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Old 28th April 2011, 13:41   #1
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Default Diff ratio for MDI3200 TC DI engine ?

I am working on modifying a CJ3B for OTR's with the following spec,

MDI 3200 TC DI engine
MM 550 front diffs with disc brakes
MM 550 rear diffs with LSD
4WD NGT 520 or KMT 90 Gearbox - Still not decided.

I would like to know what diff ratio I should use for the front and rear diff if I use a 4WD - NGT 520 or a KMT 90 gearbox.

Is a NGT 520 gear box good or better than KMT 90 for OTR's?.

I intend to alter an armada chassis to fit the above specs to suit my CJ3B body. The reason for using an altered chassis is that the original CJ3B chassis will not get damaged due to abuse in the OTR's.

Is it safe to cut and reduce the length of an armada chassis to suit the CJ3B body spec ?.
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Old 28th April 2011, 14:54   #2
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by joe3tom View Post
I am working on modifying a CJ3B for OTR's with the following spec,

MDI 3200 TC DI engine
MM 550 front diffs with disc brakes
MM 550 rear diffs with LSD
You mean 550 Axles. How much did these axles cost you?

Quote:
Originally Posted by joe3tom View Post
4WD NGT 520 or KMT 90 Gearbox - Still not decided.
Quote:
Originally Posted by joe3tom View Post
I would like to know what diff ratio I should use for the front and rear diff if I use a 4WD - NGT 520 or a KMT 90 gearbox.
I think you can stick with the 1:4.xx ratio series which comes standard in the MM540 (arka, please fill - I did not attend your workshop this year and I have forgotten these things). The 5.xx series will be too much for an MDI engine and your on road cruisability will suffer.

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Originally Posted by joe3tom View Post
Is a NGT 520 gear box good or better than KMT 90 for OTR's?.
KMT90 is far more rugged, can be fixed by anyone. NGT 520 is more expensive, but more smoother. That said, I drove Robi's invader which comes with a factory fit KMT90 and it was as smooth as an NGT.

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Originally Posted by joe3tom View Post
I intend to alter an armada chassis to fit the above specs to suit my CJ3B body. The reason for using an altered chassis is that the original CJ3B chassis will not get damaged due to abuse in the OTR's.
Why dont you just get another 3B Chassis from somewhere? I think this will be far easier to procure than cutting up an armada chassis.
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Old 28th April 2011, 16:17   #3
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Default Re: Diff ratio for MDI3200 TC DI engine ?

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Originally Posted by joe3tom View Post
I would like to know what diff ratio I should use for the front and rear diff if I use a 4WD - NGT 520 or a KMT 90 gearbox.
The diff ratio is generally decided more by max engine RPM rather than the gearbox you will use.

For XD3P or XDP4.9 use 4.88 final drive for MDI3200 TC use 4.3 for better overall usage and 4.88 for off-road bias or 3.73 (OEM) for highway/touring bias. This applies whether you are using NGT or KMT.

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Originally Posted by joe3tom View Post
Is a NGT 520 gear box good or better than KMT 90 for OTR's?.
From pure off-road perspective KMT90 is a more durable gearbox. However, your comfortable top speed will be restricted to about 80Kmph with KMT90 (XDP4.9) and about 90Kmph with XD3P (Army 2.5).

With NGT and right gearing 100 to 110 Kmph is comfortable.

Quote:
Originally Posted by joe3tom View Post
I intend to alter an armada chassis to fit the above specs to suit my CJ3B body. The reason for using an altered chassis is that the original CJ3B chassis will not get damaged due to abuse in the OTR's.

Is it safe to cut and reduce the length of an armada chassis to suit the CJ3B body spec ?.
You can alter the chasis but only at a shop that has experience with this kind of stuff else you will end up with two vehicles during the OTR.

[quote=Red Liner;2330871]
That said, I drove Robi's invader which comes with a factory fit KMT90 and it was as smooth as an NGT.
[quote]
No way mate. KMT and NGT are poles apart.


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Originally Posted by Red Liner View Post
Why dont you just get another 3B Chassis from somewhere? I think this will be far easier to procure than cutting up an armada chassis.
doubht you can find a good 3B Chasis alone. Getting a decent 3B is hard enough. Most of them are abused and in very bad shape.
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Old 28th April 2011, 17:57   #4
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Hi Red Liner,

I havn't bought the axles yet. Can you suggest some place I can get a good MM 550 set with rear LSD and at what price?.

Thxs

joe3tom.

Hi 4x4addict,

Thanks for the input.Yes, as you rightly said finding a good CJ3B chassis is read hard.

joe3tom

Last edited by Jaggu : 28th April 2011 at 18:13. Reason: Back to back posts, please use Multi Quote (Quite+) instead. Thanks
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Old 28th April 2011, 18:47   #5
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Default Re: Diff ratio for MDI3200 TC DI engine ?

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Originally Posted by 4x4addict View Post
You can alter the chasis but only at a shop that has experience with this kind of stuff else you will end up with two vehicles during the OTR.


Quote:
No way mate. KMT and NGT are poles apart.
I agree!

Quote:
Originally Posted by Red Liner View Post
That said, I drove Robi's invader which comes with a factory fit KMT90 and it was as smooth as an NGT.
Robi's Invader has a KMT90? Which model Invader is it?

Spike

Last edited by SPIKE ARRESTOR : 28th April 2011 at 18:49.
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Old 28th April 2011, 19:40   #6
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Default Re: Diff ratio for MDI3200 TC DI engine ?

It seems to me that it would be much easier to have your original chassis fortified and reinforced at key stress points. Chassis damage merely from off roading is not that common. Of course, people do find ways to destroy their vehicles.

"Hardening" or reinforcing a chassis also has to be done by someone with experience. While you man is doing that it might be a good time to install skid plates. Do a search in this forum if you are unfamiliar with their function.
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Old 28th April 2011, 22:46   #7
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by SPIKE ARRESTOR View Post


I agree!



Robi's Invader has a KMT90? Which model Invader is it?

Spike
[quote=4x4addict;2331008]

[quote=Red Liner;2330871]
That said, I drove Robi's invader which comes with a factory fit KMT90 and it was as smooth as an NGT.
Quote:
No way mate. KMT and NGT are poles apart.
You drive it first. I drove Sree's 550 which came with the NGT and Robbie's which came with the KMT. I dont know whether its factory fit, but it was so bloody smooth...I drove it partially Bangalore-Pune-Bangalore. My KMT almost feels like a ship's anchorage mechanism.

Both of you should try it too. Free rides in Munnar this week-end, last I heard
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Old 29th April 2011, 00:13   #8
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by joe3tom View Post
MDI 3200 TC DI engine
MM 550 front diffs with disc brakes
MM 550 rear diffs with LSD
4WD NGT 520 or KMT 90 Gearbox - Still not decided.

Is a NGT 520 gear box good or better than KMT 90 for OTR's?.

Is it safe to cut and reduce the length of an armada chassis to suit the CJ3B body spec ?.
here is my list.
  • MDI 3200 TC DI engine
  • army MM 550 front axle with disc brakes & FFRA with LSD
  • NGT 520
  • BW manual shift
  • 4.88 Differential ratio
  • RCBT steering
but due to small wheelbase of cj3b you will have serious issues with rear prop shaft alignment & with its length. (so not recommended)

this drive train will be better in cj 500 or 550. (MWB)

BTW what type of armada chassis you have?
is it box section or C section?

box section chassis is not easy to cut & weld.

rgds,
Nikhil

Last edited by jeepster : 29th April 2011 at 00:14.
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Old 29th April 2011, 08:28   #9
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by Red Liner View Post
You drive it first. I drove Sree's 550 which came with the NGT and Robbie's which came with the KMT. I dont know whether its factory fit, but it was so bloody smooth...I drove it partially Bangalore-Pune-Bangalore. My KMT almost feels like a ship's anchorage mechanism.



Venky, Sree's 550 does not come with NGT AFAIK (unless he has done something very recently), IIRC both Viji and Sree had MM5x0 XDB model with them. Can anyone confirm this?

Spike

PS- What's wrong with your post? I'm not able to edit it.
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Old 29th April 2011, 09:19   #10
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by jeepster View Post
here is my list.
  • MDI 3200 TC DI engine
  • army MM 550 front axle with disc brakes & FFRA with LSD
  • NGT 520
  • BW manual shift
  • 4.88 Differential ratio
  • RCBT steering
but due to small wheelbase of cj3b you will have serious issues with rear prop shaft alignment & with its length. (so not recommended)

this drive train will be better in cj 500 or 550. (MWB)

BTW what type of armada chassis you have?
is it box section or C section?

box section chassis is not easy to cut & weld.

rgds,
Nikhil
Hi Jeepster,

I have a 'C' section chassis. I also have commander chassis, which is also a 'C' section. Do you think a commander chassis is also ok for the alteration. I belive its only a little longer than the MM540 or MM Major chassis which I understand is best suited for this modification.

Joe3tom.
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Old 29th April 2011, 10:24   #11
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by joe3tom View Post
I am working on modifying a CJ3B for OTR's with the following spec,

MDI 3200 TC DI engine
MM 550 front diffs with disc brakes
MM 550 rear diffs with LSD
4WD NGT 520 or KMT 90 Gearbox - Still not decided.

I would like to know what diff ratio I should use for the front and rear diff if I use a 4WD - NGT 520 or a KMT 90 gearbox.

Is a NGT 520 gear box good or better than KMT 90 for OTR's?.

I intend to alter an armada chassis to fit the above specs to suit my CJ3B body. The reason for using an altered chassis is that the original CJ3B chassis will not get damaged due to abuse in the OTR's.

Is it safe to cut and reduce the length of an armada chassis to suit the CJ3B body spec ?.
Quote:
Originally Posted by Red Liner View Post
You mean 550 Axles. How much did these axles cost you?

I think you can stick with the 1:4.xx ratio series which comes standard in the MM540 (arka, please fill - I did not attend your workshop this year and I have forgotten these things). The 5.xx series will be too much for an MDI engine and your on road cruisability will suffer.
Hi Joe,

If you are keen on using a CJ3B, it is easier to use a XD3P+KMT90 with MM550 Front & Rear Axles.

The MDI3200TC is quite heavy compared to the XD3P (80Kgs Heavier).

Also the MDI3200TC has a very pronounced Crank Case, when fitted in an MM540, these disadvantage can be overcome to an great extent because it is easier to
i) Wider Track
ii) Taller Tyres (to compensate for Diff-Ratio)

The MM550XD uses a 4.88:1 Diff-Ratio, which can be used with a KMT90, but you need 31-32" Tall Tyres to get a speed of 60kmph.

The NGT520 will be a very tight fit in a CJ3B, 81" WB.

I would suggest you mod an MM540 to the above specs or if you want the CJ3B Looks, take a Mahindra MAJOR, and widen the Track and Lower Diff-Ratio with taller Tyres.

Regards,

Arka
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Old 29th April 2011, 11:07   #12
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Default Re: Diff ratio for MDI3200 TC DI engine ?

Quote:
Originally Posted by SPIKE ARRESTOR View Post


Venky, Sree's 550 does not come with NGT AFAIK (unless he has done something very recently), IIRC both Viji and Sree had MM5x0 XDB model with them. Can anyone confirm this?

Spike

PS- What's wrong with your post? I'm not able to edit it.
It always was with the NGT 5 speed - right from the time he got it. And so was Viji's green 550 jeep. So what if they are XDB? Wanna bet? Lets see now...what does Mahindra & Mahindra have that I will want...

No, I dont want the THAR
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Old 29th April 2011, 12:05   #13
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Default Re: Diff ratio for MDI3200 TC DI engine ?

@Sree's & Viji's jeep has the BA10 5 - Speed

Robbie's Invader has the Non Turbo MDI3200 with KMT90.
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Old 29th April 2011, 12:39   #14
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Default Re: Diff ratio for MDI3200 TC DI engine ?



Quote:
Originally Posted by Red Liner View Post
It always was with the NGT 5 speed - right from the time he got it. And so was Viji's green 550 jeep. So what if they are XDB? Wanna bet? Lets see now...what does Mahindra & Mahindra have that I will want...
Hehehe, see below post-

Quote:
Originally Posted by 4x4addict View Post
@Sree's & Viji's jeep has the BA10 5 - Speed

Robbie's Invader has the Non Turbo MDI3200 with KMT90.
Tini, you are right, I know this, now it is confirmed.

@Venky, if you still don't agree, you can call Viji / Sree and confirm, I can forward their contact numbers if required, they are located in Bangalore.

Spike
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Old 29th April 2011, 15:04   #15
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Default Re: Diff ratio for MDI3200 TC DI engine ?

I stand corrected. Like I said, I did not attend Arka's workshop this year - hence I got my facts wrong.

:P
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