Flywheel step very crucial ?

[relaxedcruiser]

Hi all,
had a bit of a disappointing day today - got the flywheel machined - but instead of the agreed 0.5 mm / 0.197 in. step
I measured only 0.36 mm / 0.0141 in
Unfortunately I had to travel about two hours one way to that shop as the local engine builder is already in christmas mode and was not available. I don't want to do that trip again.
Probably not the best time during the year to do such things - but that's annother story and there is a reason behind it.
So I'm a bit stressed - being a fussy type type of mechanic I really want to have things as per the WSM and that is 0.5 mm bang on - and not more or less.
But in the real world, the status is now like a each side 0.07 mm / 0,0027 in worn clutch plate. Not much at all.
I really think that between different clutch manufacturers, the standart thickness of a clutch plate varies probably in that range if not more.

So to stress - or not to stress - and just get that thing with the all nice and shiny new Exedy HD clutch back together ? Otherwise I would just get that flywheel on a lathe and machine those missing 0.14 mm / 0.055 off for peace in mind.
The HD pressure plate will probably make easily up for the lost preload.... so I'm between those decisions...

What are your thoughts ?

 

[Hardy]

I would only turn down enough material to remove the groves. The 0,5mm measurement specified by Toyota might be the maximum. But I'm not a engine builder.

 

[relaxedcruiser]

In my slightly tired state I used a precision straight edge and new feeler gauges to measure - and I was wrong - it is even worse.
With the dial gauge it is only 0.29 mm / 0,0114 in

 

[duncanrm]

Interesting.. I just had a flywheel for a 2H machined (a week ago).. I asked them to preserve the step and said I wasn't sure what the spec was and they nodded sagely, looked at the flywheel, and asked if it was a from a Landcruiser - which gave me confidence.

Its come back at point 0.63mm. Opposite problem to yours. (straight edge/feeler gauge)

I am fitting a genuine Aisin clutch over Christmas, I really dont want to be going back in there any time soon so I am doing rear main seal, thrust bearing, spigot bearing, and trans input seal at the same time. In short, like you I'd want to awfully sure of the impact the step change will have so I'm not going back in prematurely..So I am following to understand if my oversize step is going to be an issue.

No useful thoughts though sorry.

 

[Eurasiaoverland]

I assume you've upped the engine output and hence want an HD clutch, in which case you want to give it the best chance of performing well... I would be getting that step height corrected. I think my 15B flywheel came with a 0.60 mm step.

I had a different problem to you: I kept the correct step but the lathe did not take out the heat discolouration (PO must have cooked it). So I bit the bullet and bought new. The last thing you want with a new engine, clutch and transmission is clutch judder or slipping.

 

[relaxedcruiser]

Interesting.. I just had a flywheel for a 2H machined (a week ago).. I asked them to preserve the step and said I wasn't sure what the spec was and they nodded sagely, looked at the flywheel, and asked if it was a from a Landcruiser - which gave me confidence.

Its come back at point 0.63mm. Opposite problem to yours. (straight edge/feeler gauge)

I am fitting a genuine Aisin clutch over Christmas, I really dont want to be going back in there any time soon so I am doing rear main seal, thrust bearing, spigot bearing, and trans input seal at the same time. In short, like you I'd want to awfully sure of the impact the step change will have so I'm not going back in prematurely..So I am following to understand if my oversize step is going to be an issue.

No useful thoughts though sorry.

Hi Duncan, that's funny - we are doing really same stuff same time - I'm also doing rear main seal and g/box input plus the usual bearings.
I'll pay the local engineering shop a visit tomorrow, I hope that he can just skim the 0.21 mm of the step - it won't be as shiny as the machining but should be absolutely good enough to mount the pressure plate. In your case you get 0.13 mm more preload - which feels ok to me.
Just out of interest: How thick is your new Aisin clutch plate ? I measured the Exedy one at 8.7mm while the old one is still 8.00mm That is with not compressed leaf springs (the ones between the friction material)

I assume you've upped the engine output and hence want an HD clutch, in which case you want to give it the best chance of performing well... I would be getting that step height corrected. I think my 15B flywheel came with a 0.60 mm step.

I had a different problem to you: I kept the correct step but the lathe did not take out the heat discolouration (PO must have cooked it). So I bit the bullet and bought new. The last thing you want with a new engine, clutch and transmission is clutch judder or slipping.

That is exactly what happened - after a long time not touching the full load screw - I did it and together with the intercooler that thing is just pulling so nicely .....but on uphills the clutch started to slip.
I really dont know at which power output I am - but I believe that I'm well over the stock torque values.
Sort of hesitating to get it on a dyno, and have some random bloke reving the s*** out of my engine - I'm really not after top HP I never rev past 3000 if at all reaching it anyway.

 

[duncanrm]

Just out of interest: How thick is your new Aisin clutch plate ?

I am hopeful its arriiving with all my other parts on Wednesday.. I will report back.

 

[relaxedcruiser]

Little update here, put everything back together WITHOUT getting the step height corrected. I was literally parking in front of the engineering shop but decided not to get the step lathe machined. I did not want to risk any misalignment between the surfaces, they really need to be done in one go.
In real life terms the missing 0.2 mm preload are not going to change much. I measured the total preload with that clutch at about 4.5 mm. Now it is at 4.3mm thats about 95% The HD clutch plate has 20% more clamping force....that should work out ok.
Still lessons learnt - next time I'll take my own dial gauge and check it on the spot.