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Old 27th April 2011, 10:19   #31
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Default Re: Off-Roading terms

Pitch
actual incline & decline angle while offroading.
it varies from vehicle to vehicle.

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Roll-over angle
the max angle after which the vehicle may roll over. (mostly side ways)

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Flex vs Articulation
flex is the amount of suspension travel from no load to full load.
articulation is when we hike one tire up on a rock or tree and the other 3 remain on the ground.

an RTI ramp (ramp travel index) measures a vehicles flex (articulation is the same as flex) depending on how far up the ramp they get, the degree of the ramp, and the wheelbase of the vehicle. the farther the more flex (articulation) the truck has and thus a better RTI score!
no flex/articulation
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full flex/articulation
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CV joint
Constant-velocity joints (aka homokinetic or CV joints)
mostly used on FWD cars & 4wd with independent suspension.
ex. Thar, Safari, Grand Vitara.

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ECM
Engine Control Module (ECM)
found in most high-end cars with electronically controlled engines.
  • Control of fuel mixture
  • Control of ignition timing
  • Control of idle speed
  • Control of variable valve timing
  • Electronic valve control
ex. Thar crde, Scorpio crde, Safari Dicor 2.2 VTT.

there are some after market programmable ECM's available too.
in which we can change the following parameters accord to our needs.
  • Ignition
  • Rev. limit
  • Water temperature correction
  • Transient fueling
  • Low fuel pressure modifier
  • Closed loop lambda
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types of differentials
there are mainly three different types.
  • open differential
  • limited slip differential
  • lockable differential.
see following links.

http://www.team-bhp.com/forum/4x4-te...-lsd-suvs.html (Center Differential and LSD in SUVs)

http://www.team-bhp.com/forum/4x4-te...ks-vs-lsd.html (Diff-Locks vs LSD)
effect of lifts on steering and suspension
its a big topic which needs a separate thread it self.
see following threads for more information on lift & sopa.

http://www.team-bhp.com/forum/4x4-te...spoa-cj3b.html (Spoa on a CJ3B)

http://www.team-bhp.com/forum/4x4-te...e-options.html (Raising a Jeep's ground clearance : Options?)

http://www.team-bhp.com/forum/4x4-te...arted-now.html (Gypsy on Steroids -- The SPoA Project. EDIT: Stage-2 Started now..)

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rgds,
Nikhil

Last edited by jeepster : 27th April 2011 at 10:21.
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Old 27th April 2011, 10:34   #32
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Default Re: Off-Roading terms

@jeepster : Good explanation and really useful.
Thank you
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Old 27th April 2011, 12:39   #33
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Default Re: Off-Roading terms

When It comes to reporting & presenting a 'case' , Jeepster is full of surprises . Well done

Can you demonstrate the ' Ramp over Angle ' to me ?


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Old 27th April 2011, 22:01   #34
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Default Re: Off-Roading terms

Quote:
Originally Posted by Sudarshan View Post
'case'
since when i started to report the case.
dont pull my leg Rajubhai.

now as per your 'case' here are my 'citations'.

break-over angle
or
Ramp over Angle

its the angle measured from the end of wheel base (tyres) to the mid point of wheelbase (lowest part of under body).

the smaller the wheelbase the batter the brake over angle. (in stock vehicle)

in other words the vehicle with high ramp over angle will drive over a sharp ridge without getting its under-body scrapped.

see the pictures at the end.
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jeep with 25 degree BOA.

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jeep with 20 degree BOA

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check out the wheelbase & brake over angle of cj3b, 540 & thar mdi.
wheel base & brake over angle is inversely proportional to each other.

vehicles with SPOA setups & big tyes have bigger ramp over angle than stock vehicle.

http://www.team-bhp.com/forum/techni...ver-angle.html (What is "Ramp Breakover Angle")





Last edited by jeepster : 27th April 2011 at 22:21.
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Old 28th April 2011, 05:43   #35
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Default Re: Off-Roading terms

Jeepster,
Thanks a lot for the detailed reply with pictures. I will got through the threads in detail. In the last 2 pics what is happening? Did you illustrate that a Medium wheel base (which has a greater BOA) could not clear the obstacle and being towed?
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Old 28th April 2011, 07:17   #36
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Very informative and educational thread. Thanks Jeepster for the explanation.

Can someone please explain if there is any difference while having MLD and LSD and why LSD is predominantly used for rear axles and MLD in the front ?
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Old 28th April 2011, 12:03   #37
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Default Re: Off-Roading terms

Quote:
Originally Posted by madhkris View Post
In the last 2 pics what is happening? Did you illustrate that a Medium wheel base (which has a greater BOA) could not clear the obstacle and being towed?
i used it just as a example.

well in this case its not the problem of 550's BOA but the this particular ledge/ridge was big for MWB vehicle.

in most of the situations SWB vehicles will clear the obstacle. (cj3b)

MWB vehicle will clear 80% of the obstacles. (540/550, gypsy, MWB gurkha etc.)

LWB vehicles will have big problems in same situations. (scorpio, safari, armada, bolero, LWB gurkha etc.)

also note that a experienced drive in Scorpio getaway will our perform newbie driver in cj3b.
Quote:
Originally Posted by MileCruncher View Post
Can someone please explain if there is any difference while having MLD and LSD and why LSD is predominantly used for rear axles and MLD in the front ?
this question belongs to following thread.

http://www.team-bhp.com/forum/4x4-te...ks-vs-lsd.html (Diff-Locks vs LSD)

Last edited by jeepster : 28th April 2011 at 12:04.
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Old 28th April 2011, 12:49   #38
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Default Re: Off-Roading terms

Jeepster thanks for the detailed insight with the pics.
Especially like the picture of the jeep with one wheel in the air, what a FLEX!
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Old 28th April 2011, 12:57   #39
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Default Re: Off-Roading terms

Great Thread and very well explained Jeepster. When its explanation like the above which includes pictorial representation besides copy, it makes things absolutely clear. I think this thread can be very useful for anyone wanting to know about the 4X4 terms. This could well be a 4X4 Jargon for Dummies. I hope other members with such queries will post their queries on this thread for all to see, instead of asking in individual thread. In that way the explanation does not reach everybody.

Mdsaab, please use the "Thanks" Tab/Button on the bottom of the post, to thank a particular member for his particular post

Last edited by V-16 : 28th April 2011 at 12:59.
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Old 28th April 2011, 13:50   #40
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Default Re: Off-Roading terms

AFAIK MLD is nothing but Eaton M-Locker.

its a top secret in mahindra stable so not much information is available. (at least to me )

Last edited by mobike008 : 28th April 2011 at 15:44. Reason: Threads merged. Hence, edited out the links
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Old 28th April 2011, 18:06   #41
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Default Re: Basic 4X4 Terms

While going through the apollo tyres site came across this - a book on 4x4. I have no idea how good or bad this book would be and I have no commercial interest in the same.

Apollo - India - Products - Alloy Wheels# - a special pre-launch price or Rs. 1200 and valid till 30 Apr 2011

@Mods, please delete the post if this is inappropriate.

p.s. If you preorder the book and find that it is not good, do not blame me.

Last edited by pjbiju : 28th April 2011 at 18:08.
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Old 28th April 2011, 21:25   #42
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Default Re: Basic 4X4 Terms

Quote:
Originally Posted by pjbiju View Post
While going through the apollo tyres site came across this - a book on 4x4. I have no idea how good or bad this book would be and I have no commercial interest in the same.

Apollo - India - Products - Alloy Wheels# - a special pre-launch price or Rs. 1200 and valid till 30 Apr 2011

@Mods, please delete the post if this is inappropriate.

p.s. If you preorder the book and find that it is not good, do not blame me.
It's a very good book at a good rate. It's more of a coffee table book cum manual on offroading. Worth a buy.

PS: once you buy it, see the thanks section.
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Old 30th April 2011, 22:35   #43
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Default Re: Basic 4X4 Terms

Doubler/tripler

as the name suggests its the doubling/tripling of gearing ratios.

in simple words when we add a additional TC (or two) we get doubler (or tripler).
ex.

KMT90 GB ratio X T18 ratio = stock ratio. (the differential ratio is constant in following)
1st 3.986 __X 2.46 = 9.8056

with double TC. (KMT90+T18+T18)

1st 3.986 __X 2.46 _x 2.46 = 24.318

with triple TC. (KMT90+T18+T18+T18)

1st 3.986 __X 2.46 _x 2.46 _= 59.339
most of the times its NP203 & NP 205 TC's used for doubler & triplers.
but there are some DANA 20+ DANA 18 doublers available.

the rear output of 1st TC is used as input for second TC & rear output of second one is used as input for third TC.

the front prop shaft is connected to third TC.

the 1st & 2nd TC are used for lowing the ratios only.

when we () need 4x4 low the third TC is used.
if again lower ratio is wanted 2nd TC is lowered.
if again lower gear is needed 1st TC is used.

Doubler
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tripler

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pictures from
www.alaska4x4network.com

www.pirate4x4.com

disclaimer:
all the information given here is for pure general knowledge. please do not try this under any circumstances. (unless you got 400bhp engine, DANA 60/70 axles & spare TC's lying around)
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Old 17th May 2011, 10:49   #44
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Default Re: Basic 4X4 Terms

Dear Off-roaders,
What is the minimum ground clearance of a stock MM540( I have 235 75/R 15 tyres)? Also it will be helpful to list the GC of commonly used offroad vehicles by us.
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Old 17th May 2011, 13:26   #45
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Default Re: Basic 4X4 Terms

Quote:
Originally Posted by madhkris View Post
Dear Off-roaders,
What is the minimum ground clearance of a stock MM540( I have 235 75/R 15 tyres)? Also it will be helpful to list the GC of commonly used offroad vehicles by us.
540 has Ground Clearance of 200mm.

attached some scans of 540 leaflet that i had.(printed in 1997)
Basic 4X4 Terms-scan0002.jpg

Basic 4X4 Terms-scan0001.jpg



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