For a ball bearing type trans input shaft (e.g. L43): Choices in bearing specs

Discussion in 'Maintenance/Repair' started by DAW, Mar 22, 2016.

  1. DAW

    DAW Member

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    Regarding radial clearance greater than normal, under what circumstances would that be good or needed; and when is it best to use the lower clearance?

    I searched and found this:
    http://bearings-catalog.ntnamericas.com/results/ball-bearing
    and this re clearance and preload:
    http://www.ntnamericas.com/en/product-support-and-training/frequently-asked-questions#b7

    Compare: http://www.ntnamericas.com/en/produ...data-sheet/datasheet?pid=3121&cid=RBSRD&ctc=B
    to:
    http://www.ntnamericas.com/en/produ...data-sheet/datasheet?pid=3122&cid=RBSRD&ctc=B

    They are not identical. The different part numbers address the difference in radial clearance.
    Misalignment factor, or type of clutch plate, or wear factor for input/pilot bearing, etc??

    If you know, thanks for response.
     
    Last edited: Mar 24, 2016
  2. DAW

    DAW Member

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    Two other questions related to the above:

    In selection of a replacement input bearing I see that there are some different part numbers by even the same mfgs for the early L43 trans? They share the same physical dimensions but some are three digit and some are 4 digit numbers. For example, 207 is offered by some sellers as the replacement, but 6207 specs show a higher rpm capability than the 207 (and the price difference is minimal). I'll choose a 6207.

    Second, and this pertains to suffix of part number, I pulled a 6207 from my trans that had a shield on one side (vs both sides, or open). The shield was on the inboard side of the bearing. That doesn't make sense to me. I could see having a shield on the outboard side, if at all, but not the inboard side. A shield is a dirt/dust barrier. If this is the original OEM input bearing could it be that Toyota did this to limit back-sloshing of oil from the bearing? It isn't a seal, and a shield would make sense facing the outside world re dust (and there is already an outboard oil seal on the shaft anyway). Maybe it acts like a windage tray does in a crankcase?
     
  3. DAW

    DAW Member

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    OK, I keep researching and finding some of my own answers but maybe it will save others some time and effort if I post it.
    Disregard what I said above re 6207 vs 207 part numbers because the "6" applies to SKF re rpm limit, most other mfgs use prefixes and suffixes to distinguish.
    The "2" is the series of single deep groove bearings in light range size and load parameters. The "07" is the bearing i.d. bore size reference (multiply by 5 = bore size mm. e.g. 07 x 5 = 35 mm).

    I don't think the radial clearance options I asked about apply to this application. They are for thermal expansion at higher temps use. I'm going to select the std clearance bearing.

    BTW the suffix "ZNR" translates to a shield (not seal) on one side of the bearing at the opposite side of the bearing as the outer snap ring [that configuration is exactly what I removed from my trans]. The shield does go inboard and slows the drain of oil/keeps a reservoir in the bearing for cooling.

    The 207 bearing specs are woefully wimpy so it is no wonder that the input bearing has a weak link reputation on this trans. 35x72x17 is the size. On later models it was upgraded to 32x75x20 (different nomenclature for that bearing mfg: 63/32RNZ) but that requires boring the case and the input collar to fit. Later still they used a 35x80x21 medium load range bearing (307) but that requires even more manipulations to try to retro fit to the vintage case.

    What I decided to do was to stay with the original bearing fit dimensions of 35x72x17 but attempt to upgrade the performance/load capacity by using a different bearing type. I want to substitute a BL207ZNR (35x72x17) which is a maximum capacity type single deep groove radial ball bearing. It has more balls in it (figuratively too I hope) and significantly increases radial load bearing at the compromise of some reduced axial load bearing capacity and reduces the rpm limit in oil from 11,000 rpm (std OEM bearing) down to 9,500 rpm. My 20R won't see 6,300 rpm so that's moot.

    Ceramic ball (termed "Hybrid" in ball bearing circles) ugh...would be another option in 35x72x17 but mainly provides increased rpm limit (13,200 rpm) which doesn't help me.

    My choice of maximum capacity style bearing may result in faster wear than std capacity but hopefully synthetic oil will fight that factor.

    Update later.
     
    Last edited: Mar 24, 2016

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