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Old 4th November 2015, 20:27   #361
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Default Re: planning to restore mm550 ngcs 2006 model

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Originally Posted by dhanushs View Post
You are right. But then, a heavier engine will mean the axles need to handle more torque.

Essentially, the FAW of an offroad prepped vehicle is much much more higher than stock. Eg: Winch 50kgs, Steel Wheel and Big Tyres 20kgs atleast more each, Power steering Assy, AC, Bull Bar, Lights, Hi Lift Jack on bonnet, etc etc.. Add to that a 150 kgs heavier engine means the FAW has gone up atleast 300kgs.
Okay, think I'm understanding - so you're saying the GVW (gross vehicle weight - FAW=?) being higher, then on steep uphills, etc, the added weight having to be moved upward itself creates the drivetrain loads...???

I really wonder whether that is as significant vs. the fact of a 35" tyre's maximization of traction, especially if driven by a much more highly powered engine that would be able to use every bit of that. In which case, sheared splines on the axles, etc, might be the more likely failure mode. So in your experience, what is the actual failure mode in axle failures you've seen (and were they the front or rear axles)?

A 150kg-heavier engine weight increase alone would be kind of like having the stock engine / drivetrain but two extra passengers aboard. Are you saying that having two passengers aboard a stock rig would be a feasible culprit re: the breaking (torsionally) or spline-shearing of axles?

Anyway, just to clarify for the less-informed, excepting the above consideration, if 300kgs extra is going to be a problem, on a full-floater it'll be a problem for the spindles / bearings / ball joints / springs / knuckles / chassis, etc - and NOT on the axles themselves, if by "axles" we mean the things that via splined long shafts connect the Dana 44 carrier to the drive hubs - these do NOT carry any weight at all; inner side is supported by the carrier splines, outer end supported by the bronze spindle bushings. Only weight it has to support is its own . And that's regardless of vehicle weight.

-Eric

Last edited by ringoism : 4th November 2015 at 20:30.
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Old 4th November 2015, 22:43   #362
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Default Re: planning to restore mm550 ngcs 2006 model

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Originally Posted by ringoism View Post
Okay, think I'm understanding - so you're saying the GVW (gross vehicle weight - FAW=?) being higher, then on steep uphills, etc, the added weight having to be moved upward itself creates the drivetrain loads...???
Hi Eric, by FAW, I mean Front Axle Weight. I got this from Behram Dhabar sir, and somehow stuck to my mind. .
The torque each axle shaft carries is depended on vehicle weight (the load), the traction of the tyres (which highly increases with 35x12.5x15) and torque from the engine. From a stock vehicle, to a fully prepped up offroading vehicle, the front end alone carries ~300-400kgs more weight. Add to that the increased torque output from the engine, the axle shaft has transfer much more torque.

Also a heavier engine with low torque output might not break the axles (eg: Simpson's S4 engine). Also, same stock engine with more weight upfront might not break axles.

Quote:
I really wonder whether that is as significant vs. the fact of a 35" tyre's maximization of traction, especially if driven by a much more highly powered engine that would be able to use every bit of that. In which case, sheared splines on the axles, etc, might be the more likely failure mode.
Right. With bigger tyres, the torque the engine develops is put to use, and with a heavier vehicle weight , the torque requirement is up.
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So in your experience, what is the actual failure mode in axle failures you've seen (and were they the front or rear axles)?
Most of the times, axle u joints give away. If you have lockers, then while powering up over huge boulders, the short side shaft itself breaks. Neatly.

Quote:
Are you saying that having two passengers aboard a stock rig would be a feasible culprit re: the breaking (torsionally) or spline-shearing of axles?
Not a stock rig eric. We are talking about engine swaps. And, its not 2 passengers. A fully prepped up vehicle will mean, you have 4-5 people standing on your front bumper. I'm saying, when you get more torque, keep it light to reduce failures. Keep the torque requirement minimum.

btw, I've never seen the splines shear. Its always the axle shaft or the u joints. And, I have a high regard for mahindra rear axles. With my Turbo Nissan engine (250+NM@ approx 1500rpm, I guess), and 33" tyres, I've never broken even the OE 540 axles.
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Old 5th November 2015, 12:01   #363
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Default Re: MM550 XD NGCS - The War Horse

Few things I've kept in mind/observed while having a heavier engine (14B) on my 540 with OE axles for the past 4 years:
1) Keep a light foot and avoid sudden pedal-to-the-metal kind of driving offroad & onroad. Maybe not appropriate for competitive events but I offroad for fun only.
2) My vehicle is pretty light as such (no doors or top body except a roll-cage and a checkered-plate roof). The result is that if and when I get stuck, the lower body weight kind of works like a pressure-release valve on the axle/spline/shaft stresses. The whole vehicle starts rocking up and down. Rather layman-ish analogy for lack of a better word.
3) Not sure if I am accurate, but I have seen more issues with my steering setup (OE-540) on some of the articulating obstacles I have tried. The engine torque does to at times ,work in a direction opposite to wheel movement.
4) To some extent the heavier front has helped climb inclines better. Am assuming the front-bias does help with traction to the front wheels. Again, I can't prove it with a formulae but more of seat of the pants observation.

Cheers,
Adi
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Old 8th November 2015, 20:23   #364
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Default Re: planning to restore mm550 ngcs 2006 model

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Originally Posted by dhanushs View Post
Most of the times, axle u joints give away. If you have lockers, then while powering up over huge boulders, the short side shaft itself breaks. Neatly.

Not a stock rig eric. We are talking about engine swaps. And, its not 2 passengers. A fully prepped up vehicle will mean, you have 4-5 people standing on your front bumper. I'm saying, when you get more torque, keep it light to reduce failures. Keep the torque requirement minimum.
Hey Danush, appreciate all your clarifications. I meant that two passengers would be the equivalent of the heavier engine alone, all other things being equal. This could be the proverbial "straw that broke the camel's back" of course.

And definitely lockers introduce a whole different thing into it, since over large boulders or really any high-grip uneven surface, you will have tyres on either side that might WANT to move at different rotational speeds (what a differential would normally allow for), but they can't, if tyres on opposing sides are both getting good grip - so ultimately either the traction has to give way at a very high threshold, or a component has to break. In that scenario, I see your point - bigger tyres add grip, and higher weight from any source increases downforce (and thus traction) on those tyres, so no surprise that axles / u-joints and other stuff will start breaking then, unless correspondingly upgraded. We're not supposed to engage 4x4 when on pavement, etc - same sort of thing there, as there's no differential action between front / rear drive systems and windup (due to differing amounts of ground covered) becomes an issue - and there again, if traction doesn't give way, a component will.

Lots of ways this could be entertainingly further analyzed...

1) Suppose a particular engine, heavier and higher-torque (I think the Scorpio engine was being questioned orginally?), besides being more drivable on-road, could power me through a lot more tight spots in my sort of off-road use than the original Peugeot engine; Hence I'm getting stuck a lot less. Then maybe I'd ask whether I really needed the winch and the larger front bumper structure required to hold it at all. That omission offsets the heavier engine weight, and the net effect might be that I actually have a more powerful, capable vehicle off-road / on-road, that's not necessarily more prone to breakages (and less prone to getting stuck) than a Peugeot-equipped rig weighed down with a bunch of extra stuff ahead of the bumper. Hmmm...???

2) Or, for that matter, I keep the lighter Peugeot but install lockers and similarly drop the winch. I get through more tight spots with the extra grip, and the "locker" load described earlier is minimized since there's less downforce on my tyres.

3) Or else: If the function of reduced breakages you've wisely recommended is the avoidance of excess weight, thus limiting the downforce on the tyres and thus limiting maximum traction (which reduces torsional loads on my drivetrain components)... then for certain types of offroad uses (surfaces), I could just as easily swap in a heavier, more powerful engine, but move to equally tall (for ground clearance) but skinnier tyres (less maximum grip), so that my overall torsional forces on axles will be the same!!!

Like most things, multiple options and compromises. If I want zero compromises, then I'll need to strengthen every "weak" link progressively, simultaneously trying not to add too much weight (and then my bank balance is certainly compromised!).

Thanks for taking the time to reply, and that more than once. Mind you, though I relatively recently own a 4x4, I'm certainly nothing like an off-roader, so am not speaking from that sort of experience. You guys have lived it.

Guess what made me raise the question it is that, well, our Marshal (and all the dozens / hundreds of 4x4 Bolero Campers / pickups in use up here, which are sometimes very heavily loaded besides) use the same Dana 44 stuff as all these MM340's, etc, and both the weight of the DI over the axles and the weight of the entire vehicles are much, much higher (likely higher than an offroad-ready 340/540), and yet in normal 4x4 use breakages are pretty uncommon. Wonder what the net downforce / available grip / torsional loads with our heavy Marshal & DI engine sitting on 6.00x16 skinnys is, compared to that available on a prepped 340's...hmmm...

Of course, I'd think lockers, especially in combination with huge tyres, certainly compound the critical stresses, and "real" offroad use will exploit every weak link in a system.

I do wonder whether, if the U-joints are the main weakness (apart from shafts themselves, if huge boulders are an aim), they should automatically be upgraded in cases of larger tyres/lockers. What are the options here? I mean, if the main argument against an engine swap is essentially that my u-joints won't hold, then that might be relatively easy to rectify, so long as someone is not intending much rock-crawling???

Your Nissan-powered rig must be a complete blast to drive... something I can only dream of... and you must've put a LOT of work into it - stop in if you're ever in H.P.

Thanks again,
Eric

Last edited by ringoism : 8th November 2015 at 20:33.
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Old 10th November 2015, 17:30   #365
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Default Re: planning to restore mm550 ngcs 2006 model

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Originally Posted by ringoism View Post

Lots of ways this could be entertainingly further analyzed...
Hi Eric,

The Winch, and the Engine are different ways to get out of an obstacle. Though the winch is a more practical way of getting out of an obstacle without much damage, getting out using a powerful engine is fun that cant be matched using the winch. And, when you have a powerful engine, you always push a little more, and there you need the winch.
Quote:
...upgraded in cases of larger tyres/lockers. What are the options here? ..
You get imported RCV axles, albeit at a higher price. Much higher (~1.25 lacs)
Quote:
Your Nissan-powered rig must be a complete blast to drive... something I can only dream of... and you must've put a LOT of work into it - stop in if you're ever in H.P.
Thank you!
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Old 15th November 2015, 23:49   #366
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Default Re: MM550 XD NGCS - The War Horse

Apologies for my off topic query but need help and suggestion on this one. My 2006 NGCS brakes are rear biased. I have replaced the TMC and both the rear brake assembly. Still the rear wheels are lo king up on hard braking. Checked the front calipers to be working fine when jacked up. Checks correct outlet ports ports(F and R) on the TMC. Is the issue with the GP valve ? Is there a proportionate valve for biasing ? Do I need to replace the booster ?
Thanks in advance for any help.
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Old 25th December 2015, 19:48   #367
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Default Re: MM550 XD NGCS - The War Horse

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Originally Posted by dieselhead View Post
Apologies for my off topic query but need help and suggestion on this one. My 2006 NGCS brakes are rear biased. I have replaced the TMC and both the rear brake assembly. Still the rear wheels are lo king up on hard braking. Checked the front calipers to be working fine when jacked up. Checks correct outlet ports ports(F and R) on the TMC. Is the issue with the GP valve ? Is there a proportionate valve for biasing ? Do I need to replace the booster ?
Thanks in advance for any help.
Mod: feel free to move this (and the preceding query) elsewhere if need be.

And sorry to get to this late, haven't been on the forum in over a month...

Briefly: I'm going to guess the proportioning valve (definitely would have one if disc-brake equipped) in your case, since F/R biasing is primarily its job. Booster has a single actuator and doesn't differentiate between F/R systems, so that wouldn't be it. If you've already replaced the master cylinder, and the lines are well-bled (of air) and brake pads/shoes are in acceptable condition all around, I can't really think of what else it would typically be.

Though I have to say, in all my years with a couple dozen cars (pretty much all of them 10 - 25 years old), I've never actually seen a proportioning valve failure...

Maybe really low-grade front brake pads or badly glazed front rotors/pads that aren't doing their part, friction-wise (this is not the sort of thing you'd discover by jack-up type testing)?

If only one rear side was locking, it might be a matter of a line blockage/seized wheel cylinder/oil-soaked brake shoe on the OPPOSITE side (seemingly a strange effect of the differential that I've seen happen a couple times). But you've done your rear brake work, and if it's definitely both locking, it would seem to point to the prop. valve.

-Eric

Last edited by ringoism : 25th December 2015 at 19:52.
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Old 31st May 2016, 23:36   #368
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Default Re: MM550 XD NGCS - The War Horse

Bumping an old thread.
How much should I expect to spend for a 2006+ Army NGCS running or non running condition.

How much one need to spend to restore it & make it driveable?

Does the NGCS model has LSD front & rear as well?

Anyone near Thane, Pune area has a Army auctioned 2006+ NGCS vehicle for sale?

Last edited by offroad_maniac : 31st May 2016 at 23:38.
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Old 2nd June 2016, 12:52   #369
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Default Re: MM550 XD NGCS - The War Horse

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Does the NGCS model has LSD front & rear as well?
NGCS 550 doesn't come with with LSD in Rear or Front. The non NGCS comes with LSD in rear only.
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Old 26th September 2016, 15:41   #370
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Default Re: MM550 XD NGCS - The War Horse

Hi sorry if a bit off topic. I understand the ngcs rear leaf springs can be replaced with thar crde/di rear leaf springs. But i am unable to find the stock front leaf springs for my 2006 ngcs, does anyone know which model springs can be used for the front, and what is the oem camber on the stock ngcs leaf springs both front and back? thanks in advance

Regards,

Saurav Singh
Pune
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