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Bronze dizzy gear faliure in Hemi need help!
Posted By: Teamx
Bronze dizzy gear faliure in Hemi need help! - 03/09/13 09:24 PM
Hi, bronze dizzy gear has falied in my Hemi after 2000 road miles, what is the best brand gear to buy to replace it. Also a friend pointed out I may have to much oil presure which is componding the wear problem. The motor has 65psi hot idle and 90psi when the revs are up, it has a meling H/V pump.
Does anyone offer a softer bypass spring for these pumps, would this help?
Thanks Tim
Posted By: Bad340fish
Re: Bronze dizzy gear faliure in Hemi need help! - 03/09/13 09:29 PM
Quote:
Hi, bronze dizzy gear has falied in my Hemi after 2000 road miles, what is the best brand gear to buy to replace it. Also a friend pointed out I may have to much oil presure which is componding the wear problem. The motor has 65psi hot idle and 90psi when the revs are up, it has a meling H/V pump.
Does anyone offer a softer bypass spring for these pumps, would this help?
Thanks Tim
Lowering the oil PSI certainly wouldn't hurt. Maybe try a thinner oil? I went from 15W40 to 10W30 and my idle picked up 200RPM for an idea of how much load is on that gear. I just recently tore mine down for inspection and with 2500 miles on it the bronze gear was perfect(20psi idle 65psi on the road at 3000rpm).
Posted By: Stanton
Re: Bronze dizzy gear faliure in Hemi need help! - 03/09/13 09:57 PM
Swap out that HV pump for a standard one, pressure is a function of volume.
Posted By: jbc426
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 03:55 AM
Don't run too thick of oil, cut the relief spring down a bit, and be sure to run the collars on the distributor shaft. It helps keep the wear pattern more consistent.
Posted By: Stanton
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 04:06 AM
The problem with just cutting the spring is that the pump will still have to move the same volume - but push it through the bypass. So power is wasted driving the pump and the oil is heated needlessly going though the bypass - not to mention the strain on that drive gear! With the kind of pressure the OP has he does not need the hv pump.
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 04:53 AM
Thanks for the replies,current oil is ULX 20w50 what would you recomend and is there any preferances for bronze gear manufactures?
I will also drop back to a std pump. Tim
Posted By: jbc426
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 07:59 AM
It's the thick oil you're running. Try a max of 10-30wt. You may need the extra volume with the thinner oil.
Posted By: jbc426
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 08:00 AM
When mine wears out, I'm going to have my next bronze gear cryogenically treated.
Also, I switched to the new Milodon pump body and am using the stock cover on it. It reportedly takes significantly less power to drive it due to a more pointed shape of the gerator lobes.
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Posted By: Thumperdart
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 07:43 PM
Quote:
Thanks for the replies,current oil is ULX 20w50 what would you recomend and is there any preferances for bronze gear manufactures?
I will also drop back to a std pump. Tim
I never run anything thicker than 10w30 and I run the same HV pump w/70 psi hot and down to 30-40 at cruise..........stock springs no mods. 
Posted By: HPMike
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 08:29 PM
Although your posted oil pressure is a bit high, Im going against the grain here and saying its not the oil.....
Ive run 20W 50VR1 in my own driver Challenger and the gear lasted years, I inspected it regularly, but there wasnt any appreciable wear. How many miles?? WAY more than 2000 and 10+ years. And I live in an area where I did start it on some pretty cold days.
You live in Australia, so I assume you arent staring the car in zero degree temps..
I notice you are running a chrome sheetmetal timing cover. How are you controlling cam end play. If you think that cover wont deflect, you are wrong. Ill bet that cam is walking like crazy if you dont have something in front of that cover to limit endplay..
Edit: My apologies, I thought the pic another memnber posted was the OP's. Anyway, how are you(OP) controlling end play? What type of timing cover are you running?
Look into that.
MB
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 09:18 PM
My first thought was cam walk, also loose bushing, or bushing not seated all the way down, or shaft to long for the pump.
Posted By: John_Kunkel
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 09:29 PM
With that kind of pressure I'd scrap the HV pump and go to a standard volume. It's obvious that the motor can't handle the volume being pumped and the excess volume is causing the high pressure.
A softer spring probably won't help because the relief valve, even wide open, can only handle so much volume.
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 11:21 PM
To reply to some of the answers.
The bush in the block is now worn but I beleive this is a result of debris from the bronze gear getting in between the drive and the bush as the drive is marked up in that area.
I have one of those Diamond roller thrusts on the front of the cam and a factory timming cover.
The motor is a 557ci using a World block.
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/10/13 11:29 PM
factory cover and roller do not mix without support
Posted By: Stanton
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 01:09 AM
Bronze gear against bronze bushing = wear. Same reason you don't use a steel gear with a steel roller cam ... similar metals !!
Posted By: HPMike
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 02:40 AM
Quote:
factory cover and roller do not mix without support
Yep...that cam is deflecting that cover. If you dont believe it, install the cam and cover just take a long screwdriver and carefully see how easy and how far that cam will walk..
Here is what I do...
Install the cam without the cover and put some paint on the nose of the button. Install the water pump housing and push the cam forward until it contacts the back of the housing(paint will leave a mark).
Build up some weld(Ill start with a half dollar in diameter) and about 3/16" thick weld.
Install the cover with gasket and then the housing also with the gaskets. Obviously dont glue anything in place yet-this is the mock up phase. Usually in the beginning, you wont be able to get the housing on(weld too thick). Then just keep grinding that weld "button" down until you have the desired end play.
Takes a little time, but makes for a better stop.Or you can use one of Andy F's covers.>>I think they have a provision for obtaining end play. 
MB
Posted By: Stanton
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 03:53 AM
You want one of these cast covers - available from Promax in Indianapolis for $100. They fit under a stock pump and are thick enough to drill and tap for a plug so you can accurately measure cam endplay.
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 08:03 AM
Bronze gear against bronze bushing = wear. Same reason you don't use a steel gear with a steel roller cam ... similar metals !!
The bush in the block is not worn on the top where the bronze drive runs on it is worn inside where the oil pump drive runs, that is why I suspect dedris from the bronze drive failure got between the drive and the bush. The drive is marked up where it runs in the bush.
Correct me if I am wrong but dosnt the turning of the dizzy/oil pump drive force the cam to the back of the block, I thought this is what the torrington on the back of the timmig gear set was for?
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 08:21 AM
The bushing is worn inside from the cam walking forward and trying to put pressure on the drive shaft. The roller button mounts on the front and is stopped by the timing cover. A factory cover will flex and allow the cam to move forward, even with the roller button
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 10:56 AM
The end play is set at .015thou. I understand the timming cover may flex a little if the button runs against it.
Correct me if I am wrong but dosnt the turning of the dizzy/oil pump drive force the cam to the back of the block, I thought this is what the torrington on the back of the timmig gear set was for?
Tim
Posted By: Performance Only
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:09 AM
Quote:
The end play is set at .015thou. I understand the timming cover may flex a little if the button runs against it.
Correct me if I am wrong but dosnt the turning of the dizzy/oil pump drive force the cam to the back of the block, I thought this is what the torrington on the back of the timmig gear set was for?
Tim
On a B/RB/Hemi, the cam is pushed forward. The torrington bearing is useful if your cam end play is run without enough end play and will help to stop premature wear on the face of the block. Otherwise the torrington is almost useless on a big block.
Smallblocks will push the cam to the rear since the distributor is mounted on the opposite side of the cam.
Posted By: cudaman1969
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 02:40 PM
You guys have been hanging around chevys too much with this cam walk. A b engine cam is forced into the block by the resistence of the oil pump not out. Now it MIGHT walk out at idle but not under throttle. The thrust surface is on the back of top gear, right. As for wearing check for lining up , centered up and down, sounds like mismatched some how.
Posted By: John_Kunkel
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 09:04 PM
and the roller cam lobes are flat in relation to the centerline of the cam so there is no lobe taper to force the cam in one direction or the other.
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 10:03 PM
Yeah. I hang around chevy guys, ford guys, pontiac guys, buick guys, so what does that mean? If you spin your roller cam engine in the direct of operation, with the dizzy drive out, and the lifters on the lobes, it will walk the cam up to the front of the block, and you can visually see what will happen with the roller lifters vs the lobe when it does. Oil pumps and drives on a bb mopar are driver front. dizzy gear on drivers side and counter clockwise timing. Dizzy on chevies is in back and clockwise rotating. Mopar sb is counter clockwise to but on the other side right?
You don't wear out the block face on a bb mopar, it is very rare to do, but you will see a bunch of mopars failures or damaged when the cam went forward. If you don't get the lateral travel right, a failure will happen sooner or later.
Posted By: cudaman1969
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 10:28 PM
Do you think Chrysler would design the cam to (walk) out of the block? The front gear is oiled by the front cam journal. Look at a cam and the lifter rides to the back of the lobe therefore pushing the cam in not out. Take the oil pump off put dist.gear in and lock it so as not move then turn the cam, see which way cam moves. There could have many reasons you'rs walked out but who knows ask a chevy guy they know everything.
Posted By: Performance Only
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 10:49 PM
Quote:
Do you think Chrysler would design the cam to (walk) out of the block? The front gear is oiled by the front cam journal. Look at a cam and the lifter rides to the back of the lobe therefore pushing the cam in not out. Take the oil pump off put dist.gear in and lock it so as not move then turn the cam, see which way cam moves. There could have many reasons you'rs walked out but who knows ask a chevy guy they know everything.
So i guess a lot of people have wasted a lot of money worrying about putting a cam button on a roller cam in a big block mopar? Ummm, No, I don't think so.
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:07 PM
My roller cams, the lifter rides in the center of the lobes. Not the back. Everything in cars and for that matter everything is engineer'd that doesn't make them perfect. Chrysler didn't engineer the slant six to kick rods out of the #6 cylinder either,taking out the starter, but it will. I am going on what I see, what I experienced and what has been seen as failures. If it was pushed backwards, there would be all kinds of posts over the yrs asking what to do when your mopar keeps eating up the back of the sprocket and the front of the block. Chrysler didn't design the old mopars to run on a roller cam either, they were designed with flat tappets and hydraulics. We all can debate on here, it creates options, but bottom line, like most complaints, the cover was flexing or the cam went north not south, and it isn't the first or last time. If something is not controled, then it will be out of control.
Posted By: cudaman1969
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:28 PM
Quote:
Quote:
Do you think Chrysler would design the cam to (walk) out of the block? The front gear is oiled by the front cam journal. Look at a cam and the lifter rides to the back of the lobe therefore pushing the cam in not out. Take the oil pump off put dist.gear in and lock it so as not move then turn the cam, see which way cam moves. There could have many reasons you'rs walked out but who knows ask a chevy guy they know everything.
So i guess a lot of people have wasted a lot of money worrying about putting a cam button on a roller cam in a big block mopar?
Roller cams are not flat Tappets, not ground the same. It is good insurance to put a button in a roller app. not in a hdy. We could pi!! all day over this but to the question The guys cam is alignment problem like a rear end gear. 
Posted By: HPMike
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:28 PM
Quote:
My roller cams, the lifter rides in the center of the lobes. Not the back. Everything in cars and for that matter everything is engineer'd that doesn't make them perfect. Chrysler didn't engineer the slant six to kick rods out of the #6 cylinder either,taking out the starter, but it will. I am going on what I see, what I experienced and what has been seen as failures. If it was pushed backwards, there would be all kinds of posts over the yrs asking what to do when your mopar keeps eating up the back of the sprocket and the front of the block. Chrysler didn't design the old mopars to run on a roller cam either, they were designed with flat tappets and hydraulics. We all can debate on here, it creates options, but bottom line, like most complaints, the cover was flexing or the cam went north not south, and it isn't the first or last time. If something is not controled, then it will be out of control.
Ill post up a pic of a stock cover that was properly "set up" but you can clearly see where there is a circular mark left by the button putting stress on that cover. It wasnt just "kissing" it either...
MB
Posted By: MR_P_BODY
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:36 PM
Ill post up a pic of a stock cover that was properly "set up" but you can clearly see where there is a circular mark left by the button putting stress on that cover. It wasnt just "kissing" it either...
MB
The cam changes direction when its accelerated to
decell (moves in or out)
Posted By: Stanton
Re: Bronze dizzy gear faliure in Hemi need help! - 03/11/13 11:55 PM
Quote:
So i guess a lot of people have wasted a lot of money worrying about putting a cam button on a roller cam in a big block mopar?
Ya mean I spent money on a good cover, bought and farted around with four different buttons, two different gasket thicknesses, assembled, measured, disassembled, then did it all again trying to get just the right endplay ... and I did all that for nothing ?!? Sheeeet!
Posted By: Mopar-Al
Re: Bronze dizzy gear faliure in Hemi need help! - 03/12/13 12:54 AM
Teamx, I have run Milodon bronze gears the most. only 1 mp bronze drive gear. I can tell you that when all is set up the Milodon gives no problems. They make a few different ones for all pump designs. I would agree on a lighter weight oil as well, or as stanton suggested, you may even consider a stock pump. It sounds like your engine is built on the close side of tolerances. You did say you were street driving and it's not a race car. It may even run cooler. Also, set your cam run out to as little as you can get. Your tare downs won't be as dramatic. You have a great looking engine.
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/12/13 09:34 AM
Does anyone know the part# for the Milodon gear with a factory length oil pump drive?
Posted By: nz383man
Re: Bronze dizzy gear faliure in Hemi need help! - 03/12/13 10:27 AM
Wedge and Hemi using stock-style pan and tube pick-up. Also used with Milodon Oil Systems #21000, #21010, #21100, #21110 and systems using a Keith Black pump.
Bronze Gear #21525
Posted By: Teamx
Re: Bronze dizzy gear faliure in Hemi need help! - 03/25/13 09:00 AM
Update: Std volume oil pump and Milodon gear and drive installed, oil presure has dropped from 65 psi+ at idle to 45 psi and at revs from 90 psi down to 60 psi.Will keep a close eye on the new gear!
Thanks for all the imput Tim
Posted By: torkrules
Re: Bronze dizzy gear faliure in Hemi need help! - 03/25/13 10:23 PM
Quote:
The end play is set at .015thou. I understand the timming cover may flex a little if the button runs against it.
Correct me if I am wrong but dosnt the turning of the dizzy/oil pump drive force the cam to the back of the block, I thought this is what the torrington on the back of the timmig gear set was for?
Tim
.015" end play on the cam is a bit too much. I would drop that down to about .005-.006". Two things force a stock flat tappet cam backwards on a big block Chrysler. One the position of the distributor drive and the helix on the cam/distributor drive gear and the other is the taper on the lobes. Roller cams are ground flat so the only thing driving it back is the first point.
However, acceleration/deceleration will cause the cam to walk. Also, if your lifter bores are not straight or out of alignment, this could cause the cam to walk forward.
I would side on the opinion that thicker oil can wear out the gear prematurely. It takes more force to spin the pump. Also, if there are any burrs or imperfections on the cam drive gear it will wear the gear early. Usually the first gear wears out faster until the cam gear takes a "set".
Posted By: Mick70RR
Re: Bronze dizzy gear faliure in Hemi need help! - 03/25/13 10:46 PM
It doesn't matter whether the engine is accelerating or decelerating, the crank is still turning in the same direction. The crank is still driving the cam in the same direction, and the cam is still driving the oil pump in the same direction. The cam is being forced back towards the back of the block by the resistance of the oil pump drive.
Posted By: torkrules
Re: Bronze dizzy gear faliure in Hemi need help! - 03/25/13 11:14 PM
Quote:
It doesn't matter whether the engine is accelerating or decelerating, the crank is still turning in the same direction. The crank is still driving the cam in the same direction, and the cam is still driving the oil pump in the same direction. The cam is being forced back towards the back of the block by the resistance of the oil pump drive.
my meaning is the changes in velocity of the cam that occurs when the engine changes speed(rpm). Yes, if you want to be specific, the resistance in the oil pump contributes greatly to this action. Same thing happens with the rear axle gears when you get on an off the throttle.