Manky's Pop.

[Archie]

I reckon that's fair.

[poprodder]

oh s**t, should it have a panhard rod? wheres kev!!!

[Manky Monkey]

Yeah, he's enormous. A ton & a half at least -joking Archie.  
On the plus side, the new steering wheel's fine.
Don't think you need a Panhard with triangulated 4 bar linkages Chris. I've emailed Kev!
I'm insured with Adrian Flux & have their recovery service, so I gave them a call ...we can't find you on our system. So how come I'm holding a recovery card with your phone number on it then? I only took the policy out 6 months ago. We can collect you, but if it transpires you're not covered there'll be a charge of £300. Maybe I should've just phoned Scottie the hotrod haulier instead.
2 1/2 hours later a very nice Polish guy arrived in a flatbed recovery truck, by which time we were the only vehicle left in the field -thanks for staying to keep me company Baychimp. Half an hour later, following directions on his Polish SatNav, we were unloading it back at Loony's yard. The driver asked if he could take some photos of it, then I waved him off.
Bugger. Ahh well, cover it up again & worry about it tomorrow. Could've been worse. I was going to take it to Kent last night, but didn't cos it rained. At least it only broke in a big field, in the sunshine, 6 miles from home. In front of several thousand people. Could've been in the fast lane of the M25 in the rain & the dark last night.
So it's first major mishap. I've been expecting far worse. The component that failed wasn't made by us, though obviously we may have built in a design fault. I'll jack the body up off the axle tomorrow & investigate further.  

[Archie]

AHA!!

I was sat on the other side of the bed. The non broken side.

[Manky Monkey]

Oh now you say that. Love that gangsta lean.
By the time we got back, the broken section of rod had dropped out. Can't see any other obvious damage.

[Olds]

Don't think you need a Panhard with triangulated 4 bar linkages Chris. I've emailed Kev!
  

You shouldn't, but I think a watts linkage might be in order if the triangulation is to shallow
Can't see how sideways movement would have snapped the rod!

[Manky Monkey]

Really not sure what's gone on at the moment.

[kapri]

It's the bushes usually as you have the  4 bar bolts going across and the shocks front to rear so loading up the shocks bolts .Shock bolts are very much man enough as it has transmitted load to the weakest part of the set up Normally only happens with urethanes at at higher mileages ie 10-20K .I know of probably half a dozen that have broken like this. They usually for either at the base of the screwed on top eye or where the eye is welded on.

Even if you reverse the mounts so the bolts go across then you still have the sideways load so will still break eventually . Best answer is rose jointed shocks  which allow movement in all planes. Only problem normally is some increased road noise as no insulation.

To be perfectly honest I'm not a big fan of coil overs despite having used them myself on several motors ( and still on the back of one I haven't finished). They are really for competition use and don't cope well with normal road use plus are only ever correct poundage for one single criteria /time of use.

Though not as neat or simple to mount,or get the poundage right ,you really can't beat big springs with a shocker though the middle.

Triangulated is fine without a panhard . Only trouble you get with triangulated is a bit of axle tramp under hard acceleration compared to parallel 4bar and panhard.


If they are rubber bushed and not urethaned then they really shouldn't have broken at low mileage, speak to the shocker manufacturer .Regardless of when they were bought it is obvious by the condition they have seen very little road use  and also they need to be made .

Other thing that can do it is too stiff springs .I remember one that broke the guy fitted softer springs and it was fine afterwards...that is until a later owner put some stiffer springs back on and it broke again!

Do you know what rate you have on the back ?

[Manky Monkey]

Hiya Kev.
Just got home from work, so haven't been out to the workshop yet, but Loony's taken the shock off this morning. He reports the rod only snapped at the top, where the eyelet screws on, (so what I assumed was the rod having dropped out on the way home may be just it sliding down into the main shock body).
They're rubber bushed top & bottom on something like 12mm shouldered bolts.
We started with 160 pound springs but swapped them at Valley Gas Speed Shop, (who supplied the shocks), for stiffer ones. Can't remember off the top of my head, but 200+ pounds.
Loon suggested rose jointed mounts too -I didn't know they made them.
My own theory is that we boxed in the underside of the top mounts too tight to either side of the eyelet. We made box section outriggers with a section cut out of the bottom face for the eyelet to pass up through. I reckon there isn't enough clearance. Fine for normal road use, with no load in the bed, but under hard acceleration/cornering with Archie's weight in the back transferred onto that shock, it's tried to compress & travel in an arc up & outwards towards the wheel, hit the underside of the outrigger & snapped.
I'll crawl underneath & try & get some better photos later.
Fortunately it happened in a large field, well away from other people & no-one was hurt. It's not my daily driver, just my weekend car & we have the facilities to fix it. I've never built a car from scratch before. It's annoying, but just an expensive lesson. 

[Manky Monkey]

O.K, preliminary investigations complete & it looks like I was right -there's a first.
It was a design flaw on our part, rather than a fault in the shock itself.
Here's the busted shock. It's snapped off clean at the weakest point, the thread on the top of the rod where the top eyelet screws on.
The spring's got a slight curve in it, but should hopefully settle into shape once it's back on, (these "Gaz" shocks are completely rebuildable).

[Baychimp]

Does that mean you can put a new ram in it Andy.

[Manky Monkey]

Hopefully Bob, yes.
No signs of previous fatigue or internal weaknesses in the rod. It was simply a matter of it not being able to withstand the strain of being whacked against an immovable object -the chassis.

[Manky Monkey]

The rubber bushes & sleeves are a bit beat up, but that's not suprising really either.

[Manky Monkey]

By the time we'd got back to the yard yesterday evening, the rod had slid down into the main body, which is why I thought it'd dropped out. It moves perfectly freely so even though the rod's buggered, hopefully means the body's O.K

[kapri]

Have you a picture of the top chassis mount Andy?

Like I said before this isn't unheard of and I'd be surprised if you had enough axle arc of travel to provide the leverage required to shear through that . Would take at least 20 ton at 1/2" thick shaft.