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Old 2nd April 2015, 10:06   #16
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Default Re: The infamous Death Wobble

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Originally Posted by Sutripta View Post
Hi,
How likely is the Thar CRDe to get a death wobble?
Any other (common In India) vehicle which has this problem?

Regards
Sutripta
The Bolero does not face it, so I guess the Thar Crde should also be safe.
Can this be a function of IFS being more "handling friendly" that solid axles ?

I had once faced the DW in a 1996 1st gen Sumo (IFS) when one of the steering tie rods got dislodged. The tie rod had actually lost the nut that holds it to the axle and might have come off while negotiating a speed breaker. The moment I gathered speed (~40 Kph) after cross the speed breaker, the front end went haywire and the steering became hard at the same time. Luckily, speed was low so no calamities.
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Old 2nd April 2015, 11:45   #17
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Thumbs down Re: The infamous Death Wobble

Yes, I had a first hand experience of it on a Thar Crde, when the Thar owner who had brought the vehicle to ASS, wanted a 2nd opinion and we test drove it and i replicated the scenario. It was definitely a ball joint issue as per me, whereas the ASS was talking him out stating a tyre issue, stating he had upsized the tyre,the ASS service head gloated that "isme IFS iseliye dala hai, yeh normal driving me nahi hota hai" DONT tolerate a death wobble, sit on the service guys and get it fixed.The poor Thar owner sure took the bait.Could not help him more :-(

A basic knowledge with mechanics or a workshop manual is critical for vehicle like Thar or FT since the ASS is terribly braindrained and do not have a clue on doing root cause analysis.The attitude sucks though they never say a clear "no" its usually the "yes Saar, No Action" that bothers the most.
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Old 2nd April 2015, 21:08   #18
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Default Re: The infamous Death Wobble

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Originally Posted by Rsen View Post
The Bolero does not face it, so I guess the Thar Crde should also be safe.
Can this be a function of IFS being more "handling friendly" that solid axles ?
It was a rhetorical question!

It is almost mandatory in a rigid axle setup with even slightly worn kingpin bearings. (Something to do with coupled rotating masses.)

IFS should be far far less prone. But does not mean does not occur. Ask any high mileage Omni taxi driver.

Regards
Sutripta
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Old 2nd April 2015, 21:36   #19
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Default Re: The infamous Death Wobble

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Originally Posted by Sutripta View Post
It was a rhetorical question!

It is almost mandatory in a rigid axle setup with even slightly worn kingpin bearings. (Something to do with coupled rotating masses.)

IFS should be far far less prone. But does not mean does not occur. Ask any high mileage Omni taxi driver.

Regards
Sutripta
Thanks Sutripta for the clarification. Does it mean that rigid axles have a lower tolerance than IFS purely from wobble tendency perspective ? I mean if rigid axles wobble at X amount of wear, IFS will wobble at X+Y amount of wear will all other factors remaining constant. Or am I oversimplifying things ?
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Old 3rd April 2015, 10:45   #20
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Default Re: The infamous Death Wobble

I had owned a MG 410 for five years. Gypsy never faced a wobbling problem as long as it was with me.I guess shocks fitted to the steering link helped.

Few cents from my side to solve the problem,

-I use to fit Benz steering shocks to the main steering link of my friends Jeep. This really helped in solving wobbling issues. Shocks are quite expensive.
-Cutting the steering play also helps a bit.
-Resetting the king pin bearing. See that there is no play in the King pin.
-Jeeps OE ribbed tyre also plays a part in the wobbling issues.
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Old 3rd April 2015, 11:05   #21
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Default Re: The infamous Death Wobble

DW! We had Jonga with us to transport loads within campus. It was modified & repaired for n times. Do not know which engine it was running. It was bought for just 20K. Max speed it could achieve was 40 kmph. And It used to give DW every journey at speeds of 35 kmph
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Old 3rd April 2015, 20:32   #22
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Default Re: The infamous Death Wobble

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Or am I oversimplifying things ?
Oversimplying. But does it really matter?

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Sutripta
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Old 3rd April 2015, 21:52   #23
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Default Re: The infamous Death Wobble

Quote:
Originally Posted by Sutripta View Post
It was a rhetorical question!

It is almost mandatory in a rigid axle setup with even slightly worn kingpin bearings. (Something to do with coupled rotating masses.)

IFS should be far far less prone. But does not mean does not occur. Ask any high mileage Omni taxi driver.

Regards
Sutripta
Its there in the Safari. A common cause is the center link road bush wear. It can also be cause by steering cross issue.
Very scary. Hit a pothole at 60-70, and the entire car starts dancing as if it would disintegrate.
However, sometimes, even after changing bushes etc., it persists. So, how do you recommend, we go about debugging it to the root cause. Going for random bush replacements is frightfully expensive in 4x4s like the Safari.
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Old 3rd April 2015, 22:07   #24
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Default Re: The infamous Death Wobble

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Originally Posted by tsk1979 View Post
Its there in the Safari. A common cause is the center link road bush wear. It can also be cause by steering cross issue.
Very scary. Hit a pothole at 60-70, and the entire car starts dancing as if it would disintegrate.
However, sometimes, even after changing bushes etc., it persists. So, how do you recommend, we go about debugging it to the root cause. Going for random bush replacements is frightfully expensive in 4x4s like the Safari.
Root cause I'd leave to BD.

Any sketch (or better) showing the Safari's steering setup.

In the Omni, the culprit was the centre bush.

Regards
Sutripta
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Old 3rd April 2015, 22:09   #25
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Default Re: The infamous Death Wobble

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Originally Posted by Sutripta View Post
Root cause I'd leave to BD.

Any sketch (or better) showing the Safari's steering setup.

In the Omni, the culprit was the centre bush.

Regards
Sutripta
Safari has RCBT steering with steering box and center pin. Center bush, you mean center link road bush, or steering center pin bush? As for BD, I guess we have to change Safari's name to Thar for him to comment!

Last edited by tsk1979 : 3rd April 2015 at 22:10.
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Old 4th April 2015, 12:55   #26
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Default Re: The infamous Death Wobble

In Safari, wobbling is due to worn out idle arm bush or steering ball joints.

Basic theory, any Steering system which has least link & steering ball joint, less prone to wobbling.
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Old 6th April 2015, 22:00   #27
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Default Re: The infamous Death Wobble

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Originally Posted by tsk1979 View Post
Safari has RCBT steering with steering box and center pin.
A sketch showing the layout of the various linkages would be useful.

Quote:
Originally Posted by narendra.vw View Post
Basic theory,
Any difference (wobble/ shimmy wise) between solid axle and IFS?

Regards
Sutripta
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Old 6th April 2015, 22:51   #28
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Default Re: The infamous Death Wobble

I could not find much info on steering via diagrams, but the Center link rod I think is the Anti Roll bar. I could be wrong
http://www.99rpm.com/tata/antiroll-b...fari-2008.html

http://www.99rpm.com/tata/front-wish...fari-2008.html

Kingpin, you mean Center pin? That is the only part named "pin" the safari Recirculating Ball type Steering.
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Old 7th April 2015, 19:31   #29
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Default Re: The infamous Death Wobble

Reference to my previous posting,
I forgot to mention, I used to add a thicker felt while replacing knuckle kit(Might help some Jeep owners).

To, tsk1979,

-King pin in Jeeps refer to pivot point for turning, located at the end of either side of the solid axle housing. Jeeps have two bearing(top & bottom at knuckle joint) on each side .

-Safari center ink is the main link where one end is connected to the steering box other end to the idle arm. From the idle arm, link goes to both sides of the wheels. Center link is very important & has to be in good condition( quite expensive).
-I used to add a Benz steering shock to the above link. Once done driving experience will be in a different league . Needs bit of clamping & welding. Any fab worker can do the job.
If you look below the chassis between engine & gearbox centre link can be located. Some are cast, some are ms tubes.

To, Sutripta,

-Basically solid axle & spring leaf suspension has no choice but to go for Multi links. The unit consist of steering box, single or two idle arm located on either side of the chassis, center link & Finally links to the wheels. Each link carry two ball joints.
-If I am correct, MM 550 has two less ball joints in comparison with MM540. The Steering box is fitted in front of the grill to the chassis.
-Any undulation on the road faced by one of the wheel is instantly(thanks to solid axle & leaf spring) transferred to the other wheel. If there any kind of play in the links or the Bearings they react back. Like giving a momentum to oscillate wall clock lever.
-Rack & pinion steering box is not suitable for the above setup. I think the leaf spring suspension & solid axle plays a part.

IFS is fortunate to have both the design adoptable.
--From my experience, chassis mounted body IFS has multi link type design. Eg, Safari, old Benz, Tavera, old Fiat.
--Here, Multi link is less sensitive to wobbling in comparison with solid axle. Wobbling is due to ball joints reaching itís max life & tyres of balanced & misalignment. Caster holds the key. Mostly, 60% of worn tyres face this.
--Adv, they can handle rough roads better. Road undulation less felt in the steering(non PS steering).

Most of the Mono block IFS has rack & pinion type design. Eg. Any Hatch, mid sized saloon, old amby, & some compact SUVs.
--Rack & pinion has the least link. Two links & four ball joints.
--Here wobbling is mainly due to tyre of balanced. Can be felt only in speeds.
--Adv, steering is precise & cornering is more predictable.
--Road undulation can be felt in the steering( non PS steering) They have their limitation when it comes to heavy duty work.

My experience & thoughts for you. Thanks
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Old 8th April 2015, 20:54   #30
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Default Re: The infamous Death Wobble

^^^
Was wanting to know whether there is any fundamental/ theoretical difference in the way in which IFS and rigid axle will behave w.r.t. wobble. Or is it just a function of how the steering system/ linkages are laid out.

Regards
Sutripta
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