internal noise due to a bearing not being pressed properly, but that was completely
covered by the seller (Thank you Ian!), including shipping to and from. I replaced a clutch disc, when the springs became a bit loose(practically fell out of the disc), but since then haven't had any problems. My engine dynoed (chassis) at 349.7 @ 355.7ft/lbs, so I'm not far beyond the G50's capabilities.

Snatching gears hasn't hurt my G50 a bit, but I don't do standing burnouts often either. My u-joints are original and still tight. The box is tight and shifts very smoothly in all gears. I did miss 3rd once, but that was MY fault! /ubbthreads/images/graemlins/blush.gif

Bottom line: As long as you aren't prone to 5K line launches on a regular basis, your G50-03 should be fine, mated to a 400HP 289.

I agree about Roger Brown. He was a huge help to me, when I was in the research phase. A great guy!

Best of luck with your car! Only a month and a half to go!
Getting anxious yet?
Keep us posted.


Bill

 

[Lynn Larsen]

Gear Oil??

I noticed the compiled info says to use a GL-5 gear oil in the G50 family. I had planned on using Redline MT-90 but it is only GL-4. According to this info, it looks like I should use the Redline 75W90 NS.

What are you all using? What does PHII recommend? Any other words of wisdom on transaxle lubrication??

Regards,
Lynn

 

[Chris Martino]

Any help?

www.paragon-products.com/product_p/rl_transfluid.htm


MTL® Manual Transmission Lubricant
a 70W80 GL-4 gear oil (SAE 5W30/10W30 engine oil viscosity) designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting.

MT-90 Manual Transmission Lubricant
a 75W90 GL-4 gear oil designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting.

75W90 Gear Oil - recommended for most street driven and racing differentials. Excellent performance in conventional and limited-slip units. Also for limited-slip manual transaxles which require a 90 WT oil. Contains limited-slip friction modifiers.

75W90NS Gear Oil - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140.

75W140NS Gear Oil - recommended for manual transmissions and non-limited-slip transaxles that recommend 140 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140.

80W140 Gear Oil - generally used in commercial trucks which will climb long, steep grades and some racing applications where power is not critical. Generally 0.5% less efficient than 75W90. Can also be used in differentials and transmissions where excessive noise is a problem and limited-slip differentials which vibrate excessively when turning a corner. Exceeds API GL-5.

SYNTHETIC ATF - synthetic Dexron II, Mercon, and Mercedes-Benz approved fluid. Superior stability allows high-temperature operation without varnishing valves and clutches. Also provides improved shifting in cold weather.

D4 ATF - synthetic Dexron III and Mercon fluid meeting the requirements of most transmission manufacturers, while satisfying GL-4 gear oil requirements. Superior stability allows high-temperature operation without varnishing valves and clutches. Also provides tremendously improved shifting in cold weather. The best low-temperature shiftability for manual transmissions and transaxles which require ATFs.




Features

* DIFFERENTIALS - Red Line 75W90 Gear Oil provides excellent protection in nearly all differentials, conventional and limited slip, in both racing and street use. 75W90NS can be used in certain limited-slip units in racing to lock-up the differential. 80W140 should be used in commercial hauling, problem limited-slip units, racing applications which see tremendous torque at low speeds, and where noise deadening is desired. LightWeight or SuperLight can be used to obtain maximum power transfer in racing differentials which do not see high temperatures.

* TRANSMISSIONS - MTL® can be used in most manual transmissions and transaxles for both street and racing use unless the manufacturer requires the additional protection of an SAE 90 or the extreme-pressure protection of a GL-5. In those situations the MT 90 (GL-4) or 75W90NS (GL-5) will provide good shiftability and synchro compatibility and extra gear protection. LightWeight Gear Oil can be used in transmissions calling for a 75W or 80W GL-5.

Chris

 

[Bill Musarra]

I have a question that is a little unusual. An old time master mechanic from Porsche told me some time ago of a differential fluid used by Porsche that is used in the limited slip units that has a very distinctive smell. He said, once you smell it you will never forget it. Something akin to burnt oil. Anyone ever heard of this, or do you think he was just pulling my leg???

Bill

 

[Bill Bayard]

Bill

Most gear oil has this smell, even directly out of the bottle. After a few miles of driving, it gets a LOT worse. The only thing that comes close is a dirty diaper!
/ubbthreads/images/graemlins/shocked.gif You'll never forget either fragrance! /ubbthreads/images/graemlins/crazy.gif





Bill

 

[Lynn Larsen]

Chris,

Thanks for posting the Redline specs this will come in handy for someone, for sure. If you read the Porsche specs for gear oil, the MT-90 fits it perfectly. But, the guys who wrote the recommendations say that one should use GL-5, which means that the 75W90NS would have to be used. While the source you quoted with the lube specs does not state this, the Redline website shows the two "NS" gear oils as being GL-5 rated; whereas the others are only GL-4 rated.

Recommendations and ratings are great guidlines, but I always like to temper that information with real world experience. So, again I'll ask, what gear oil are you guys using? Maybe there is a Lucas oil that better fits a G50/XX with a LSD?

Regards,
Lynn

 

[Craig White]

I think most of the local guys here with DRB GT40's run Castrol Syntrax 75W-90. This is also the oil that Peter Ransome, DRB/GT40 Australia owner, recommends for G50 transaxles.

Here is the blurb from the Castrol website:

"Castrol Syntrax is a synthetic SAE75W-90 manual transmission fluid with outstanding thermal stability and synchronizer performance. Castrol Syntrax is particularly recommended for transaxle applications with combined transmission and hypoid differentials. Ideally suited for motor sport and high performance applications and where maximum protection and lower transmission temperatures are required.

Exceeds API GL5"

 

[Bill Bayard]

Lynn,

I've been using Castrol 75W-90 for 3 years now. Seems to work well, but still doesn't smell any better than other brands. /ubbthreads/images/graemlins/tongue.gif

I changed mine once, and had the drained oil tested for metal particles, etc. No apparent problems.


Bill

 

[Chris Martino]

I've read that Porsche recommends SWEPCO-

"Special adhesive/cohesive formulation eliminates "dry starts", dramatically reducing initial start-up wear on pinion and ring gears

Helps improve "stiff shifting" manual transmissions

Reduces operating temperatures

Blended with highly refined pure paraffinic base stock and a high tech additive package, including SWEPCO's proprietary additive, LUBIUM®

Helps keep gearbox and transmission seals soft and pliable, reducing leakage

Meets all AGMA specifications, API GL-5, and MT-1

EP and limited slip differential additives"

Chris

 

[Chris Duncan]

"What does PHII recommend?"

Redline

Lightweight Shockproof Gear Oil for street

Heavyweight Shockproof Gear Oil for street/racing

LINK

The G50 needs extra protection and extra slipperyness for the syncros and slip diff.

""The viscosity characteristics allow the lubricant to resist throwoff and provide a film thickness similar to a 75W250 grade, while providing the same low fluid friction as an SAE 75W90.""

 

[Lynn Larsen]

Kalun,

I will give PHII a call on this, but I read the ShockProof literature with much interest and enthusiasm. The one aspect that kind of toubles me a little is the statement that it "not recommended for most syncro-type transmissions." This statement is found in the LightWeight ShockProof verbiage, but it is infered in the repeated statement that ShockProof is designed for competition transmissions and transaxles (read by me as dog engagement, but could also include stright cut gears.)

Does PHII differentiate between sychro and dog engagement when it makes this recommendation? Slipperiness is a problem with older Porsche transaxle's synchronizers and that is why dino is recommended for the old school synchros (admittedly these are found in the pre G50 family of gearboxes.) But, the bottom line is that if the lube is too slippery, it can cause the the synchro cones to not spin up the gears enough to allow smooth engagement. I have to wonder if this isn't why Redline doesn't recommend ShockProof for synchro-type gearboxes. I have to assume you are using one of the ShockProof gear oils; have you found gear engagement to be at all notchy?

Thanks,
Lynn

 

[Chris Duncan]

Lynn,
All I remember for sure is that the Shockproof oils work best in the G50-02 ('94) according to PHII. The conversation was a few months ago and I didn't write anything down.

Still a few months away from being able to test it first hand /ubbthreads/images/graemlins/grin.gif

 

[Lynn Larsen]

After reading and rereading the Red Line sight, I had come to the decision that I liked the idea of using 75W90NS with just enough LSD additive (if any) to keep the LSD quiet. A talk with Bobby Hart confirmed that I was in the ball park with his statement that he liked the basic stuff like Swepco 201 and/or Red Line 75W90. He did pass on this one rule of thumb that he was very adamant about: do not use anything over 90 wieght for normal use.

But, I didn't want to post anything since I was (and am still) waiting for feedback from Rennlist Tech and from Roger Brown at PHII. Well, being the obsessive that I am, I of course kept looking for info, until I found a tech article on Paragon's website (very well known Porsche guys) that basically recommended exactly what I had been thinking. Now before I post in their recommendations and opinions, I want to caveat this by saying this: One must consider the particular transaxle he has G500x, G50/5x (with a better R&P) and whether it has an LSD or not. (G500x owners may indeed want to consider Shockproof oil if they have high horsepower and drive either on or like they are on the track. I'll, hopefully, have more on this after hearing from the other guys.)

Paragon's Transaxle Fluid Info -

Transaxle Fluid - Info Author: Skip

The Basics:

Friction Modifier (FM) is slippery stuff. The FM is in place to reduce LSD clutch chatter upon engagement. The amount needed is relative to the application and the age of the differential. In full race cars, you want the clutch to lock up nice and strong while not being so concerned with a little chatter. In high mileage (or worn) LSD cars, the clutches will be worn and need less FM to attain the desired effect. The downside, or catch-22, is that the syncros don't need or even like the FM. In most cars this is not a problem because the differential and transmission are separated and do not share the same lubricant. Our transaxled P-cars do share, so we must prepare for that.

FM options:

FM needs to be used in LSD cars, we know that. It's the amount that is variable. As a general rule, what comes out of the bottle is sufficient for most applications. Some folks will mix FM stuff with non-FM stuff (75W90NS and 75W90) until the desired effect of "no chatter" is attained... the reason for this being again, that syncros don't like FM.

Oil weight:

In high-performance applications where the temperatures may get higher than street use, it is common practice to use a bit higher weight oil (75W90 vs. 70W80), and higher still if the tranny/diff is not externally cooled (80W140).

What about GL-5 vs. GL-4:

The main complaint against GL-5 use in syncro'd trannies is because the chemicals used to provide the extreme pressure protection can be corrosive to synchronizers, which are commonly made of brass or bronze. Here's what the 944 factory manual has this to say: "Filling capacity Approx. 2.0 liters hypoid transmission oil SAE 75W90 to API Class GL5 or MIL-L-2105B, or SAE 80 to API Class GL4 or MIL -L-2105."
<font color="red">
(Note from Lynn: Redline says their GL-5 is NOT corrosive.)
</font>
Which one is right?:

In the end, it is up to the owner. Though statements of GL-5 use in a syncro'd tranny are somewhat against... history and sales of GL-5 lubricants (like Redline 75W90) continue to be favorable. This is a heavily debated topic, even within the industry. The only things we can assume for sure is: 1. Don't use FM in non-LSD transaxles 2. Don't add FM to make the clutches lock up sooner in LSD equipped cars.


Regards,
Lynn

 

[Lynn Larsen]

I had a conversation with Roger Brown late yesterday afternoon. PHII has been recommending Red Line ShockProof gear oils for a while now. When asked if they had experienced any degredation in the shifting of gearboxes using Shockproof, his response was that they have had no complaints. I suppose we have to view this as, at least, a passive approval of its use, in that, if someone had spent the kinds of dollars we all know it costs to regear and set up a transaxle, they would certainly have complained if they were experiencing any problems with shifting. Roger did say that a lot of people use 75W90, 75W90NS and, when a LSD is present, will add friction modifier if chatter is problem. Indeed, this is what they had recommended in the past, but they felt that, as long as they don't see a downside (get compaints), they feel that ShockProof gear oils get the edge because of the added protection for the gears faces. This protection coming from two characteristics of the oil: the ability of the oil film to stay on the gear teeth and the cushioning provided by the microscopic solids in it.

I am still waiting to hear from Bill Gregory at Rennlist Tech, but I am beginning to form the opinion that, for the vast majority of us, wether one uses the ShockProof or the other high quality, synthetic gear oils, we probably will never see a difference. I think the differences in the two types are probably only seen at the extremes of usage. By the vary nature of the use we put these gearboxes to, we are certainly approaching the "extremes." So, as one considers whether to spend the few extra dollar on a ShockProof oil or not, this should be taken into consideration.

So, as is often the case when there is no clear cut opinion from within the industry, the answer to which is best seems to be "it depends." What is needed here is the real world experience that would either say, "yes, the Shockproof gear oils will make your shifts very notchy" or "the Borg-Warner style synchros in the G50 family will work just fine with Shockproof gear lubes." To that end, I think I will register on the Rennlist forum and see if I can get some active input from long time Porsche drivers on their experiences with different types of gear oil, rather than relying on the lack of complaint.

Regards,
Lynn

 

[Lynn Larsen]

Well I have posted a question on the Rennlist Perfromance and Modifications Topic area. We'll see what comes of it.

I can say that, in searching the Rennlist forums, it is quite apparent that the Porsche people really like Mobil 1 products:

Mobilube 1 SHC 75W-90
Mobilube HD LS 80W-90 (limited slips)

BTW, Castrol Syntrax = Castrol Syntec in the US:

Castrol SYNTEC Full Synthetic Gear Oil 75W-90 is the only synthetic they offer. They do have dino based hyphoid GL-5 gear lubes as well as does Mobil.

Regards,
Lynn

 

[Tim Kay]

Lynn,

Great info and thanks for taking the time on this subject.

In respect to the oil and syncro's, what would be, if any, the consideration if using steel syncro's vs brass?

 

[Lynn Larsen]

Tim,

The obvious advantages of steel being stronger synchros, but also, I would think, that the steel would be less prone to corrosion. That said, it appears that the modern synthetic gear oils have addressed the corrosion issue with brass synchro cones.

In terms of the effect of the different gear lubes, I don't think there would be much difference. If I had to guess, I'd say that the surface of brass, on a molecular level, would be smoother since it is more malleable than steel. This could make brass slightly more sensitive to very slippery oils. (Syncros work using the drag between the metal surfaces to spin up the mating parts to similar rpms; if the lubrication between them is too good, they won't work as well.) But, to be bluntly honest, this is pure conjecture on my part or, at best, an educated guess.

Regards,
Lynn

 

[Lynn Larsen]

Well, I am not sure I've gotten enough responses to be statistically valid , but it does appear that the majority of racers do use Red Line and are happy with it. I have posted on Porsche 964, 964 Turbo, Porsche Performance Mod, forums on Rennlist. Also, the Porsche, Ultima, and Kit Car forums on Pistonheads.

Orinn at Eurosports Ltd in Denver, an independent Porsche technician, says that they use Red Line ShockProof exclusively, unless directed otherwise by the owner. He also said, "We have also seen very good success with the Redline gearlube running in GT3R's in the Speed Challenge Series...if it works well for them, that is another good datapoint." Taylor Racing also endorses Red Line Shockproof gear oils in their racing-- Hewland, Webster, Staffs-- transmissions and transaxles; see Taylor Racing "All About Oils" where he says that, "Redline “Shockproof” oil is the only recent development we have seen that actually works, and we highly recommend it."

Several of the Rennlist Forum crowd use Mobil 1 in their gearboxes, but I got the feeling that they were following the liturgy of the church of Renn. Not to say that it isn't very good gear oil, I am sure it is outstanding, but I did not see an extreme pressure or shock proof type of gear oil listed for Mobillube. Amsoil, while not mentioned by anyone responding to my posts, also has an Extreme Pressure synthetic gear lube whose web pages read almost identically to Red Line's technical discussions. Castrol, like Mobil, did not have an extreme pressure product either. I was somewhat surprised by the Lucas Oil's lack of a product that I would consider a candidate for use in a G50. Swepco, the preeminent oil for pre '87 Porsche transaxles, is dino oil also and probably not suitable for G50 use for us.

Here is a listing of the synthetics I found:

Redline 75W90, 75W90NS, ShockProof Light/Heavy Gear Oil

Mobilube 1 SHC 75W-90
Mobilube HD LS 80W-90 (limited slips)

Amsoil SEVERE GEAR™ Synthetic Extreme Pressure (EP) Lubricant 75W-90 (SVG)

Castrol SYNTEC Full Synthetic Gear Oil 75W-90

I'd have to say that, if I were going out to buy gear oil today, I believe I'd be buying ShockProof Heavyweight gear oil. If I had a freshly rebuilt transaxle, I'd probably run the Lightweight for break in and then switch to the heavy. The only knock that I heard on the heavyweight is that it is hard to pump in during the winter months. From a cost perspective, it is less than a buck more per quart.

Regards,
Lynn

 

[Chris Martino]

Well that was easy - Red Line Redline 75W90 Shockproof it is! ha!

Thanks for the research Lynn, I did read a lot of what you posted on the different manf sites but I ended up with a migraine after trying to figure out which type made the most "sense" to use.

Glad you made out the other side-

Chris