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Old 15th January 2011, 19:43   #46
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by Samurai View Post
DD, thanks for providing such a detailed information. If I recall correctly, you used to work DANA corporation. Isn't the Invader (or Thar) rear axle Dana 44? In that case, any ring and pinion designed for Dana 44 must be a straight fit, is it not? They are even sold separately in shops. Why is the 4.88 ring thicker than the 3.73 ring if both are designed for Dana 44 pumpkin.
Samurai, the fast answer is " I dunno why they did that."

My guess is that the thicker crown gears are more robust and meant for slightly heavier vehicles. Maybe Dana 44 is a genus name and not just a species name. I think the designation "44" has more to do with the diameter of the crown gear than the thickness.

Yeah, I worked for 3 years off and on for Dana as a test driver. They liked me because I drove very precise test routes, as monitored by test equipment and recorders, not because of any engineer/mechanical skills....I just don't have them. Nor because I am a throbbing bag of hyped up testosterone, pedal to the metal, death defying case of mutant hand-eye coordination and masculinity....which I am, actually, but this was not a skill needed for the job.

Here is a pic of the Dana test facility. The oval thing is a 3 lane expressway grade track 2.5 miles around. There are off-road courses there, too. At bottom center are huge garages where vehicles are prepped. In the middle of the track is a huge soy bean field. The job did not pay well and the soy beans lost their allure after a few thousand laps so I moved on.
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Old 15th January 2011, 22:33   #47
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by Samurai View Post
DD, thanks for providing such a detailed information. If I recall correctly, you used to work DANA corporation. Isn't the Invader (or Thar) rear axle Dana 44? In that case, any ring and pinion designed for Dana 44 must be a straight fit, is it not? They are even sold separately in shops. Why is the 4.88 ring thicker than the 3.73 ring if both are designed for Dana 44 pumpkin.
May I attempt to explain, subject to correction from gurus / engineers :

Given that one wants to keep the differential case the same (and mount it in the same place on the same bearings) for both the ratios (3.73 and 4.88); the cross-car distance from the face on which the crown wheel mounts to the centre line of the pinion is fixed.

When one has a 3.73 gear pair, usually the ring gear has 41 teeth and the pinion has 11. 41/11 = 3.72727... ~= 3.73.

When one has a 4.88 gear pair, usually the ring gear has 39 teeth and the pinion has 8. 39/8 = 4.875 ~= 4.88.

Depending on how much torque has to be transmitted by the system, the tooth size (i.e. tooth thickness at point of contact with the other tooth in layman's terms ... module for the engineer) gets decided, so it can reliably handle the stress created by max torque the system sees.

When an OEM gives options on final drive ratio, the tooth thickness / module remains constant across different final drive ratios.

What this does is : for a pinion with more teeth, given that the thickness of each tooth is already decided, the pinion head is larger in diameter. And for a pinion with fewer teeth, the pinion head is smaller in diameter.

Now, since the cross-car distance from the face on which the crown wheel mounts to the centre line of the pinion is fixed; for a pinion head smaller in size, for the crown wheel to mate with it, the teeth on the crown wheel will have to further away from the differential case mounting face. This requires the crown wheel to be thicker, as it still has to mount to the same mounting face.

See illustration attached to quickly explain the above.

If the differential housing casting is made in such a way as to accommodate only certain maximum thickness of crown ring, then this limits ones ability to go to a numerically higher final drive ratio.
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File Type: doc Ring and pinion.doc (29.5 KB, 477 views)
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Old 16th January 2011, 00:00   #48
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by SPIKE ARRESTOR View Post
Correct, the position of steering column (center line) is offset towards the left w.r.t the seat center line, this distance is 70.8 mm and is a perennial case, be it Bolero, Invader, Thar MDI or Thar CRDe.

Spike

PS- Seats of Thar MDI and CRDe are also different.
Spike, On both points a simple question. Why?

Quote:
Originally Posted by cool_dube View Post
Has anyone confirmed the availability of Thar MDi 4x4 with any M&M dealer in Bangalore?
As per RTO rules it should not be registered in Bangalore so the Bangalore dealers s/would not be selling them.

Quote:
Originally Posted by DirtyDan View Post
Newer vehicles equipped with the MDI3200tc motor also come with 3.73 crown gears. So does the Thar MDi. This ratio was forced upon M&M by government
emission/fuel average standards.

The results were better than expected. My Invader with the 4.88s has roughly 15%-20% more low end power.
Dan, So what was your comfortable highway cruising speed (Not top speed) on the 3.73 Vs the 4.88s?
Also did not know this was due to Govt Standards. Thanks for sharing the intricate details.

Quote:
Originally Posted by DirtyDan View Post
Here is a pic of the Dana test facility. The oval thing is a 3 lane expressway grade track 2.5 miles around. There are off-road courses there, too. At bottom center are huge garages where vehicles are prepped.
Dan, where is this facility?

Quote:
Originally Posted by NIP View Post
I think my bumper sticker would be "the CRDe went to the supermarket".
Nice, make it "Thar CRDe went to the supermarket"

Last edited by IronWolf : 16th January 2011 at 00:01.
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Old 16th January 2011, 11:52   #49
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Default Dana 44

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Originally Posted by offroad_maniac View Post
So what are the chances of fitting Lockers / LSD?
Hi Offroad Maniac,

Dana 44 use 2 Different Carriers for the same pumpkin.

This is known as the Carrier Break
1) 3.73 and Below - 3.73:1 to 2.72:1
2) 3.92 and Above - 3.92:1 to 5.89:1

Dana 44 - Wikipedia, the free encyclopedia

To convert a 3.73:1 to 4.88:1 you will have to change the carrier to the Older Mahindra JEEPs Differential Carrier.

Rustys Offroad: Dana 44 Low Ratio Carrier

3.73=41/11
4.88=44/9
5.38=43/8

Typical cost of the conversion.
1) Differential Carriers 2X Rs500-1000
2) Crown & Pinion 2X Rs3000-5000
3) Carrier Bearing 2 X 2 X Rs 500
4) Labour Charges 2 X Rs1000-2000

The Locker/LSD Specification will be for a Dana 44 19 Spline 3.92 and Up Carrier.

Regards,

Arka

http://www.team-bhp.com/forum/4x4-te...le-debate.html (The Axle debate)

http://www.team-bhp.com/forum/4x4-te...a-classic.html (Diff Lock for the Mahindra Classic)

Last edited by ex670c : 16th January 2011 at 11:54.
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Old 16th January 2011, 19:03   #50
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Default Re: Dana 44

Quote:
Originally Posted by ex670c View Post
Hi Offroad Maniac,

Dana 44 use 2 Different Carriers for the same pumpkin.

This is known as the Carrier Break
1) 3.73 and Below - 3.73:1 to 2.72:1
2) 3.92 and Above - 3.92:1 to 5.89:1
Thanks Arka, this is very interesting to know. However, why did DD's mechanic prefer to grind it than use the right carrier? Not available locally?
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Old 16th January 2011, 19:05   #51
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by cool_dube View Post
Has anyone confirmed the availability of Thar MDi 4x4 with any M&M dealer in Bangalore?
yes I did, Sireesh Auto (hosur madiwala junc) clearly denied of the Di being available in any form (4x2 or 4x4) in bangalore due to the BS IV requirement.

However, the same guy confirmed that the Di is definitely available in both the functions 4x2 as well as 4x4 (optional) and the cost difference is merely 50k.

The sales guy said one very weird thing that they're not taking bookings for the moment as its the instructions they've got (not sure why did he say that), also there is no TD vehicle available with them, hoping by next month to get one. How come speedy booked his machine whereas this dealer is denying the booking?
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Old 17th January 2011, 02:41   #52
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Default Re: Dana 44

Quote:
Originally Posted by ex670c View Post
Hi Offroad Maniac,

Dana 44 use 2 Different Carriers for the same pumpkin.

This is known as the Carrier Break
1) 3.73 and Below - 3.73:1 to 2.72:1
2) 3.92 and Above - 3.92:1 to 5.89:1

Dana 44 - Wikipedia, the free encyclopedia

To convert a 3.73:1 to 4.88:1 you will have to change the carrier to the Older Mahindra JEEPs Differential Carrier.
Thanks Arka,
I think the differential pumpkin size of Thar DI 4wd seems to be smaller than earlier/ Older Jeeps like CJ/CL & MM- series jeeps.
Is it so?

One more question w.r.t above nice post by 4WDrift,
that in DD's case was it possible to fit the original size ring gear with smaller pinion in the same housing? As the diameter was same, only thickness was different which can be compensated with smaller pinion as per the attached diagram.
(I guess then the mount pt. towards the driveshaft wont match)

Else, remove & swap everyhing inside from diff. housings of both the different axles. i.e. betn 3.73 with 4.88
(Hope my question is understood)

[quote=Samurai;2211283]Thanks Arka, this is very interesting to know. However, why did DD's mechanic prefer to grind it than use the right carrier? Not available locally

To add more, what will be the best & safe way to change the ratio to 4.88 keeping the axle same or any other 'cheaper but safer' alternative?

Thanks & regards.
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Old 17th January 2011, 10:03   #53
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Default Re: Dana 44

Quote:
Originally Posted by Samurai View Post
Thanks Arka, this is very interesting to know. However, why did DD's mechanic prefer to grind it than use the right carrier? Not available locally?
Quote:
Originally Posted by offroad_maniac View Post
Thanks Arka,
I think the differential pumpkin size of Thar DI 4wd seems to be smaller than earlier/ Older Jeeps like CJ/CL & MM- series jeeps.
Is it so?

One more question w.r.t above nice post by 4WDrift,
that in DD's case was it possible to fit the original size ring gear with smaller pinion in the same housing? As the diameter was same, only thickness was different which can be compensated with smaller pinion as per the attached diagram.
(I guess then the mount pt. towards the driveshaft wont match)

Else, remove & swap everyhing inside from diff. housings of both the different axles. i.e. betn 3.73 with 4.88
(Hope my question is understood)

To add more, what will be the best & safe way to change the ratio to 4.88 keeping the axle same or any other 'cheaper but safer' alternative?

Thanks & regards.
Hi Sharath,

DD's mechanic may not be aware about the Carrier Breaks.

@ Offroad_Maniac, haven't I explained how to convert 3.73:1 to 4.88:1, safely and cheapest alternative.

If the Thar MDI was using a smaller differential don't you think I would have noticed or SPIKE ARRESTOR would have waved the red-flag!!!!

I'm not able to understand your cryptic question.

Regards,

Arka

Last edited by ex670c : 17th January 2011 at 10:13.
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Old 17th January 2011, 12:41   #54
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Default Re: Offroading with Thar DI: The Sensible Option

And i thought it was a straight fit lol. Good to know that with a carrier change it can be fitted easy. Carriers are relatively easy find also Thanks DD and Arka
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Old 17th January 2011, 13:49   #55
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Default Re: Offroading with Thar DI: The Sensible Option

The main thing I wanted to express, and I think Arka will agree, the 3.73 gears do not fit the off road purpose of this jeep generally. And, with a change to 4.27, 4.88 etc. the increase in performance at low speeds is quite dramatic and well worth the money to get it done IMHO. Don't let your local shade tree mechanic do this. Take it to some one who really knows what he is doing. Differential stuff is finicky. Dial up "gear lash" on your
google-ometer and you will see what I mean.

A properly geared jeep MDi will give a Tavera or Scorpio all it can handle from a standing start, for a few seconds anyway. Don't let that low looking number, 63Hp, put you off. Sadly, a local dealer told me that this BSIII version will not be for sale in H.P.

Last edited by DirtyDan : 17th January 2011 at 13:54.
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Old 17th January 2011, 18:34   #56
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Default Re: Dana 44

Quote:
Originally Posted by ex670c View Post
Hi Sharath,

DD's mechanic may not be aware about the Carrier Breaks.

@ Offroad_Maniac, haven't I explained how to convert 3.73:1 to 4.88:1, safely and cheapest alternative.

If the Thar MDI was using a smaller differential don't you think I would have noticed or SPIKE ARRESTOR would have waved the red-flag!!!!

I'm not able to understand your cryptic question.

Regards,

Arka
Sorry sir. My bad.
May be because of early hours..

(Didnt know what does the carrier means so googled it & found this pic which helped)
Name:  GearPattern 008.jpg
Views: 4178
Size:  76.8 KB

(source: explorerforum)

Thanks
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Old 18th January 2011, 12:47   #57
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Default Re: Offroading with Thar DI: The Sensible Option

I have not been following the legalities regarding BSIII, BSIV, anti-pollution equipment etc. so let me ask this...

Do you guys think that either the MDi will be made BSIV compliant or that maybe M&M might come out with a replacement for the MDi3200tc altogether?

This motor is used widely by M&M in Boleros, pikups, Army jeeps. Will they have to change it or replace it in the near future?

I have been told that Himachal will not allow sale of the BSIII MDi Thar. I am wondering if we are going to get an upgrade to clear this hurdle across India.
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Old 18th January 2011, 16:45   #58
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Default Re: Offroading with Thar DI: The Sensible Option

@DD:

There is a CRDe version of the MDI engine doing duty in the Taxi XYLO (D2 Versinon). This is probably what M&M will have to do to meet BSIV compliance in their Mass Market vehicles.
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Old 18th January 2011, 16:53   #59
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by 4x4addict View Post
@DD:

There is a CRDe version of the MDI engine doing duty in the Taxi XYLO (D2 Versinon). This is probably what M&M will have to do to meet BSIV compliance in their Mass Market vehicles.
well if M&M launched the current Thar MDi to replace major and invader, it would be atleast 1-2 years before the xylo heart is transplanted into Thar MDi to meet the BS4 norms.

lets call Thar CRDe with IFS as Thar1 (T1) and Thar MDi with live rigid axle as Thar2 (T2).

now M&M would launch Thar2 with Xylo CRDe only if they see the sales of Thar1 not picking up!

till then M&M would like the sales of Thar1 to go up and cross atleast 100 units and the 2nd batch goes into production.

we all should wait till 1st quarter to get a good clear picture of the sales numbers for Thar1 and Thar2.
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Old 19th January 2011, 01:33   #60
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Default Re: Offroading with Thar DI: The Sensible Option

Quote:
Originally Posted by Parm View Post
.. it would be atleast 1-2 years before the xylo heart is transplanted into Thar MDi to meet the BS4 norms.
Neither I nor 4x4addict said anything about such a transplant, if you are referring to the present common Xylo/Thar CRDe motor.
Past posts by B.D. and Spike seem to indicate that such a transplant, Xylo CRDe to solid axle MM540, would be difficult at best for M&M to do.

Quote:
Originally Posted by Parm View Post
..now M&M would launch Thar2 with Xylo CRDe only if they see the sales of Thar1 not picking up!..
Why? I can not see why this would be a likely consequent.

Quote:
Originally Posted by 4x4addict View Post
@DD:

There is a CRDe version of the MDI engine doing duty in the Taxi XYLO (D2 Versinon). This is probably what M&M will have to do to meet BSIV compliance in their Mass Market vehicles.
Thanks, Tini. I find this news very interesting. A CRDe 2523cc motor!

Actually, I have come to realize that all this concern about pollution, fuel average, horsepower, reliability, is all rubbish and nonsense. The TRUE criteria or test of a great motor is how it sounds.
The Tata 3.0L found in many Sumos is the clear winner here followed closely by the Harley Davidson motorcycle and certain American "muscle cars" of the 1960s.

Somebody ought to start a thread on "the best LOOKING motor" as well.

Last edited by DirtyDan : 19th January 2011 at 01:51.
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