KMS Differential Questions

[cobrakiwi]

David
Just an idea, could you leave material on the inside of the cover (1 inch square by 1/4 or so) where the breather hole is, then drill from the outside in but not all the way through, then from the bottom edge of the square block inside drill two small holes to intersect?

[cobrakiwi]

Or, could a small baffle be made up and tig welded in?
I would think your covers could stand up to two small welds with out warpage.

I have placed many baffles on the steel covers and would think it could be done with the aluminum covers as well.

[patrickt]

Originally Posted by cobrakiwi

I have placed many baffles on the steel covers and would think it could be done with the aluminum covers as well.

I think I could whip one up with the bottom of a beer can and some JB Weld.

[1795]

Here is a picture of what Ross did based on Morris' suggestions to the rear cover of mine and it was an aluminum cover.



Jim

[CompClassics]

Originally Posted by David Kirkham

Actually it wasn't a mistake. The differential covers with the hole in the Cobra location (lower) have not been available for a long time now. The jeep covers are also much thicker so they tend to hold the back of the differential case together better than the original covers which were quite thin (they are only something like 1/16" thick). We ultimately decided to billet the covers for a variety of reasons, the most important being we were able to put the fill hole in the right location.



If anyone can figure out how the billet in the deflector I'd LOVE to hear!!!


I'm really surprised at the size of those holes???

David

I was amazed as well that someone could have that kind of work ethic, really makes me worry about the rest of the “roller” construction that was completed prior to purchase. I do believe however that it is the installer of the Shelby American supplied parts to complete the “roller” here in the United States by Hillbank that is the one responsible for the shoddy work ethics. This is the same chassis that I had previously started a thread on regarding knowing how to select the proper hardware for the application a while ago.

Per your inquiry on matching a deflector in the billet differential cover. Why not CNC or fold a deflector up out of sheet aluminum and then weld it in place? You have an abundance of people capable of welding aluminum. It won’t detract from the external appearance either.

How many people like seeing this much oil plus whatever overflows out of the catch can not inside their differential while driving, this is a pint container?

[Morris]

Originally Posted by David Kirkham

Morris,

That is some really clean work--as always. Thanks for sharing the pics--I may need to "borrow" some of your ideas!!!

David

David

You are welcome to anything I have.....your quality is 2nd to none....and appreciated.....

[patrickt]

Morris, Compclassics, et. al., I put a Thermax strip on my differential. What sort of temperatures are you normally seeing under non-racing conditions? This is a non-cooled differential, basically Jag, but it does have fresh Moroso climbing gear lube in it.

[David Kirkham]

Differentials will get to 150 F within a few seconds of running--maybe 30. It's amazing how fast they heat up. Running temperatures are 200 F or so on the street and 220 F on the track is not uncommon. 240 F is too hot and it's time to get a cooler going.

250 F is time to stop and change the oil before you spend lots of $$$ to fix it.

David

[CompClassics]

patrickt,

I did not try to measure the differential temperature, the vehicle in question will never see Track time. I did measure the oil displacement vs mileage driven, any transfer of fluid out of the differential during operation should be unacceptable.

[patrickt]

Originally Posted by David Kirkham

Differentials will get to 150 F within a few seconds of running--maybe 30. It's amazing how fast they heat up. Running temperatures are 200 F or so on the street and 220 F on the track is not uncommon. 240 F is too hot and it's time to get a cooler going.

Good to know. I like taking measurements of stuff when everything is running fine and then logging it so if it changes in the future I at least have a little advance notice that something is either behaving differently or, more likely, is about to go south on me. It didn't occur to me to stick a Thermax strip on the diff until this thread came out.

[Morris]

Originally Posted by David Kirkham

Differentials will get to 150 F within a few seconds of running--maybe 30. It's amazing how fast they heat up. Running temperatures are 200 F or so on the street and 220 F on the track is not uncommon. 240 F is too hot and it's time to get a cooler going.

250 F is time to stop and change the oil before you spend lots of $$$ to fix it.

David

On a short track we saw temps of 270*degrees....on a longer track like Road America we saw about 280*degrees.....that was when we changed Diff fluids to Mobil 1 75w140 Synthetic.....temps went down to 240*degrees and below....that was on a hot day in July....and we are using a cooler with a fan on it.....and we are using a Quaiffe Differential instead of a limited slip.....which will create less heat......and the Mobil 1 is good to approximately 500*degrees...so no concerns of a failure....

Do remember when we take KMP259 to the track ....we test the first & second sessions ....then we go as fast as we can....very typical of most racers....

[CompClassics]

I wanted to let everyone who has participated in my input to this posting and make you aware of my findings. I have reinstalled the rebuilt differential, new ring and pinion, bearings and seals were put in at the cost to my client, who purchased the car new less than 1500 miles ago, and myself. We installed the differential and following David Kirkhams instructions on using the breather port at the front of the differential case above the pinion to attach the differential breather hose to instead of the way the vehicles manufacturer installed the breather hose, to the differentials rear cover port like they were advised NOT to do. We also fabricated a proper breather catch can that has a proper, top inlet, oil air separator element and a drain. We secured this catch can in a way that under no circumstance will it allow fluid or debris to re-enter the differential. Following the break in procedure outlined by the rebuilder we completed the differential repair and will be delivering this Shelby American Inc CSX6000 Series Continuation Cobra back to its owner in Monterey. During the break in procedure the rebuild shop recommended that there be several driving procedures to follow for proper break in. After each one of the driving cycles was complete we opened the breathers catch can drain to monitor for fluid being "pumped" out as had happened previously with the original breather system installation, there was NO fluid within the breather catch can noted at any time during the procedure. The differential fluid remained exactly where it was supposed to, within the differential.

TIC TOC, So when is the differential in your Superformance Mk2 or Superformance built Shelby American Continuation Cobra going to expire due to lack of lubrication from an incorrect differential breather installation? TIC TOC

I can categorically confirm that the damage to my clients differential was caused by lack of lubrication within the differential due to the incorrect installation of the differential breather system that was installed by the vehicles manufacturer prior to the delivery of the vehicle to my shop. I approached the manufacturer regarding this issue and the manufacturer denied any responsibility on their part, BUYER BEWARE!

[CompClassics]

And the damage.....don’t let this be you.

[Mark IV]

Originally Posted by CompClassics

TIC TOC, So when is the differential in your Superformance Mk2 or Superformance built Shelby American Continuation Cobra going to expire due to lack of lubrication from an incorrect differential breather installation? TIC TOC

I can categorically confirm that the damage to my clients differential was caused by lack of lubrication within the differential due to the incorrect installation of the differential breather system that was installed by the vehicles manufacturer prior to the delivery of the vehicle to my shop. I approached the manufacturer regarding this issue and the manufacturer denied any responsibility on their part, BUYER BEWARE!

I understand and appreciate the issue you had HOWEVER the standard differential in an SPF MK II (roadster or FIA) is a ZF and has none of the issues you encountered. The aluminum "Shelby" diff is an option or you can delete the diff and use a Jaguar Salisbury with adapter mounts that are supplied.

When you say "manufacturer" are you referring to the differential manufacturer or Hi Tech who assembled the chassis and installed the diff? There is a difference in who would be responsible in such a case. I think when you indicate "manufacturer" you are really talking about the "distributor" who denied your claim.

The work and feedback you have provided here is of great value to those who have the alloy differential I would like to thank you for sharing your findings and resolution.

[patrickt]

Originally Posted by CompClassics

... who purchased the car new less than 1500 miles ago...

Were these only gentle street miles? Or did he track it? Not that it matters all that much. And, I'm curious, how bad did the differential sound and feel when he brought it to you?

[CompClassics]

Mark IV,

I am referring this problem as a manufacturing issue since this was the way the vehicle was setup as delivered new. I do not know the individual steps that were taken from the start of the vehicles build to when the vehicle was floored, and to be frank it does not matter, so it is the manufacturer's responsibility for the damage caused by the incorrectly installed differential breather system. If the differential is an option in a Mk2 Superformance be it a street model or an FIA model the issue still pertains to those vehicles, it's up to the individual owner to verify what is installed in their vehicle and if this issue pertains to them or not.
I do not consider this issue the responsibility of the differential manufacturer for several reasons, first is that the differential was not purchased separately from the vehicle, second the differential was not installed by the differential manufacturer, third the breather system was not installed by the differential manufacturer, four I have an email from the differential manufacturer stating that they had repeatedly told the manufacture how to properly vent the differential, fifth and the most important the manufacturer did not stand behind HIS product and left the problem up to HIS customer to deal with both mechanically and financially. Being that you are a Superformance dealer, who does the differential and differential breather system installations? Since you will not state who installs these parts I have to come to the conclusion from your statement above that it is Hi Tech that is the installer of both the differential and the incorrectly designed differential breather system. I would be curious in knowing how a distributor could be at fault when it was the manufacturer that built the car?

When you purchase a new car you don't go after the individual component manufacturers if something fails, you go after the manufacturer that installed the part when the car was being built.

patrickt,

There were less than 1500 very cautious street miles on the vehicle when I went to the owners location in Palm Springs to check out the issue he was having. The noise that was transmitted by the differential was low when at low speeds and became much louder as the speed increased. Being that the owner is "new" to this type of vehicle he very cautious about the possibilities of the car getting away from him and drove it accordingly.

[CompClassics]

Dropping the ball...

After consulting with Shelby American Inc regarding my clients issue with their product and consulting with both Austin Craig and Vince La Viollet both confirming that the differential breather system installed by Hillbank Motorsports, the Shelby American Inc distributor, was installed incorrectly and lead to the damage of the differential in my clients (and Hillbank’s client) Cobra. Unfortunately Shelby American Inc has decided that they have no responsibility as they have no control over Cobra production any longer. They have referred the matter to Hillbank / Lance Stander who denies any responsibility for the way they assembled their product as they state they have sold over 150 Cobras that have been assembled just like this Cobra was, buyers and owners beware! I would like to compliment Hillbank / Lance Stander on their awesome customer relations but I simply can not. If you have purchased a Cobra from Hillbank Motorsports be it a Shelby American Inc Continuation Series or a Mk2 Superformance with the Kirkham differential be aware that your cars differential may fail do to an improperly installed differential breather system, it has the potential to seize at speed and possibly cause an accident.........TIC TOC!

[CompClassics]

All I can say is how disappointed I am in both Hillbank / Lance Stander and Shelby American Inc position in this matter and the fact that they would leave THEIR/MY client shouldering the financial burden for the repair of the differential caused by the improper installation of one of the components that had been installed by Hillbank Motorsports prior to the vehicle being delivered.

[patrickt]

Originally Posted by CompClassics

All I can say is how disappointed I am...

Unfortunately, the fake-o Cobra game is not for the faint of heart. You can not rely on the game's players to "do the right thing" any more than you can leave a hundred dollar bill unattended on the bar when you head to the men's room. Shaming will not work, outing will not work, and harassment will not work. The fact that you've brought the potential mechanical break-down to light for others to avoid is about the best you can hope for.

[eschaider]

When it comes to Detroit vehicles there are usually enough examples of a problem to support a class type of action. With Cobra replicas that is not the case.

Your (CompClassics) client is not however, without recourse. He has both Small Claims Court and also the use of a counselor in a regular court room. I suspect the small claims path might be both the more efficient and less time consuming approach for this type of a matter. There are a number of good small claims primers on Amazon. The cost of the book(s) can be added to the claim ...


Ed