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Discussion Starter #1
The linkage adjustment and the Synchromax lube did the trick; shifts like "butta" as they say; the 1-2 problem is gone for now, done at the dealer today; then dropped off at Franz Blam racing for the FD mods!!!!
 

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Are you sure it was Royal Purple Synchromax that they put in it? I took a look at Royal Purple's website and see that Synchromax is for manual gearboxes that call for an ATF weight lubricant. I believe Maserati calls for a 75W90 in our transaxles. Might it have been Royal Purple Max-Gear that they put in? Remember, the transmission shares lube with the limited slip differential.

Just wanting to confirm that this was the choice of lube by a Maserati dealership. I'm not all that crazy about the factory documentation anyway and maybe there has been a revision of the recommendation.

Have you noticed any growling or other behavior from the limited slip when you accelerate from a stop while turning left?

Have you noticed a difference in your fuel economy. If this stuff is OK in the gearbox, it should give better mileage and power to the wheels.

I don't mean to be an alarmist and I am glad to hear that you are happy with the shifting. Maybe it would be a good idea to contact Royal Purple's tech support about this. [email protected]

Has anybody else put ATF weight or motor-oil weight lube in their transaxles?
 

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Fastfreddy...

I was going to say something as well but was waiting to look at the service manual first which I did last night.

I put in Mobil 1 75W-90 full synthetic in mine,love the stuff but would be interested in checking this other stuff out if it is that good and it's the 75W-90 that is called for..... So is this the 75W-90 weight version?
 

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I did some searching on the 'net and found that Synchromax seems fine for BMWs M5 Getrag transmissions (which also have notchy clashing shifts like our cars). Because it is an ATF weight lube, the added friction will enable the synchos to grab better, so smoother shifts with less clashing. My concern is that, unlike the M5 Getrags, our transmissions share lube with a limited slip differential. That part of the box is going to need gear-lube with a "GL" rating and friction modifiers for the limited slip. Here's where our problem seems to lie.... the added viscosity, lubricity and limited slip friction modifiers are NOT conducive to smooth synchronizer functioning. The stuff is too slippery and thick, especially cold, especially in 1st and 2nd which are triple synchronized (I think).

I want my gearbox to shift "smooth as butta" too. It should. A car like this requires a smooth shift to fulfill its potential. However, I don't want to go wiping out the differential to accomplish this.

With the conflicting lubrication requirements within our transaxles, a proper compromise is essential. Maybe one of the Royal Purple products is it. Maybe it's Synchromax. Maybe it's Gear-Max.

Anyway, I think this is a crucial topic for our cars. Heck, maybe this is the reason Maserati chucked the transaxle in favor of an automatic.

My only experience so far is that changing whatever the PO had in there to Mobil1 75W90 yielded a very small improvement in the inadequate notchy clashing 1-2 shift.
 

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Redline

I was thinking of trying the redline products. MT90 is rated GL4 and 75W90NS is rated GL5. Which one should I use and does anyone have experience with these - I have heard that they are fantastic!
 

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I corresponded with Redline's tech desk. They recommended the use of 75W90NS. This is the one that has NO friction modifiers for limited slip differential. They further suggested that if our transaxles exhibit growling/chattering from the limited slip, to add their separately available friction modifier in small quantities to get just enough to get rid of the symptoms. I have not tried it yet.
 

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Interesting....

I do know that General Motors also recommended the 75W-90 in the differential for their cars and had a separate conditioner that was added to the mix in order to get rid of howl and other noise via more lubrication. I used to use this in manual transmissions from GM as well...

http://www.westcoastcorvette.com/p-957-c5z06-gm-differential-additive.aspx


I think you could put this stuff in our system and solve the problem, I know it did amazing things for my Camaro, Nova and Chevelle back in those days...
 

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As an FYI from the Owners Manual on Pages 174 & 175:

Engine Oil: SAE 5W/40
Power Steering: ATF Dexron II D (SAE 10W)
Gearbox (both Manual and Cambiocorsa): 75W90 API GL4-GL5C API MT1-PG2 Standards
Cambiocorsa system: Oil Type CHF
 

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The linkage adjustment and the Synchromax lube did the trick; shifts like "butta" as they say; the 1-2 problem is gone for now, done at the dealer today; then dropped off at Franz Blam racing for the FD mods!!!!
Doc - what did the dealer charge you for the service/lube?
 

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What is meant by a clutch adjustment, and what was the dealer charge for that?
 

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Discussion Starter #15
IT states Synchromax!

It is on the invoice, I will call the SA to see if they are gonna pay for my torn up tranny.........it was an adjustment on the linkge, not the clutch; the adjustment was $62.00 and the fluid change was $120 I believe...will post an update, thnx guys!!!!!!!!! Dogdoc
 

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Damage would not be immediate from using the wrong transaxle lube. It would be gradual wear that would cause premature differential failure over 10 or 15K miles. I will be interested to hear the Maserati dealer's case for using this lube. Maybe it's been found to be fine. Maybe it just shifts great, solves the customer's immediate concern, and who cares what happens next year. I'm on a quest to find the optimal compromise for the conflicting requirements of a limited slip differential and synchronizers in the same gearbox. The limited slip needs to be real slick and the synchros need some bite.
 

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Discussion Starter #17
It gets more confusing!

Well..........I spoke to the dealer and Royal Purple. The dealer put their top Ferrari guy on this as he is supposed to be very knowledgeable on oil,lubes, etc. The way they explained it is that the problem is NOT with the limited slip but with the ring and pinionand this fluid fights the shearing effect along the tranverse and longitudinal axis if that makes sense; So.....they read the forum and felt that the target was hit but we all missed the bullseye as they put it. They went on too say they would replace the fluid back at NO charge if I was worried; and that Maserati would of course NOT recommend the change at all; the Synchromax is used they said in the Tesstarosa and other rather frail gear boxes with no problems; the comment they used was that the Masi is a very "robust" tranny and they have seen no issues at all.........then I called Royal P.; the tech guy says that due to the HIGH FILM STRENGTH(said it over and over) it would NOt matter what weight you used; it is very protective; but his advice was to change back to Max Gear or factory BECAUSE of the GL Rating; needless to say I am way confused........:confused:
 

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Discussion Starter #18
more info!

Spoke directly to the Ferrari tech; he said the concern would be the "hyphoid" gear if I am saying it right; the fact that it sweeps back and this is where you need the heavy weight lube.......he did tell me that one customer in his tesstarosa using synchromax(not a spec fluid) has been thru 3 clutches and all other componets are well; says the guy drives it like a "American muscle car", I may change back since the offer was for free and not worry..........
 

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How about if you drive it and let the rest of us know how it works out for you :D

You need a GL-4 rating, such as Max-Gear, for the hypoid ring and pinion. GL-4 means it has an additive package that stands up to the severe shear stress of that configuration. Hypoid refers to the shape of the teeth in the ring and pinion designed for a big offset from center and to be quiet. BTW, most GL-5 lubes have a lot of sulfur added, which is fine in a differential but can damage the soft metals in the synchros of a transmission-fine in your BMW rear, not in your Maserati or Porsche transaxle. I note that Royal Purple Max-Gear claims to achieve a GL-5 without the sulfur so safe with synchros.

So, the RP Max-Gear is good to go for the differential. It also has the friction modifiers needed for the limited slip. Here's where we need a test. It is those friction modifiers that hamper the function of the synchronizers, making the shifts slow and notchy. It may well be that the additive package in the Max-Gear will be more satisfactory for "shifting like butter". Your Synchromax has NO limited slip friction modifiers so the sychronizers work great. Have you tried accelerating from a stop while turning sharply left to see if the limited slip chatters or otherwise acts weird?

There's only one way to find out. If you were to choose the swap to Max-Gear, you could get a great before and after comparison (at the dealer's expense in this case). It's your car. I would be concerned running a 10W lube. Besides, it seems to take Testarossa owners 30 years to get 15K miles on their cars so they wouldn't notice the wear rate.
 

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I've been considering using Redline 75W90NS, which is a GL-4 gear lube with no friction modifiers for limited slip. This takes care of the hypoid differential and the needs of the synchronizers but leaves the limited slip clutches without the friction modifier. If you do the before and after thing, and find the Max-Gear still shifts like butter, I'll go that route. If the Gear Max puts you back to notchy shifting, I'll try the next step of the experimentation with the Redline 75W90NS.
 
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