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Jul 19, 2020 21:11:51 GMT
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Sweet adaptor. I wont have enough room for something that tall but could make a shorter one to suit I'm sure.
Yes- I like the idea of visiting Shropshire for the cycling alone! I doubt we will be coming over next year. Will be busy here plus not keen on catching any of that yucky thing you guys have floating about over there.... :-) (but I think its here to stay in the world and NZ will have to one day deal with it- but that's another story and we are here to talk cars)
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eurogranada
Europe
To tinker or not to tinker, that is the question...
Posts: 2,556
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Jul 20, 2020 10:24:59 GMT
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I love where this is heading!!
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v8ian
Posted a lot
Posts: 3,832
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Jul 20, 2020 11:04:17 GMT
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Some of the shortest ITBs I found were jenvey Hayabussa one, not the cheapest by any means, but they seem to turn up on Evilbay on a regular basis.  Or as a more appealing thought, a double log plenum, 2 small throttle bodies and a small turbo?  ?? |
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Last Edit: Jul 20, 2020 11:06:26 GMT by v8ian
Atmo V8 Power . No slicks , No gas + No bits missing . Doing it in style.
Austin A35van, very different------- but still doing it in style, going to be a funmoble
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jikovron
Part of things
mechanical chaos
Posts: 633
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Jul 20, 2020 11:16:34 GMT
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Love the work involved getting this to work!
Also don't worry about the reversed thrust loads in the gearbox because each selected gear becomes static in relation to the thrust washers and they will take loads of static force, only the remaining none selected gears rotate dynamically with only oil drag resistance!!
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Jul 20, 2020 11:23:15 GMT
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The 955 ones are fairly long, but don’t forget they have a mounting flange integral already where most others you still need a stub and a bit of hose to connect it.
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fer4l
Posted a lot
Testing
Posts: 1,497
Club RR Member Number: 73
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Jul 20, 2020 18:04:41 GMT
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Now you’ve started something ! Hillman GoldImp ? Impwings ? Goldheart ? Heart of gold ? Engine looks completely epic in there BTW. Carry on James what about a tenuous honger chamwing ? sounds more like one of those porn name generators GLImp...? |
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teaboy
Posted a lot
Make tea, not war.
Posts: 2,126
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Jul 20, 2020 18:46:46 GMT
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Jul 20, 2020 20:55:53 GMT
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Some of the shortest ITBs I found were jenvey Hayabussa one, not the cheapest by any means, but they seem to turn up on Evilbay on a regular basis. Ooooh they do look nice don't they. But I know Jenvey and I know their price bracket is not within scope of my money tree, in fact not even in my money tree orchard. I think they belong in the orchard up the road where the posh people reside. Or as a more appealing thought, a double log plenum, 2 small throttle bodies and a small turbo? ??  Love the work involved getting this to work! Also don't worry about the reversed thrust loads in the gearbox because each selected gear becomes static in relation to the thrust washers and they will take loads of static force, only the remaining none selected gears rotate dynamically with only oil drag resistance!! You might be right there! I'm going to have to have a think about this one and look at it again. If so then you have effectively removed that annoying spanner that was dropped in the works, cleaned the oil off it and placed it back on my shelf, in the correct place and then made me a nice cup of tea just how I like it. If wrong then its still game on because I'm just going to go for it anyway  Please can all the other brainy boffins on here look at what Jikovron has said and discuss over tea and biscuits if he is correct? |
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Jul 20, 2020 21:29:41 GMT
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I'll give it a go:
The shafts and synchro hub will be locked to the loaded gear and rotating at the same speed, the adjacent gear pairs will be rotating at a different speed and spinning on the shaft. The thrust will be reacted somewhere either through the other gears and hubs or through the bearings on the shafts these will be in the oposite direction to original intent.
An ideal solution would be an epicyclic gearset in the centre of the flywheel, would take some engineering and keeping the lube in would be a challange too.
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Jul 20, 2020 21:44:22 GMT
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The laygear cluster will see rotating thrust loads and they will be reversed with reversed rotation. Not familiar with Subaru boxes, but on Triumph boxes they have a big washer at the front and a smaller one at the back - presumably this reflects the relative load directions. On that box it would be fairly easy to swap them over...... Imp with a flat six will be Impatient (in traffic)...... Nick EDit: you may well have found this already but just in case..... grassrootsmotorsports.com/forum/grm/spinning-a-transmission-backwards/17183/page1/I particularly liked the bit where someone is selling the OP the opportunity to become the world expert on the subject..... and hoping for dramatic failures at the same time. Just do it man - it'll be fine...... probably  |
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Last Edit: Jul 20, 2020 21:56:52 GMT by vitesseefi
1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Darkspeed
Club Retro Rides Member
Posts: 4,883
Club RR Member Number: 39
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Jul 20, 2020 22:48:46 GMT
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Last Edit: Jul 20, 2020 22:59:42 GMT by Darkspeed
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When I used to be the world leader in Vw Beeetle gearbox disposal, I often wondered if the thrust washers were there to counteract the thrust loads generated by the gears themselves,or were they mainly there to counteract the thrust exerted by some yoof banging it into the next gear before the scynchro ring even had a chance and trying to equalise things on the shaft ...🤣🤣
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I'll give it a go: The thrust will be reacted somewhere either through the other gears and hubs .... This is incorrect in that seeing one of each of the remaining gear sets are not physically attached to the shaft as that particular gear hasn’t been selected, no power can be transmitted and therefore no thrust can either. It can only be transmitted through the selected gear set,through the lay shaft and “to ground” ,ie the gearbox casing in the opposite direction to what it would have been had it been rotating in its original direction of rotation. |
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Last Edit: Jul 21, 2020 6:29:10 GMT by Deleted
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Oh thanks! I've now just spent a good deal of valuable tinkering time reading Trents 850 thread. What a mighty fine read too! I'll give it a go: The thrust will be reacted somewhere either through the other gears and hubs .... This is incorrect in that seeing one of each of the remaining gear sets are not physically attached to the shaft as that particular gear hasn’t been selected, no power can be transmitted and therefore no thrust can either. It can only be transmitted through the selected gear set,through the lay shaft and “to ground” ,ie the gearbox casing in the opposite direction to what it would have been had it been rotating in its original direction of rotation. Is there a bit of types of thrusts getting mixed up here? What I'm (not so much now)concerned with is the side thrust created by the helical gears (which in this box look to be about 30 degree tooth angle) which runs axially along the shafts. I think it fair to guess that the total amount of side thrust are shared by the two engaged gears meshing- both trying to force the other sideways whilst at the same time doing the usual turny power transfer thing that gears are meant to do - which is what straight cut/spur gears do 100 % with no side thrust. These side thrusts are still there. But now they've changed direction. |
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jikovron
Part of things
mechanical chaos
Posts: 633
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I had a look at your box opened up pic and I was somewhat wrong about the first 4 gears,,,but not all is lost!! , so all the gears thrust in the same direction, however 1st and 4th thrust towards end stops and 2nd and 3rd thrust through the synchro hub and paired gear so by changing direction your only swapping which gears are pressing into the synch hub and unused gear, and which are pressing the gears away from the synch hubs
5th gear is fully independent and does work in the manner I initially described, once selected it becomes locked and static to the shaft and by extension is merely loading the thrust washers on that gear statically
The bearings will be loaded in opposite directions and rotate backwards but once swapped for new ones will take to it no problem imo
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Jul 21, 2020 10:24:08 GMT
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I'll give it a go: The thrust will be reacted somewhere either through the other gears and hubs .... This is incorrect in that seeing one of each of the remaining gear sets are not physically attached to the shaft as that particular gear hasn’t been selected, no power can be transmitted and therefore no thrust can either. It can only be transmitted through the selected gear set,through the lay shaft and “to ground” ,ie the gearbox casing in the opposite direction to what it would have been had it been rotating in its original direction of rotation. If a gear is not selected, it acts as a kind of spacer and can still transfer trustloads, in other words it can still transfer forces in axial direction to the next gear. It can not handle loads between gears and shafts
In general. If you look at the trust loads on the 2 axles and which are brought over to the gearbox housing, these are being transfered to the housing by the large bearings on the left in the picture of the opened gearbox. I cannot see what kind of bearings these are but i assume that these are double row ball bearings. For these bearings it does not matter if the trust load is reversed as they can handle the same load in both directions. Then there is the trust load from the gears to the shaft and for this load, it is important that there is a sort of trust bearing and oil feed between the gears of the 2 and 3
For the helicoil gear, it does not matter much which direction it rotates. With both directions, the trust load between axle and housing is handled by the large bearing on the left and if this is a double ball bearing, it can handle trust load in both directions.
For the standing axle with the large helicoil gear rotation is not an issue as the trustload will have the same direction whatever way it rotates
Interesting project!
Peter
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Jul 21, 2020 11:03:47 GMT
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Looking at the pictures the only thing which would need a closer look is the bearing at the left end of the lower shaft in your picture, as Peter says the bearing should be fine but it looks like it current reacts against the flange which bolts onto the case, what is it reacting against in the other direction?
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Jul 21, 2020 11:51:20 GMT
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The outside of the outer bearing ring has a grove as you can see clearly on the upper shaft in the picture. The housing also has such a groove and there is kind of circlips which fils both grooves and this keeps the bearing in a fixed position and therefore you can see this is the bearing which transfers the trustload to the casing. The lower shaft may also have such a groove but its difficult to see
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Jul 21, 2020 12:06:55 GMT
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Aren't gears cut helically to reduce noise/improve transmission efficiency though? And are they always cut the same direction (clockwise/anti-clockwise/however you define the direction of cut)?
Or just fit a straight cut gearset - problem solved. If there was ever a problem in the first place.
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Jul 21, 2020 12:12:33 GMT
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Its all getting a bit technical now so I think just pop it all together and see how it goes!
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??
