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Old 10th February 2010, 17:15   #16
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Originally Posted by Samurai View Post
Ram, the Dodge Durango weighs as much as two MM540s. No wonder it needs a 6.35mm steel skid plates. But for CJs and MMs at half the weight, 4mm is very much enough. I am yet to see any dent/bend in my Jeep skid plate after so much offroad abuse.
An MM540 weighs 1,540 kg.
A Dodge Durango is 2,333 kg or 1.5X

But how does that affect a rough granite rock contacting
a cast aluminum gearbox casing or cast iron transfercase casing at 36 km/h?

If you shoot a cannon ball at an engine oil sump or gearbox casting at
10 metres per second, how will the damage done to the gearbox, be any different, whether the gearbox drives a 1.5 ton vehicle or a 2 ton vehicle?

Why will the armor protecting the gearbox need to be thinner on a lighter vehicle? I don't understand.
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Old 10th February 2010, 17:33   #17
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Originally Posted by Ram View Post
An MM540 weighs 1,540 kg.
A Dodge Durango is 2,333 kg or 1.5X
Wrong data Ram, MM540 4WD weighs 1370Kgs.

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But how does that affect a rough granite rock contacting
a cast aluminum gearbox casing or cast iron transfercase casing at 36 km/h?
Ram, we don't offroad in rocky terrain at 36km/h. Less than 10km/h or even 5km/h is the real speed at which skid plate will take impact. In fact, the front differential is placed lot lower and ahead of the skid plates. If we encountered a big rock at 36km/h, it will hit the front differential much before the skid plates.

The speed of 36km/h may be reached in trail driving, but if we see a rock, we avoid it or totally slow down. That's what I would do.

We are worried about vehicle getting beached on the rock. That is why weight matters.

Last edited by Samurai : 10th February 2010 at 18:00.
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Old 10th February 2010, 18:58   #18
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Hi guys as far as i know Kunal (motocamp) he really does some hard core offroading so for him thinking of putting a full skid plate is really a necessary, his jeep is only built for offroading purpose and nothing else. Correct me if i am wrong Kunal, sorry my spare skid plate was sold of to the scrap guy by the mechanic. Heres some thing to help you.
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Old 10th February 2010, 19:19   #19
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Hi guys as far as i know Kunal (motocamp) he really does some hard core offroading so for him thinking of putting a full skid plate is really a necessary, his jeep is only built for offroading purpose and nothing else.
Unlike rest of us?

Putting large boxy skid plates to cover large parts of the underbody would surely buy you piece of mind. However, it will be a curse when you get stuck, the whole body will sit on it. I have been there, done that, and removed that. People who have followed my GV skid plates story would know that. Sudev made a much better design after my fiasco. Check out his design in the same thread.

The skid plates should only cover essential parts, and very close to the body. Boxes should be avoided.
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Old 10th February 2010, 21:15   #20
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Samurai , I am sure and know you guys do very hardocre stuff , I appreciate the fact that you guys have gone down this road before, but the same thing can be achieved in different ways.

I have decided to build this skid plate after 3.5 years of owning my jeep and with very good reason... a very bent and damaged gearbox cross member.

I want to protect my gearbox from heavy impact not just getting high centered at ramp breakover.

I am trying to protect it from hitting the cross memeber at speed ,as we all know some obstacles can only be overcome with momentum.

In my offroading experience with the jeep i have found it consistently makes contact with the ground via the crossmember which is quite lowslung and in the centre of the vehicle. everything else can be avoided with skill.

It will not be boxy or reduce my ground clearence and i can assure you it is not for peace of mind....

James what you have in the picture is pretty close to what i am designing.What plans for the weekend?
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Old 11th February 2010, 06:13   #21
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In fact, the front differential is placed lot lower and ahead of the skid plates.
When you're cresting a hump on the trail, differentials are protected by one or both wheels. That is why you never crest a ridge diagonally. Always attack it at right angles. It is transfer cases which hang down where there is no wheel to protect them. That is why it is more common that transfer cases have skid plates on them, than differentials.

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We are worried about vehicle getting beached on the rock. That is why weight matters.
And how does light weight prevent you from getting high-centered or "beached" as you put it? Short wheelbase hobby-horses like the 80-inch CJ-3B are less likely to get high-centered than a long-wheelbase station-wagon like the Grand Vitara.
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Old 11th February 2010, 08:01   #22
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When you're cresting a hump on the trail, differentials are protected by one or both wheels. That is why you never crest a ridge diagonally. Always attack it at right angles. It is transfer cases which hang down where there is no wheel to protect them. That is why it is more common that transfer cases have skid plates on them, than differentials.
Exactly, and who would attack such a hump at 36km/h? You would just take off after the crest and never really need the skid plates.

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And how does light weight prevent you from getting high-centered or "beached" as you put it? Short wheelbase hobby-horses like the 80-inch CJ-3B are less likely to get high-centered than a long-wheelbase station-wagon like the Grand Vitara.
Light weight doesn't prevent. I have beached both GV and CJ340 on humps. When that happens, almost the whole weight of the vehicle will be supported on the skid plate. That is why skid plate thickness is decided based on the weight of the vehicle. We never hit the skid plates to anything at high speeds. We don't do that kind of offroading in India, not with our humble Jeeps and Gypsies.

Ram, this is very easy to see after just one offroad excursion. You should join the Pune Nomads in their next trip.
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Old 11th February 2010, 13:22   #23
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Originally Posted by motocamp View Post
I have decided to build this skid plate after 3.5 years of owning my jeep and with very good reason... a very bent and damaged gearbox cross member.

I want to protect my gearbox from heavy impact not just getting high centered at ramp breakover.

I am trying to protect it from hitting the cross memeber at speed ,as we all know some obstacles can only be overcome with momentum.

In my offroading experience with the jeep i have found it consistently makes contact with the ground via the crossmember which is quite lowslung and in the centre of the vehicle. everything else can be avoided with skill.
Hi Kunal,

Most of your problems can be overcome by adding an OEM style skid plate.

What you have described is typical of MM540s without the Skid-Plate.

How ever if you are planning a Cross-Member cum Skid-Plate for the Gearbox & Transmission, that would be interesting.

The Belly Pan type makes servicing and access an issue.

Why should you end up hitting the Cross-Member at high speeds?

Are you starting the Indian version XRRA?

Regards,

Arka
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Old 11th February 2010, 15:26   #24
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Guys if the skid plate is designed well i don't think its going to create problems, service i don't think anyone removes the gearbox quite often other than just a oil change. At the last OTR i beached the 550 on just a plain mud banking (my foolishness i was just crawling up), the jeep just could not be even pushed of it because it was totally stuck on the OE skid plate and a part of the cross member. If the skid plate was a bigger and better designed i might have got stuck but with a little push it might have slid back down the slope. A skid plate should help you to skid over stuff like that and also give protection to the gearbox etc.
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Old 11th February 2010, 16:05   #25
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Originally Posted by whicked wheels View Post
Guys if the skid plate is designed well i don't think its going to create problems, service i don't think anyone removes the gearbox quite often other than just a oil change. At the last OTR i beached the 550 on just a plain mud banking (my foolishness i was just crawling up), the jeep just could not be even pushed of it because it was totally stuck on the OE skid plate and a part of the cross member. If the skid plate was a bigger and better designed i might have got stuck but with a little push it might have slid back down the slope. A skid plate should help you to skid over stuff like that and also give protection to the gearbox etc.
Hi Wicked Wheels,

The OEM Stuff works better in conjunction with all other OEM stuff i.e Tyres MRF Sandgrip/Apollo Bullet i.e 31/32" Tall.

Also driving technique is very important, you have to know how to skid off, the skid-plate.

Instead of crawling up, as your front wheels started climbing/midway up the slope, you could have tapped your accelerator/pumped your accelerator, it would have done the trick.

In 4 1/2 years of Off-Road driving I have got stuck on my Skid-Plate only once, in TPC2008, that was because of driver error.

I realized the importance of Skid-Plates in early 2005, when I saw a couple of JEEPs stuck on their cross-members, twisting and nearly destroying it.

So hurriedly before Yelagiri 2005, I had a two Skid-Plates made for my CJ3B and Anjan's STUD, my CJ3B Skid-Plate does Duty on Dr.Jones PROWLER.

In December 2005, I had another Skid-Plate made for my MM540XD, at the time of the 4x4 Conversion. Its 8mm and doing a very good Job.

I made a few alterations, to the original Skid-Plate design, removed, all the holes excepting the Bolt and the T-Case Drain Nut.

Many a times my skid has been bashed really hard, TPC2009, and Avalakonda 2010, but nothing happened to the Cross-Member or to the Skid-Plate.

A new design will be definitely welcome.

Regards,

Arka
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Old 12th February 2010, 00:35   #26
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Hi Wicked Wheels,

The OEM Stuff works better in conjunction with all other OEM stuff i.e Tyres MRF Sandgrip/Apollo Bullet i.e 31/32" Tall.

I too believe the same as long as you don't cross its limit but when offroading you tend to try something new or something extreme thats when you think of upgrades.

Also driving technique is very important, you have to know how to skid off, the skid-plate.

Instead of crawling up, as your front wheels started climbing/midway up the slope, you could have tapped your accelerator/pumped your accelerator, it would have done the trick.
Arka
I certainly agree with you Arka, But that day i just wanted to see if the jeep had the power to just crawl up that steep incline. The jeep did crawl up but once the skid plate touched the jeep just skid a bit ahead and stuck, with front two wheels in air and then the rear wheels just lost total traction by digging holes into the mud. If i had a better skid plate the jeep might have just skid of the top with the momentum she had.

A new design for sure is in the making. I am learning a lot form you veterans in this sport so for sure ill try to make things better for all of us. I love this kind of challenging jobs. Not being offensive here but i love doing stuff like this, its a part of my job.
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Old 12th February 2010, 10:47   #27
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I certainly agree with you Arka, But that day i just wanted to see if the jeep had the power to just crawl up that steep incline. The jeep did crawl up but once the skid plate touched the jeep just skid a bit ahead and stuck, with front two wheels in air and then the rear wheels just lost total traction by digging holes into the mud. If i had a better skid plate the jeep might have just skid of the top with the momentum she had.

A new design for sure is in the making. I am learning a lot form you veterans in this sport so for sure ill try to make things better for all of us. I love this kind of challenging jobs. Not being offensive here but i love doing stuff like this, its a part of my job.
Hi Wicked,

You are expecting too much from the Skid-Plate.

If the OEM Cross-Member/Skid Plate is eliminated then

1) Something higher up will get snagged, making it even more difficult to recover.

2) The Cross-Member and Aluminium Spacers dictate the drive line angle, I have meddled with it enough, to know that the Stock Drive-Line Angles are the most optimised. Having said that, if a newer design of cross-member cum skid-plate is made, you will gain at most an inch (25.4mm). which you can gain with taller tyres i.e 31" vs 28/29".

3) Try the same obstacle with same driving technique with 7.50X16 and tell us what happens.

Its your time, money & vehicle, so any mods you do and is successful will show the way for others.

Regards,

Arka
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Old 13th February 2010, 00:08   #28
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Hi Wicked,

You are expecting too much from the Skid-Plate.
a}No i am not expecting too much i just want it too act like one.

Quote:
If the OEM Cross-Member/Skid Plate is eliminated then
b}I am not going to eliminate the cross-member and the skid plate just want to upgrade it.

Quote:
1) Something higher up will get snagged, making it even more difficult to recover.
c}Not going to keep my gear box and transfer case unprotected so no question about that.

Quote:
2) The Cross-Member and Aluminium Spacers dictate the drive line angle, I have meddled with it enough, to know that the Stock Drive-Line Angles are the most optimised. Having said that, if a newer design of cross-member cum skid-plate is made, you will gain at most an inch (25.4mm). which you can gain with taller tyres i.e 31" vs 28/29".
d}I can gain more gain more with Spoa set up and have no problems with the change in drive line angles as it is a tried and tested over the years.

Quote:
3) Try the same obstacle with same driving technique with 7.50X16 and tell us what happens.
e}The three jeeps which i have the 550 runs on 235\70\16, mm540 and the classic i have driven them with 31x10.5-15 mudzillas so it has enough of clearance under the gear box. The point i am trying to make is that the OE skid plate is not performing much of its duties of skidding but more acts as a bash plate for protection. I want to make a skid plate that really acts as a skid plate and also provides protection.

Quote:
Its your time, money & vehicle, so any mods you do and is successful will show the way for others.
f}Sure i am going to waste time and money but success will also be sure to come, sooner or later.

Regards.

Last edited by khan_sultan : 14th February 2010 at 08:09. Reason: fixed quotes
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Old 13th February 2010, 13:46   #29
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Can anyone help me designing a suitable skid plate for Gypsy as last time i have seen the t-case sitting on a rock.i remeber viji was refering something similar this.

Raj
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Old 13th February 2010, 13:50   #30
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Can anyone help me designing a suitable skid plate for Gypsy as last time i have seen the t-case sitting on a rock.i remeber viji was refering something similar this.

Raj
Design is ready with Vijay, only need to manufacture it.
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