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Old 28th September 2012, 22:33   #31
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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I don't understand why the two tie rods will oppose each other. Even if their is bump steer and the upper tie rod is pushing the wheels in a particular direction, the lower tie rod, which is without the drag link, would simply follow the direction of push. Bump steer notwithstanding.
Hi jeskirat,

i have made an animated line diagram of the rack and its tierods. You tube has kind of blurred it up, sorry about that.
i have just assumed the dimensions here.
The Solid green line represents the steering rack (assumed to be 20 inches wide, mounted on the chassis)
the two white lines represent the tie rods (assumed to be 15 inches in length)

the lowest white line simply shows the distance between the two tie rod ends. the figure in brackets being the live distance measurement as the tie rods move.

For simplicity's sake, i have animated only one tie rod (roughly mimicking axle articulation)



Notice how the distance between the two tie rod ends changes? this is how it will cause bumpsteer.

Now your lower tie rod connects the same parts as the upper ones, but it is a solid piece of metal, whose length is constant. hence it will resist the change in distance required for free movement.
Notice the change in distance (which the lower tie rod is resisting ) is more than an inch in this simulation. it will increase further if both upper tierods were to articulate.

This is how both the tie rods will bind. the upper tie rods want the lower one to stretch, while the lower one want the upper ones to compress. these stresses will eventually cause a failure.

Hope i was able to explain properly.
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Old 28th September 2012, 23:22   #32
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Quote:
Originally Posted by dhawcash

Hi jeskirat,

i have made an animated line diagram of the rack and its tierods .....

Hope i was able to explain properly.
Hi dhawcash, great animation. Though the angles used by you are exaggerated, but I am trying to see your point.

What in your opinion would happen if I remove the lower tie rod?

Regards, Jaskirat

Last edited by Jaskirat : 28th September 2012 at 23:23.
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Old 29th September 2012, 01:06   #33
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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Originally Posted by Jaskirat View Post
What in your opinion would happen if I remove the lower tie rod?
Jaskirat, Bumpsteer is what will happen.

As you see in the animation, the distance between the tie-rod end is increasing while articulation. Well, we know that it is not possible, and the distance should remain constant. So, the spindle casing of the wheel with least resistance will be pulled in.

Well.. what I mean is, the vehicle will not track true to the steering.

EDIT: Can you please also post some more pics of the leaf spring perches, if possible. Also, Please can you share how you finalized on it? It would be really helpful for prospective members trying to covert into SFA.

Last edited by dhanushs : 29th September 2012 at 01:32. Reason: Add question about leaf spring perch.
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Old 29th September 2012, 08:16   #34
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle


what if a single tube in tube fitment ( just like the motorcycle front suspension tubes ) be fitted in place of lower tie rod ( track rod ) ??

It will match the changing distance but with some resistance as there will be a double action damper inside it

Will it give more stability ? will it reduce jerks ? will it help the steering system survive more ?

Disclaimer ; I am not an engineer

Sudarshan

Last edited by Sudarshan : 29th September 2012 at 08:22.
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Old 29th September 2012, 09:48   #35
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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What in your opinion would happen if I remove the lower tie rod?
Dhanushs sir nailed it!

I think the lower tie rod is a must have to avoid bump steer
(which can be very dangerous and unpredictable consequences as whichever tyre has more weight the vehicle will follow that tyre's direction- and this weight distribution keeps changing as we drive)

The immediate solution i can think of is to remove one of the tie rods from the rack and pinion rack. This will eliminate any binding in the system and the single upper tie rod would behave like a drag link. { will remove the binding as the upper pair of tie rods would not be trying to stretch the lower one as the suspension moves.}

But this ingenious drag link would still not be optimized regarding steering geometry and the wheels would change direction slightly as the suspension moves.
{say if you remove the left tie rod- both wheels would try to steer towards right if you hit a bump momentarily -or as long as the suspension is compressed}
this would add some vagueness to the steering but should be safer than the present setup.
Of course the whole steering would be dependent on the single upper tierod- i have no idea how long that lone soldier would last. try comparing the ball joint sizes of the rack to the original armada's drag link ball joints to get an idea of their strength.

Quote:
what if a single tube in tube fitment ( just like the motorcycle front suspension tubes ) be fitted in place of lower tie rod ( track rod ) ??

It will match the changing distance but with some resistance as there will be a double action damper inside it

Will it give more stability ? will it reduce jerks ? will it help the steering system survive more ?
Hey sir,

You will still have bump steer with the luxury of it being slightly damped

a solid track rod is a must if you have a solid axle! [I was wondering what the correct name for lower tie rod in this set up is. its the track rod! thanks]
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Old 29th September 2012, 10:47   #36
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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Originally Posted by Jaskirat View Post
I am an enthusiast and willing to try out few things. I have been part of a supply chain to automotive industry and do not undermine the importance of RAW, FAW, DFMEA, PFMEA, DMU etc., but when has enthusiasm been held hostage to these
Dear Jaskirat - I agree to your comments completely. Only if somebody tries, something will happen. Your concept was never incorrect, everybody wanted me to do it, I could not do it for various reasons which everybody knows. However, your execution needs much more basic work to be done on it, for it to work properly. I am happy to see other like minded TeamBHPians guiding you on bump steer and things like that. As a small input, in the 8th photograph, the weld joint of the front shackle to the chassis does not provide any factor of safety whatsoever. It can break anytime, please be very careful. I also agree completely that "Auto Passion" cannot be held hostage by FAW / RAW / DFMEA / PFMEA / DMU etc.

Dear all - after all, what is DFMEA? It is nothing but "Design Failure Mode Effect Analysis". In simple terms, it means "why something failed as it did?", and, "what will you do after you find out why and how it failed or get the failure analysis in your hand to ensure that it never fails again?" The real answer (not the "presentations in meetings" answer) to the second question exists only in the brains of "Auto Passionate" people who can think like this. Sadly, this capability is in extremely scarce supply these days, so if you have it, assert yourself!

Best regards,

Behram
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Old 29th September 2012, 12:02   #37
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

Jaskirat,

It is an ambitious project that you have undertaken and executed.

Whenever any major mechanical changes like yours are done, the reliability factor comes into force. Only real time testing on and off roads will be conclusive to your endeavor.

As an interior designer, I am not empowered enough to comment or give inputs on the technicalities here, like the learned members have. But one thing I can advice you is, remove the license plate from the front grille which is blocking the air flow to the ac condenser and radiator by 25% approximately and below that is a huge winch doing the same.

Wish you success.
Regards,
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Old 29th September 2012, 13:44   #38
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

Quote:
Originally Posted by dhawcash View Post
Dhanushs sir nailed it!

I think the lower tie rod is a must have to avoid bump steer

The immediate solution i can think of is to remove one of the tie rods from the rack and pinion rack. This will eliminate any binding in the system and the single upper tie rod would behave like a drag link.
Hi dhawcash,

The lower tie rod (now renamed Track Rod) has to remain. I will try removing one end of the R&P tie rod and see how the system works. Thanks

Quote:
Originally Posted by fazalaliadil View Post
Jaskirat,

... But one thing I can advice you is, remove the license plate from the front grille which is blocking the air flow to the ac condenser and radiator by 25% approximately and below that is a huge winch doing the same.

Wish you success.
Regards,
Dear Mr. Fazal, a very valid input, which I will ask Karan (the Thar's owner) to immediately rectify. Thanks

Quote:
Originally Posted by DHABHAR.BEHRAM View Post
Dear Jaskirat - I agree to your comments completely. Only if somebody tries, something will happen. Your concept was never incorrect, everybody wanted me to do it, I could not do it for various reasons which everybody knows. However, your execution needs much more basic work to be done on it, for it to work properly. I am happy to see other like minded TeamBHPians guiding you on bump steer and things like that. As a small input, in the 8th photograph, the weld joint of the front shackle to the chassis does not provide any factor of safety whatsoever. It can break anytime, please be very careful. I also agree completely that "Auto Passion" cannot be held hostage by FAW / RAW / DFMEA / PFMEA / DMU etc.

Dear all - after all, what is DFMEA? It is nothing but "Design Failure Mode Effect Analysis". In simple terms, it means "why something failed as it did?", and, "what will you do after you find out why and how it failed or get the failure analysis in your hand to ensure that it never fails again?" The real answer (not the "presentations in meetings" answer) to the second question exists only in the brains of "Auto Passionate" people who can think like this. Sadly, this capability is in extremely scarce supply these days, so if you have it, assert yourself!

Best regards,

Behram
Dear Mr. Behram, thanks for your feedback on the front shackle mount. I will re-look at the same immediately. I think its the picture that is giving an impression of weak joint. I am attaching another picture from a different angle along with the one for the rear mount. The shackle mount actually overlaps with the chassis and we have done welding on both the inner and outer side. Nevertheless, I will re-examine the whole thing for safety and strength.

Also, your interpretation of DFMEA is the best I have ever encountered.
Thanks
Attached Thumbnails
Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-thar-front-mounting.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-thar-front-mounting-1.jpg  

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Old 3rd October 2012, 14:34   #39
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

1) Didnt realize my double-TR question would grow into a tech talk, nice

2) Jaskirat - one question? How much of the original chassis was altered/cut/grinded? Meaning, can you just remove the 2 shackles, leafs, 1 rigid axle, TR's and just BOLT on the old lower arms, diff, CV's, etc and make it OE? (Of course leave the shackle mounts welded on?)
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Old 4th October 2012, 17:17   #40
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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Originally Posted by svsantosh View Post
1) Didnt realize my double-TR question would grow into a tech talk, nice

2) Jaskirat - one question? How much of the original chassis was altered/cut/grinded? Meaning, can you just remove the 2 shackles, leafs, 1 rigid axle, TR's and just BOLT on the old lower arms, diff, CV's, etc and make it OE? (Of course leave the shackle mounts welded on?)
Dear svsantosh,

You did stir up a hornet's nest for a while. But nevertheless, great learning for me.

We did not cut the chassis at all, but only removed the IFS mounting brackets attached to the chassis. Reverting back to IFS would require great deal of precision work (including welding). Not an easy task.


Regards

Jaskirat
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Old 10th October 2012, 14:11   #41
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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Originally Posted by svsantosh View Post
Sir, how much is it? just for our knowledge! Couple of friends decided against the Crde for the same reason about cost of the critical CV joint. I recall Tanzeem/brothers spending close to 25K (?) for their scorpio's, is it the same figure?
This is my jeep which mr Jaskirat did modification on..and believe me he did a fantastic job . It was a bit risky proposition as no body had done it before.

And the best part was that it took him just 15 mins to decide and confirm that it could be done .. And rest his history. And for your information i have also brocken atleast 5 axels and many more things

Note from Team-bhp support: Please do not type an entire post in capital letters.

Last edited by moralfibre : 10th October 2012 at 16:18. Reason: Please do not write an entire post in capital letters.
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Old 10th October 2012, 16:46   #42
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

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And the best part was that it took him just 15 mins to decide and confirm that it could be done .. And rest his history. And for your information i have also brocken atleast 5 axels and many more things
Hi TharPlus:

I am interested to know what other parts were broken apart from the 5 Axles. Is your clutch still OE?

Cheers
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Old 22nd October 2012, 13:02   #43
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

Hi Guys,

Karan Bali and his Thar, (which we refer to as Thar Plus), participated in an off-road event called UnCaGeD 10 12 held near Chandigarh. He and his partner, Kabir Waraich came first in the Team category.

Some pictures of Karan's modified Thar in action. It was quite a test for the modifications done.

Regards

Jaskirat
Attached Thumbnails
Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-9.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-8.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-6.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-7.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-1.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-2.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-4.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-5.jpg  

Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle-uncaged-10-12-bali-3.jpg  


Last edited by Jaskirat : 22nd October 2012 at 13:06.
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Old 22nd October 2012, 14:33   #44
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

Last 2 pics - Why is 1 wheel in the air?
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Old 22nd October 2012, 15:12   #45
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Default Re: Mahindra Thar - *Converted* Independent Front Suspension to Solid Axle

That's quite a demonstration man. Kudos to you and the owners. Just shows sometimes even our hard learnt science can be trumped by creative thinking. This was the purpose of this machine and it has achieved it. Perfect.
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