Noisy ZF / transmission options

Lotuss7

Lotuss7

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Xmas holiday and with the break I have been spending a bit of time in the coupe (when dry!).

My ZF is a screamer. Silent at idle with the clutch engaged (not a throw out bearing issue). Clutch out, stationary at idle, crunchy noises (bearing / gears?). Same in 1st through 3rd when running. Silent in 4th however. Trans shifts smoothly, no grinding, balking, syncro issues when changing gears.

I have read the ZFs are inherently noisy transmissions and question whether a rebuilt will achieve desired results? I like the idea of keeping the original trans and gear noise itself is not a problem….a consistent smooth whine, OK. Grinding?…not so cool. I know a great transmission guy and if these transmissions can be civilized this would be an option.

I have considered a 5sp swap but am OK with a 4sp and would like to take a simpler approach if one is available. Appears the Getrag 4sp is a quieter trans??? They seem to be readily available…but is it a simple drop in? I read in one post the change over requires drive shaft length adjustment and trans mount and slave cylinder swap. Not a big deal, but at some point the 5sp option becomes more attractive.

New Year is approaching and one of my resolutions is to dump the trans white noise so I can enjoy the sounds of the six.

Any thoughts, tricks, similar experiences, etc. are very welcome.

John
 
+ 5 speed

I did the 5 speed swap (from an automatic) and am very pleased. The swap is very straightforward and there is tons of help on the forum. Besides refreshing the clutch, PP & TOB and a new slave, there will be the correct drive-shaft swap and you're done. Keep in mind that (according to a local expert here in Austin, TX) there will still be a slight noise when the clutch is engaged from the main shaft of the transmission if you use the performance -period correct- gear oil (red). If you use the original gear lube the noise should be all but eliminated. Of course you may want to start with a heavier gear lube before doing the swap just in case that is the issue.

Mine is still in the paint shop, but hope to have it out in a few weeks. I plan on using it as a daily driver so I should be able to report all the issues, mostly self inflicted I'm sure, but at least I can help by reporting my mistakes.

Good luck with your trans!
 
Heavier oil...

If you haven't already, I would try a heavier transmission oil before anything else. I was complaining about my noisy gearbox to Carl Nelson earlier this year and this is exactly what he told me to do. He also mentioned his own oil "blend" which he puts in all gearboxes and which helps a lot with this.
 
IS3FIFTY said:
If you haven't already, I would try a heavier transmission oil before anything else. I was complaining about my noisy gearbox to Carl Nelson earlier this year and this is exactly what he told me to do. He also mentioned his own oil "blend" which he puts in all gearboxes and which helps a lot with this.
Click to expand...

Pretty obvious first step and I probably should have given this a go before bending my mind on alternate solutions. I am familiar with Carl's recommendation on 50% synthetic and 50% normal gear oil. My coupe is currently using 100% Redline MTL.

I just returned from picking up 3 quarts of Lucas HD 85/140W gear oil. Going to give this a go at 100%. If it does the trick I can experiment with a mix after.

Good advice and a true price performer if successful.
 
IS3FIFTY said:
If you haven't already, I would try a heavier transmission oil before anything else. I was complaining about my noisy gearbox to Carl Nelson earlier this year and this is exactly what he told me to do. He also mentioned his own oil "blend" which he puts in all gearboxes and which helps a lot with this.
Click to expand...

Some transmission noise is unavoidable and usually obscured by road noise and cabin soundproofing. Anyone familiar with straight cut gears found in the Muncie M22 4-speed knows why it is nicknamed "rockcrusher." Neither the ZF nor the Getrag transmissions use those style gears - but they both can be quite noisy when worn or poorly constructed. Transmissions are not wear-free. As the mileage increases, gears, bearings. synchronizers and bushes all give up metal particulates. If the lubricant is not routinely changed and the magnetic drain plug wiped clean, some of those same metal particulates can accelerate the wear. Hard service necessitates even more frequent maintenance. Often some of the noise and wear can be addressed with shimming, but the effort to tear down the transmission to measure and include the shims can be cost ineffective. Maybe there are some magic pellets that can be added to the transmission as a substitute for worn parts, but I am not familiar with them.

While a heavier viscosity lubricant will undoubtedly have a quieting effect, it may come with trade offs. First, it may cause sychronizers to hang or become sluggish - especially in cold weather. This, in turn, can result in even more wear when engaging gears requires extra effort. (Some may even use ATF for the opposite effect with balky synchronizers.) A thicker oil can also cause more friction/drag on gears, which is why it is usually reserved for slower moving equipment like tractors and earth moving equipment.

I have limited experience with a product called Liquidmoly and cannot say that I have personally used it on a noisy transmission. However, I have heard a couple of people claim both reduced transmission noise and operating temperatures with the product. I have also heard similar things about a witches blend of standard GL4 75 W-90 and STP (or other viscosity improvers with heaps of zinc additives. As before, I doubt it is a substitute for a extremely worn transmission parts.

Getriebeöl (GL4) SAE 85 W-90 High-pressure gear oil which is manufactured from carefully selected base oils and special additives. Universal use for all types of transmissions: Spur gear, bevel-gear and worm-gear transmissions. Reduces wear and minimises running noise. Excellent temperature-viscosity behaviour and outstanding resistance to ageing. Resistant to cold and very compatible with sealing materials.
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http://www.liqui-moly.de/liquimoly/produktdb.nsf/id/en_1403.html?Opendocument&land=DE

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nashvillecat said:
... Maybe there are some magic pellets that can be added to the transmission as a substitute for worn parts, but I am not familiar with them....
Click to expand...
In some countries, it's called sawdust... An Italian mechanic once confessed to me that it was routine for most shops to add sawdust to gear oil when customers complained about clunky gearboxes. :roll:

Other than that there's Slick 50 or similar products which have microscopic PTFE parts in them that are supposed to compensate for wear. Was very popular in the '90s.
 
nashvillecat,

This trans is falling into the old and worn catagory.

I had a Leeson racing transmission for a bit. Straight cut gears it was a screamer too, but in a very consistant mechanical way. In an open / unsilenced exhaust car it was it only a small component of the noise generated. In that context it was a brilliant sound.

Asking a lot to silence this box, but what the heck. I swapped out the Redline MTL for Lucas HD 85-140W gear oil. A bit quieter, but not so much quieter that I will now drain about half and add back Redline.

Still going to investigate a Getrag 4sp, but the 5sp swap is probably the ultimate answer.
 
I have a ZF 4-speed

I have a ZF 4-speed from a 2800CS I parted out 25 years ago. It's been sitting unused under the porch at my mother's house. I believe it to be a runner, but I never drove the car it came out of so I don't know for certain. I'd be happy to sell it to you for short money. I haven't been on this forum in a while, as I've been working on my tii, but I'll check for PMs.

--Rob
 
It's a bit of an old thread this one, but I thought I'd chime in. I rebuilt one of these ZF boxes 15 or so years ago. They're beautiful transmissions and actually the best shifting of any of the transmissions found on BMWs of the era and beyond, because the shifting lever acts straight into the transmission, without any levers or bushings. Also, the synchros are the best of the best brass ones. It really is a gem, pity it is not a 5-speed, and a pity that ZF did not use stronger bearings than the ball bearings found in it. And no, it is not normal for it to be noisy.

You will not find a manual transmission that is easier to overhaul than this one. If you are trusting yourself to fix an engine or a wheel bearing, you can fix this box. There are a few minor challenges with bearings pressed on shafts, but that is very easy as soon as you have the right puller. You will need to replace five bearings in total, all four corners, of which two 'special' bearings with outer retaining rings, and the main shaft needle bearing supporting the main shaft in the input shaft.

Do not worry too much about shimming, as I understand it the builders who originally built it also didn't. If you just change the bearings and keep the shims where they were, you will very likely be fine as bearings have very tight manufacturing tolerances. Measure old vs. new bearing to be sure and check that the rebuilt box does not have more resistance than before when turning in any gear.

With a 3.25 diff on a 3.0 carburetted engine (instead of the original 3.45), I never really missed a fifth gear, and I still miss that box, having sold it with my previous CS where my current one has a Getrag.
 
Reviving this old thread. My ZF 4 speed has the same symptoms as Lotuss7 "Clutch out, stationary at idle, crunchy noises (bearing / gears?). Same in 1st through 3rd when running. Silent in 4th however. Trans shifts smoothly, no grinding, balking, syncro issues when changing gears. "
I have the opportunity to buy a 4 speed Getrag with linkage out of an E3 -77 for roughly 300 USD. Are these noisy as well or better than the ZF?

My question really is whether I should renew the bearings in my ZF (I like my ZF besides the noise) or if it's wiser to go with the Getrag?
 
frogish said:
I have the opportunity to buy a 4 speed Getrag with linkage out of an E3 -77 for roughly 300 USD. Are these noisy as well or better than the ZF?

My question really is whether I should renew the bearings in my ZF (I like my ZF besides the noise) or if it's wiser to go with the Getrag?
Click to expand...

Hard to source a 5 speed Getrag without similar bearing noise (in the US), and bearing is NLA... Fix the ZF unless the 4-speed Getrag can be tested on the E3 to be perfect.

I had a 4-speed on my 77 Euro 633CSi, and it was the best tranny I ever had. I was too young to inquire whether it was ZF or Getrag, but 77 was a good year for a 4-speed tranny...
 
Ha! My solution was somewhat tangential. Great excuse to swap for a 5sp.

Don did his magic and I love it.

John
 
My cs had a zf originally. I agree that it was THE best shifting trans I ever have driven.
It also became very noisy.
I had it rebuilt in 1984 so you would think that the parts would be easily available.
NO. There is a flaw in the mating of 2 gears that face to face mesh together, not geared. The mating surface gets worn. They quit making them, and parts!
No i don't know which gears.
That said I changed it out 3 years later with a 4sp Getrag, because it was still noisy. Still shifted great.
Sold it(zf) to a forum member many years ago after warning him about the issue. He wanted to replace his ZF with same. I had a 4sp Getrag also but he didn't want it.
It went belly up within 3-4 years.

I don't believe it is an isolated problem.

I have never had a problem with any Getrag. Doesn't shift as good as the ZF, but I haven't had one break.
 
today I drove the Taiga for 350 miles. It has the ultra rare ZF 5 speed box, with 1:1 on 5th, mated to a 3,64 diff. The engine is a heavily modified 3,5 with mapped ignition and modern FI. Has 365 hp and 420Nm of torque,
The box was rebuilt by a ZF specialist in Kassel, Germany. It is inherently noisy!. Very nice to operate, and a long lever.
i also have a NOS 4 speed ZF, with matching prop shaft with smaller screws. I might use it in the very early 2800 CS that my father bought used in 1971. I have heard that BMW changed to Getrag because they were cheaper, but donˋt know if itś true
 
Lotuss7 said:
Xmas holiday and with the break I have been spending a bit of time in the coupe (when dry!).

My ZF is a screamer. Silent at idle with the clutch engaged (not a throw out bearing issue). Clutch out, stationary at idle, crunchy noises (bearing / gears?). Same in 1st through 3rd when running. Silent in 4th however. Trans shifts smoothly, no grinding, balking, syncro issues when changing gears.

I have read the ZFs are inherently noisy transmissions and question whether a rebuilt will achieve desired results? I like the idea of keeping the original trans and gear noise itself is not a problem….a consistent smooth whine, OK. Grinding?…not so cool. I know a great transmission guy and if these transmissions can be civilized this would be an option.

I have considered a 5sp swap but am OK with a 4sp and would like to take a simpler approach if one is available. Appears the Getrag 4sp is a quieter trans??? They seem to be readily available…but is it a simple drop in? I read in one post the change over requires drive shaft length adjustment and trans mount and slave cylinder swap. Not a big deal, but at some point the 5sp option becomes more attractive.

New Year is approaching and one of my resolutions is to dump the trans white noise so I can enjoy the sounds of the six.

Any thoughts, tricks, similar experiences, etc. are very welcome.

John
Click to expand...
I'm pretty sure they were only designed to take so much punishment, I've got a ZF manual in our 2800cs, never gave me any problems shifting, but is really loud once warm, assuming they can be rebuilt better as long as the gears are not worn, even then parts can probably be source for these early ZF manuals, perhaps someone will chime in on the subject, there were some rare ZF 5 speeds made for coupes but very limited, the transmission is used in many other applications so there has to be a parts network for these...
 
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