FM (Flush Mount)is usually for disc brake and the 7900 standard is for when you use a drum backing plate the bearing stick out the 1/8" same thicknees the backing plate is so when your retaining plate is clapped it does not crush the bearing surface are too much compromising the bearing. I do not know how far you are from Akron, But we can do it for you. A20 bearings are junk for drag racing, stick with the ball bearings. A20 is if you are on the road more...Your going to get the same headaches as your freakin set9 / a9 BS.... Don't need tapered bearings for the axles... No muscle car puts that many miles on in a year. Sealed bearing and the inner doughnut seal will work great for your application....DRAG RACING If you have true 700 foot lbs. get the 33 spline axles and full spool. well worth it. it you are going to be on the street more just hang with the 30s and a posi be careful at the track as you choose to be more street-able than track bound... JIm J D
0 street time, motor should be pushing 700 to 725 hp, saw a dyno of a very very similar build, had a little more compression than mine by about .75......it had a torque line above 625 fromm 3500 to 6700 with peak pushing near 700 but not over. It appears the housing ends are about 100 bucks......any questimate on expense to have the cut off and installed? Does the price of axles and bearing change from the 30 spline to the 33 and the proper bearings. I live in Mansfield so Akron is no big deal
A ballbearing is good for going straight ahead,so if that s all you are doing,it should last longer than us. I use the SET20 and other tapered-roller bearings for street/strip because they are able to take side loads better than a ballbearing design. I haven’t had any failures ever. Yes,you do need to make sure that you don’t have any endplay with a tapered-roller,or the cone will unseat from the cup. The 7900 is still the correct end for either bearing.
While doing the axle upgrade I am also planning on doing a disc brake addition, nothing crazy just a nice easy weld on kit like one found from speedway motors https://www.speedwaymotors.com/Weld...ch-Backspace,2000.html?OriginalQuery=91031936 Fronts are going to be a little nicer willwood https://www.speedwaymotors.com/Wilw...t-Black,251075.html?OriginalQuery=83514015272 With the planned rear kit not bolting on where the backing plate goes would you look for the 7900 or the 7900fm. They make the same rear kit in a bolt on, but not sure if it fits the new housing ends.....I thunk it might https://www.speedwaymotors.com/GM-10-12-Bolt-Bolt-On-Rear-Disc-Brake-Kit,14015.html
The type of bracket shown in the last link,is very tight getting it around the bigger housing end. A die grinder will be helpful to help clearance it.
