[f5fstop]

Originally posted by Sean K.:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by f5fstop:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Sean K.:


http://www.pirate4x4.com/forum/attachment.php?attachmen...5&stc=1&d=1143223579


f5fstop,

You make a very valid point especially concerning autos.....however, none of you have actually run a full belly pan, correct? I know several people running them on everything from small SUVs, to buggies to fullsizes....yes, heat builds up more at slow speed without air flow....

What I'm saying is: it's not significant enough to cause a transmission failure, IME. As you eloquently stated: transmission fluid and oils both have ranges of acceptable operating temperature. Unless we did a real test to find out just what the temps are running without a full belly skid and then with....how can ANYONE say for certain it will raise the temperature above the acceptable range? The obvious answer is: you can't. That is just my opinion though and you guys are welcome to your own (not that you need my permission).

I apologize if I ruffled any feathers with my comments. That was not my intent. I was only trying to give my own personal experience with belly pans as well as some general comments about lift height vs. CoG.

Take care,
Sean

Maybe I should have further qualified my response since it appears to have been missed.
First, I'm talking an H3, and probably goes over to an H2 and H1, but I will be first to state I'm not that familiar with these vehicles.
Second, I'm talking a vehicle with a full body, not a frame unit. It doesn't take a brain surgeon to note that the type of vehicle you are showing in the photos, would have plenty of airflow from top of the vehicle since there is NO body. In addition, heat rises, and it appears there is no place to trap heat and cook the fluid. I don't believe you would be driving this down Interstate 10 at 75 mph, or doing any city, stop and go driving.
I also believe that running rigs like that would tend to blow the trans for other reasons, thus when it is rebuilt, I would hope you would use new fluid.

Now, let me explain something. ALL GM authorized accessories have to be tested by GM.
First, if they affect a safety area, such as a front brush guard, they must be crash tested to assure it has no affect on the front discriminating SIR sensor. Don't want a front brush guard that is so strong, the front sensor does not trigger when required. Someone could get seriously hurt. This means plenty of input from safety engineers, as well as body engineers.

Second, they must not screw with emissions, or else places like CA will come after GM with a big hammer (called a recall). Other states would also be involved like in the NE states. This means input from the emission engineering section in the emission lab. If there are sound concerns, such as an exhaust system, then the requirements for states must be followed.

Third, it must not affect the warranty of the vehicle. In the case of the underbody protection, yes, there was input from the transmission engineering section. Concerns of overheating are stressed. Testing is done on all types of shields, over a long period of time, and then the approvals are given.
Again, any testing is done on the full H3, not an H3 without a body, it has to be a production intent vehicle.

If heat cooking the trans fluid is not a concern of GM (or the owner), then why does the owner's manual state under normal use, the trans fluid must be changed at 100K, but if under severe service it must be changed at 50K:

(h) Change automatic transmission fluid and filter if the vehicle is mainly driven under one or more of these conditions:

• In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher.

• In hilly or mountainous terrain.

• When doing frequent trailer towing.

• Uses such as found in taxi, police, or delivery service.

These four types of service allow trans fluid to get hot and stay hot, thus breaking down the fluid.

As I said in my previous post, GM assumes (yes this might be an incorrect assumption) that the person who has this underbody protection installed will leave it on the vehicle at all times. They will not install before running a trail, and remove after the trail has been run.
If a person desires a full underbody protection, and installs when required, and removes after, problems with heat destroying the fluid would be minimal (my assumption, not GM's).
For a rig like you show, I'm sure the protection stays on all the time, but again, that will not be used for commuting in rush hour traffic, or at least not on a normal basis.

I will also say that the trail you show looks like a hell of a lot of fun, but I will also state that my H3 will never run it. Maybe I'm wrong, and I would love to see someone prove me wrong, but I don't believe the H3 is designed to run a trail like that, even with a 2-6 inch body lift. </div></BLOCKQUOTE>

f5fstop,
I hesitate to even reply considering my comments seem to be just making more people angry, however, I would just like to say again (and you quoted it above) that I was also talking about full bodied rigs like small SUVs (Cherokess, Tjs, Cjs, 4Runners) as well as fullsize trucks (some have a bed, most don't), so in all fairness, it wasn't just buggies I was referring to (and most buggies have more heat restriction b/c unlike the one pictured or mine, yet, they have full floor pans and a much more confined space for the trans/tcase(s) to be housed)....some of these vehicles are in fact, daily drivers and DO NOT have an overheating problem; but you're correct, most are not driven on the road regularly.

This brings up another point though. As you pointed out in your other post....low speed crawling will generate more heat b/c of lack of air flow. Stop and go driving and highway driving are going to see more air flow and associated lower temps just b/c of the higher speeds, right? (Now, I'm not talking about a mud packed skid.....again, my narrow viewpoint coming out).

I'm not sure I understood your first two points about GM testing accessories and having to meet emissions standards. Do you mean that no accessory should be put on the vehicle unless GM approves it through their engineering and test department? Please elaborate.

As for your 3rd point about warranty of the vehicle....I never said, "heat cooking the trans fluid is not a concern of GM" and I surely didn't mean to imply that. Heat is the number one reason an automatic transmisssion fails....but it's too much heat. We've yet to determine through any kind of analysis that a skid would raise the temperature enough to be "too much". That's all I was saying.

You seem to have an intimate insight of the transmission engineering process at GM according to this quote: "the trans engineers at GM I know would never recommend a full body undershield". So did GM actually test the UCP with full shielding? Perhaps you know something we all do not. Any chance you could get one of your friends to register on the site and discuss the issue in detail? As an engineer myself, most of us nerds love nothing more than to talk tech.

Oh, and please don't take my comments as anything more than my opinion. I feel like we're adding some technical discussion to a thread that has been devoid of it and is really just people's opinions not backed by any real experience (coupled with childish insults).

Sean </div></BLOCKQUOTE>

Can't answer all, but just to say, read my previous posts. I have stated that using a full underbody shield when off-roading will probably cause no problems, if it is a temporary item. The problem is, GM assumes you will leave whatever they sell on the vehicle at all times. This is the problem. I don't care if you are going 100 mph, if there is no airflow around the trans, and the heat generated by the trans and the cats is trapped, it will cause the trans fluid to degrade at a faster rate. I do not mean to imply it will show an overheat condition, it will just heat it up and cause it to degrade faster than designed (the severe maintenance schedule). If the engine flashes a code for overheated trans fluid, you have a big problem.
Will you notice this slippage? No, it will be gradual overtime, until it is a problem. Someone driving a vehicle, where the trans starts to slip over a period of time will not notice this slippage, it will be so slight, it will seem normal.

As for added accessories. You can add anything to your vehicles that you wish; however, GM as the manufacturer has to follow all the laws and safety regulations issued by the countries that they sell the vehicle in. That is the reason many accessories you see sold by aftermarket companies are never offered by GM, they can't, through their official channels.
GM can't offer a set of headers unless they meet emission regulations, you can add a set and not violate the law, unless you have a local I/M requirement. GM can't offer a super loud exhaust, since many states outlaw these loud exhausts, but you can install a loud exhaust. GM will not offer a front end brush guard that affects the operation of an SIR sensor. Not only is it against the regulations, but it would also lead to liability lawsuits. However, if you want to install one, they can't stop you, but if the bags don't go off as designed, you can bet they will fight you tooth and nail in court if you sue.
Only input GM (or any manufacture) has in regard to what you install on a vehicle is the warranty may be voided if the addition could cause a failure of a part (e.g., supercharger, turbocharger, etc.).

My last words on the subject are: You whatever you wish to use, chances are in some cases the trans will fry outside of warranty. Just don't bash the manufacturer; GM, Chrysler, etc., if it does fail.