OUR VIDEOS GALLERY MEMBER SPONSORSHIP VENDOR SPONSORSHIP

User Tag List

Page 3 of 3 FirstFirst 123
Results 21 to 28 of 28

Thread: OldMav technical information thread!

  1. #21
    Advanced
    Join Date
    Feb 2014
    Location
    Caboolture
    Posts
    63
    Thanks
    2
    Thanked 154 Times in 46 Posts
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by RLI View Post
    G'day Pete,

    I note that you might be putting 35'inch tyres on your Patrol in the future, if so, what diff ratios will you be using?

    Is there any chance for you to give the forum members one of your informative tutorials on the importance of getting the right diff and gearbox ratios when putting larger wheels/tyres on your vehicle.

    PS, also could you please advise me again on which is the best automatic gearbox to suit the chev 6.5 V8 diesel engine. unfortunately, my phone was dropping in and out the other day when you were explaining to me about the military spec automatic transmission.

    Regards,

    RLI
    Paul yes I am going to try 35" tyres legal side disregarded here for the moment but I will do the basis for my own experiment. Gearing is about response and feel so its very much engine torque and power related and at what point the torque peaks. For my engine which is now different with its torque response and amount of torque. I have decided to venture into loading up the rig using gearing hence the turbo will respond to this different load. So I have chosen to use 3.9 gears on 35" tyres giving me a 2050 ish rpm for 100 klms. Obviously this will make boost a bit higher at cruse speed, but if torque is high enough and volumetric efficiency is high enough there is the potential to gain economy and still have good 80 to 120 klm passing times. But also because I am using a GTX3071 I will have my boost level in its lower sweet spot hence torque rise is higher and I have the bonus of pre water injection to make the engine/turbo respond to change rather over fuel added to gain this response. This sort of thing can be improved in the lower revs/ gears if the cam and turbo is matched, there is always going to be a under boost point unless we use a switchblade type designed turbo with I am working on for future improvements.

    But basically for this first bit we try and match our engine torque to our gearing, diesels have the added bonus of producing a wider more consistent torque curve so there is the ability to match our torque to the gearing to make the turbo more responsive and progressive so the rig feel a lot stronger without having to add higher revs and power KW's to do so.

    Which brings us to your 6.5 which as I have told you is a lazy slow short torque engine, This is not a terrible thing but hopeless if you want a manual gearbox or a manual gearbox with only 4 gears and over drive. There is not enough gear ratio to spread across the rev torque range. This becomes even worse if you are trying to match a std type turbo too this engine, as you just don't get enough rev or engine load time to get the turbo to build torque to its potential because you are constantly running out of rev duration time.

    The Allison auto box is very special it doesn't function like a normal old school auto where by it has to change gears in sequence of have oil flow to adjust its load transfer. So what we have here is a gearbox that is always in its right gear or can be adjusted to be in it right gear always. It sort of doesn't change down it just is in the lowest gear required for that rev/torque point of the engine when adjusted, then changes up as the torque drops off not so much engine rev related. The military combination of the 6.5 is very near as good as the duramax/Allison but not as good because that engine has many electronic to adjust and control how the box changes gear. If you ever get to drive a duramax with Allison or the newer Merc BMW you will understand about always in the right gear and near undetectable up changes its all so effortless. The military 6.5 has this type of gearbox and works with the same effortless moving the rig forward ability, sort off lol. But even for this the 6.5 is still to short in its torque response or range to be ideal so doesn't feel so effortless as the duramax combo. But I can tell you the military spec Allison combo will make the 6.5 slug feel so much stronger and will allow the turbo to actually find its legs to be a benefit.

    But it will still need gearing to be selected to get the 6.5 and turbo enough time to build torque to revs to get the best potential relative to the weight of your rig. Which brings me to my other experimental very important criteria as to why I have chosen 3.9 gears to 35" tyres, gross weight, my rig will not weigh much more than 2200kgs fuel and water. For example my rig with the KKK which was a very quick and responsive rig to drive but it weighed 2750kgs with this weight loss with the KKK and my 180rwkw I have given back to my engine a full 65rwkws. So I can use some of this unused torque to drive my turbo into its sweet spot for longer so to speak. I know its a difficult subject but I am sure this will explain the concept.

  2. The Following User Says Thank You to OldMav For This Useful Post:

    PMC (25th February 2014)

  3. # ADS
    Circuit advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many

     

  4. #22
    Smart like tractor Ben-e-boy's Avatar
    Join Date
    Dec 2010
    Posts
    4,440
    Thanks
    735
    Thanked 4,041 Times in 1,746 Posts
    Mentioned
    22 Post(s)
    Tagged
    0 Thread(s)
    Hi Pete.

    A quick question about vertical separation. I have taken onboard what you said about flatter links and I am at the stage where I dont want to lower the links at the chassis end any further.

    I have raised the axle end slightly, it is still below the axle centre line.
    I understand the consequences if there isnt enough vertical sepration but I dont know how little is too little.

    25% of the tyre size comes to mind but I cant remember where I read it or who told me, or whether it is right.

    I have been using that figure in the latest changes, which is 8.75 inches, the upper links still sit just above the housing andthe lower links are a bit over an inch below the axle horizontal centreline

    Is that a sufficient amount of separtion?

    Thanks
    Ben
    Last edited by Ben-e-boy; 1st March 2014 at 08:04 PM.
    96 GQ coil/Cab
    08 G6eT


  5. #23
    Smart like tractor Ben-e-boy's Avatar
    Join Date
    Dec 2010
    Posts
    4,440
    Thanks
    735
    Thanked 4,041 Times in 1,746 Posts
    Mentioned
    22 Post(s)
    Tagged
    0 Thread(s)
    Here is another attempt, the links are a bit flatter and hopefully enough angle on the upper arms for lateratal support.
    Attachment 41304
    Attached Images Attached Images
    Last edited by Ben-e-boy; 1st March 2014 at 10:05 PM.
    96 GQ coil/Cab
    08 G6eT


  6. The Following User Says Thank You to Ben-e-boy For This Useful Post:

    BigRAWesty (1st March 2014)

  7. #24
    Advanced
    Join Date
    Feb 2014
    Location
    Caboolture
    Posts
    63
    Thanks
    2
    Thanked 154 Times in 46 Posts
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    The STD Nissan separation is 230mm, I used that dimension for my system because it is a good compromise for 33 or 35 tyres and allows the links to be set within the chassis for the ride height that can be achieved to get my ideal best compromise.

    Maverick-Model_zps05fc2110.jpg

    Also I have calculated a few assumed torque load values like 1000Nm on that separation using STD Nissan rubber bushes with 75 duro rubber hardness this loading will compress the rubber about 35% so is well within a expected longevity for our bushers.

    My DWG is for a leaf spring chassis so it is a bit different and probably a bit more ideal for fitting connection positions.

    There can be to little separation of course as this will put to much or more load on the bushers causing then to deform or reduce their usage life. But also the separation does help with torque hop as well but 8 inchers is ok for our diesel and 800Nm for a constant load using 33 or 35 tyres. Also the separation does allow the loading to be reduced on the links but 44mm 6mm wall Dom tube is fine for this loading with the lengths we can use on our patrol.

    Remember Ben all this has to fit in the patrol chassis and the simulator is only a guide and a tool to understand how the values interact. Trying to get ideals in the excel sheet first is difficult because it all changes when you try and fit it in your rig. I started with my chassis first using CAD, fitting the links then transferred this to the excel sheet to try and fiddle my ideals and to adjust within my chassis confines for the ideals I wanted so compromise was very high but still quite good in the end.
    Last edited by OldMav; 2nd March 2014 at 12:34 PM.

  8. The Following 2 Users Say Thank You to OldMav For This Useful Post:

    growler2058 (2nd March 2014), NissanGQ4.2 (2nd March 2014)

  9. #25
    Smart like tractor Ben-e-boy's Avatar
    Join Date
    Dec 2010
    Posts
    4,440
    Thanks
    735
    Thanked 4,041 Times in 1,746 Posts
    Mentioned
    22 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by OldMav View Post
    The STD Nissan separation is 230mm, I used that dimension for my system because it is a good compromise for 33 or 35 tyres and allows the links to be set within the chassis for the ride height that can be achieved to get my ideal best compromise.

    Maverick-Model_zps05fc2110.jpg

    Also I have calculated a few assumed torque load values like 1000Nm on that separation using STD Nissan rubber bushes with 75 duro rubber hardness this loading will compress the rubber about 35% so is well within a expected longevity for our bushers.

    My DWG is for a leaf spring chassis so it is a bit different and probably a bit more ideal for fitting connection positions.

    There can be to little separation of course as this will put to much or more load on the bushers causing then to deform or reduce their usage life. But also the separation does help with torque hop as well but 8 inchers is ok for our diesel and 800Nm for a constant load using 33 or 35 tyres. Also the separation does allow the loading to be reduced on the links but 44mm 6mm wall Dom tube is fine for this loading with the lengths we can use on our patrol.

    Remember Ben all this has to fit in the patrol chassis and the simulator is only a guide and a tool to understand how the values interact. Trying to get ideals in the excel sheet first is difficult because it all changes when you try and fit it in your rig. I started with my chassis first using CAD, fitting the links then transferred this to the excel sheet to try and fiddle my ideals and to adjust within my chassis confines for the ideals I wanted so compromise was very high but still quite good in the end.
    Thanks Pete. I really do appreciate the help.

    To be honest being the first time with only an excel spread sheet and only enough knowledge to be dangerous it is a bit daunting for me.
    There is just so many variables and compromises in which you can build something that ends up being pretty ordinary.

    I am planning on making eveything with as mush adjustment as possible in order to try and gain a getter understanding through real world experience.

    Thanks
    Ben
    96 GQ coil/Cab
    08 G6eT


  10. #26
    Advanced
    Join Date
    Feb 2014
    Location
    Caboolture
    Posts
    63
    Thanks
    2
    Thanked 154 Times in 46 Posts
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Give me a bit of time and I will do a coil chassis mock-up with a excel sheet for you to play with. That will give you a starting point to play with values. But really Ben its really what fits then adjust your ride height to get closer to ideals your see as best. I will find some sites with good write-ups to give you an understanding of the different values and their effects. Do you have a CAD program like autocad and know how to use it.

  11. #27
    Smart like tractor Ben-e-boy's Avatar
    Join Date
    Dec 2010
    Posts
    4,440
    Thanks
    735
    Thanked 4,041 Times in 1,746 Posts
    Mentioned
    22 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by OldMav View Post
    Give me a bit of time and I will do a coil chassis mock-up with a excel sheet for you to play with. That will give you a starting point to play with values. But really Ben its really what fits then adjust your ride height to get closer to ideals your see as best. I will find some sites with good write-ups to give you an understanding of the different values and their effects. Do you have a CAD program like autocad and know how to use it.
    That would be great thanks. We have autocad at work but I dont really know how to use it besides doing electrical schematics
    96 GQ coil/Cab
    08 G6eT


  12. #28
    Hardcore
    Join Date
    Jan 2012
    Location
    Coffs Harbour
    Posts
    2,289
    Thanks
    4,404
    Thanked 2,196 Times in 881 Posts
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by OldMav View Post
    Give me a bit of time and I will do a coil chassis mock-up with a excel sheet for you to play with. That will give you a starting point to play with values. But really Ben its really what fits then adjust your ride height to get closer to ideals your see as best. I will find some sites with good write-ups to give you an understanding of the different values and their effects. Do you have a CAD program like autocad and know how to use it.
    G'day OldMav,

    I am back, sorry about the abrupt manner in which I left the forum, unfortunately I have been suffering in a dark place in my mind. Depression is a horrible illness.

    Could you please grace us with you outstanding knowledge again please Peter.

    Kind regards,

    Your humble servant Paul
    The halls been rented the bands been paid, time to see you dance!

Page 3 of 3 FirstFirst 123

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •