Test ride - bang - broken suspension picture

750hp · #1 (**permalink**) 07-08-2010, 02:34 AM

I went to look at a local Cobra for sale on behalf of another CC member who lives thousands of miles away. Initial inspection looked reasonably promising. Time for a test ride - I offered to go as passenger for an initial idea of how it felt. The owner was sensible - gave me a bit of an idea of the performance without doing anything over the top.

About 1/8 mile from where we could have changed position for me to drive, we hit what seemed like a fairly small hole in the road. It wasn't the size of a dime, but it wasn't the Grand Canyon either...

BANG!!!!!!!

That didn't sound good. I was thankful that at least I wasn't driving when we found this as a result...

spookypt · #2 (**permalink**) 07-08-2010, 03:59 AM

Hmmm... NEXT!

Rebel1 · #3 (**permalink**) 07-08-2010, 04:09 AM

Hmm ... not good, same shock and make of springs as mine.

What's your thoughts as to the problem Craig?.

Rebel1 · #4 (**permalink**) 07-08-2010, 04:52 AM

OOps, I think I see the problem, I should have looked more closely.

Those shocks in standard form take a 57mm ID spring. That's the old 2.25". King springs (which they look like ) do not make a 57mm spring, they make a 60mm ID spring.

I suspect that MAY be the problem. Looking at the bottom of the spring in the pic it seems to have moved off center of the spring seat. If the spring was the correct size ( or aftermarket seats and hats installed) then the spring could not move off center.

I suspect that over time the off center spring has been flexing the shock plunger /shaft causing the failure.

Ron61 · #5 (**permalink**) 07-08-2010, 05:36 AM

Whatever the cause, it is good that it happened now instead of after the person bought the car.

Ron

RICK LAKE · #6 (**permalink**) 07-08-2010, 06:09 AM

750HP Craig looking at the picture, it looks like the angle of the shock is to much and the spring and shock couldn't react fast enough coming out of the hole and the shaft bent. I have seen this on many off road trucks that are jumped. I would recheck the hole for a water buffalo. This is fixable. The main question is will this happen again??? I would look at changing the angle of the shock to a straighter one, if you have room there. If not rework the front end. Rick L.

750hp · #7 (**permalink**) 07-08-2010, 06:18 AM

Interesting ideas. As a point of reference, here's what the other side looks like (albeit from a slightly different camera angle)

Ron - I agree that it's better that it happened before a sale, but I'm glad it didn't lead to an accident that I was about to be a part of

...

spookypt · #8 (**permalink**) 07-08-2010, 05:40 PM

Craig is it just me or does that spring in the non rooted side look like it is bowing out (away from body) as well?

I reckon the spring has too much pressure (wind up - compression) on it in an unloaded form making it want to bow out. Thus once it gets a decent load its willing is to flex out rather than compress as it should up the shaft.....

Spookypt

wetdog · #9 (**permalink**) 07-08-2010, 05:50 PM

Hideous safties on the caliper bolts!

Rick Parker · #10 (**permalink**) 07-08-2010, 06:12 PM

There is a huge amount of stored energy in the spring the way it is show. I'd be VERY careful in contemplating how to remove it. A Flame wrench might be the best.

Gaz64 · #11 (**permalink**) 07-08-2010, 06:32 PM

I don't see any form of bump stop.

What limits suspension compression and droop?

Shock absorber topping out or bottoming out?

Spring coil binding?

A dangerous setup in my opinion, not meant for the street.

spookypt · #12 (**permalink**) 07-08-2010, 06:33 PM

Removed comment due to my dumbness... Thanks Gaz

Gaz64 · #13 (**permalink**) 07-08-2010, 06:36 PM

Quote:

Originally Posted by spookypt

Also as Les indicates the upper spring seat has pulled through the spring....indicating something isn't right there as well O dear!

Of course it will when the top of the shock is sheared off.

Zedn · #14 (**permalink**) 07-08-2010, 08:00 PM

Quote:

I don't see any form of bump stop.

This system removes the jag bump stops from upper arms. This is a G-force yes? I wonder if there is anything on the lower arm.

I was planning to eventually convert my kit to be the same (mine uses full jag front end). Bump stops are something i hadnt thought of. Also i think if the shock mounted more like it does in the jag (between the upper control arms) it would have less preloading. But that would be a tight fit.

Rebel, i wouldnt be worried about having the same shock, probably more the way its mounted. Thats one of the problems with shocks. It only has to be slightly out of square and puts huge loads on the components.

Rebel1 · #15 (**permalink**) 07-08-2010, 09:16 PM

Zedn the pic depicts exactly how the RMC front suspension is installed and I suspect g-force is the same.

I have however fitted my shocks with top and lower seats sized for a 60mm ID spring.

Some local RMC owners have modified the top mount to make the shock more vertical as some-one has mentioned but often involves using different upper arms to provide clearance.

It is a trap for the unwary that spax shock seats are sized for 57mm ID springs.

victor · #16 (**permalink**) 07-09-2010, 12:34 AM

Thanks Craig for stepping in and checking it before i did

.God only knows what would have happened if i would have givin it a good flogging.

750hp · #17 (**permalink**) 07-09-2010, 09:23 AM

It's the least I could do Victor... What did you get me into???

All ended well when the car kept tracking straight after the suspension failure...

Excaliber · #18 (**permalink**) 07-09-2010, 09:37 AM

Poor guy, the current owner. About to sell his ride, goes for a test drive and has a BIG failure. Man he has GOT to be bummed out.