RCD crank support problem BBC

Howdy...

I am having a problem with an RCD crank support on a BBC. I have lost just about every bolt in it now. The crank hub (RCD) has a small amount .0015 -.002 run out but I would have thought that the roller bearing would have a bigger plus or minus tolerance to take care of that. I spoke to a guy at the track who runs one if he ever had a problem and he just said Red Loctite

Any other clues please or should this thing be Loctited and why don't RCD send fitting instruction with thier products?

Cheers Pete

 

We run one, to make sure that the bearing is fully centered to where then hub runs, what we did was to undo the 4 bolts securing the bearing carrier (only enough to allow the carrier/bearing to move under little load. Then turn the motor (plugs out) by hand and allow the bearing to self centre. Then nip them all up. We do use a whisper of loctite on them all just so we don't lose any and miss it and allow it to be weaker.

 

Thanks Relentless...

I actually centered the bearing as you described, I actually lost the four main bolts that hold the sucker on. Maybe the extra 6mm that I loose from the engine plate is not offering enough purchase?

Pete

 

Perhaps studs and nuts would do better?

Dave Koehler
http://www.koehlerinjection.com

 

I run crank supports on both BBC's (studs and nuts, no loctite) and have never had this issue. Might there be something elsecausing this. Detonation in the motor has a lot to do with bolts loosening up or so I have been told. Loctite will probably help, but I would double check everything as far as fit. JW

 

I had the same problem with the gear drive cover coming loose in one pass. It was early in the tune-up and I was putting out cylinders and setting up a vibration. The same thing happens with detonation. Once I got the tune-up right and it was firing on all 8 I never had any more problems.
Steve

 

One more thought...but not a good one!
cracked crank ??????

 

Maybe less expensive:
Excessive bearing play in front main bearing. The crankshaft will move around due to combustion forces and the blower belt pulling it.

 

Just a thought could you take your block to your engine builder and check the line bore with the crank support installed. This might take some creative calculating on the machinist part,but at least this will show exact center of the block/support.If this is good,proceed to the next area,balance.Hope this helps DAVE

 

Thanks for all the clues guys... This is quite a new combo, only about 6 laps and I did get on the wrong side of the tune up a bit at the previous meeting. I was a lot happier with everything on the one pass I had last weekend (starter motor threw in the towel) but the support came off. I guess it is possible that the bolts loosened the meeting before, I know for sure that I did not check them. I guess I will try the simple things first, double check the runout and see if has gotten worse and reinstall it with longer bolts or studs and a drop of locktite and see how it goes....

Cheers Pete

 

http://www.kenlowe.com.au/Documents...ank support installation instructions BBC.pdf

 

How are the bolts on your drive plate? Ive been having trouble with mine on my BBC, had the trans out at the last meeting because we could hear the driveplate rattling, re-tapped the holes in the back of the crank, torqued the bolts and put high stength loctite on them and we pulled the engine out after another 2 passes and the bolts were loose again. The engine is definitely not detonating, everything is balanced so im at a loss.

 

We had all kinds of issues with flywheel bolts coming loose, on our engine there is an adaptor with 6 bolts to the crank and then 8 bolts between adaptor and flexplate. We have used Nordlock washers and safety wiring and so far so good through 20+ runs.

 

yeah we are about to put nordlock washers on it so good to hear its worked for you

 

It sounds like a balancing problem or detonation to me.
Just a thought but I would check it out. Joe