SOHC.co.uk Forums > Project Board
CR750 replica build
Trigger:
I think the CR would of had a different hub and a different heat displacement system ?
When I have been fitting new liners to the rear hub, I have had quite a few customers ask, if I could also remove the fins as it is in the lathe and I always refuse because I have known a few people do this and had over heating problems. More so with a front drum but, a few with a disc.
CR21:
--- Quote from: Trigger on October 21, 2019, 11:13:11 PM ---I think the CR would of had a different hub and a different heat displacement system ?
When I have been fitting new liners to the rear hub, I have had quite a few customers ask, if I could also remove the fins as it is in the lathe and I always refuse because I have known a few people do this and had over heating problems. More so with a front drum but, a few with a disc.
--- End quote ---
Hi Trigger,
Yes you are correct it was a different part, and was cast in Magnesium but my bike is a replica. I don't think It will be problematic due to the size of the disk, and surface area change, but I will certainly keep an eye on it,
Cheers,
CR21
Trigger:
You will need to get info on heat displacement in alloy of that grade, it is totally different than magnesium. You will always see more fins on a rear drum as, it needs to cool the shoes and bearings. The front hub fins will just cool be bearings, no fins means a overheating problem to the bearings.
Heat always transfers to the smaller area with alloy. Think about removing all the engine fins on a air cooled engine, it will overheat ;)
I studied this years ago but, can remember all the tech on it and I had a look around last night for the study and data paperwork but, it must of been binned when I moved.
CR21:
--- Quote from: Trigger on October 22, 2019, 08:00:15 AM ---You will need to get info on heat displacement in alloy of that grade, it is totally different than magnesium. You will always see more fins on a rear drum as, it needs to cool the shoes and bearings. The front hub fins will just cool be bearings, no fins means a overheating problem to the bearings.
Heat always transfers to the smaller area with alloy. Think about removing all the engine fins on a air cooled engine, it will overheat ;)
I studied this years ago but, can remember all the tech on it and I had a look around last night for the study and data paperwork but, it must of been binned when I moved.
--- End quote ---
Hi Trigger,
I understand this, as I also studied it and will do some calcs at some point as I have the part drawn up. Before doing the calcs my gut is that as this bike will never be 'raced' and that I have not removed much material/area I will still have a good factor of safety,
Cheers,
RD17
CR21:
A little more progress from today:
Rear hub stripped and inspected:
Filler neck bezel offered up:
And welded on:
This replaced the Monza part.
I have linished this down so the weld is flush, but I forgot to get an image!
Seat
Rear hoop tweaked to fit, holes drilled in the fibreglass (always hate that bit!)
Front seat mounts jigged up:
Seat fitting well now, and the bike is starting to resemble a CR!
Cheers
CR21
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version