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| Idler Gear Variations https://www.ausmini.com/forums/viewtopic.php?f=2&t=96442 |
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| Author: | cooperess [ Mon Dec 11, 2017 8:57 am ] |
| Post subject: | Idler Gear Variations |
I am trying to sort out what to use in my gearbox Mk2 4 speed synchro rebuild from a box of many gear parts Would anyone explain all the differences in idler gears. Dimensions of shafts Tooth count Any other differences |
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| Author: | drmini in aust [ Mon Dec 11, 2017 11:58 am ] |
| Post subject: | Re: Idler Gear Variations |
Shafts are 0.750" diameter. One end is longer. That end goes into the main gearbox case. |
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| Author: | cooperess [ Tue Dec 12, 2017 6:44 am ] |
| Post subject: | Re: Idler Gear Variations |
So all idler gears have the same tooth count (24) and the only differences are shaft lengths and diameter? |
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| Author: | drmini in aust [ Tue Dec 12, 2017 7:23 am ] |
| Post subject: | Re: Idler Gear Variations |
Unless it's A+. They have finer teeth but 7/8" shafts. Not common here except Rover. I am ignoring straight cut race gears... |
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| Author: | miniron [ Thu Dec 14, 2017 6:20 pm ] |
| Post subject: | Re: Idler Gear Variations |
There have been at least 2 variations of the non A+ idler gear. The first had equal length shaft and used 1" O/D caged needle rollers. The second had the unequal length shaft and used 1 1/16" O/D caged needle rollers. Shaft diameters are 0.75" dia and the gear teeth are identical. My first S, a 66 build date with 3 synchro gear box, used the equal shaft length idler gear and 1' dia bearing. My second S, a 68 build date also with 3 synchro gear box, used the unequal length shaft idler gear and the 1 1/16" bearing. The unequal length shaft idler gear is also used on 4 syn boxes. My theory goes something like this: The 66 S had the specific 1275 only gear box casting, as the standard gear box casting wouldn't fit the 1275 crank. Non 1275 engines used a different gear box casting and they couldn't fit the 1275 engine on this gear box. The 68 S has the remote version 3 synchro box, with the 22A1288 casting. The 4 synchro gear box was introduce in the UK in 1968 but didn't reach OZ until l969 with the Mini K and MK2 S and the last few MK1 cars. The 4 synchro box used the larger dia idler gear bearings with the offset shaft lengths as this gear box is, IIRC, 1'' longer than the 3 synchro box. My 68 S used the later 3 synchro box with the 4 synchro idler gear and bearings and seems to be a transition mix of bits. My 68 S also has the 1100S flywheel housing with the breather casting but it hasn't been machined to take the breather. John Sneddon's book mentions the use of the Morris 1100S flywheel housing and the 1 1/16" idler gear bearing on page 80 for the Mini Deluxe due to supply problems but it doesn't get a mention in the section on the S. Hope this helps. RonR |
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| Author: | cooperess [ Thu Dec 14, 2017 6:46 pm ] |
| Post subject: | Re: Idler Gear Variations |
Thanks RonR for your comphesive answer to my initial question. |
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