Original 4 Speed Transmission Noises?

[RMBaiada]

I purchased my BMW 2002 new in 1974. After 135,000 miles on the odometer, I started completely rebuilding my 2002 in the mid-1990s, and in 2021 it was finally drivable.

 

I had the engine completely rebuilt. The clutch, throw out bearing, Guibo, universal and center bearing are all new. The driveshaft is rebuilt and balanced and the diff has been rebuilt.

 

But on my original 4 speed transmission, I only replaced the seals. The transmission shifts smoothly in and out of all 4 gears and reverse and I am using 2.1 pints of Royal Purple HPS 5w30.

 

I don't remember any noises when I pulled the car apart 25 years ago in the mid 1990s, but I now have the following concerns after 2,220 miles since reinstalling the transmission and getting the car back on the road in 2021.

 

1. I get a whine in first gear when accelerating and a much louder whine when deaccelerating when in first gear. This seems to come from the front of the transmission. No whining in any of the other gears.

2. I get a slight rattle in all 4 gears, which seems to come from under the shifter. It is not bad, but annoying.

 

Any suggestions?

 

1. Do I need a trans rebuild?

2. Are parts still available for the original 4 speed transmission?

3. What price should I expect to pay to have the trans pulled and rebuilt?

 

I live near San Diego, so any suggestions on shops would be appreciated.

[2002iii]

I would try using Redline MTL. 

 

Check the shift tower bushings and linkage for looseness and clearance.

[Preyupy]

That gearbox was designed to use a thicker oil than the Redline MTL.  The spec is 80 or 90 weight non hypoid gear oil OR a HD grade engine oil (usually 30W or 40W)  

 

If you are hearing gear rattling in neutral with the clutch engaged this is completely normal and will be worse with a lighter weight oil (it also gets worse when the transmission is hot). 

 

As far as the whine in 1st gear, this is usually caused by a bad countershaft bearing inside the transmission but also could be worn gears.  The only way to know for sure is take it apart.  

 

[dlacey]

4 hours ago, RMBaiada said:

Any suggestions?

 

Heavier oil, ignore the noise and enjoy the car. These gearboxes are very reliable, so theres limited spares and rebuilders...best just keep an eye on eBay and buy another as a spare... 
as for why its now noisy after 25 yrs storage... any chance water might have got inside via the breather?? If theres a chance that happened then better accelerate the eBay replacement.

[RMBaiada]

It sounds like the Royal Purple HPS 5w30 is too thin. From reading other threads, it sounds like I should switch to the Redline MTL.

[Mike Self]

1 hour ago, dlacey said:

as for why its now noisy after 25 yrs storage.

You've been driving much newer (and quieter) cars for the past quarter century, and likely forgot the higher normal noise level for the mechanicals in your '02 (not to mention wind and road noise).  

 

I've been running Redline MTL in both my original 4 speed and its replacement 5 speed since the early 80s, and it works very well and in fact cured some notchiness in my '73's 4 speed.  I agree that the 5w30 is more suited for the sump of a new Toyota than an 02 gearbox.

 

mike

[jimk]

I believe the 100C viscocity of RedlineMTL is the same as SAE 30 engine oil.  MTL probably has GL4 wear additives where the engine oil does not.  Same for Amsoil MTF.

 

Original substitute lubricant was 10W-40 engine oil that has the same 100C viscosity as a SAE 90 gear lube but is on the heavy side for synchro wear (if the driver is a gear jammer).

[RMBaiada]

Thank you all.

 

I decided to try the Redline MTL.

 

Just curious, since I couldn't find any BMW FAQ threads on swapping the transmission, how difficult is it to replace it? Do I need to pull the engine?

Edited December 22, 2022 by RMBaiada

[jimk]

28 minutes ago, RMBaiada said:

how difficult is it to replace it? Do I need to pull the engine?

Engine can stay in.

Here are a couple of docs.

Trans Upgrades .PDF Tech BMW Procedure, 5 Spd Convers.PDF

[TobyB]

I'm with Byron- you need a front countershaft bearing.

 

Up until not so long ago, decent 4- speed B-W synchro transmissions

were pretty easy to find.  But I'm not sure what the supply

is like, now.

Repairing a BMW transmission is labor- intensive and has

some tricks to it.  I don't know if the countershaft

bearings on the 4- speed are hard to find, but I suspect not.

 

t

 

[2002iii]

I've never liked the idea of engine oil in a transmission. There's a reason we have transmission fluid, its designed for gears and has additives and cleaners that last longer than the ones in engine oil. Think about how much more often you change your oil versus transmission fluid.

 

It could be a bearing problem, but new fluid is cheaper than a rebuild and worth trying.

 

4 speeds are getting a little harder to find because so many people tossed them long ago for a 5 speed. All the bearings in the 4 speeds are pretty common sizes and still readily available.

 

 

[Jam3422]

You might try MTL90, it's a little higher viscosity than MTL, and it helped quiet down my 4 speed.

 

Replacing the front layshaft bearing is straightforward, if you have the tools (kind of a big if).  You don't even have to remove the shift forks/shafts.  The last time I checked, the bearings were easy to find, and pretty cheap.  I think there's a roller bearing equivalent replacement, but I was never able to track that down.

[RMBaiada]

Thank you.

[jimk]

3 hours ago, 2002iii said:

There's a reason we have transmission fluid, its designed for gears and has additives and cleaners that last longer than the ones in engine oil.

They weren't around in the 1970s.

[TobyB]

The design philosophy for engine oil is that there's a filter in the system, 

and the fluid's actively circulated through that filter.

 

The design philosophy for gear oil is that there's no filter,

and that any active circulation's by splash and gear mesh.

 

So in theory, an engine oil holds things suspended, so the filter can get them out of the engine.

Whereas the gearbox oil lets them settle to the bottom where they'll do no harm.

 

But given that Honda and others have used engine oil in their manual

transmissions since the '70s, and Austin since the 50's,

I suspect it doesn't matter that much at all.

 

t