Date: Thu, 14 May 2020 17:59:26 -0700
Reply-To: Neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil N <musomuso@GMAIL.COM>
Subject: Re: Mono Tube vs Twin Tube Shocks (dampers)
In-Reply-To: <MN2PR08MB62393A9529260509C2F14286A0BC0@MN2PR08MB6239.namprd08.prod.outlook.com>
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Wow. Thanks Dennis. I think I get the gist of what you're saying. I
now wonder if the Gowesty "zero lift" progressive springs in my '81
have set the van higher than OE height and if they factor in to what
may be premature wear on my low mileage Sachs shocks. I have newer
lower mileage Sachs shocks in my '88, which has seen *some* dirt
roads, but that bus still has OE springs. And, I don't know if those
springs have gotten "shorter" due to wear.
In hindsight, the Bilstein HD shocks I installed on my '81 way back in
2007 came with spacers that got installed inside the dust boot. I
guess they might effectively lengthen the shock but maybe it was
simply a means of adapting a shock that was built for several
different vehicle applications? The mostly likely factory OE Boge
shocks that were removed struck me as being a stout looking part and I
did wonder if replacing them was actually warranted. But I knew much
less about wrenching at that time.
Personally, my only real concern is finding an affordable or budget
shock that can handle some off road use.
Gowesty comments in one of their ads that the Bilstein HD is not
actually a heavy duty shock but maybe thats a marketing ploy to direct
customers to their XHD Bilstein shocks.
I agree about Fox shock price. I have no plans to buy those. Maybe
I'll stick with Bilstein HD's and call it done. There are Munroe mono
tube shocks that looked promising but they're listed for truck
applications. None listed for the Vanagon.
I will be curious to open up the Sachs I plan to replace on my '81.
See what failed and what design they are though I suspect they're a
twin tube design.
Neil.
On 5/14/20, Dennis Haynes <d23haynes57@hotmail.com> wrote:
> So I finally have a chance to respond to this thread. So here some Dennis
> thoughts to ponder.
>
> The vanagon in general is not tough on shocks and the original shocks were
> of outstanding design and quality. There are many out there still working as
> they should. Like many things aftermarket you can replace 20 year old, 200K
> mile parts and the replacements are temporary!
> For Vanagon 2WD front shocks things go downhill very fast. To begin with
> there is a dual part design dilemma that needs attention. Most all
> aftermarket shocks are too long. So what's the big deal? Well, let's also
> add that many upper ball joints do not have enough articulation to
> accommodate the suspension drop when the wheels are unloaded. Add another
> 1/2" of drop and the upper ball joint doesn’t stand a chance. The pricey
> Moog joints are now not right either. I just destroyed a pair before it even
> left the lift. GoWesty ball joint spacers to the rescue. Of the Ball joint
> brands out there the Meyle HD is still fitting the best. How did that
> happen.
>
> So back to the shocks. For some reason many of us think stiffer is better.
> Remember the primary purpose of the damper is to control wheel bounce and
> then vehicle motion. Shock dampening does not stop or eliminate leaning,
> only the rate at which it happens. Now when you hit a road impact, whatever
> the resistance the shock has to the impact becomes pressure on the
> hydraulics. Too much pressure and seals get damaged. Now here comes the bad
> part. So on an impact instead of compressing the overly stiff shock now
> lifts the vehicle. Raise the vehicle high enough and the suspension will
> drop to the limit before the tire gets back on the ground. Since the shock
> is the suspension travel limiter this damages the top of the shock piston
> and bottom of the end cap. This extension also stresses the top ball joint
> mentioned earlier.
>
> But wait, we have more! Since we didn’t make things difficult enough with
> parts quality and original design mistakes we also changed the springs to
> increase ride height. So now instead the shock spending most of its time mid
> travel we reduced the available travel up top so that every time we go over
> a significant bump we test the shock by banging the piston against top cap.
> Also when we extend the shock the steering geometry puts it at an angle
> relative to the top mount which adds a side load to the piston-rod assembly.
> With the shaft extended the side leverage is high and the shorter distance
> between the piston and cap give the piston and rod little leverage to resist
> this so the piston and top seals get damaged.
>
> Over the years I have cut some failed shocks to what happened. I've seen the
> smashed pistons and caps along with the sheared or twisted seals. Even
> without lifted springs. Could be this is the real reason VW lowered the
> suspension height for the later years. I remember when VW did one of those
> service bulletins to replace the upper ball joint bolts. Yes they used to be
> hex heads. And they would come loose or break.
>
> So for shock selection in my mind the Fox shocks are just too pricey. The
> Bilsteins are my usual first choice and while I don’t think the GW HD are
> needed just because you have a camper, I think the increased rebound damping
> for the front may avoid or at least reduce some of the damage mentioned
> above. My 91 destroyed a set of Bilstein fronts and now needs upper ball
> joints. This is running the Syncro org springs and last year I put on the
> 235/55-17 tires/wheels. I will be adding the ball joint spacers when I
> replace the joints. I have also had good results with Gabriel shocks for
> economy fitments. The Monroe, not so much. The Sachs, Boge, B4 Bilsteins
> also work well with stock springs.
>
> Dennis
>
>
> -----Original Message-----
> From: Neil N <musomuso@gmail.com>
> To: ddbjorkman@verizon.net <ddbjorkman@verizon.net>
> Cc: vanagon@gerry.vanagon.com <vanagon@gerry.vanagon.com>
> Sent: Thu, May 14, 2020 12:27 pm
> Subject: Re: Mono Tube vs Twin Tube Shocks (dampers)
> Thanks. Yes I recall something about GW developing a shock possibly one
> better suited to their progressive springs (as I have).
>
>
> On 5/13/20, Neil N <musomuso@gmail.com> wrote:
>
>
>> My Sachs OE type shocks don't seem to hold up for very long given that
>> I drive on bumpy dirt roads at times. ......
>
--
Neil n
VE7TBN
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1981 Westy 15º ABA swap: https://tinyurl.com/y9n4xob8
VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>
