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Old 14th January 2011, 16:34   #31
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by Samurai View Post
...If you need phenomenal onroad performance and acceptable offroad performance, pick Thar CDRe....
Just one particular point in the official THAR CRde review is still a point of concern as per as on road behaviour is concerned, "Nervous steering feel in 100+ speed"...definitely not a desirable feature.

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Front 57" OKBJ = 35k? 10k More than many of us imagined..
This is an approx. idea, exact price might be lesser and it includes all parts including new tie-ends plus labour charges (done in an authorised Mahindra workshop). Let me get hold of the bill if i can find, then i can confirm.

Quote:
...Rear 53" FFRA + parts = 70k .
Sorry for the confusion created. That amount to the combined cost of front and rear set-up and not only the rear one! IIRC it was the catalogue for 4wd pick up. But as 4x4addict has already mentioned the rear set-up is not straight fit for the Jeeps.
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Old 14th January 2011, 16:40   #32
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Default Differential Ratio

Hi Guys,

Dirty_Dan is running a MDI3200TC with NGT520+T18 and has changed his Differential Ratio to 4.88:1.

He is using the vehicle up in the Himalayas, Dharamsala.

I hope he shares his overall experience with this upgrade on the MDI3200TC+NGT520 combo.

Regards,

Arka
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Old 15th January 2011, 01:43   #33
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Default Onroad performance

If the DI is expected to touch just about 100 Kmph on the road with 3.73 ratios, it would just about touch ~76 Kmph with 4.88 ratios. That brings it back in the league of the 540s. Well apart from the racket that the 540 creates at that speed.

Am I missing something here in the calculation?

Adi
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Old 15th January 2011, 03:26   #34
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Default Re: Onroad performance

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Originally Posted by AVR View Post
If the DI is expected to touch just about 100 Kmph on the road with 3.73 ratios, it would just about touch ~76 Kmph with 4.88 ratios. That brings it back in the league of the 540s. Well apart from the racket that the 540 creates at that speed.

Am I missing something here in the calculation?

Adi
I have done 120kmph in 4th gear in a cl550mdi with 4 people in the jeep in no time. The fifth gear wouldve prolly sent it to 130-135kmph comfortably I would guess. Considering the engine and gearbox is the same the Thar mdi I presume would perform similarly minus the performance loss due to the slight additional weight!
Note: As against conventional belief here higher diff ratios which are slightly higher than the stock will actually help achieve top speeds quicker due to better gearing torque conversion advantage at the point where the engine's natural torque starts dropping. Only extremely higher ratios will cause suffocation but a vehicle with a 5th gear will achieve better top speed with higher ratios for the above mentioned reason. In this case the 5th gear, which is close to an overdrive ratio will start behaving like a power gear assisting in achieving top speed quicker. I know not too many of you will agree with me straightaway on this one but this is how it will always be

Having said the above, I can almost guarantee that Thar mdi with 4.25 diff ratio will achieve better vehicle top speeds (practically) in comparison to 3.73 in 5th gear.

Last edited by The Wolf : 15th January 2011 at 03:39.
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Old 15th January 2011, 08:40   #35
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Default Re: Offroading with Thar DI: The Sensible Option

Taking quick feedback from this thread, in all probability Mahindra is going to hold back Mdi to push Crde sales. Expect dealers to be either ignorant or in refusal mode on Mdi.
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Old 15th January 2011, 10:06   #36
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Default Re: Onroad performance

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Originally Posted by The Wolf View Post
I have done 120kmph in 4th gear in a cl550mdi with 4 people in the jeep in no time. The fifth gear would've prolly sent it to 130-135kmph comfortably I would guess. Considering the engine and gearbox is the same the Thar mdi I presume would perform similarly minus the performance loss due to the slight additional weight!
Typically top speeds are always achieved in 4th gear, Overdrive only allows engine to run at lower rpms. So I guess something around 110+ kmph sounds plausible.

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Originally Posted by The Wolf View Post
Note: As against conventional belief here higher diff ratios which are slightly higher than the stock will actually help achieve top speeds quicker due to better gearing torque conversion advantage at the point where the engine's natural torque starts dropping. Only extremely higher ratios will cause suffocation but a vehicle with a 5th gear will achieve better top speed with higher ratios for the above mentioned reason. In this case the 5th gear, which is close to an overdrive ratio will start behaving like a power gear assisting in achieving top speed quicker. I know not too many of you will agree with me straightaway on this one but this is how it will always be
This does sound contrary to what I've heard and non-intuitive too. Of course, I am comparing 5.38 to 3.73 which would have the expected reduction. Do you think having an overdrive would possibly reduce the effect of 5.38s on top speed?

Whatever be the case, 4.88 does seem like a good balance in case of either theory.
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Old 15th January 2011, 11:43   #37
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Default Re: Offroading with Thar DI: The Sensible Option

The Thar DI's Steering seems centered to the seat (broucher pics) unlike the Thar CRDe or is it just my eyes ?
I still can't believe how MM couldn't get this right in the first place after so many years of the so called "R&D + Engineering" claimed to have gone into the making of it.

Regards,
Kumar
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Old 15th January 2011, 11:49   #38
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Default Re: Offroading with Thar DI: The Sensible Option

Nope, it doesn't look centered in the pic. It's more towards the middle of the vehicle.
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Old 15th January 2011, 12:16   #39
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Default Re: Offroading with Thar DI: The Sensible Option

Considering I have an estate (booking possible), I am also thinking this is a better buy than the CRDe. Points made by Samurai seem very valid, plus a whole lot of money saved over the CDRe for mods. More than AC/Hardtop, I would spend on wheels and adjustable/better seats. And readily available in white.

I think my bumper sticker would be "the CRDe went to the supermarket".
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Old 15th January 2011, 12:19   #40
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Default Re: Offroading with Thar DI: The Sensible Option

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Originally Posted by Tejas@perioimpl View Post
Nope, it doesn't look centered in the pic. It's more towards the middle of the vehicle.
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.
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Old 15th January 2011, 13:01   #41
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Default Re: Onroad performance

Quote:
Originally Posted by AVR View Post
If the DI is expected to touch just about 100 Kmph on the road with 3.73 ratios, it would just about touch ~76 Kmph with 4.88 ratios. That brings it back in the league of the 540s. Well apart from the racket that the 540 creates at that speed.

Am I missing something here in the calculation?

Adi
Hi Adi,

What you say is correct, if you put taller tyres i.e 31" the speed will improve by another 11-13% approx.

Regards,

Arka
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Old 15th January 2011, 14:22   #42
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Default Re: Offroading with Thar DI: The Sensible Option

Has anyone confirmed the availability of Thar MDi 4x4 with any M&M dealer in Bangalore?

Last edited by cool_dube : 15th January 2011 at 14:29.
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Old 15th January 2011, 15:01   #43
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Default Re: Differential Ratio

Quote:
Originally Posted by Samurai View Post
...Obviously, that has to be changed to 4.88 at least...
Quote:
Originally Posted by ex670c View Post
Hi Guys,

Dirty_Dan is running a MDI3200TC with NGT520+T18 and has changed his Differential Ratio to 4.88:1.

He is using the vehicle up in the Himalayas, Dharamsala.

I hope he shares his overall experience with this upgrade on the MDI3200TC+NGT520 combo.

Regards,

Arka
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.

I bought an Invader, with MDi3200tc, October 2009 when prospects for the launch of Thar looked bleak and I wanted a new car going into winter up here in the snow and cold. Straight away I was very disappointed with the Invader's power at low speeds, from a standing start, and its poor performance climbing the steep slopes here at the front range of the Himalayas. One fine day I was trying to go down a mountain. I had to go around a sharp, steep, narrow curve. I had to go uphill in reverse to crab around this curve and almost dumped the whole works down into a gorge because the motor fizzled out on me, it didn't have the juice to go up in reverse. This dangerous "last straw" convinced me to make a change. Quick. After exchanging emails with Arka and Brutus (Brutus designs his own differentials.) I resolved to change the crown gears from the factory 3.73 to
4.88. I knew this was likely to be a bit complex and/or in need of skilled experienced hands so I went to a flagship M&M dealership in the Punjab to see what could be done. The head mechanic said that the crown gears could be changed but that it was not a simple bolt in proposition. The 4.88 crown gear fits in the "pumpkin", the differential housing, okay height-wise but was a bit thicker than the 3.73 crown gear and hence would not fit width-wise.

His solution was to carefully grind down the bearing housings (see below), fit in some shims, precision washers, around the bearings to guarantee a smooth friction surface and add new matching input spindles to fit the 4.88 crown gears. The input spindles attach to the propeller (driveshaft) on one end and fit into the crown gears on the other end. He also put in a new speedometer gear from an army jeep that matched the speedometer to the new gear ratios. He might have altered some other parts slightly but if so whatever else he did was inconsequential and was lost in the lanuage barrier between us.

The results were better than expected. My Invader with the 4.88s has roughly 15%-20% more low end power. I now have a great second gear that charges up hills. First gear, low range,
is very much a creeping gear. In 2wd I can keep up with Scorpios and Innovas up to 30kph and a lot of times around here that's as fast as you get to go before the next switchback curve.
on very steep hills and I can out accellerate Taveras. On the flat, up to about 30kph I can out accellerate Scorpios provided they are old and belching a little blue smoke.
With the 4.88 crown my fuel average around town is 12.1-12.3, highly acceptable. Out on the road at higher speeds...I dunno. I never checked. We don't have real roads here, only old goat paths that they paint black the week before the road inspector visits the area. We don't see speeds over 60kph here much. On trips into the Punjab where they actually have roads worthy of the name, I can only say that the engine did not seem to be laboring excessively at speeds around 100kph.
The work took 2 days to complete.

Upside: you get a vehicle with a lot more low end power. The difference is amazing. This ratio seems to take advantage of the MDI motor's low end grunt.

Downside: It is risky. Its a mod that is only as good as the mechanic who does it, and it is expensive if he messes up.

Cost: I will let those who are interested figure this out. It could go anywhere from between 16,000 to 25,000 ruppees, my guess, depending who does it. Much of the cost
is labor since it was a repeated process of grinding and fitting. I am sure I paid a premium price since it was a M&M dealer who did the work.

The head mechanic said that he expects the differential with mod will last as long as a normal differential. He said when its life cycle is thru that I could just replace the whole
differential with a normal complete 4.88 unit. I have had my differentials inspected twice locally since the modification 16000K ago and
there is no appreciable wear.

I don't know if this is the right diff but here is the idea.
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Old 15th January 2011, 16:48   #44
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Default Re: Offroading with Thar DI: The Sensible Option

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.
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Old 15th January 2011, 18:57   #45
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Default Re: Offroading with Thar DI: The Sensible Option

Thanks a lot DD. That was very informative.
The results are sweet but the job is risky. With 4wd it will be twice the headache.
Now what?

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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.
So what are the chances of fitting Lockers / LSD?
Why is CMVR so cruel to us????
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