is the big bearing worth it on the 800 cranks?
- Thread starter rmkboxer
- Start date
Search for IndyDan's threads on this. Clutch balance, good motor support, proper clearanced case halves, proper oiling, proper oil, clutch/belt clearance... and then it will live longer, but still eventually break. Dan has upgraded the PTO end to a different size which he believes fixes it even further.
I have an IndyDan bottomend, with the standard PTO end, in my 910. 3 seasons and it's still running strong, under .001" runout which is where it was when he sent it back to me. I haven't had an 800 bottomend last 3 straight years before.
sled_guy
I have an IndyDan bottomend, with the standard PTO end, in my 910. 3 seasons and it's still running strong, under .001" runout which is where it was when he sent it back to me. I haven't had an 800 bottomend last 3 straight years before.
sled_guy
C
clutch man
Well-known member
We have the case halves line bored and a ring type bearing installed they hold up better and are far tighter than stock.
this crank has lasted for several yrs and is one of indy dans original testing cranks, I do think the clutch is a issue since I sold the motor to a friend and my original clutch was put on another motor. he used a new clutch but obviously it was not balanced. this crank lasted over 4yrs. it lost a rod bearing and I pulled it apart to see how much damage was done. clutch balancing is important. mor important then a big bearing IMO
B
boxster7614
Well-known member
The question was is it a waste of money? I don't think it’s worth tearing your motor down just to install it but I think it’s a good idea when you have crank problems to replace it with the wide bearing. But like mentioned above, this is not a fix all. I think some guys are under the impression that the wide bearing will prevent broken cranks and this simply isn't true. It does help though.
The first 800 I had I tore down before I ever rode it to put the wide bearing in and 800 miles later the rod pin still broke at around 2500 miles. (The only thing I did was put in the one wide bearing) The rod pin breaks from cyclic fatigue. The rod pins in the 800 motors are solid, where the pins on the 700 motors are hollow. I think the hollow pin serves to relieve some of the stresses in the pin. Maybe that’s why we see less rod pin failures on the 700. Now let’s talk about the PTO end spinning off (which both motors see failures) I think this is because of inclusions in the forming process or the improper heat treating that weakens the PTO shaft. Sometimes you get a good one and sometimes you don't.
My recommendation is if you have your crank out ALWAYS replace the PTO side rod pin and if you can afford it replace the PTO end also.
Just FYI Polaris no longer makes PTO ends for the 700 engines.
The first 800 I had I tore down before I ever rode it to put the wide bearing in and 800 miles later the rod pin still broke at around 2500 miles. (The only thing I did was put in the one wide bearing) The rod pin breaks from cyclic fatigue. The rod pins in the 800 motors are solid, where the pins on the 700 motors are hollow. I think the hollow pin serves to relieve some of the stresses in the pin. Maybe that’s why we see less rod pin failures on the 700. Now let’s talk about the PTO end spinning off (which both motors see failures) I think this is because of inclusions in the forming process or the improper heat treating that weakens the PTO shaft. Sometimes you get a good one and sometimes you don't.
My recommendation is if you have your crank out ALWAYS replace the PTO side rod pin and if you can afford it replace the PTO end also.
Just FYI Polaris no longer makes PTO ends for the 700 engines.
I didn't put the big bearing in my 2000 800. The sled had 1500 miles when I checked the runout in '04, it was a bit over .003" then. So that summer I had a shop true and weld the crank and they left the stock bearings in there. I milled about .005" off the case halves and had a grinding shop hone them and reset the bearing fits. Haven't had to touch the motor since. It does have every brace ever created for the 800 though..
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