Recalling The Problem...
For those of you that have been on the forum for awhile, you may recall that a fair amount of research and discussion took place with the folks at Rocore. This was prompted by the failure of Tim Bentley's transmission cooler failure at 140K miles, which caused his transmission to self destruct due to anti freeze contamination of the transmission fluid. It cost Tim $10,000 to replace his cooler and transmission. This follow on effort was to see when we might want to change this cooler out preventatively before it failed (seemed a 100k miles was prudent) and to seek out and encourage an offering of a better cooler design.
You may also recall that there were two designs of Rocore Transmission Coolers, one being a fixed bundle design like in the current 3-1249T that Beaver used. This design has a weakness due to stress from heat cycles that eventually causes cracking of a tube in the bundle or a solder joint. There was also a floating bundle design that eliminated the stress by accommodating the expansion, allowing the cooling bundle to expand and contract (float) using Oring seals against a machined housing. The Viton O rings seals by design is only exposed to transmission fluid, if there ever was any O ring fail, the design does not put antifreeze on one side of the seal and transmission fluid on the other. It is a very robust design that evolved to eliminate cooler failures. The problem was that a 3-1249T replacement did not exist.
The 3-1249T New Replacement Floating Bundle Design 5-7063F:
In the drawing I attached of the new 5-7063F you can see the detail A that shows the floating seal design, 3 is the oring, 4 is a retaining clip, in the overall drawing 5 is a dust seal cap covering and protecting all of the seal area. This is a far superior design that has virtually eliminated any failures based on Rocore testing and about 10 years of field experience on other PNs.
As part of evolving a floating bundle design replacement, I had Dave Wheatley run the cooling model for the 1249T vs the 5-7063F design. He used a C13 525HP and a 4000 Allison given the C12 data was not readily available online from Cat any more regarding coolant flow. All things being equal the new cooler design should cool about 4% better than the current design and passed the critical temperature limits set by Allison for the 525HP C13. Dave was later able to get coolant flow information for the C12 from a Cat distributor and confirm that the calculations are also acceptable for this configuration. The new design gets its slight cooling improvement from a tighter bundle design and a longer tube length for heat transfer.
Design Differences To Consider
-Both units have #16 oil ports, 3-1249T CL to CL spaced 12 inches apart, 5-7063F 14.5 inches
-Length of 3-1249T 19.6 inches, 5-7063F 20 inches
-Diameter of 3-1249T is 5 inches, 5-7063F 4 5/8th inches. Dave suggested using mud flap rubber as a spacer and isolator or ordering new clamps. If existing mounting brackets are not useable, U-bolt clamp brackets can be sourced from Clamps, Inc PN U-450, or McMaster-Carr PN 3042T39.
-The cast end caps on the 5-7063F with the 3 inch cast ports have a narrower clamp space and may or may not need a narrower clamp then the 3-1249T
Availability And Price
The current price of the 3-1249T is $807. I am pleased to inform you that the new design comes in at $759. The lead time is 4-5weeks on the first unit which drives the 3 inch cast end cap order. One to two weeks lead time for follow on orders. You can call Rhonda at 800-645-2665, ext 1027 to place an order with Rocore or make a call to a truck parts supplier and make them aware of this new PN Rocore cooler.
This has been a long and winding road to get here, but it is done. I would like to personally thank Dave Wheatley at Rocore Engineering for working with me to make this happen.
This is one item, in my humble opinion, that you should consider changing out preventatively given the age of the current units and the significant cost and inconvenience of an on the road failure. I personally would not consider buying another 3-1249T, it is an inferior design with known failure issues, it is not as efficient at cooling, and it cost more :-) Hope this helps.
Later Ed
