 | Home > Technical > R380 stubby gearbox conversion. |
 
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| Scott R Member Since: 21 Jan 2016 Location: Northampton Posts: 25   
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Anyone else building or built one as I'm struggling with the front cover/plate. The original R380 hasn't got the guide tube for release bearing and the Lt77 one isn't thick enough for the bearings to sit in. Ashcroft's website shows a picture of a thin Lt77 with a guide tube welded on so is confusing me.
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12th Feb 2018 8:42pm |
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| Defendermatt Member Since: 15 Sep 2016 Location: Derbyshire Posts: 313  
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You need the conversion part from Ashcroft
http://www.ashcroft-transmissions.co.uk/di...using.html |
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13th Feb 2018 6:52am |
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| Scott R Member Since: 21 Jan 2016 Location: Northampton Posts: 25
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Thanks for the reply and I have seen that but it still doesn’t answer my question. The input shaft bearing on the R380 gearbox needs to stick out the gearbox casing by 14mm, the layshaft bearing approx 5.5mm. The LT77 front cover is 8mm thick so won’t be able to be machined to 14mm deep. The picture on Ashcrofts website doesn’t look like it is going to be thick enough unless there is something I’m missing? And with the lug each side tells me that’s the LT77 cover as the R380 only has a lug one side. Perhaps I just need to go there and look at the item and buy it if it looks right.
This is the difference of thickness between the LT77 and R380 front covers.  Click image to enlarge |
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13th Feb 2018 9:48am |
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| Scott R Member Since: 21 Jan 2016 Location: Northampton Posts: 25
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Thank you for that, deceptive picture from Ashcroft then.
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13th Feb 2018 2:05pm |
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| Defendermatt Member Since: 15 Sep 2016 Location: Derbyshire Posts: 313
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I think it does look quite slim on Ashcroft's website, but I assure you it is correct - I have used the list of Ashcroft parts for 2 boxes now.
I'd recommend fitting a new input shaft bearing as the old is difficult to remove from the original R380 shaft. |
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13th Feb 2018 2:55pm |
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| Scott R Member Since: 21 Jan 2016 Location: Northampton Posts: 25
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An update. I couldn’t justify the £67+vat for the front cover so went for plan b, machine the LT77 one out to accept the input bearing to a depth equal to the difference in hieght between the two bearings then make a spacer the correct thickness equal to how much the layshaft bearing sticks out so it butts upto the cover. Only problem is that when I did machine it the depth way more than the thickness so that was a no go.
So plan c, use the original r380 and attach a guide tube to it. First was to cut the one off the now scrap Lt77 cover, as you’ll see in the picture you can see where I machined the back out and broke through making it scrap. Click image to enlarge I then machined the hole out to clean it up up being that but was still rough cast and then put a screw thread in of no particular size. Click image to enlarge Next was to machine the guide tube and thread the end leaving a small step to match the cover. Click image to enlarge Which then just screw the two together. Click image to enlarge Not sure whether to just use thread lock or to weld it? Just need to mock it up and make sure it’ll work and that the tube isn’t too long or the release bearing will go back far enough after engaging the clutch. Total cost is 20 minutes of my time. |
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17th Feb 2018 11:58pm |
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| dorsetsmith Member Since: 30 Oct 2011 Location: South West Posts: 4554 |
thread lock not weld
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18th Feb 2018 9:02am |
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| Defendermatt Member Since: 15 Sep 2016 Location: Derbyshire Posts: 313
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Very neat! Although I think I would weld it for peace of mind
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19th Feb 2018 7:25am |
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