Engine Balancing? - Broken Flexplate

[81stubee]

Hey Guys,

97 P38 HSE 4.6 and It appears i have a broken flex plate...AGAIN!! :(

Brief run down.

May 2009 - Engine Rebuilt & Balanced with Flanged Liners, 9.55:1 Pistons, High Lift cam etc...
- Blown Welsh plug within 50km's of starting engine, head removed and repaired
- Noticed vibration, told not to worry about it
- Tappet noise on cold startup

August 2009
- Flex Plate Broke (bolts not done to right torque - or so we thought)
- Rebuilt Gearbox & Balanced TC due to wear on the Torque converter spigot. Reinstalled by gearbox builder.

Easter 2010
- Engine started misfiring on easter Trip. Engine done about 20K
- After several months and mechanics, my local diagnosed stripped camshaft.
- Engine rebuilder agreed to reapair
- New cam, lifters etc...

May 2010
- Car returned, noticed engine vibration was still there
- Tappet noise on cold startup still exists

November 2011
- Noticed vibration slightly worse
- December, noticed rattling/crashing noise on Idle

Feb 2012
- Inspected and noticed Flex plate slightly out alignment with Ringgear bolt holes but no damage to four outer bolt holes, suspect cracked around spigot aligner.

Engine rebuilder says it happens to them all the time and i should just replace the flexplate.
My local mechanic says that if the TC has been balanced (which it is unlikely for it to be out of balance) which it has, then the only other cause assusming all fitted correctly is a badly balanced engine. The latter would go along with the vibration.

The vibration occurs just off Idle, bit like a lump, but is bad at 3000rpm. Engine has now done 40K

Any thoughts? My only suggestion has been to rebalance the motor, $4K+

Sorry about the long confusing post...but i need this sorted.

Scoobee

[bee utey]

The most common cause of broken flex plates is due to misalignment. In the LR V8's sometimes one of the engine-to-bell housing dowels is lost during removal.

[p38arover]

I had a full balance done on mine when it was rebuilt. Cost under $400.

When the torque converter is removed, have them check the nose of the TC and the matching hub aligner on the crank. Mine was damaged and probably caused the second flexplate failure.

I had a new hub aligner fitted and the TC repaired.

https://www.aulro.com/afvb/images/imported/2012/03/468.jpg

https://www.aulro.com/afvb/images/imported/2012/03/469.jpg

https://www.aulro.com/afvb/images/imported/2012/03/470.jpg

https://www.aulro.com/afvb/images/imported/2012/03/471.jpg

[Blknight.aus]

ewww, hammery.....

to check them for round cut a piece of carbon paper to exactly the circumference of the inner race and install it then face the TC up to it on some long guide bolts.

bring it home replacing the bolts one at a time till its just touching evenly (you still want it to slide) then very slowly turn the engine over by hand.

remove the TC carefully and eyeball the witness marks the carbon paper has left, if you see very distinct lines that run forwards and back (that you cant attribute to getting it in and out) clean it up and install the TC in a different position and go again. (and with the crank in a different starting position)

If the marks come up in the same way in the same position relative to the crank then the crank is potentially damaged. If the marks come up the same relative to the TC then the TC is damaged. IF you get 2 new sets of marks that look similar to the first lot then both are gone.

Careful Repetition of the test adjusting the start position of the crank AND the relative position of the TC is important to ensure that its not misalignment on installation thats causing the problems

[p38arover]

Probably not so easy to do in the car, Dave. :(

[Blknight.aus]

still doable. you have to pull either the box or the engine to get to the TC... It'd be a lot of a bugger to do on your back on the floor under the vehicle with the Box out.

IMO Its a check that you should do IF youve had a damaged flex plate but dont have obvious signs (like the photos you put up) of hammering on the TC and the Spigot) I think its especially important if you're thinking about reusing the TC.

[81stubee]

Thanks Ron, i had seen your photos, and looked the first time the plate broke. I'm just concerned why this has happened again. Last thing i want is to fix the flex plate, then have to replace it again in another 20K.

Sorry, I left a bit out....

When the gearbox was done, the gearbox builder knew that the flex plate had broken, so they double checked alignment, and also installed a new spigot. Plus they also found that one of the dowels was missing, so it was reinstalled. I also went through all this the first time the plate broke.

My question is in regards to the vibration.. Does anyone think it could be a badly balanced engine, that has caused the plate to break again. Ever heard of this before?

Stu

[Blknight.aus]

yes, but not so much overall engine balance but the harmonic balancer. It was stiffer than an alcoholics nightcap. changed that and no more weird drone at certain RPMS and AFAIK it hasnt done a plate since.

[81stubee]

Well, finally got around to gettting the motor out. The poor old girl has been sitting in the driveway for 6 months :(

And this is the result :o

http://img802.imageshack.us/img802/7812/20130102105354.jpg

The big thing i have noticed is that the Cracks are directly between the bolts.

Thoughts, Suggestions? I'm considering VCAT as this motor has been a disaster from day one.

[boofdtl]

Have you spoke to the eng guy about i have a mate doing vcat and he went through the same as you ..
Its looking good for but time is a big part...

[Pierre]

HNY Scoob,

Looks to me like the hub on the TC is not sitting in the correct position and the flexplate is being pulled out of shape by the fixing bolts. I'd look for the TC as the big bad booger, and if it's now in bits, trial fit the TC to the engine assy to look for an obvious standoff or misalignment by the Dave technique - an excellent explanation, BTW.

It would not be a usual thing for a minor engine inbalance to cause this damage. Continual missing may shunt some weird vibrations into the driveline, but you would have noticed and repaired them as they occurred.

If you need a flexplate for comparison, give me a call on 0419587107 - I have a flexplate on a 4L Disco long engine at home.

Pete

[p38arover]

That flex plate looks conical. That shouldn't be. It looks like the torque converter has been pushing the flex plate forward.

Is it now conical and no longer flat?

[Pierre]

Scoob, has the mount boss to the crankshaft got a bronze bush in it? The piccie seems to indicate a step in the boss which may foul the correct seating of the TC, causing the "coning" that p38a has noted. If there is a bush there, remove it. The TC may then fit correctly. It would be there for a manual gearbox installation, indicating a possible change when the engine was done over.

Pete

[wanglemoose]

looks to me like the last person that put it back together didnt get both internal splines of the torque converter lined up on the input shaft. after spending 2 hours fighting with mine when the engine was done its a complete pain to get it right. if they are not lined up correctly you are left with bout 4mm gap between bellhousing and block this can be seen as just tight dowels and pulled up with the bolts causing warping of the flex plate.
with the converter installed correctly the bellhousing and block will mate and then you bring the converter forward to meet the flex plate after you have a couple of bolts tight. the converter should have a small gap to the flex plate with the bellhousing bolts done up which you then close by pulling on the converter before tightening the flex plate bolts.
good luck

[81stubee]

Yes to all of the above!!

I have since removed the puzzle that was once a flex plate (13 pieces :o). As ron said, it appears conical on the floor. That sounds like a possibility about the Torque Converter.

The question is how do i prove it? I guess i ring them up on monday and say "Hi.... broken flex plate... appears flexed in the wrong direction, you guys were last to bolt it up", or the question is were they? Because the engine builder has had the car since them to replace the camshaft that stripped itself, but i am unsure whether they removed the motor or not!.

*slaps forehead* :wallbash:

[Hoges]

I see no specific reference in any of this conversation to the "drive plate setting height" specified for particular engine numbers when bolting the flex plate to the torque converter. RAVE makes specific mention of this and when/where it applies.

There's a 3 digit code on the plate affixed to the auto transmission box which specifies the shim stack required. This is critical to preventing cracked flex plates... Ashcroft transmissions has a Table on their website Ashcroft Transmissions - ZF4HP22 (http://www.ashcroft-transmissions.co.uk/index.php?act=viewProd&productId=51)

Check your engine number to see if the depth calculation is a requirement (see RAVE) for your vehicle. If it applies and if when reassembling the job, whomever didn't take account this, then it may be one of the significant factors contributing your problems... perhaps you could ask them a leading question like:" Can you remember what size shim pack you used between the TC and flex plate...etc and how did you calculate it? :angel: see how much they know/understand...:twisted:

Good luck with it

[81stubee]

I cant find any reference to these shims in my rave, and the Ashcroft website just talks about them not where they go. My box ends in 909 and that doesnt even list in there table.

There were no shims on the original engine when i first removed it years ago. I'm just wondering if the shims are there to adjust the flex plate spacing from the flywheel... hmmm.

[Pierre]

Scoob, is there a bronze bush in the end of the crankshaft?

Pete

[Hoges]

FWIW: Here's what's in my version of RAVE:

Up to engine (4.6L) number 46D00450A, and (4.0L) engine 42D00593A : setting height is 7.69mm-7.81mm

From 46D00451A, and from 42DD00594A and all petrol V8 engines with serial number prefixes 47D-51D: these do not require a setting height

cheers

[Pierre]

Ron, the TC bolts to the flexplate. If the TC centre hub is not entering the crank hub correctly (perhaps being obstructed from entering) the flexplate will tend to bow outwards towards the transmission.

I cannot see how it would bow the other way, that is, towards the engine because the mount ring on the face of the TC can go no further than the flexplate.

IMO, the culprit is still the relative positions of the TC hub and the crankshaft hub. That stress alone would lead to cracking.

Pete

[p38arover]

FWIW: Here's what's in my version of RAVE:

Up to engine (4.6L) number 46D00450A, and (4.0L) engine 42D00593A : setting height is 7.69mm-7.81mm

From 46D00451A, and from 42DD00594A and all petrol V8 engines with serial number prefixes 47D-51D: these do not require a setting height

cheers

I can't access RAVE on this Win 7 machine but if I recall correctly, the info about shimming is in a Tech Bulletin on the RAVE CD.

[PLR]

G`day ,

seems like Pierre has the right idea , there normally wouldn`t be a bush/bearing in the hub for the auto .

Earlier you say the auto shop replaced the spigot , pressume this means they welded a new end on the TC .

Along Pierres line , if you measure the OD of the spigot and ID of the bush and the figs don`t work that`s all you`ll need .

Maybe not likely if std but is possible for a TC to balloon in days gone by .

It may be an idea to check the crankshaft end float , gently lever the ring gear out and push back , std 4.6 is 0.10mm , 0.20mm range so not much .

[Blknight.aus]

genericaly speaking and without delving into things like crank float/position missing adaptor plates/alignment plates (Ive seen that before)

if the Flex plate is pulled towards the TC there are 3 causes.

1. the TC has not been spigoted correctly, either the TC spigot is to large or too long and is not correctly sitting into the spigot bush in the crank shaft or the shoulder on the spigot bush is too far out. tightening up the the bolts pulls the flex plate towards the TC.

2. the wrong flex plat has been used

3. the correct flex plate has been installed incorrectly

if the flex plate has been pushed away from the TC theres a few more causes, in some circumstances 2 or more must occur at the same time for failure to occure.

1. the wrong flex plate has been installed

2. the flex plate has been installed incorrectly

3. the spigot is to short or too small and is not providing the correct stand off

4. the TC is incorrect with one/any/all of the following

the TC mounting bolt blocks are too wide
the TC mount spigot is too short
the tc shaft is too long
the tc splines are too short
The TC was not installed correctly
the TC pump drive flanges are too long
the pump drive collar is too long


5. The flywheel assembly is installed incorrectly pushing the flex plat too far towards the auto.


In this case I would be getting my hands on a schematic representation of the auto/engine and taking about 300 million measurements then working out where the misalignment has come from.

[justinc]

I feel your pain :( Recently had THE SAME issues , again with a 1997 Build P38a.

3 flex plates in 100K, engine vibes since car was new, and a chewed out spigot etc etc.

Ended up at 120K with another complete exchange engine. Got the 5 litre treatment , forged pistons, and flanged liners etc etc.

I have had several faulty/ poorly machined/ misaligned crank tunnels etc 4.6 engines in the past. 1 lasted only 6000km out of the crate. On disassembly it had destroyed the thrusts and the crank was using the rear main block turrets as a thrust surface. Absolute disgrace. Total factory machining fail. The other arrived from LR, I removed it from the crate to see swarf spilling from some of the oil ways, and none of the bored surfaces where the poorly installed / scored cam bearings sat had been deburred at all. It went back too.

I would toss the block or at the very least get a full align check of the crank bore and crank balance checked. Personally I would start with another short motor.

JC

[81stubee]

I agree that looking at the damage to the plate, i dont believe it is down to the balance of the motor. I'm beginning to wonder whether the TC is somehow out of alignment. I'll take some measurements today, but i'm not sure where i'd find a diagram of what the correct measurements should be.

Here are some pics of the bits all cleaned up.

http://img801.imageshack.us/img801/7161/20130103092017.jpg

http://img546.imageshack.us/img546/1607/20130103092131.jpg

I have measured the distance of the spigot length which is 18.5mm. The bush you can see inside the aligner is 18.5mm, so this wasnt stopping the TC homing.

Basically, i just want to get this car back together so i can sell it. I lose my garage in a few months so wont have any room for the car :(

[81stubee]

I feel your pain :( Recently had THE SAME issues , again with a 1997 Build P38a.

3 flex plates in 100K, engine vibes since car was new, and a chewed out spigot etc etc.

Ended up at 120K with another complete exchange engine. Got the 5 litre treatment , forged pistons, and flanged liners etc etc.

I have had several faulty/ poorly machined/ misaligned crank tunnels etc 4.6 engines in the past. 1 lasted only 6000km out of the crate. On disassembly it had destroyed the thrusts and the crank was using the rear main block turrets as a thrust surface. Absolute disgrace. Total factory machining fail. The other arrived from LR, I removed it from the crate to see swarf spilling from some of the oil ways, and none of the bored surfaces where the poorly installed / scored cam bearings sat had been deburred at all. It went back too.

I would toss the block or at the very least get a full align check of the crank bore and crank balance checked. Personally I would start with another short motor.

JC

This is the original block. Its been Top Hatted and had the full works. Its supposedly got 9.55:1 Pistons and a High lift cam. At the end of the day, i spent a lot of money on this engine and gearbox, and i just want it working. I've even been tempted to part the car out.

[81stubee]

Went and spoke to my local Indy today. He believes that to do that kind of damage the TC spigot is off centre. So on Monday I'll take the TC down to TCE engineering in Ringwood and get their thoughts. He suggested they put a longer nose on the TC as well, which should ensure it is pulled straight.

[Blknight.aus]

you dont have to have the original sizings draw up the configuratation and the locations of all the parts and start taking measurements, to .5mm with a ruler is good enough to start with and if that doenst add up then break out the verniers.

[81stubee]

Time for an update!

Got word from the Torque Converter boys this afternoon.

It appears that the Spigot on the TC is undersize and was never checked whe not was put in last time :eek: However, this is only circumstantial and cant be proven :(

The Fix:

Split the TC, Fit a larger nose to the TC, and machine out the Spigot Aligner to suit. Check the internals and rebalance. Hopefully, this fixes the problem once and for all. *fingers crossed*

[Blknight.aus]

I'd be flipping the TC off, with a busted flex plate and incorrect support from the spigot it will have been trying to run off center and will potentially have damaged the internals of the lockup.

Id also be having a very close look at the autos pan and filter and if theres any evidence of metal or lockup material having a good look at the front of the auto.

[PLR]

Time for an update!

Got word from the Torque Converter boys this afternoon.

It appears that the Spigot on the TC is undersize and was never checked whe not was put in last time :eek: However, this is only circumstantial and cant be proven :(

The Fix:

Split the TC, Fit a larger nose to the TC, and machine out the Spigot Aligner to suit. Check the internals and rebalance. Hopefully, this fixes the problem once and for all. *fingers crossed*

G`day ,

Pretty common to split a TC , the way to mod for high and low stall ETC.

I would pressume they cover there work and you`ll have the bits to check .

I can get how the spigot as is may break the drive plate and has to be rectified but i don`t see how it is going to shape the broken drive plate you have .

Was the first broken drive plate the same shape as the current one or was it still flat ? ( manual says there`s paint on one side and they only go one way )

From your first , does it explain the vibration ?

You had it with both or do you consider the first was already broken when the engine was fitted ?

It seems , you say only 50km when the head came off and the vibration was first noticed , if this is right and only one head came off , there will be a possibility that a different thickness gasket or head was fitted and this could cause a roughness which may appear to be a balance problem .

I only suggest the above because again i would pressume that in the 50km of the first run it would have been monitered very closely and if the vibration was there you would have noticed .

Peter .

[81stubee]

G`day ,

Pretty common to split a TC , the way to mod for high and low stall ETC.

I would pressume they cover there work and you`ll have the bits to check .

I can get how the spigot as is may break the drive plate and has to be rectified but i don`t see how it is going to shape the broken drive plate you have .

Was the first broken drive plate the same shape as the current one or was it still flat ? ( manual says there`s paint on one side and they only go one way )

From your first , does it explain the vibration ?

You had it with both or do you consider the first was already broken when the engine was fitted ?

It seems , you say only 50km when the head came off and the vibration was first noticed , if this is right and only one head came off , there will be a possibility that a different thickness gasket or head was fitted and this could cause a roughness which may appear to be a balance problem .

I only suggest the above because again i would pressume that in the 50km of the first run it would have been monitered very closely and if the vibration was there you would have noticed .

Peter .

The TC has to be split to balance it, as its too hard to drain the oil completely and put pressure on the lock up clutch, and balance it all at the same time.

When i first installed the new engine, i did the TC bolts up to the RAVE spec of 45nm and not 65nm as per the TSB that was issued. Hence the first plate broke because it fretted around the bolt holes. The way this first plate split was entirely different to this latest one. As you can see form the pics, this one has broken from halfway between the bolt holes into nearly four equal pieces, where as the first plate you could see it broken where it had fretted around the bolt holes.

I'm about to order the new drive plate so that we can fit it to the spigot aligner on the bench and mesh it up with the TC. That will prove that the TC is not flexing the plate at all.

Your pretty much on the money about the vibration, which i dont believe was there upon first starting the engine. I'll try this, and if the vibration is still there i'll dig a little deeper into the idea of the head. Basically, once i'm done with the alignment of the TC and gearbox, then it has to be something else.

From here i will ensure everything is aligned and tripple checked. Refit the motor, and replace the Harmonic Balancer. If there is still a vibration, well we'll cross that bridge when i come to it.

This whole scenario has been a disaster. If you have work done by professionals you expect it to be done properly. I have spent nearly $10,000 on just the Gearbox and motor, thats not a small amount of money to put into a car. I would expect it to be pretty much Mickey mouse.

Anyways, i'm taking it one step at a time. Piece by piece. The car has to be fixed and sold by April. So who knows, there might be a bargain for someone who has access to a decent workshop.

[81stubee]

I'd be flipping the TC off, with a busted flex plate and incorrect support from the spigot it will have been trying to run off center and will potentially have damaged the internals of the lockup.

Id also be having a very close look at the autos pan and filter and if theres any evidence of metal or lockup material having a good look at the front of the auto.

Spot on,

The TC guys, are fully checking it for wear and damaged internals including metal pieces. When i get back to melbourne, i'll be going over the Oil seal on the front of the box and going from there.

Can you see any harm in dropping the pan and checking the filters before putting the TC back in?

[81stubee]

SO finally its time for an update, with pics.

The TC has been completely rebuilt and balanced. They have fitted a new larger 34.5mm spigot and machined out the Spigot Aligner to match. The overall finish of the TC is so much better than the original gearbox build.

http://imageshack.us/a/img17/5504/20130216170019.jpg

Here is the complete setup on the Bench. TC through to Spigot Aligner including flex plate.

http://imageshack.us/a/img708/4949/20130216170010.jpg
http://imageshack.us/a/img825/5268/20130216165908.jpg

As the ringgear had to be replaced due to the damage, i have had the new 2nd hand one balanced, luckily, as it was a fair way out. So maybe this was another cause of the vibration.

I'm now waiting on a new Flange ring FTC4609 as the old one was damaged.

I was servicing the gearbox yesterday, when i hit a snag :( It appears the new filter has damaged the bag and somehow had water in it. So i need to wait until Tuesday for a new one.

http://img46.imageshack.us/img46/1127/20130311103444.jpg

Plus, i'll pick up some new engine mounts at the same time.

Scoobs

[Hoges]

I doubt there's any damage to the filter... Methylated spirits is an excellent drying agent for this sort of situation...Put the filter in a shallow platic container and pour metho (about 100ml) into the filter inlet and give it a good rinse. Let it drain, dispose of the metho in the plastic container and then repeat using fresh metho. Dry the filter either in the air or give it a good shake to get rid of residual liquid and put it in the kitchen oven @ 60 degC (fan forced setting) for 10 mins. Job done;) If there's a lady in the house and she objects to your conscripting the oven, then borrow "her" hair dryer... works just as well. :angel::wasntme:

[Blknight.aus]

concur, the mesh is stainless, if there's no obvious sign of rust on the casing Id go the clean and dry then use it.

however as its the only internal protection is the filter always err to the side of caution

[81stubee]

The engine is in... But...

So i've got the motor in. Am about to do up the Bellhousing bolts, but just thought i'd check the alignment of the TC to Flex plate. While it all looks good, as i pull the TC forward towards the flex plate, it likes to pull back about 3-4mm once i release the pressure. I thought it should just sit there. Matters are not helps by the Alloy sump, which means i cant see much.

It all lined up perfectly on the bench.

Any thoughts?

[PLR]

The engine is in... But...

So i've got the motor in. Am about to do up the Bellhousing bolts, but just thought i'd check the alignment of the TC to Flex plate. While it all looks good, as i pull the TC forward towards the flex plate, it likes to pull back about 3-4mm once i release the pressure. I thought it should just sit there. Matters are not helps by the Alloy sump, which means i cant see much.

It all lined up perfectly on the bench.

Any thoughts?


G`day ,

i pressume the TC has no oil so a lack of weight and it possibly just means the seal should work .

With what you`ve had done i don`t think it has any option but to be aligned .

[Blknight.aus]

The engine is in... But...

So i've got the motor in. Am about to do up the Bellhousing bolts, but just thought i'd check the alignment of the TC to Flex plate. While it all looks good, as i pull the TC forward towards the flex plate, it likes to pull back about 3-4mm once i release the pressure. I thought it should just sit there. Matters are not helps by the Alloy sump, which means i cant see much.

It all lined up perfectly on the bench.

Any thoughts?

IT might just be springing back against the new pump seals, 3-4mm is a bit excessive, it might be getting a bit of helping hand from the spigot bushing if its oiled and sealing up tightly enough to be making an air spring.

[81stubee]

:D:D:D:D:D

DONE!!! It works.... No engine vibration now, its quite smooth. I'd like to replace the injectors, and its booked in for a coolant flush this week, but otherwise ok.

Now to get to those niggly little problems that i've been ignoring the last few years while i try to fix the vibrations. Blend Flaps, Broken Sunroof, etc...

[Pierre]

Well done that boy!

Pete