Engine Block to Bell Housing Dowels
 

Who makes offset dowels,of choice?....Thanks for any recommendations.

Re: Engine Block to Bell Housing Dowels
 

why?

Re: Engine Block to Bell Housing Dowels
 

Mercury doesn't use them in the Bravo application.

Re: Engine Block to Bell Housing Dowels
 

Might check TransDapt. They specialize in making engines and trannys that were never made to go together work. They have all kinds of engine to tranny adapters so I guess they would have offset dowels as well.

Re: Engine Block to Bell Housing Dowels
 

This application is drive line transmission.....The purpose of offset dowels is to "dial in the bell housing to the crank shaft centerline"....Subject to the amount of variance between the bell housing centerline and crank shaft centerline would be the value of the off set dowels.....When both,crank shaft and bell housing are centered,the transmission input shaft will not be required to turn in an angle of deflection......That is,if the transmission bell and input shaft don't have run out.......A little less bearing stress , reduced harmonics,heat and flex plate abuse.

Re: Engine Block to Bell Housing Dowels
 

Boy, nobody ever checks that!! And it causes a lot of trouble. It is VERY common for the crank to not be concentric with the bore in the flywheel housing.

Instead of the dowels, we use a fixture from Tilton, block is drilled oversize and an oversize dowel is inserted (just bigger on one end).

Re: Engine Block to Bell Housing Dowels
 

CcanDo,
Tavia, Lakewood and Moroso make the pins you are looking for. We used the Lakewood products in our roadrace projects.
http://www.tavia.com/cat6.html
http://go.mrgasket.com/pdf/bellhousi..._procedure.pdf
http://www.moroso.com/catalog/catego...?catcode=23004
Bob

Re: Engine Block to Bell Housing Dowels
 

Thanks guys for the information!!!!!Mbam,a dumb question,do you check the transmission case for run out before installing the input shaft,on new or rebuilt units?.....Second,have you considered designing an input shaft long enough to provide a pilot bearing shaft end?.......Third,are there words of wisdom pertaining to the flex plate?........Fourth,is a dampened drive line such as Aqua Drive recommended?......Everyone,please feel free to chine in!!!Thanks

Re: Engine Block to Bell Housing Dowels
 

run out would be a bent shaft, concentricity would be a trans housing out of spec, yes we do check. The shaft is way too hard and short to bend without cracking. In the case of a problem exceeding the float in the drive plate it usually will take out the bearing. Have thought about a pilot, does not really solve the problem. The drive plate we use has abut .030 float built in but to me that is a band aid. Much better to eliminate the run out and concentricicity issue. What drive are u using?

Re: Engine Block to Bell Housing Dowels
 

Mbam,I stand corrected on loosely using run out....The point is,concern for tolerance of the case centerline to shaft centerline...The next concern is centering the flex plate to the crankshaft....Then preserving the integrity of the flex plate hub assembly and transmission front bearing....The pilot would support the over hung load...The drives are dry sump #6 w/ 27" drive line....Thanks

Re: Engine Block to Bell Housing Dowels
 

Both Imco & Konrad use a shock absorber on the output of our trans for some applications.

Drive plate run out is a concern, we have seen some production plates off by .060, transmission did not last very long on that one.

The hub will move, it is designed to have some float. If you mount the drive plate on the flywheel and put an indicator on it you can center it with a hammer and brass drift. If not -- dump that drive plate.

We like to see no more than .007 total run-out & misalignment but I promise there are 100's of units running with far more than that. It does make the unit run hotter and will cause low line pressure if off too much. Very seldom do we see a shaft or bearing that has been damaged.

The tolerance of the transmission case is a non issue, they are within a couple of thou worst case. If the crank/trans centerlines line up there really is no overhung/radial load to speak of as the drive plate will handle the .007 spec no problem. If they don't line up a pilot is not going to solve the problem, something will eventually break.

Re: Engine Block to Bell Housing Dowels
 

Thanks Mbam,good information,other people may benefit from your statements also.....FYI,Mr.Gaskets @216-398-8300 offers a Lakewood Industries offset dowel in three sizes.The dowel appears user friendly and does not require drilling or tapping.....Some flywheel,drive plate, crankshaft bolt combinations create drive plate hub/crankshaft bolt interference....Therefore,is it acceptable to shim washer between the flywheel and the drive plate,thereby creating clearance between the hub and crankshaft bolts?....Further,is it recommended to use fasteners on both inside and outside bolt circles of the drive plate/flywheel?....It seems there is less risk of heat/work hardening without shim washers and both bolt circles are used.

Re: Engine Block to Bell Housing Dowels
 

MBAM, Ok, we have checked bell housing to crankshaft run-out. With dial indicator on zero at 3 o'clock, we found .006 @ 12, .0145 @ 9 o'clock, .0065 @ 6 o'clock. Please correct me if this is wrong, but my conclusion is that we have zero run-out top to bottom, and .00725 run-out side to side. If this is correct, do we need to re-dowel to reduce the +-.007 run-out, or is this value acceptable?

Re: Engine Block to Bell Housing Dowels
 

Yes, that is what is sounds like. .0145 is a bit much, would be nice to see it lower. Did u check the drive pate hub run out?

I would not shim the drive plate out, is it the hub hitting the bolts or the flywheel, sometimes the recess is not big enough. We use a dished drive plate, gives better engagement on the input shaft and avoids the interference issues.

Re: Engine Block to Bell Housing Dowels
 

Mbam,with your tutor age,the flywheel is at "0" and the drive plate is at.0035.The drive plate is fastened at both the inner and outer bolt circles without spacers or interference......Sure a lot of trouble just to make these Bam Transmissions happy.....Thanks Again

Re: Engine Block to Bell Housing Dowels
 

Marc, Lloyd-
Great info here guys.
I'm going to check the runout on my setup when I have the chance.
Thanks!
John

Re: Engine Block to Bell Housing Dowels
 

Guys, a somewhat related question, I use Merc crashboxes and spline drives,I posted when initially set up ,about 45 hrs ago, to see if I should use a pilot bushing, Everyone told me not needed although the tip is on the input shaft. There are no wear issues thus far but this has me thinking. Food for thought.....good info...but maybe more work! Due, the Chris's engines are done AGAIN :mad: and she will be ready to fight in a few weeks. :D

Re: Engine Block to Bell Housing Dowels
 

Greencard,I would run a sealed,hi rpm ball bearing pilot....Because,the drive plate hub splines have tolerance and the hub itself can move....The bearing will stabilize the drive plate assembly....However,the bell housing bore and crash box flange should be close to a press fit and centered.

Re: Engine Block to Bell Housing Dowels
 

Andy-
Is this the second time for your engines? Hope they stay together.

By the way, you can trust CCanDo's advise; he's never led me astray.
Altho, he may have let me stray... at my own peril.

John :D

Re: Engine Block to Bell Housing Dowels
 

CC, thanks for the tip, I will look into it. Trans fits tight to belhousing.
Due, when the seastrainer lid exploded one engine got hot and the other sucked the spaying water into the carbs :eek: A Couple pistons and some bent valves so I got off easy..just need relief valves or different strainers. Alot can happen quickly at 100+.