Driving Noise

[Bernd]

Hi to all,

as I am new here, I guess I should introduce myself before asking for help. I live in Innsbruck, Austria, and got myself a 712K ex fire engine with just 15 K miles. It had some rust problems in the rear wheel arches (well really small, had to replace everything.... ), and is on the road for 2 weeks now.

So now to the problems: I got some highway toll stickers last weekend and drove the Pinz at "higher" speeds for a longer time (half an hour) and found the noise quite unbearable, and yes, I´m used to loud cars (Landrover NA diesel...).
The main problem is a eytremely loud whining from the back that gives me literally headache, I can´t hear anything else (engine, tires ...), it sounds like a very bad bearing or so.
Has anybody an idea where I should start looking?
( I don´t guess it´s normal, or are you all waering ear protectors...)


Greetings

Bernd

[75pinz]

and they are all pretty loud and make some strange noises that most other makes of trucks don't when coasting, slowing down, etc. I find the 712 to make strange noises and whining when barely maintaining speed. Ie; not coasting, not accelerating. pretty annoying but everyone I have ever seen makes similar noises. I am by no means an expert so pehaps someone else will chime in here.

[mjnims]

Knowing how much noise an 712M makes, I can imagine how noisey a 712K would be. The first place to look to make sure that the noise is in the normal range would be your fluids. Hearing protection would be a good idea in the Pinz especially a 712K.

[lindenengineering]

Yes I know of the earsplitting very high pitched whine you talk about.

It is due to the depth of mesh being incorrect on one pinion/crown wheel assembly in the differential. (usually the rear). In short the gear sets for quiet operation need to be set as they were matched on production. Any out of spec settings will set up a vibration and noise due to the teeth trying to "find" their true running position. Common with the involute tooth form of the Orliken cut, any excessive backlash on a gearset has a phenominan of causing a ringing sound that in some cases creates a very high pitched sound that you are reporting.

Without going into a huge explanation, there is always a distinct possibility of getting the settings wrong on production. This is more common than you think due to time constraints and human error. The other is that some "compromise" is commonplace when setting the axle gear mesh and one of the gear set is at its "top end" of the settings.

The last problem(s) are due to wear causing "the first" viz gear set(s) out of correct mesh.

My suggestion before a tear down and correction of the gearset shim positions or repair/elimination of excessive play that may exist, you first try a few different types of oils or weights of oil. This has been shown to "dampen" the noise from "harmonics" set up in the ring gears.
In some cases we have seen the problem go away by itself by changing to some new tyres, this is particularly so when changing from Maloyas.

PS: there are two manufacturers of differential machine cutting tools in the world, Orliken (Swiss) and Gleeson (USA). The use of each man ufacturers' products are a bit nationalistic, American and British/Japanese makers have historically drifted towards Gleeson, the Euro manufacturers go Orliken.
I have always had a fondness for the "Gleeson form" which from my experience has a more tolerable characteristic when speed of assembly and out of tolerances are concerned.
Hope that helps
Dennis
Linden Engineering Inc

[Bernd]

Thanks to all for the quick replies,

I guess I´ll have to invest into some sound insulation, at the moment it´s bare metal (+paint) in the back, so I hope some padding will diminuish the noise to tolerable levels. Incorrect pinion height does seem to be a good guess, but I´d expected such things more on my Landrover side of toys....

Additionally I will switch to lighter gear oils, at the moment there´s SAE 85W90 in it, I will change to SAE 75W80 or 90, depends which one I can get in sizes bigger than a 500ml can..


Bernd

[2012]

a trick re cancelling a resonating object: couple an object to it that has a different (and non-harmonic) resonant frequency. that holds both objects still.

also, we're dealing with sound damping here in a machine that creates huge racket. sound damping is a dang science! here's a site for you: http://www.b-quiet.com/

good stuff. at least as good (and cheaper) than dynamat. we're using it.

[75pinz]

I think rather than lighter. I would guess that would be the general consensus. I use 80w140 redline with good results. I would think you ay just have to live with it unless you are exceptionally anal about these things.

[pinztrek]

Additionally I will switch to lighter gear oils, at the moment there´s SAE 85W90 in it, I will change to SAE 75W80 or 90, depends which one I can get in sizes bigger than a 500ml can..


Bernd

This may work against you. The best results seem to have come from 85w-140 gear lube specifically formulated for additional "cushion".

Red-line and Chevron both offer gear lubes with this aspect. Basically it's polymers in the oil which curl when at higher temperatures, thus keeping the effective viscosity.

Redline "shockproof" is one that works, but is extremely expensive in quantities the Pinz needs.

Chevron Delo® Gear Lubricants ESI 85W-140 is available in 5 gallon pails for about what a few quarts of the Red-line is. It should be easier to source outside of the US than the red-line as well. I do use the redline tranny oil with good results. But for about $40 for a 5 gallon pail, the Chevron has worked out well. Here's a quote, albeit from the mfg:

"Delo Gear Lubricants ESI rival the performance levels of synthetic gear lubricants and are a cost-effective alternative to synthetic fluids.

Tests prove that Chevron Delo Gear Lubricants ESI provide a wear protection film three to five times thicker than the conventional antiwear film. This patented anti-wear technology reduces friction to ensure superior gear protection and cooler operating temperatures. Chevron Delo Gear Lubricants ESI maintain thermal stability, contributing to improved fuel economy, longer gear and lubricant life as well as energy conservation. Use of these lubricants will not adversely affect seal materials."

Note the comment on seals, as that's a biggie. I noticed significant quieting when I went to this lube, though you still hear a whine. There have been many discussions as to what causes it, exact sources, and how to deal with it.

Diffs are one key source, the hubs another, and mud tires the third.

With better gear lube and a spray-in bedliner I've abated the diff & hub noise some, to the point my tires are the loudest. That and the engine fan, which contributes much "whine".

Many have cut & used horse stall mats in the bed as an additional dampening. From there, using the sound absorbing materials on the engine cover, canvas, and cab interior seem to be the next most productive area.

Good luck in your quest! The pinz will never be quiet, but it's part of it's nature and is due to all the gears and over-engineering the vehicle offers. You have to remember a pinz has 2x the number of diff gears, plus 8 additional gears in the hubs that a conventional 4wd does not have.

Have fun,

Alan

[hrafn]

I am using Red Line Heavy Shockproof gear oil in all gear cases (except the transmission) with excellent results. The noise reduction, while not dramatic, is nevertheless noteworthy. And, I have had no problems with leakage.

Yes, it is expensive, but well worth it IMHO.

[Charles]

Hi Guys,
This works like a charm:
http://www.sdp-pinzgauer.org/html/noise_reduction.html

Won't fix any underlying "problems" if you have em, but really does wonders in perceived noise.

Thank Jim LaGaurdia for this one.

Took me 15 minutes or less, and really worked. I know it sounds too easy to be true, but I was pretty amazed. And my pro mechanic buddy who came along for the test run was pretty amazed too.

[Buzz]

I too had terrible noise problems at high speeds when I first bought my truck. I wore ear plugs for a while. Like the others above, I changed the oil and used Lucas Gear Oil which helped somewhat. But what really helped was putting sound dampening material in the bed. My friend Scott gave me several sheets of sound dampening material similar to B-Quiet. And it helped. That stuff is made out of asphalt and is not cheap. Later I realized the roofing shingles are also heavy and made out of asphalt and ARE cheap. So now I have two or three layers of shingles along with the stuff Scott gave me covered up by some shop carpet I bought at the Big Box hardware store. I also keep a couple 5 gallon jugs of water back there to keep the rear tires flat on the ground. Lastly, check that the dog house seals well all around. Mine was missing those gussetts at the corners near the air tunnel, and I have soft foam stuffed in there.
Now its possible to hold a conversation while on the highway. Very similar to riding a yellow school bus at the same speed. - Buzz

[pinzinator]

I did the Jim LaGuardia fix yesterday, and it does work. Took a half hour, and well worth it. The noise is less, and the Pinz just sounds better. I recommend everybody to make this repair, only 4 bolts and 1 mount bolt.

[Bernd]

Hi,

I changed to SAE 75W90 before the weekend, found the sound somewhat improved. I lost the strong resonant sound, so now its only LOUUUUUUD, but not ear splitting anymore. I will invest in some insulation and the La Guardia fix is on the line....

On a side note: Did you experience any troubles when driving with oils that much thicker than originally specified?


Greetings


Bernd

[lindenengineering]

Bernd
Glad to notice by changing the oil you managed to reduce that ear splitting noise. In fact a few owners in our area have adopted the horse stall as an effective method of sound deadening.

Now to that "Magic Pin" and the rubber sleeve fix.

Gentlemen first ask yourselves why did those clever Steyr people put that pin there in the first place?
Manufacturers rarely put anything at their cost in a vehicle unless its absolutely necessary.
In this case it is to stop the powerpack dropping down should the gearbox mount fail. Doing so would disconnect the slip coupling with expensive results and the truck would cease to proceed.

For those of you technically challenged the mount will "sag' over a period of years due to changes in its shore hardness and lose its resilience. This is not a phenominan associated with a Steyr. All vehicles deteriorate over a period of time. Engine/gearbox mountings go hard, split and detach themselves over that same period of time. There are hundreds of fixes posted by mechanics on tech networks indicating that deteriorated mountings are/were the causes of vibration problems in all sorts of cars.

The mounts on a Steyr are subjected to alot of movement especially if you are an off roader. Why not consider changing the mounts, they are simple to replace and the reduction of vibration can be significant when the originals are severely deriorated. After all the ones we often see are more than 30 years old.
Dennis

[Bernd]

Hi Dennis,

I did the fix anyway, its really just 15 min work, the effect isn´t very big with my Pinz, the Diff howling is still predominant, but in a more "pure" form...

You are for sure right, replacing the mounts after they have sagged considerably is the correct way to go, but looking at the clearance this safety pin has to the metal mount, it is still a cheap an quick fix and might make an improvement even with new mounts.


Bernd