2.8 Flywheel balancing
Discussion
Being that a few here seem to be clued up in the world of the Cologne boat anchor fitted to my S1 
I thought I'd pose the question....
In the process of doing up my S1 currently, and that involves all new gaskets across the engine, cleaning/paint the block, new cam etc etc. I pulled the flywheel off the other day, and having never touched a Cologne to this level before (we don't get many at work) I noticed the flywheel has no dowels or woodruff key to align it to the crank. You could refit it in 6 different positions around the crankshaft!
I'm planning to have it refaced and lightened, but need to know if it's neutrally balanced (ie, can go on any which way as it doesn't matter), or whether it's balanced to the crank and I've just made a hole load of aggro for myself as the crank will now have to come out? The engine's only done 60k and is in great shape - would be annoying to have to pull it apart just because of the flywheel!
The local engineering firm can skim and lighten, but not balance. There is another firm 20 miles away who I used on my Citroen engine rebuild and they can balance the flywheel to the crank, so it's a case of pre-planning and logistics.
Anyone?
I thought I'd pose the question....In the process of doing up my S1 currently, and that involves all new gaskets across the engine, cleaning/paint the block, new cam etc etc. I pulled the flywheel off the other day, and having never touched a Cologne to this level before (we don't get many at work) I noticed the flywheel has no dowels or woodruff key to align it to the crank. You could refit it in 6 different positions around the crankshaft!
I'm planning to have it refaced and lightened, but need to know if it's neutrally balanced (ie, can go on any which way as it doesn't matter), or whether it's balanced to the crank and I've just made a hole load of aggro for myself as the crank will now have to come out? The engine's only done 60k and is in great shape - would be annoying to have to pull it apart just because of the flywheel!
The local engineering firm can skim and lighten, but not balance. There is another firm 20 miles away who I used on my Citroen engine rebuild and they can balance the flywheel to the crank, so it's a case of pre-planning and logistics.
Anyone?
Being that the mass the engine has to shift around is a fair bit lower than that of a Sierra/Capri or Granada, I figured the engine could afford to sacrifice a bit of rotational momentum in favour of throttle response! Not a huge amount, but many of the Capri chaps I've spoken to said it improves throttle pickup, which is pretty leisurely at best!
Reducing the overall weight of the engine wasn't quite what I had in mind
Reducing the overall weight of the engine wasn't quite what I had in mind
Alan Whitaker said:
Hi All
Don't think the bolots are all on the same PCD, so it will only go on one way ??
Alan
I have to be honest, I haven't actually tried refitting it as the engine's on a stand and access is restricted. But I have measured the spaces between the holes with a vernier and they appeared to be the same.Don't think the bolots are all on the same PCD, so it will only go on one way ??
Alan
It's possible the PCD is unequal, and I know I'd be happy if it was!
IF my memory serves correctly, (doesn't always). I Think you will find the bolts are all on the same PCD but not evenly spaced around the circumference of the circle, if that makes sense. Hard to describe better but should be obvious when offering fly to crank that it will only fit in one position.
HTH
Carl.
HTH
Carl.
In propshaft manufacturing, we mark the light side of each end of the shafts after balance correction. When assembled to the gearbox and diff, these marks are aligned with the heavy side of the mating parts, if they're balanced.
Unless your flywheel and crank were balanced as an assembly, your best bet would be to get the flywheel balanced a close to zero gcm as possible, and just bolt it back on at random. Of course, balancing the crank and flywheel together would be better, but a lot more hassle.
Unless your flywheel and crank were balanced as an assembly, your best bet would be to get the flywheel balanced a close to zero gcm as possible, and just bolt it back on at random. Of course, balancing the crank and flywheel together would be better, but a lot more hassle.
Ceejay73 said:
IF my memory serves correctly, (doesn't always). I Think you will find the bolts are all on the same PCD but not evenly spaced around the circumference of the circle, if that makes sense. Hard to describe better but should be obvious when offering fly to crank that it will only fit in one position.
HTH
Carl.
Cheers Carl, was hoping for something similar after a mate just had the same scenario with an Alfa 75, but having measured them with a vernier I think they're all equal. Hope not though!HTH
Carl.
Loach1 said:
In propshaft manufacturing, we mark the light side of each end of the shafts after balance correction. When assembled to the gearbox and diff, these marks are aligned with the heavy side of the mating parts, if they're balanced.
Unless your flywheel and crank were balanced as an assembly, your best bet would be to get the flywheel balanced a close to zero gcm as possible, and just bolt it back on at random. Of course, balancing the crank and flywheel together would be better, but a lot more hassle.
This was my plan really, just get it balanced to zero. I've since heard the cranks are zero balanced, so the theory lends itself. Unless your flywheel and crank were balanced as an assembly, your best bet would be to get the flywheel balanced a close to zero gcm as possible, and just bolt it back on at random. Of course, balancing the crank and flywheel together would be better, but a lot more hassle.
Well, curiosity got the better of me so just popped out to the garage and dug out the flywheel, (car already spread all around garage, I wasn't that curious). Measured all the bolt holes and as you found Richard, all appear to be equal in both PCD and relative angle. There are four drillings on the rear face of my flywheel which shows some attempt at factory balancing. Based on this I can only guess as you did that they are balanced to zero (tolerance unknown). I wouldn't have thought that they would have balanced them with the crank on a mass produced barge engine.
Carl.
Carl.
IMHO lightening the flywheel is a great idea on our cars balancing shouldn't harm either.
I will try to dig out but there is a tech article showing how reduction in rotating mass impacts acceleration iirc 1kg reduction in flywheel weight was equivalent to n off the car can't remember n but iirc it was like 50kg in first gear reducing as you work up the gears.
I am interested to hear how it feels first hand as I've not done mine yet.
Cheers
Damian
I will try to dig out but there is a tech article showing how reduction in rotating mass impacts acceleration iirc 1kg reduction in flywheel weight was equivalent to n off the car can't remember n but iirc it was like 50kg in first gear reducing as you work up the gears.
I am interested to hear how it feels first hand as I've not done mine yet.
Cheers
Damian
If you are running a 2.9 engine then you already have a lighter than stock flywheel.
The 2.9S uses a 2.8 flywheel in order to mate with the type 9 gearbox. The stock 2.9 flywheel is thicker and heavier and is used in conjunction with the MT75 box. I cannot remember the difference in mass exactly but seem to remember something like 3 to 4KG or 20 to 25%, not an insubstantial amount.
None of this helps with a 2.8 engine of course.
Carl.
ETA. This is all from memory and I could be talking complete bunkum.
The 2.9S uses a 2.8 flywheel in order to mate with the type 9 gearbox. The stock 2.9 flywheel is thicker and heavier and is used in conjunction with the MT75 box. I cannot remember the difference in mass exactly but seem to remember something like 3 to 4KG or 20 to 25%, not an insubstantial amount.
None of this helps with a 2.8 engine of course.
Carl.
ETA. This is all from memory and I could be talking complete bunkum.
........(but I'm not convinced 
)Just popped the 2.8 flywheel on the bathroom scales....6kg, so pretty light already.
Have conducted more research and been quoted £380 (yup, three-hundred & eighty pounds sterling) to balance the flywheel to the crank. Because it's a V6, they need all the rods....the lot.
The more I read, the more I'm hearing it's neutrally balanced, along with the crank. Like it's already been pointed out - it's a mass-production barge engine, and a pretty archaic one at that. I can't imagine Ford going to the trouble of balancing to that level.
What I'm going to do is have the balancing checked, to see if it is balanced to zero, and that being the case I'll have it refaced and lightened slightly. See where we go from there!
Cheers!
Have conducted more research and been quoted £380 (yup, three-hundred & eighty pounds sterling) to balance the flywheel to the crank. Because it's a V6, they need all the rods....the lot.
The more I read, the more I'm hearing it's neutrally balanced, along with the crank. Like it's already been pointed out - it's a mass-production barge engine, and a pretty archaic one at that. I can't imagine Ford going to the trouble of balancing to that level.
What I'm going to do is have the balancing checked, to see if it is balanced to zero, and that being the case I'll have it refaced and lightened slightly. See where we go from there!
Cheers!
Richard,
could you measure the thickness of your 2.8 flywheel? As apparently this is where the difference is, (no surprise). I put the vernier caliper on mine today and it was exactly 1" (25.4mm).I also weighed it with spring balance at about 8.4Kg, but the thickness measurement is probably a better judge as to what it is. The difference is supposed to be significant (around 5mm) and I would like to know as if I do turn out to have the heavy 2.9 item I will source a 2.8 one before I reassemble the car.
Cheers,
Carl.
could you measure the thickness of your 2.8 flywheel? As apparently this is where the difference is, (no surprise). I put the vernier caliper on mine today and it was exactly 1" (25.4mm).I also weighed it with spring balance at about 8.4Kg, but the thickness measurement is probably a better judge as to what it is. The difference is supposed to be significant (around 5mm) and I would like to know as if I do turn out to have the heavy 2.9 item I will source a 2.8 one before I reassemble the car.
Cheers,
Carl.
For Mike, (maybe to clarify things in my head a little too). 
Here are a standard 2.9 flywheel (dirty manky one) and the flywheel from my S3 side by side. The differences suddenly are very clear.
I weighed them both again with the spring balance and the difference is 3Kg. The standard 2.9 being approx 11.5Kg and the S/2.8 item coming in at approx 8.5Kg.
This is the first time I have actually put the two side by side for comparison so thought maybe the pics would be useful for future reference.
Carl.
Here are a standard 2.9 flywheel (dirty manky one) and the flywheel from my S3 side by side. The differences suddenly are very clear.
I weighed them both again with the spring balance and the difference is 3Kg. The standard 2.9 being approx 11.5Kg and the S/2.8 item coming in at approx 8.5Kg.
This is the first time I have actually put the two side by side for comparison so thought maybe the pics would be useful for future reference.
Carl.
Ceejay73 said:
For Mike, (maybe to clarify things in my head a little too).
Thanks Carl, from your two flywheels do you reckon the ring gear is identical.... same number of teeth/diameter and ends up in the same position relative to the back of the engine block? ETA, just looked at last photo again, looks like ring gear is in same relative position?
PS nice rack of spare keys
Edited by phillpot on Wednesday 30th July 20:43
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