I have a Muncie M-21 in my '66. The tranny has been completely rebuilt, gears syncos etc. This was done about 5 years ago and it has about 6000 miles on it now. The problem is that when shifting from 3rd to 4th I get a grinding noise, it goes into gear but something isn't meshing properly. It does not happen all the time, cold or warm does not make a difference althougth I believe it happens more when it is warm. No other gear just 4th. If I shift from 3rd and wait a second or two it will slide right into 4th without any grinding. You can actually feel the synco spinning as it slows down you can shift right into 4th without a problem. Shift linkage and clutch are adjusted properly and I'm using GM 80w90 GL-4 Gear Lube.
Any ideas.............
Thanks,
DFA

 

4th gear synchro ring is going bad, or your clutch is not fully releasing...
Bill

 

Has anyone tried "Red Line " MT-90, 75w90 GL-4 Synthetic Transmission Oil ? It was suggested to me to try this. It is designed manual transmissions.
DFA

 

Bill.... now this is another muddy area. Synthetics were originally like Mobil-1 and based solely on PAO (polyalphaolefin) chemistry. These fall in the Group IV base oil category. In order to keep the additives from dropping out, PAO's needed different kinds of Ester based stocks added. Also Group IV stocks. These often lead to a more friction modified type fluid. Often in the"slippery" version. These oils are so different they required flush changes and other annoying problems. There is no doubt that these oils are high quality and very long lived.



The Courts later decided the Synthetic issue by allowing new Group III highly refined base stocks to be classified as synthetic. These are not truely synthetically made, but are extremely refined and narrow cut out of crude stocks. This process is expensive, but not as expensive as Group IV. The process does result in very stable high quality base oils. Today, most lubricant companies formulate their synthetics using Group III stocks and the advantage is less cost, more compatibility with normal oils, but still with a longer life and high quality.



Thus, you have another decision. For engine, automatic tranmission, differential, and even grease applications I would recommend the synthetics. Not only do these oils add protection and reduce wear, but can save money by increasing fuel economy. However, for these and other applications you should follow the manufacturers recommendations. I know of different applications where either synthetics or mineral based fluids are specifically called out. It is not always prudent to substitute unless the manufacturer supports that option.



Regards,



Don Eggimann

Technical Director,

Amalie Oil Co.

813-248-1988x250

800-368-1264



-----Original Message-----
From: Bill Fleckenstein [mailto:bfleckenstein1@earthlink.net]
Sent: Tuesday, August 23, 2005 10:29 AM
To: Don Eggiman
Subject: Re: XCEL brand multipurpose 80W-90 GL-5 gear oil



Don



thank you for your candid response. so far; Valvoline, Royal Purple, & Red Line are the only ones that have said that their GL-5, non-synthetic (more on the synthetic/non-synthetic thing in a second) gear oils are usable (Mobil, AMSoil & Chevron say their's is not). unless you might know of a reason why not, i will go with the Valvoline as it is available locally.



now, as to the synthetic/non-synthetic controversy.... the short version: many say that it CAN be too slippery and will result in synchronizer clash. that in itself leads me to be leery of synthetics... any advice there?



Bill

----- Original Message -----

From: Don Eggiman

To: Bill Fleckenstein

Sent: Tuesday, August 23, 2005 9:19 AM

Subject: RE: XCEL brand multipurpose 80W-90 GL-5 gear oil



Bill,

There is considerable disagreement in the industry over this issue at present. The older school of thought is based on older chemisty that did contain active sulfur as an EP (extreme pressure) agent. The recommendation you find based on this is to use a GL-4 lubricant. It contains about 1/2 the additive treat level (and is the same additive chemistry) as GL-5. Newer chemistry from some of the best additive manufacturers, contains EP that is not active sulfur. These are GL-5 gear oils and they have the higher additive treatment level but they are reputed to be safe for manual transmission applications. We are at present looking seriously at changing to this type of chemistry. In the mean time, our present additive supplier for our GL-5 applications does not recommend GL-5 oils for GL-4 transmissions, and neither can I. Unfortunately, GL-4 oils are such low volume for us we can't provide them in convenient sizes for the non-industrial user. Thus, for this time, I can't help you with either Amalie or Xcel brand offerings. I do expect in the near future to have a GL-5 certified oil that will also be safe for your application.



For your enjoyment, the following are excerpts from recent discussions we have had with our suppliers on this subject:



"Let me start by differentiating between the API service designations of GL-4 & GL-5. According to API Publication 1560, Lubricant Service Designations for Automotive Manaul Transmissions, Manual Transaxles, and Axles:

· "The designation API GL-4 denotes lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid (see note) gears operating under moderate speed and loads. These oils may be used in selected manual transmission... The manufacturer's specific lubricant quality recommendations should be followed.

Although this service designation is still used commercially to describe lubricants, some test equipment used for performance verification is no longer available."

· "The designation API GL-5 denotes lubricants intended or gears, particularly hypoid (see note) gears, in axles operating under various combinations of high-speed/shock load and low-speed/high torque conditions. Lubricants qualified under U.S. Military Specification MIL-L-2105d satisfy requirements..."

· "NOTE: Frictional requirements for axles equipped with limited-slip differentials are normally defined by the axle manufacturer."

Say what? you ask. In summary, GL-4 lubricants are widely recommended for manual transmissions outside North America. Most often, these transmissions are constructed with synchronizers made of various materials including yellow metals like brass. As you noted, gear lubricants are generally formulated to be compatible with yellow metals. The primary concern with GL-4 lubricants in synchronized manual transmissions is there ability to provide the frictional characteristics needed by the specific synchronizers in the transmission since they vary from OEM to OEM. Nevertheless, OEM's generally will not recommend a GL-4 lubricant if they have any real concern about the ability and compatibility of a typical sulfur/phosphorus gear oil.



Years ago when the GL-5 service category became effective, the gear lubricant industry adapted the practice of recommending a 50% GL-5 additive dosage for GL-4 lubricants. This came about because the Coordinating Research Council (CRC) GL-4 reference gear oil (RGO 105) treats at 5% and the CRC GL-5 reference gear oil (RGO-110) treats at 10%. "



Here is one that is more to the point:



"At this point, I would not recommend using a GL-5 lubricant for GL-4 applications. OEM's are still building under the assumption that GL-4 lubricants contain only 50% of the additive used in GL-5 lubricants. While the additives are the same, GL-5 lubricants may contain "too much of a good thing." This is especially true of the primary extreme pressure agent used in most gear oils. These agents are good, but the GL-4 transmissions and axles were not designed to be compatible with that much additive. It's kind of like eating too much candy -- it can cause a variety of other unexpected problems, and it's really difficult to pin point how long it will take for the problem to manifest itself."



So Bill, my best recommendation for you is to be careful to select a product from a respected source with credientials that will protect your transmission. I hope to soon have an offering for you under the Amalie (or Xcel) brand, but for now must send you elsewhere.



Regards,



Don Eggimann

Technical Director,

Amalie Oil Co.

813-248-1988x250

800-368-1264



-----Original Message-----
From: Bill Fleckenstein [mailto:bfleckenstein1@earthlink.net]
Sent: Monday, August 22, 2005 6:08 PM
To: Don Eggiman
Subject: XCEL brand multipurpose 80W-90 GL-5 gear oil



Don

it is my understanding that XCEL lubricants now fall under the AMALIE umbrella. if this is true, then i have a question about XCEL multipurpose 80W-90 GL-5 gear oil:



i have read many articles (and have gotten the same information from AMSOil & Mobil in inquiries similar to this one that i'm writing to you to) on the internet that GL-5 gear oils should not be used in many manual transmission because GL-5 additives can react with bronze/brass parts such as synchronizer rings, bushings, etc because of reactive sulfurs in the formulation. what is Xcel's position on this; is the XCEL gear oil i referenced safe for my synchronizers; and, if not, what lubricant do you recommend for a GM MY-6 4 spd (3spd w/OD) transmission?



Bill

 

sure sounds like it........ sure you got a new snycro/gear?

or have you missed 4th a few times (during power shifts, etc)?

 

A simple test would be to drain the existing fluid, and replace it with a standard non-synthetic 80-90 wt gear oil. Drive it some and see if that helps/corrects the problem.

 

New synchros for sure during the rebuild.

Mike,
I currently have 80w90 GM GL-4 gear oil in the tranny. Are you suggesting draining and refill with new 80w90 GL-4 ?
DFA

 

A broken or even cracked blocking ring will cause this exact problem.