Some historic race guys here in Oz have had trouble with 2 piece dampers coming apart. They are now running the 1 piece 1098/1275 damper without problems.

Thanks for all the input on the crank damper. That must be quit the motor. My brother and I watched the NZ guys at Bonneville run some pretty high sustained rpms on they way to setting a couple of world records last year.

I believe but have not taken a look for quite awhile, the S lower half of two pc. shroud and the lower bracket with the off set should clear. The small bore lower shroud and the lower bracket with just one bend push the rad out toward the inner wing rad cowl. I have one in process now and just got the crank assembly back from the balance shop. The little 850 looks funny with a big balancer hanging off the front.

Our 948 powered Seven America also was rebuilt last fall and got a two pc balancer. Just returned from Talladeda where Dean was able to get it up on the bank and hold 8000 rpm all the way around. I think I have heard you must maintain at least 110 mph to stay up there. If ask I would not have suggested holding that kind of RPM for that long. I have several complete 948 s so another crank could be in our future. The engine was a old SCCA unit. We rebuilt it using late flat top 998 pistons, press fit 998 rods a very nicely ported 206 cyl head, Cooper S camshaft, forged rockers and took a ton off the flywheel. It's at 1015 ccs and running 11 to 1 CR. Very important to have fuel and timing correct with those numbers. Steve (CTR)

Viscous damper from KAD, pricey but worth it according to Vizard.

Thks. Coopertune. I am using S lower mt. And two piece rad. Shroud. So I should plan on some minor fit issue?

I use the two pc. balancer on everything I build from std 850 to 1400. As mentioned there is some issues with the lower rad mount when using a pre S two pc rad. shroud. Everything has to be very close but no touch. I also have every engine I build balanced. While I have seen and had owners wanting to use reman. balancers, the ones I have seen have had measurable run out and wobble.

There are several suppliers and some are custom but still the same pattern as two part S unit. I have a collection of early S balancers that have started coming apart. As long as I can buy new I will. Steve (CTR) 

You can have old ones rebuilt. Mini Mania used to do it. They may still.

Thanks spank

2 piece. Keith Calver once said that they are the only ones worth a damn. My experience is that they are simple and the work. I have one of those fancy stainless ones and it has been on a motor that has broken 2 cranks. Put the 2-piece on, and it's not done it since. Everythign else is 100% the same

Note that you may need to clearance your radiator/engine mount bracket to clear it, depending on what one you have now. Not hard-- simple hand grinder.

Making up my list of parts for winter engine/trans refresh on my 20+ year old restoration. One of the parts I need to replace is the harmonic balancer. I currently have the one piece but the rubber is looking pretty bad. Since I have to replace it I was wondering what the current experience is re: one piece or the two piece? My motor is a 1380 with all the goodies, at least what was good back in the 80s when the engine was built.