SFK sprag vs. Borg-Warner sprag
SFK sprag vs. Borg-Warner sprag My sprag just broke in the 4l65e on my C5 vette. It was a double cage BorgWarner sprag but I dont know why it didnt hold. I know a lot of guys use the double cage sprag but now Im hearing that some guys prefer the single cage heat treated SFK better? Wich one should I go with?
Launching!
Joined: Oct 2008
Posts: 294
Likes: 0
From: Bowling Green, KY
Dang, how hard are your shifts? Can you post a pic of the carnage? I've always heard the B/W is the best on the market right now. If the SFK's are better, why are they almost half the price.
We use the borg warner dual cage and have excellent results,
As mentioned how hard are your shifts, Of course anything can break but I know many builders like to over do it on the shift firmness. Blocking accumulators and such.
I have used the SKF also but my experince has been the dual cage is better but to each his own of course.
As mentioned how hard are your shifts, Of course anything can break but I know many builders like to over do it on the shift firmness. Blocking accumulators and such.
I have used the SKF also but my experince has been the dual cage is better but to each his own of course.
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How firm does your converter lock up??? I had a customer with a triple disk vig that kept breaking the bw sprags. He had his apply and release %'s at 99-100 in the tune. Lowered that down some, and never broke another one.
It locks up pretty firm. Its a Yank SS 3600 and flashes pretty quick.. car really slams in if you punch it but not violent or anything.
TECH Resident
Joined: May 2006
Posts: 969
Likes: 119
I have found over the years that both sprags have had occasional "heat treating problems". I have many SKF's in 9 & 10 second vehicles with no breakage. If the heat treat is correct on the sprag itself, then the inner race "must" be perfect, and has to be flat and very smooth (mirror finish). The outer race must have the machine marks or roughen it up in the direction of rotation with 36 grit. If the tolerances are on the loose fitting side, then the sprag will "want" to "rollover". Harsh part throttle shifts do not help. Best to work "with" the accumulation setup, then against it. Borg Warner has a new sprag that is apx. .050" - .060", but is only available from GM in a "complete" front sprag assembly. It comes with inner & outer races, sprag, hub, snap ring, and sun gear. It will need to be modified for better oiling though, as in earlier BW units. BW left it out for some reason. Raybestos had discontinued the SKF. Dana
Last edited by PBA; May 6, 2009 at 12:52 AM.
