When you first hear the Getrag rattle its a little unnerving. The Getrag rattle is the sound the Getrag transmissions (particularly 5 speed’s like those found in E30’s, BMW’s and GM’s) makes when it is in Neutral and the clutch pedal is not engaged.
The sound completely goes away when either the clutch pedal is engaged or the car is in gear.
Some would describe the sound like a bag of marbles, gear chatter, or similar metal rattling.
The sound is not a fault within the transmission, rather what you are hearing is the unengaged gears vibrating against their neighbors.
If you have ever heard a large 18 wheeler idle in neutral you would have likely heard a loud metal rattling sound as well. Again its not because the truck is broken, its because of the play in the gears when not engaged. The sound is louder in an 18 wheeler because the gears are bigger.
As the transmission accumulates miles the sound may get louder as the gears and bearing clearances inside become ever so slightly larger. It is not indicative of the transmission failing.
Never the less its annoying and sometimes embarrassing.
The noise can be significantly effected depending on the transmission oil you use. The thicker the oil, the harder the gears and bearings have to work to bounce around.
The solution is to mix one part 75w80 (or similar) and one part heavy weight oil like 75w-140 or 85w-140.
Using overall thicker oil will increase shifting effort in cold winter weather until the transmission is warmed up so keep that in mind.
One critically important step is to use GL-4 oil!
All the oils I could find in NA were GL-5 “compatible” for applications calling for GL-4 or a fixed weight. Although there may be some compatibility, the composition of the grades is fundamentally different and really werent designed to be backwards compatible. Technical explanation below why it is not truly backwards compatible:
http://www.widman.biz/uploads/Transaxle_oil.pdf
I was able to find this oil from Europe which is exclusively rated gl-4 and for manual transmissions:
http://www.eurol.com/en/37-products/…w-140-gl4.html
Which I was able to order from amazon.de from a seller who ships internationally:
http://www.amazon.de/gp/product/B019…021_TE_3p_dp_1
I got a 5L instead of a 4L, nice 1L bonus!
Find below an easy way to refill your transmission fluid in your E30:
The easy and cheap way to change transmission fluid on an E30
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Hi,
I had the same issue with the Getrag gearbox.
Initially some of them were filled with ATF oil. Some can tell by the sticker on the right side of the transmission, near the bell housing.
My car’s gearbox was really noisy. I felt ashamed even because of it.
I decided to change all the bearings inside. To be sure about the quality (you can buy very cheap or very expensive bearings same type) I ordered all from the BMW. Some are very specific. Repair took some time as mechanic was unable to open the transmission so after few weeks I took it and did it by myself. I was sure I will help as some of the bearings had some wear marks on the rolling parts. I was shocked in the end because it did not really helped.
It was frustrating.
That time my friend suggested to fill the transmission with the mineral oil according to BWM specification. I did and… it worked! It was really quiet from now.
The only disadvantage was the problem with gear change during the winter for the first meters of driving.
So I can agree with the author. Do not spend money on the gearbox as long as it is not loosing gears. Just change the oil to higher grade one.
Cheers