Front suspension bangs

Issues with shocks/springs, tires, stopping, etc.
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Ian
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Location: Tasmania

Front suspension bangs

Post by Ian » Mon Jan 29, 2018 12:17 am

Hi All,
When driving along a rough road I find whenever a front wheel drops into a pothole, I get quite a bang from that wheel, whichever side it is. It sounds like maybe the spring rapidly extends and the bang comes from the axle strap snapping tight.
Does anyone else experience this? Or have suggestions? I'm wondering if the shock aborbers are weak maybe..

It is fine at low speed (like fast walking speed), just happens as soon as you speed up anything beyond that.

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rmel
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Re: Front suspension bangs

Post by rmel » Mon Jan 29, 2018 12:54 am

Does this occur when your "flying" out of a ditch or bottoming out in a ditch. The
later would be a hit during compression of the suspension system. I had a similar
bang which turned out to be the right Tire whacking the well especially on down
grade sharp left turns. This turned out to be due to a very badly set Toe-in -- actually Toe-out.
That will cause a Pinz'y to squat down 2 to 3 inches taking clearance out of the well, it
would be worse on the Right side due to the Axel offset. You have Right hand drive BTW,
which would make this seem worse than a Lefty. Also wide tires makes it worse, e.g. 285/75.
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Ian
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Re: Front suspension bangs

Post by Ian » Mon Jan 29, 2018 1:53 am

No it happens on fairly flat roads as the wheel drops into a pothole. Will also do it if the wheel drops off a small rockstep or similar.
Anything where the wheel and spring, etc gets the chance to rapidly fall.
On a rolling, rounded surface it is fine. It's only on a sharp drop

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Hotzenplotz
Austria
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Re: Front suspension bangs

Post by Hotzenplotz » Mon Jan 29, 2018 2:36 am

that sounds like the shock absorbers are weak on the extending side and you hit the limiter strap.
Cheers
Albert
========================
My Pinz has NEVER been with any army

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Ian
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Re: Front suspension bangs

Post by Ian » Mon Jan 29, 2018 2:51 am

Hotzenplotz wrote:that sounds like the shock absorbers are weak on the extending side and you hit the limiter strap.
Exactly what I think too. Just wondered if it is normal, or as you say my shocks are weak and can't control it.

undysworld
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Re: Front suspension bangs

Post by undysworld » Mon Jan 29, 2018 6:06 am

A shock should be easy to diagnose. Those must be big potholes to allow the axle to drop far enough to hit the strap, I'd think.
I wonder if you may be having issues with wear where the steering knuckle pivots?
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4x4Pinz
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Re: Front suspension bangs

Post by 4x4Pinz » Mon Jan 29, 2018 9:15 pm

Yep, sounds like a shock issue. There will always be some banging if the front springs are stiff.

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Buzz
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Re: Front suspension bangs

Post by Buzz » Tue Jan 30, 2018 9:32 pm

I would add that bad shocks can lead to unexpected issues depending on your year of production. I had the early production shock bolt and retention strap set up with a bolt on each side to hold the shock and strap independently. Long story short you can break those bolts and be faced with a long and athletic ( trust me) effort to drill out the remnant of the bolt. Later versions had a single bolt to hold both the shock and the strap.
So, I'd you think you are having shock issues, act now before you break a bolt. My $.02.
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Ian
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Re: Front suspension bangs

Post by Ian » Thu Feb 01, 2018 4:01 am

Buzz wrote:I would add that bad shocks can lead to unexpected issues depending on your year of production. I had the early production shock bolt and retention strap set up with a bolt on each side to hold the shock and strap independently. Long story short you can break those bolts and be faced with a long and athletic ( trust me) effort to drill out the remnant of the bolt. Later versions had a single bolt to hold both the shock and the strap.
So, I'd you think you are having shock issues, act now before you break a bolt. My $.02.
Funnily enough, I've just been through that on one of the rear ones 2 weeks ago, so know what you mean. I drilled and put a long through bolt (and nut) in it's place, so it it does break again, it could be easily punched out and replaced. Should do the others before another breaks!

Thinking I need to try a pair of new shocks

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Jimm391730
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Re: Front suspension bangs

Post by Jimm391730 » Thu Feb 01, 2018 10:48 am

With the original design of a bolt per limiting strap or shock, the weak point is the root of the threads which is significantly smaller in diameter than the main body of the bolt. The design puts the greatest stress exactly where the root of the threads has to be located. With the improvement of drilling out through the axle housing for a single bolt, the main body of the bolt takes the strain. Only the end of the bolt, where the nut prevents the bolt from sliding out, has threads and these are not in the high stress location. Overall a much better design and much less likely to break - and as Ian said, easier to repair if a break did occur.
Jim M.
712W and 710M

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rmel
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Re: Front suspension bangs

Post by rmel » Thu Feb 01, 2018 11:36 am

As Jim pointed out, I the treads are the weak link, esp. in the casting.

If your not all that keen on boring a hole through and through, the approach
I have taken is HeliCoil, this is a stronger joint than the original tread as it is
a larger diameter and the insert is hardened SS. If there is concern about the
strength of the bolt thread which are M16 fine 1.5mm 8.8 hardness, the same
bolts are readily available in 10,9 and 12.9.

Oh!! One other point, I do NOT Torque these bolts to the recommend 200NM, I
go to a max. of 136NM (100 ft-lb). This is more consistent with the grade of the
thread in the casting and sufficient for attachment, I've never had one loosen up.
I also use this same Torque for the Wheel Lug nuts.
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GadgetPhreak
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Re: Front suspension bangs

Post by GadgetPhreak » Thu Feb 01, 2018 2:15 pm

Swapping to the longer bolt was the first update I did :) right after I broke one of the original bolts :(Image


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Hotzenplotz
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Re: Front suspension bangs

Post by Hotzenplotz » Thu Feb 01, 2018 2:23 pm

I drilled the bolts three years ago

Image

purchased two bolts M16 x 1,5 x 70 and drilled them on a lathe to 8 and 12 mm. I used them as guide to drill. Worked like a charm
Cheers
Albert
========================
My Pinz has NEVER been with any army

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rmel
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Re: Front suspension bangs

Post by rmel » Thu Feb 01, 2018 8:50 pm

Perfect solution! I like the pilot hole idea.

One reason why I have been hesitant is not knowing how these holes were trued up against each
other in the finishing process. If you drill though are you just lucky they align on both sides or will
they align on both sides by design? With this pilot hole you find out when it pokes through on the
other side you can see if it's centered, and if not you have done no harm.
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boeing7873
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Re: Front suspension bangs

Post by boeing7873 » Tue May 29, 2018 2:38 pm

I have the same issue. I bought the truck 10 years ago, and as soon as I hit the first pothole I said, time for new shocks. Ordered a full set from SAV, changed the front two and.... absolutely no change. The damn thing feels horrible. But everything looks perfect, new shocks, springs look good, no play anywhere, runs straight, no vibrations... It is just horrible when it hits a pothole. As if suspension didn't exist for a fraction of a second.
But my conclusion is that this is normal, the way the truck feels. I got used to it. Done.
Jerome
CRJ Driver

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