MMR 4.75 Thrust Bearing Install Help....

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  1. #1

    Default MMR 4.75 Thrust Bearing Install Help....

    I am rebuilding my MMR 4.75 and don’t understand the thrust bearings. I spoke to MMR today about the 2 blue shims that are needed that go between the cap bearing and the main cap, 1 on each side. With the main cap torqued the shims are loose and seem like they will fall out. MMR said to dimple just the main cap in 3 spots on each side to keep the shims from moving. I feel like the shim AND the cap should be dimpled together to keep shims from moving. Has anyone installed them before. They are the Romeo block 2v bearings
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    Last edited by Lou94Stang; 03-18-2020 at 10:51 PM.

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  3. #2

  4. #3

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    This particular modification is MMR's approach to installing a modified Coyote crank into a 4.6L Modmotor for a small displacement increase and a corresponding small reduction in the cost of a crankshaft. The particular modification has been the source of more than a little heartburn among users over the years. Some of the problems encountered in rebuilds are what you are experiencing right now. Some are associated with the narrower oil sealing surface the Coyote crank uses in order to make room for the rear mounted reluctor timing wheel, Some of the problems are associated with guys who finally gave up and went back to a standard 4.6L crank only to find they now needed to replace their pistons because of the difference in stroke between the two crankshafts. There are other challenges also.

    In general it is to your advantage not to embrace these sorts of solutions unless you are fully versed in the distinctions between the two different builds and are both OK with them and capable of managing them on your own in an ongoing basis moving forward. A number of builders will not work on engines with these sorts of mods because the increased potential for an unhappy compared to using standard 4.6L 'stuff. Others either feel they are up to the challenge and / or throw caution to the wind. Either way your best bet is probably to embrace the not so service oriented MMR customer service solutions they offer. I know this is somewhat bitter medicine but, it does come with the territory when you elect to pursue these sorts of modifications to the basic engine design model with providers like MMR.


    Ed

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  6. #4

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    I spoke with Greg At MMR. They are sending me different thickness shims. I currently have .063 shims. I pulled my old shims out of my original MMR block and they were .070. The .070 are nice and tight and 1 shim was dimpled in 3 spots by MMR. Now it’s a new issue. WithMy new used Romeo block the crank is hitting and the block needs to be clearanced by the #1 main cap. Notified MMR and they said some blocks did need clearance

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  7. #5

  8. #6

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    Well, there you go! Looks like you are all set.


    Ed

  9. #7

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    Does the thrust bearing fully flanged mod you recommend work with a Romeo iron block and 4.75 crank. Bearing set MB5219SI to use just the upper #5.
    Last edited by Lou94Stang; 03-20-2020 at 08:11 PM.

  10. #8

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    King does not make a fully flanged thrust for your application. If you want to use one you need to buy two sets of bearings, probably from MMR at MMR pricing, and modify the lower form the second set to look like the upper from the first set..The modified Coyote crank will require a custom #5 main for your block. As painful as it is your best bet is to go back to the customer service experience at MMR — their crank design, their fix. In the future you would be better served not to embrace this sort of modification.


    Ed
    Last edited by eschaider; 03-21-2020 at 10:55 AM. Reason: Spelling and Grammar

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