MDA GT40 MK1 in Wales, UK - Page 3

Frank Catt · 08-12-06, 12:55 PM

Alistair, please review the rear spring/shock mount onto the lower A ARM, remember it carries the whole load of the car weight, plus all of the imposed loads - IS IT ADEQUATE ?

Keith Hardy · 08-12-06, 01:53 PM

Quote:

Originally Posted by wealdenengineer

Alistair, please review the rear spring/shock mount onto the lower A ARM, remember it carries the whole load of the car weight, plus all of the imposed loads - IS IT ADEQUATE ?

Sorry to butt in here, but I'm curious. How would Alistair know that unless he was an engineer? I'm sure I wouldn't just by looking. What would you suggest someone in his position do about it now you've scared him?

Frank Catt · 08-12-06, 02:18 PM

Kieth, it all goes back to the " I thought you knew " posting , where it was almost universally agreed that if you saw something questionable it should be said and then investigated as soon as identified, rather than wait for an even nastier fright later when on the road. Alistair now can review, in which ever way he sees fit, whether he needs to take any action or not. Of course there will always be criticism towards anyone who makes such a comment , but better now than "sorry, I thought you knew " after an accident

SteveB · 08-12-06, 04:30 PM

No, this is Alistairs build site. If you have a safety concern, a PM to alert him of your concerns in reasoned detail was the right thing to do.
The mount looks pretty typical of of others. GTD KVA etc.
Too quick to judgement on sight of one photograph
SteveB

alastair · 08-12-06, 04:40 PM

Steve,

You have an email.

alastair

Chris Martino · 08-12-06, 07:57 PM

Alastair - the aircraft manufacturer I illustrate for use a 2 inch bottom shock strut lug on the trailing arm in a similar configuration and it works for a 65,000 pound business jet.

Can't see it because we would have a shear on every landing.

Chris

Ian K · 08-14-06, 12:01 PM

Quote:

Originally Posted by SteveBarker

No, this is Alistairs build site. If you have a safety concern, a PM to alert him of your concerns in reasoned detail was the right thing to do.

OK, I am not passing judgement on Frank's concerns, nor on Mark'd/MDA's
engineering here.

I am passing judgement on the above statement. This has been bandied about
before, and the majority of those who spoke believed that the appropriate
method was a public statement. Why? Because the majority believed it was
better if something was out in the open for all to see, rather than behind the
scenes. As I mentioned last time, I'd rather have someone point it out to me
in public so that someone else did not make the same mistake or be ignorant
of the same problem, especially if I was headed out onto the track at 150 mph.
This is a community that shares experiences, both good and bad. We try to
help each other out. Nobody wants to see someone else get hurt, especially
if it could have been avoided.

Ian

Keith Hardy · 08-14-06, 12:22 PM

Look this ain't nothing to do with me so you can tell me to butt out if you wish, but i am all for plain speaking and don't believe English is being spoken here. My one interest is to learn about all these things so that I will be cognizant when the time comes to lay down my hard-earned.

I want to understand what it is that Frank sees and i don't. He is asking the question: "IS IT ADEQUATE?" when it is clear that he doesn't think it is. So why doesn't he say "Hey, that bottom link is not strong enough. I'm an engineer and I know what I'm talking about" or something similar. We could all relate to that.

The statement "IS IT ADEQUATE?" is merely putting doubt in peoples mind by inference, not by "alerting" members to a particular problem.

To put it another way, if a member put up a photo of a brake rotor and I spotted a defect in it, like a crack or something, what would I say? Would I say "ARE YOU SURE YOUR ROTOR IS OK"? or, "THERE'S A CRACK IN YOUR DAMN ROTOR MATEY"

I know which info I would prefer. If it can't be put succinctly or there is only a suspicion that a part or process is inadequate then I believe a p.m. is more appropriate expressing ones "doubts" so that the recipient can decide to investigate further. One must also remember that there are peoples lives and livelihoods at stake here, so plain speaking is essential. My 2 cents - not wishing to inflame anyone or anything...just asking for some solid information

Thanks

Keith......

Ian K · 08-14-06, 02:40 PM

Keith,

I am in total agreement. I want to want to know if something is wrong.
I prefer Frank would have come outright and specified what he saw,
but I have to respect his concerns of what would happen if he came
right out and stated his opinion. It's a dicey situation since he would
be stating only his opinion, but as an engineer, the courts could construe
it as more than an opinion should Alastair or MDA file suit. This was also
discussed in the thread he mentioned.

What I would like to see is an agreement between Alastair and Frank such
that Frank's opinion could be placed out in the open without any legal
ramifications. But, knowing how touchy this subject is to many, I do not
expect that to happen.

An example of how I would love to see things handled would be the RF
rear suspension bump steer thread:

Rear suspension bump steer

Ian

Keith Hardy · 08-14-06, 03:28 PM

Very good point Ian, but there isn't a Roaring 40's company around anymore so everyone can say what they like. So, where was the info regarding the incorrect (or less than optimum) geometry on the rear suspension on RF cars prior to the company going to the wall?

All I remember hearing & seeing during the "RF period" was the continued accolade to the product and the man without hint of critique.

I do see your point about liability etc but how far do you take this? The company in question is a supporter of this forum and yet there are question marks regarding some aspects of the design/construction (I'm still not sure which) publicly inferred. Isn't this confusing for customers and potential consumers?

Does this not need stating very clearly or not at all? I find it very confusing and I think there's probably another agenda that I'm not aware of. I've said my piece and I think I'll end my comments on this subject but would once again say that I'm not supporting or decrying any party or product here. Just wanted some plain answers to a confusing conundrum.

Cheers all,

keith

Ian K · 08-14-06, 05:16 PM

Well, there is a Roaring Forties company. Time will tell what happens in that
regard. Perhaps they will chime in at one point. When RL was still at the helm,
he and Ross did get into a few issues. Also, when someone came out and clearly
stated a problem with the product, RL or a rep would chime in and either
rectify the situation, or troublehsoot whether or not it was RF's fault or the
builders. As far as the rear geometery goes, who knows when someone
discovered the problem. Ross races his RF hard, and has made many mods to
the car. So, I don't doubt he would stumble across something.

As far as MDA goes, the "I thought you knew" thread really raised Mark's and
Chris's hackles. There was a lot of finger pointing and ill will tossed about.
And, in the end, regardless of any influence the thread had, the issue was
resolved by MDA with a chassis redesign to accomodate both ZF, Renault,
and I assume Porsche transaxles.

But, I suppose this discussion should come to a close since it is Alastair's build
thread, and not a "How should one go about pointing out potential problems"
thread.

Ian

Chris_K · 08-15-06, 01:20 AM

I can't see what the gauge of the bracket is but it looks like it's in double shear over the forward tube of the reversed A-arm. Perhaps an additional picture of the offending area might rest everyone's concerns?

If I'm interpreting the picture correctly it doesn't look very different than other race hardware I've seen. If I'm out to lunch, I'd really like to understand Frank's comments too. Please elaborate if so.

Thanks,
Chris

(Not an engineer)

Mark Worthington · 08-15-06, 02:14 AM

I would imagine Frank's concern is that the lower damper mount feeds the weight of the rear of the car into the A-arm, which creates a bending moment in the arm. In my RF this load is supported in double shear by sturdy brackets which sandwich the front end of the upright.

Alastair, you're doing a great job on the build - keep going.

Ron Earp · 08-15-06, 01:18 PM

Thanks for that Ian. This is a build thread, and should be left as a build thread. If people still wish to discuss the chassis design I'd urge them to continue on the "I thought you Knew" thread or start a new one in the chassis forums. Healthy discussions are encouraged, but not on build threads. Build threads are for builders to share their work and are not places to air agendas or instigate debates.

I hope Alastair is not discouraged and will continue the thread he started.

Ron