thurst bearing play in dd sbc,bbc,small block fords.

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406 JAMIE
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thurst bearing play in dd sbc,bbc,small block fords.

Post by 406 JAMIE »

Hello all and ty for looking.im thinking about doing a small DD and keep hearing about thurst bearing play was wondering how long u get out of ur motor before u have to change bearings out/do the bottom end?and this is for none LS motors.ty for ur time y all besafe polyside down. :rebel: :old_glory: :rebel: :old_glory: :proud:
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odcjohn
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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by odcjohn »

if a engines bearing clearances are right with good oil pressure it will last couple hundred hrs

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by jeepinocala1111 »

Just think of the design of the engine itself. It is designed to produce torque to a shaft that is supported so that there is no side load on the bearings so if you want to do it the right way and make your engine last get a gearbox or support bearing out shaft if they even make them.

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406 JAMIE
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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by 406 JAMIE »

ty for ur reply jeep my lil brother has figured out how to stop thurst play on none LS engines.ty for y alls time besafe. :rebel:
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pontoon outlaw
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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by pontoon outlaw »

on the DD Caddys they use a piece of polymer it's the same piece I have in my Cad 507 never wears out :)

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skinnypockets
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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by skinnypockets »

pontoon outlaw wrote:on the DD Caddys they use a piece of polymer it's the same piece I have in my Cad 507 never wears out :)
I've been running a cady DD for several years and never heard of that. Where exactly do you put the poly?

My engine had a 100,000 miles on it when I put it in the boat three years ago. I always use Lucus oil at every oil change and can't see any sign of wear in the thrust bearing.
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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by terrible ted »

I say part of the wear is what prop you run a big heavy wood paddle verse a light multi blade.

I seen what the momentum of the paddle has done. new timing chain - double row snapped raped chain around bottom gear pushed crank out the bottom of motor, it exploded.

I would thing a multiple blade like a warp drive would carry less momentum and stress on the crank

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by SWAMPHUNTER45 »

Thrust wear in a Cadillac is all about driving habits, oil blending and prop selection.

If you run a DD Caddy boat looking for "snap" your gonna have thrust wear and timing chain issues. The sudden loading and unloading exploit the weakness of both the thrust and timing components.
If you ease into the power and ease off the gas on deceleration you are greatly reducing the stress. Couple that with the oil blending ratio Mr Branch has recommended and your DD will live a good long life.

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by jeepinocala1111 »

If possible post a picture of the thrust bearing wear out fix it am very curious about that one.

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by SWAMPHUNTER45 »

There is no fix besides a weld job and then a lathe cutting it back to spec. and that is a 50/50 bet.

I did hear of someone who had machined a secondary thrust modification back 20 years ago but he has passed on and the plans were lost.

Never saw it, only heard the tale from some old timers and they are dead and gone also now.

Back 20 years ago you could get a clean 500 or SBC400 running for $200 so there was no market to sell the product. Today a 500 crank can be a G if it is a virgin. Finding a 400sbc is about impossible any more, but at least cheap parts are available to make a big inch sbc for a DD if it is desired

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by pontoon outlaw »

Bill Roberts machined them back in 2002, that's what I had in my DD 500 back then just for that reason///

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by pontoon outlaw »

:cheers: now I gotta take my old motor apart and take a pic of it :thumbleft:

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by SWAMPHUNTER45 »

There you go, probably what I had heard about !

That ties the pieces together

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Re: thurst bearing play in dd sbc,bbc,small block fords.

Post by terrible ted »

On the sbc put a slight bevel on the seam of the thrust bearing so some oil flows out and hits the faces of the bearing surface. To help prevent in out movement of the crank.

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