Solution to Caravan "thunking" on dips and holes.

I posted a while back about my caravan that had a real problem with dips and holes in the road, even though the struts had been replaced at a dealer by the
previous owner about 35,000 miles ago. It would bottom out with a very loud thunk on even minor dips in the road.
Replacing the struts today, I discovered that whoever had replaced the struts previously had completely left off the jounce bumpers - rubber blocks that prevent the struts from bottoming out. The new struts with the boot kit that included the jounce bumpers has solved the problem.
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wrote:

It;s surprising how much difference it can make doing a job "right", isn't it???
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Bob, Excuse me for saying this, but your explanation does not make sense. The rubber bumpers are supposed to engage only when the suspension is either fully extended or compressed. You stated that this occurs on minor road undulations. Those will not cause the rubber bumpers to come into play unless something else far more drastic than extension bumpers is at fault. Perhaps you meant the rubber compliance washers were missing at the shock connection to the tower. Since my explanation is far more likely than yours and you were most likely paraphrasing the mechanic's explanation, you probably didn't need new struts in the first place and could have resolved the problem with .50 cent rubber washers. So how much did this repair cost? Steve

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On Sat, 24 Apr 2010 21:05:03 +0200, "Steve Lusardi"

The man said he replaced the struts himself and found the jounce bumpers missing. - so no, he was not paraphrasing what his mechanic said - and if the shocks were weak, they WOULD bottom on relatively minor road undulations - and without the jouince bumpers that WOULD make it noisy. And they only come into play on compression - not rebound, or as you called it, extention. On MacPherson strur suspensions like this vehicle uses there are NO $0.50 "compliance washers" between the shock and the shock tower. The upper strut pivot assemblies kook after compliance between the strut and the body and cost a whole lot more than fifty cents.

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Shocks don't bottom unless the spring bottoms. I stand by my statement. Steve

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On Sun, 25 Apr 2010 09:33:54 +0200, "Steve Lusardi"

And springs don't bottom if the shocks are good. Good springs with bad shocks CAN bottom easily - and are subject to breakage. I stand by, and behind, my statement.

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snipped-for-privacy@snyder.on.ca wrote:

And probably, the lack of jounce bumpers destroys shocks, since they then are the recipient of all the forces of bottoming out. (In addition to the mounts, engine mounts, etc.)
I replaced the struts, seals, jounce bumpers and strut mounts (with a bearing - one of which was bad on the old ones). Total cost $240 IIRC. After months of "BAM" at every dip or pothole, it is a pleasure to drive now. With the lifetime warrantee on all the parts, I'm covered as long as I keep the van. Probably a worthwhile investment.
The old struts had been replaced about 35,000 miles before I got it by a Dodge dealer. If the missing jounce bumpers didn't cause the problem, I don't know what would be more likely.
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wrote:

The missing jounce bumpers could allow the shocks to violently "bottom" , damaging the shock mechanism (valving in th bottom of the oiston). The jounce rubbers ARE there for a reason.
However, the biggest noise was LIKELY the strut mount if by "bad" you mean the rubber was separated.
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snipped-for-privacy@snyder.on.ca wrote:

No. Balls fell out of the bearing when I removed it. The other side made the same noise without the bearing problem. I saw no rubber to seperate.
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