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Powercurve
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  1. #1
    Authorized Vendor SPeace-ATL's Avatar
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    Default T-5 Internet Myth: The Mustang COBRA T5 is stronger because of phosphate-coated gears

    This is a quote from the 93 COBRA page of www.mustangspecs.com:

    "The same Borg-Warner T-5 transmission found on the GT was used for the Cobras, except it came with phosphate-coated gears as well as stronger bearings."

    Technically this quote is true, but the way it is worded leads one to believe that lots of things were different and that there is a significant improvement in strength with the COBRA transmission which is not the case.

    The 93 COBRA has two gears that are phosphate-coated and two bearings that were replaced by one, more-reliable bearing.


    First, the bearing:

    The standard production T-5 input shaft has 3 bearings that hold it in place and tension the main drive-line within the transmission. The one is pressed on the input shaft and its race is in the front bearing retainer. The second is that there are 15 loose rollers in a cup machined out ot the rear of the input shaft that the front tip of the main shaft is inserted into. The third is a flat "Torrington" bearing much like you would find in a lazy susan turntable. This bearing lies flat between the rear face of the input shaft and the forward face of the 4th gear synchro hub. These two smaller bearings (#2 and #3 above) were replaced by one small caged, tapered roller bearing and race for the COBRA T5. This change was also implemented in the aftermarket T5 called the "T5Z."


    Now the phosphate-coating:

    Phosphate coating is a way to reduce wear, particularly during break-in. A coated gear can help the oil to form a "film" over the surface of a part and the better film that is in place, the better it will wear. Once the phosphate coating wears off there is no lingering effect...

    In the 93 COBRA there were only two gears that were coated in this manner. The input shaft and the counter gear. All of the other gears in a COBRA T-5 are identical to those found in a GT.

    Well, let's clarify one more thing. Actually, beginning in 1992 the Mustang GT received a counter gear that was phosphate-coated too! The Mustang GT gear set became stronger back in 1990 with the new gear set mated to what is called the #065 counter gear. In 1992 this counter gear was replaced by the #068 counter gear which was made to identical specifications except that this one was phosphate-coated! This explains why the #065 counter gear was suddenly discontinued and replaced by the #068 counter gear. The GT input shafts, however never received this phosphate coating, but the COBRA shafts did.

    EDIT:
    "The GT input shafts, however never received this phosphate coating, but the COBRA shafts did."

    Sorry, I was told wrong on this. I just looked at a NEW 93 input shaft and it is definitely phosphate coated. The early shafts were not coated. It would seem that the GT models received phosphate coating on the input shafts at the same time the counter gear changed to the #068 that is coated which happened in about 1992.

    The phosphate coating appears as a black coating on the gear almost as if it has been painter with flat black paint. Aftermarket replica gears made for the Mustangs do not have this coating.


    It seems that the bearing change and the phosphate coating were attempts to solve the issue of premature bearing failure on the input shaft and premature wear where the input gear mates with the counter gear.

    To protect the input bearing on your T5 transmission you should be careful to not run the transmission while it is low on fluid.
    Last edited by SPeace-ATL; 02-09-2012 at 08:27 AM.
    - Stan -


    Mustang 5-Speed Specialists - Authorized Distributor for Astro Performance products!
    Offering quality rebuilt T-5, T-45, and TR3650 transmissions in Atlanta

  2. #2
    Authorized Vendor SPeace-ATL's Avatar
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    Default

    Quote Originally Posted by SPeace-ATL View Post
    "The GT input shafts, however never received this phosphate coating, but the COBRA shafts did."
    Sorry, I was told wrong on this. I just looked at a NEW 93 input shaft and it is definitely phosphate coated. The early shafts were not coated. It would seem that the GT models received phosphate coating on the input shafts at the same time the counter gear changed to the #068 that is coated which happened in about 1992.

    By the way, aftermarket input shafts and counter gears do not have this coating.
    - Stan -


    Mustang 5-Speed Specialists - Authorized Distributor for Astro Performance products!
    Offering quality rebuilt T-5, T-45, and TR3650 transmissions in Atlanta

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