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Max Safe Locked Speed

Discussion in '80-Series Tech' started by turbocruiser, Feb 27, 2004.

  1. turbocruiser

    turbocruiser SILVER Star

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    The subject says it all. Search revealed several posts about someone regularly staying locked on high speed sand runs. IdahoDoug, i think, mentioned the danger factor with high speed steering problems when locked and that makes perfect sense. What I would like to know is what is the maximum safe locked speed that the 80's can do (all of this assuming that you have the center diff lock switch so that you can stay locked while in 4HI)? When I say safe I mostly mean from a mechanical point of view not a driving point of view; in other words, assuming you can do the driving part of it, at what point would damage occur to the lockers as a result of speed? Also, does any damage occur when the speedometer skips up to twenty or thirty, like on a snow run when the lockers are plowing through and then they spin out for a second? As always, thanks folks.
     
  2. Beowulf

    Beowulf

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    tubocruiser,
    The speed won't damage the locked axles, it's more the driveability problems. Many of us have done high speed snow runs with everything locked. Running at sustained 4,000+ RPM gives the engine a workout though.
    -B-
     
  3. turbocruiser

    turbocruiser SILVER Star

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    Right, we ran a high speed snow run about three weeks ago and the cruiser was regularly running btwn 3000 and 4000 rpms for periods of about two minutes or so tops but in that time we were running at about 25 miles an hour fully locked. What a rush to plow through the thick snow at that speed! I had thought that from a mechanical perspective the five mile per hour maximum listed in the manual was ridiculously low but I did not know what maximum, if any there really was. Would there be any difference between the max safe locked speed of the e-lockers in the 80s and say a autolocker like detroit? Thanks.
     
  4. Beowulf

    Beowulf

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    The 5MPH is max speed while attempting to engage the locks, not the max speed after locked.

    -B-
     
  5. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Toyota's position is that the vehicle speed should not exceed 5mph while locked. The primary reason for this (my read) is to prevent sudden, unpredictable, movement when traction conditions change. That being said, the locks are inhibited from engaging if the vehicle speed is above 5mph but they will stay locked, regardless of vehicle speed, until the operator unlocks them.

    So, go as fast as you dare, remembering that it could go sideways or worse if it hooks-up unexpectedly.

    Think of it as a version of "chicken"
     
  6. turbocruiser

    turbocruiser SILVER Star

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    [quote author=Beowulf link=board=2;threadid=12207;start=msg111996#msg111996 date=1077939816]
    The 5MPH is max speed while attempting to engage the locks, not the max speed after locked.

    -B-
    [/quote]

    Doh! Did not realize that. I need to re-read the owner manual. On the subject of snow runs, what do you who do it all the time find works best for getting through the thick stuff? My experience was that having the center diff locked, the rear locked, in 4HI and tranny in low to start was the most versatile setting. I personally did not by the 'seat of the pants' sensor think that the 2nd start function helped much. And I personally left the front unlocked as much as possible as I thought that the steering was wildly affected at about the 30 mph threshold. A friend who was with me thought that staying in 4LO with low selected on the tranny was the best way and I experimented with that as well...I guess I did not have enough 'time with the tools' that one snow run to really prove to myself what works best. If you dont mind, whhaddya think? Thanks.
     
  7. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Deep snow is very much like sand. Wheel speed and torque rule the day. Do think about the possibility of sudden, unpredictable, movement when the axles are locked.
     
  8. turbocruiser

    turbocruiser SILVER Star

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    [quote author=cruiserdan link=board=2;threadid=12207;start=msg112001#msg112001 date=1077940473]
    Toyota's position is that the vehicle speed should not exceed 5mph while locked. [/quote]

    Okay, confused, this is what I thought the manual stated, but -B- reads it differently. I grabbed my manual and it simply states not to drive the vehicle over 5mph when the lockers are locked. This is in a box that also talks about not locking the lockers with the wheels turning but I cant tell if that entire box has to do with the locking part of the process or that process plus how fast to drive with the lockers locked. In any case, I know that this 5mph is easily exceeded and I trust the advice of those on this thread that there is no problem mechanically with running faster than that but I'm sorta stumped about what Mr. T is trying to tell us with that part of the manual? Thanks again, this is awesome.
     
  9. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    You mis-understand the Wulf.

    What he said was 5mph was the maximum speed that allows diff locking and that once locked here is no "governor" that caps maximum speed.

    The reason that locking is not "allowed" with wheelspin is to prevent damage to the axles or "sudden,unpredictable, movement" when it hooks up.
     
  10. ppc

    ppc M Go Blue

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    Beo, Dan and others will try to impress the dangers as well as what is safe. Mr. T and his manuals only give guidelines that in a court of law can't hold them liable. Bottom line is that there is no one solution to everything or every condition. Understand what is happening physically in the mechanicals of your truck. It’s not rocket science how it all works. Justify to yourself how your actions and driving may impact others around you, your vehicle occupants and the amount of damage that can be done to your truck and the trail you are riding on. The next guy doesn’t want to stop and pick up the pieces but might be more than happy to rescue you out of a stuck. They're out there to have fun, not to babysit. It sounds like your friend may have a better perception taking in all the conditions etc. that you might be to busy to observe.
     
  11. turbocruiser

    turbocruiser SILVER Star

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    [quote author=ppc link=board=2;threadid=12207;start=msg112145#msg112145 date=1077959393]
    The next guy doesn’t want to stop and pick up the pieces but might be more than happy to rescue you out of a stuck. They're out there to have fun, not to babysit. It sounds like your friend may have a better perception taking in all the conditions etc. that you might be to busy to observe.
    [/quote]

    Ahhhh, what? Maybe I am misunderstanding you but who mentioned babysitting; I actually assisted my friend out of more stucks then he assisted me! I got high centered one time, he was getting sideways on tight trails, stuck on slopes and all sorts of stuff that I got through no problem. What I was saying is that as we were driving we were both sharing our opinions on what was providing better traction, control, etc. I thought a little less torque and wheel spin and vehicle speed was adequate for getting through (and in most cases it was), he thought the lowest gearing and highest speed was the way to go. His driving style is much more agressive than mine and yet he had damage and got stuck several times, I had no damage and got stuck once. Also, maybe I am still misunderstanding you but tell me why i was too busy to observe things; what I was doing was paying my maximum attention to where I was, what I was doing and how well it was going. Yea I was busy, busy learning!!!
     
  12. Beowulf

    Beowulf

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    turbocruiser,

    >> he thought the lowest gearing and highest speed was the way to go. <<

    And he was correct if I understand the conditions you were driving in. Deep snow (12"+ powder) usually requires blasting through it to carve a trail. The lead truck takes 99% of the abuse. Sometimes you have to have the front locked just to get enough torque and wheelspin to blast through a drift; yet when you come to a sudden curve in the trail you'll likely get sideways when everything is locked.

    Mr T. didn't write his owner's manual for these situations and I'm surprised you would think otherwise. Dan explained the locking procedure clearly.

    Phil's advice about understanding what is happening is right on. I posted links in a current thread that you should reread. It has diagrams and pictures of the locking mechanism. Once you completely understand what is happening I think the above advice and explanations will make more sense to you.

    As for the 2nd start, you're again not understanding what is going on. When you start in 1st gear, you have MAXIMUM torque going to your drive wheels. Most of the time this is good; sometimes this is very bad. Example: You're on an incline and the paved road or trail (could be either) is very slippery due to ice or whatever. Even light use of the throttle causes you wheelspin and you can't get started moving. What to do? Now is when 2nd start comes in. The gearing is changed so that less torque is applied to the wheels and less chance of wheelspin.

    HTH.

    -B-
     
  13. turbocruiser

    turbocruiser SILVER Star

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    [quote author=Beowulf link=board=2;threadid=12207;start=msg112203#msg112203 date=1077980691]
    turbocruiser,

    Mr T. didn't write his owner's manual for these situations and I'm surprised you would think otherwise.
    HTH.

    -B-
    [/quote]

    Excuse me, but when did I state anything about what Mr. T wanted to express via the manual? Some here are making assumptions about what I wanted to know, why I wanted to know it etc. Also, some here make the mistake of thinking that if someone asks a question they clearly have not read or understood the owners manual, the FSM, previous posts etc. I read all the above and was still wondering about some things. Well so frickin what; if this is not the place to ask these things, someone please share where that place is. Sheesh! Also, I am fully aware of what the 2nd start function is for...what I stated was that I found, through my time on the snow, that this feature was not necessary. Now if you think about it, if on slippery pavement you cannot get going and the 2nd start helps, then it would stand to reason that if you are on slippery snow and you cannot get going, this function MIGHT help. Well, guess what, in the interest of learning something for myself and not having to rely on others, I tried it and I found that in THAT particular situation, it was not helpful. That does not mean that I did not read the manual or that I did not understand it. I swear, sometimes asking something simple here is the worst way to start the day. For those of you who already know every frickin thing, how did you get there first of all and secondly why do you waste your time here now? If you want to share things politely to people who want to learn and who make no presumptions about their expertise, this is a great place to be. If you want to make anyone who asks anything feel foolish then why dont you go find another format to supplement your egos? I'm here to learn, if you experts, and B you clearly are, want to help with that then wonderful, and thank you, if not, well, do me the favor of at least not responding in an insulting way.
     
  14. Beowulf

    Beowulf

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    turbocruiser,

    I reread my responses and Phil's responses above to see if I could understand why you became so defensive. I believe you are misunderstanding the intent as it wasn't meant to insult you; rather the responses were meant to inform you.

    If you were insulted by my answers above, then please accept my most sincere apology.

    -B-
     
  15. turbocruiser

    turbocruiser SILVER Star

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    Accepted, Thanks. I think the problem is my perception and expectation that if someone posts a question after dutiful research, then they are humbly asking a question and humbly seeking an answer. I try to ask 'educated questions' and 'pre-searched questions' in respect for the others answering. Too often the response to a question gets into the "you misunderstand this or that" or "its not rocket science" realm and then it is insulting; I never stated any position, I asked a question so I could learn the answer soooo, what did I misunderstand - i never got to a point of understanding that I could then misunderstand! Remember, I know I dont know it all!!!
    I think another problem is that after the dutiful research it wont always work to refer back to the same things over and over so when someone posts something along the lines of "I posted links in a current thread that you should reread. It has diagrams and pictures of the locking mechanism. Once you completely understand what is happening I think the above advice and explanations will make more sense to you." is sort of redundant. In other words, I guess I do not understand everything there is to understand about metallurgy and all the other things one would have to understand to be able to look at a schematic of a locker mechanism and instantly say to myself, "Aha based on this, the max safe locked speed must be 42.2 mph" !!! What I am trying to say is that I am trying to learn in a learning friendly environment and sometimes I think it is irritating to the experts to field the amateur's questions and that sometimes that irritation is comes out loud and clear to the grasshoppers in the group! Thanks though for trying to help, I can see it that way too.
     
  16. ppc

    ppc M Go Blue

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    I to apologize, my post was not intended to be taken the way it was. It was by no means an attack on you and I could have chosen some better metaphors. One post made reference to a friend with you. I just assumed that he was your passenger and not driving another vehicle. As a passenger he would have more time to observe differences and his input would be of value.

    When questions like yours are posted, people with all levels of experience are reading the responses. When it comes to safety issues like the use of lockers as in this thread, I feel it is important to cover more than just an answer to a specific question.
     
  17. turbocruiser

    turbocruiser SILVER Star

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    Thanks Phil, and again, thanks Wulf. I appreciate it. :) I also apologize if I am at all antagonistic at anytime. It is easy to mis-read someone's words or someone's writing style with a format like forum. Hell, it is even easy to mis-write one's own words or writing style; I too offended two others accidentally and I felt awful about it - what they understood and what I wanted them to understand were two way way way different things. :-[ Lots of potential problems with communication. P and B, after rereading all the posts, I too can see what you wrote in a different way then I first read it. :-[ Likewise, when I accidentally offended others in the past, when I went and reread my posts, I could see how those others were offended. :-[ I'm sorry guys, I know now you were trying to help and I know now you were not trying to assault the amateur. Please accept my apology for arguing with you ... if I ever have the honor of meeting you, let me buy the first round of :beer: !!! Thanks.
     
  18. MoJ

    MoJ Moderator

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    Free beer?? Umm, uh, I was really offended too. :D
     
  19. IdahoDoug

    IdahoDoug

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    Hey, that was a textbook example of how to handle a misunderstanding by all of you guys. It can happen so easily here on a board where normal conversational cues are not there to understand each others' intents. Well done!

    DougM
     
  20. SteveLCetc

    SteveLCetc

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    Let me ask this another way - is there anything inherently mechanically problematic when running at high speed with the Toyota electric diffs locked? LIke, will they blow up at 80 mph or something? I can't see why there'd be a problem, keeping in mind the torque reduction at speed. I don't understand what the problem might be...