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Thread: Towing with T56

  1. #61
    Fuel Injected! CDeeZ's Avatar
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    Yeah. It just seems to me that they want the end user to have sense enough to know what they're dealing with more than anything. They're not saying Yes or No one way or another but just "might be acceptable". Which I still take to mean that the end user of the bearing is responsible for being smart enough to make a judgment call. I agree; if there was any doubt just replace it on a cheap bearing. But again, it all comes down to a personal judgement call, for me anyways. Can you post the failure analysis documents indicating bearing staining is a first stage indicating overheating? If so, that will be an interesting contrast to the SKF document as well as the Timken video I posted.

    Maybe I have been lucky, but I can't recall a single time I have ever had a tapered roller bearing fail on anything I've ever messed with that uses them. I had a T56 pilot needle bearing explode and wreck an LTx T56 input shaft. I have ONLY run pilot bushings after that. And bronze ones.... I check them with a magnet to be sure they're not iron bushings, that's no bueno for a pilot bushing.

    Do you care to weigh in on preloading the bearings a tad bit as opposed to having endplay like I mentioned a ways up? I have found multitudinous posts on LS1Tech where guys are setting them up with preload. Which is directly contrary to what Tremec publishes.... Here are some I found easily.

    https://ls1tech.com/forums/manual-tr...d-setting.html

    https://ls1tech.com/forums/manual-tr...ntershaft.html

    https://ls1tech.com/forums/manual-tr...-shimming.html
    Last edited by CDeeZ; 03-19-2018 at 06:19 PM.

  2. #62
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    They always leave it up to the end user. The right wording makes it easier to not get sued.

    I don't recall which manufacturer so I'd have to look for it. I've also seen it in online and print documents in industry magazines before.

    From what I've seen, taper bearings tend to have a decent life with a fairly wide range of end play, have best life with a little preload and then die quickly with too much preload. In other words, the life of the bearing is the best with a little preload and the life drops off slowly as you move towards too much endplay while it drops off quickly with too much preload.

    You can find papers where trucking companies are starting to use specialized equipment to install axle bearings with a preload. It's interesting stuff but basically comes down to them being more reliable when done with precision as opposed to putting the nut tight and then backing it off a little.

    I have no idea why the specification is how it is. There are probably good reasons behind it. 0.001" to 0.002" seems like a decent preload target for the sizes of bearing in the transmission. The only reason I could see it not working is if the shaft heats up more than the case and tightens them further, which might be possible on some of the OD gear sets while under significant load. That one bearing is the smallest so it would be the one to watch for issues due to too much preload.

  3. #63
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    What's worse, CdeeZ, isn't the bearing staining, it's the surface shear failure in that same photo. Look on the gear teeth at 8 and 9 o'clock, you see those tiny pits on the involute face? That is the material failure. They will only get worse, and there's nothing you can do to fix them. Maybe it's just dirt, but to me, that's the textbook pitting of a surface shear failure.

    Same thing happens in a flat tappet cam when you don't have enough EP lube in the oil, or the valve spring pressure is too high, or you're just running much too aggressive a profile on the cam lobe. The lube gets forced out and you get metal-on-metal right there in a tightly focused area, which results in the hard surface literally tearing off the softer core-thus "surface shear" failure. Ways to fix that issue is use a lube with more phosphorus or sulfur, although I think boron compounds are the new hotness in EP additives.

    Could also be that the oil was fine, but just breaking down from the same heat that stained those bearing rollers. Do you have more photos of similar detail on the countershaft gears?
    Last edited by Xnke; 03-20-2018 at 01:35 AM.

  4. #64
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    What's worse, CdeeZ, isn't the bearing staining, it's the surface shear failure in that same photo. Look on the gear teeth at 8 and 9 o'clock, you see those tiny pits on the involute face? That is the material failure. They will only get worse, and there's nothing you can do to fix them. Maybe it's just dirt, but to me, that's the textbook pitting of a surface shear failure.
    I noticed the same issue. But without knowing the condition of the transmission before installation I didn't want to assume all of the damage was due to towing. If the damage is due to the current application, it seems like the transmission has survived long enough to suggest that it may be worth investing time to improve it's chances.

  5. #65
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    Quote Originally Posted by lionelhutz View Post
    They always leave it up to the end user. The right wording makes it easier to not get sued.

    I don't recall which manufacturer so I'd have to look for it. I've also seen it in online and print documents in industry magazines before.

    From what I've seen, taper bearings tend to have a decent life with a fairly wide range of end play, have best life with a little preload and then die quickly with too much preload. In other words, the life of the bearing is the best with a little preload and the life drops off slowly as you move towards too much endplay while it drops off quickly with too much preload.

    You can find papers where trucking companies are starting to use specialized equipment to install axle bearings with a preload. It's interesting stuff but basically comes down to them being more reliable when done with precision as opposed to putting the nut tight and then backing it off a little.

    I have no idea why the specification is how it is. There are probably good reasons behind it. 0.001" to 0.002" seems like a decent preload target for the sizes of bearing in the transmission. The only reason I could see it not working is if the shaft heats up more than the case and tightens them further, which might be possible on some of the OD gear sets while under significant load. That one bearing is the smallest so it would be the one to watch for issues due to too much preload.
    I found this talking about how preload is gaining favor over endplay:
    https://www.vehicleservicepros.com/v...dplay-settings

    As far as the spec on setting endplay or preload as provided by Tremec I'm going to quote the guy from one of the posts I linked:

    "Setting up a transmission that has tapered roller bearings with end-play/no-preload only accomplishes one thing, and that is bearing wear/noise a few years down the road when the clearences open up and there is too much play...

    Great for rebuild shops and dealerships as they get more work. Sucks for the consumer... "

    I couldn't agree more. It seems best to me to set up a slight preload or a very MINUSCULE endplay. Just because some engineer type at Tremec somewhere decided on that spec doesn't mean much to me. I will look at their spec and still ultimately decide what I want to do. Which if you look around on LS1tech there are hoards of people disregarding the Tremec spec in favor of tighter shimming like I mentioned.

    Good point about the smaller bearing being the one to watch out for. 85MikeTPI wrote that article on building a T56 hybrid and has many posts on LS1tech pertaining specifically to the T56 which seem pretty credible to me. I'm going with the specs he used which are listed in that 3rd post I linked.... Which in the case of the counter-extension is .000 - .001 endplay.



    Quote Originally Posted by Xnke View Post
    What's worse, CdeeZ, isn't the bearing staining, it's the surface shear failure in that same photo. Look on the gear teeth at 8 and 9 o'clock, you see those tiny pits on the involute face? That is the material failure. They will only get worse, and there's nothing you can do to fix them. Maybe it's just dirt, but to me, that's the textbook pitting of a surface shear failure.

    Same thing happens in a flat tappet cam when you don't have enough EP lube in the oil, or the valve spring pressure is too high, or you're just running much too aggressive a profile on the cam lobe. The lube gets forced out and you get metal-on-metal right there in a tightly focused area, which results in the hard surface literally tearing off the softer core-thus "surface shear" failure. Ways to fix that issue is use a lube with more phosphorus or sulfur, although I think boron compounds are the new hotness in EP additives.

    Could also be that the oil was fine, but just breaking down from the same heat that stained those bearing rollers. Do you have more photos of similar detail on the countershaft gears?
    If you're talking about some of the stuff circled in red it was dust, shop rag lint etc. Also, I'm taking these pics with a new to me camera, it's on my Note 8 phone so I'm still getting used to how to operate it to depict things in the most clear manner. I'll have to revisit that when I build up that T56 for a future project. I will likely send it to Liberty to be faceplated so I'll just have them do whatever else needed at that time.

    Excellent point about flat tappets. Everything I have that is flat tappets gets an extra dose of ZDDP for that reason.

    Quote Originally Posted by 1project2many View Post
    I noticed the same issue. But without knowing the condition of the transmission before installation I didn't want to assume all of the damage was due to towing. If the damage is due to the current application, it seems like the transmission has survived long enough to suggest that it may be worth investing time to improve it's chances.
    The hybrid T56 that is going in place of the one that was pictured a few posts back will have a fluid pump which will help the trans in any conditions be it towing, hard acceleration etc. We tig welded a -6 AN bung in the case exactly where the TR6060 has one. Eventually this will be plumbed into a pump and possibly also a cooler. I'm hoping I can control it with a TPS % or boost threshold plus a manual override toggle switch for whenever I want to have it on anyways.


    Also, the specs from the Tremec service manual for endplay on the counterextension that I posted in post #57 are in contrast to this one I'm posting now. I believe this one is the correct spec (as per Tremec) but I'm ignoring them anyways hahaha. Interestingly, they both came from the same T56 service manual so there appears to be a discrepancy there. Notice the title from the service manual "Shimmin Procedures"..... Guess they couldn't be bothered to put a g on the end LOL.
    Attached Images Attached Images
    Last edited by CDeeZ; 03-20-2018 at 11:23 AM.

  6. #66
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    Notice the title from the service manual "Shimmin Procedures"..... Guess they couldn't be bothered to put a g on the end LOL.
    Engineers are constantly working to save the company a dollar here or there. So what if one of the technical writers decided to save a "g" on every manual?

  7. #67
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    Quote Originally Posted by 1project2many View Post
    Engineers are constantly working to save the company a dollar here or there. So what if one of the technical writers decided to save a "g" on every manual?
    Reminds me of one of my college roommates. He is a mechanical engineer. Every time I introduce him I say: "this is Daniel, he's an engineer............... but we like him anyways" hahaha.

    I think the problem with the technical writers is usually that they are engineers. They need to be someone with a masters degree in English or otherwise possessing a strong command of the language in order to clearly convey things.
    Last edited by CDeeZ; 03-20-2018 at 05:29 PM.

  8. #68
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    And yes, the areas that looked like damage to the gear are the areas you've circled in red. I guess it's not cavites, just linty-fresh tooth wash.

  9. #69
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    Well I got the "new" frankenstein hybrid T56 back together and drove around last night.

    Some observations:

    Shift quality is absolutely amazing with everything all freshened up inside (bronze pads, solid keys, steel 3/4 fork, Corvette synchros). I have a MGW shifter that should be here towards the end of the week to make it even better.

    The tighter shimming I elected to go with has apparently paid off, this trans is virtually silent. It doesn't even make the typical and common T56 neutral rollover rattle.

    I forsee no problems whatsoever with beating the shit out of this T56 for a long long time, AND doing truck duties with it when needed, towing etc.

    I am working on a walkaround rambletron style video of the truck so everyone can see what this is all about.



    Lionel: Are you going to post the failure analysis documents supporting your claims to contrast with my own as well as the two I posted from SKF and Timken?

  10. #70
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    Okay........ I know everyone has just been on the edge of their seat to see what all the fuss is about............

    Well here it is....... The turbocharged T56 towtruck walkaround video. Rambletron style.


  11. #71
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    Nice vid, do you have any driving vids? I like the acceleration vids when it was naturally aspirated. Gearing makes all the difference with these types of builds, both for durability, drivebility, fun factor. The transmissions are almost useless in heavy applications with stock 1/2 ton gearing with the high 2.66:1 1st and high 0.50:1 OD. A nice rear gear like those 4.88's make it all useable and fun.

    Very nice!

    peace
    Hog

  12. #72
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    Thanks Hog!

    I intend to get some driving vids up soon!! Between work and other projects, plus having to build up this T56 frankenstein hybrid I've been pretty busy. Those older acceleration videos are when it was still a SBC TBI!! It was fun even then with the T56 and only ~300FWHP! The LQ4 makes about 330HP STOCK plus 8 pounds of boost which means this old OBS really smashes around.

    You are spot on about gearing, it is very critical here. The deep ratios of the T56 plus the tall truck tires necessitate numerically high ring and pinion ratios. When I first put the T56 in years ago behind the SBC that USED to be in there, I drove around for a while with the stock 3.08 gears...... That meant that you had to slip the clutch big time to get going in 1st and 6th, well that gear was useless with the 3.08s...... The 4.88s are a perfect match...... Now that it is boosted, something a little lower (numerically) could also be good, like maybe 4.11 or so....

    I can't tell you how many times I've had people either in shock and awe or straight up try to argue with me about 4.88 and their streetability...... Pulls like a freight train/spins the tires through 4th, and if you stick it in 6th gear you are turning 1978 RPM @ 70MPH....... VERY streetable with the 4.88s.... But then you know how that goes. Just because something is written down on paper somewhere, or it makes sense in a CAD program to an engineer; none of that really matters in the real world when you're talking about a home-built hot rod.

    Did you used to post on other forums ? I seem to recall your handle.
    Last edited by CDeeZ; 03-30-2018 at 10:35 AM.

  13. #73
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    MGW shifter showed up. Damn it looks like a nice piece.









  14. #74
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    Getting ready to tear the timing cover off and ditch the stock cam in favor of one significantly larger. I'd estimate a 50HP gain N/A and somewhere in the range of 100HP in my case given the turbocharger.

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