RCU Forums - View Single Post - Will the YS 60FR bolt in the same as an OS61SF for direct swap?
Old 11-16-2014, 02:30 PM
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Originally Posted by Huang View Post
When I was mock fitting another Aurora a few months back it was apparent that the Classic... also seemed slightly wider than the original LS as well - that explains it.
Mmm... One question:

In the Classic, is there a slight filament like imperfection going through the YS 61 R text on the left side of the case? Both the R and AR had this (but not the S) and it must have been a piece of debris that got into the mold when the crankcase was being cast. All R and AR LS that I have seen have this imperfection so it's not a batch case issue in the crankcases but in the mold itself.

If the imperfection is there, then the same mold is used and the cases should be generally (dimensionally) identical, except for the lugs which as Will pointed out might be the result of not machining them square off after casting. If the imperfection is not there, well, then it is a new mold and the dimensions could have changed slightly... :-)

On the Hyde mount: looks like the header clears with plenty of space, but slight interferes with the triangle support of the beams. That triangle web could be dremeled away but the rails will be even more flexy than they already are. Any concerns or loss of power you think? Would the .40-.80 one fit or do you need the 91-115? There's a 3.3oz difference in the weight of these two sizes so I'd like to go with the smaller if possible to save weight.

if there is a difference in size of the Hyde section diameter keep that in mind too as I ran into issues when sizing such a mount in a draw up I was working on. The larger mount didn't fit width wise since the rounded sides take up more space than typical "square" side mounts. There might be enough space in the Atlanta but check with the side thrust as it puts the mount closer to the left side of the FW - obviously.