10 replies to this topic

[JimmyB]

Hi,

 

I am just finishing up an engine build on a 1310 'fast road' build and have noticed that the clutch diaphragm and back plate don't seem to be perfectly concentric to the flywheel. Everything is new so i'm thinking the drive straps are not in the right position to hold everything central. I did ask the engine builder to check this when dynamically balancing. They do outsource their balancing to another firm and it appears they haven't centralized the clutch prior to balancing.

 

You cant quite tell from the photo but the diaphragm is offset towards where they have removed a fair bit of weight from the flywheel which all adds up if the extra weight is biased that way. Has anyone come across this issue before? What would be the best course of action? I really don't want to take the engine apart again and get the whole lot redone if i don't have to. Can I just get the flywheel assembly balanced with another crank to get it close?

 

Any advice would be appreciated.

 

Cheers,

 

James

Attached Files

•  Clutch missalignment..jpg   25.1K   42 downloads

[Spider]

Have you fitted the correct dowelled type bolts and have you checked the drive straps are the same length?

It does look a way off form where it should be.

 

<EDIT: If you have to change the flywheel and other parts, providing each item was balance in a proper process initially, then you should be able to have a flywheel and diaphragm balanced on their own to give satisfactory results. >

Edited by Moke Spider, 19 April 2017 - 03:27 AM.

[JimmyB]

The drive straps and bolts are new and are the 3 strap race type. I got them from MED or swiftune I forget which.i didn't check the length as they are new and from a reputable source. The bolts have a close tolerance shank that is a very tight fit on the straps. With the strap bolts loose there is still a slight movement of the diaphragm. I'll contact the balancing place and see exactly what they did so I know the best course of action. With it how it is i can definitely see a lot of vibration happening as soon as I press the clutch pedal.

[Spider]

OK, so doesn't appear to be an installation issue then.

 

In regards to balancing, the 'proper' method of doing it is to start off with the crank and balance that on it's own, then add one piece at a time, with the flywheel being third last, the backing plate being second last and the diaphragm being the last item, balancing at each additional item as added in. In this way, a flywheel should be able to be balanced separately and then fitted while still maintaining acceptable balance with the other parts.

 

If however, all the rotating parts were assembled as one unit and then balanced, you might be in trouble here.

[JimmyB]

Yeah that's what I am afraid of as there is no evidence of weight being removed from anywhere other than the flywheel. I'll ring around and post my findings when I know what was done.

[nicklouse]

to be honest the diaphragm was never balanced. but was marked with an A to align with TDC on the flywheel.

also as it has little mass in relation to the rest it has little effect.

[JimmyB]

That seems fair nicklouse, my main worry is that its not concentric so will wobble horrendously when the clutch is depressed, and if it was made concentric would throw the balance out. There must be a way to confirm it is or isn't concentric before I start taking things too far apart.

[JimmyB]

Does anyone else have any thoughts on this? Do people usually just bolt the straps straight up without any thought to how central everything is when they replace their flywheel or drive straps? There isn't really much info out there except for a comment i read in Dez Hammil's performance A-series book where he tells you to ensure everything is set up on a lathe to get an accurate centre.

[nicklouse]

cant quite tell if you have tightened every thing up yet. do so.

 

a triangle is self aligning.

 

so if the holes are in the right place on the fly wheel and the holes are in the right place on the back plate.

 

and the straps are of equal length then everything has to be aligned.

[JimmyB]

With everything done up it is still miss aligned. Even when I undo the strap bolts slightly at the flywheel end to allow movement and try to hold it central when i do the bolts up progressively. I'm not sure what could be amiss and if i should just use it how it is and see if i get clutch judder or not.

[Northernpower]

With everything done up it is still miss aligned. Even when I undo the strap bolts slightly at the flywheel end to allow movement and try to hold it central when i do the bolts up progressively. I'm not sure what could be amiss and if i should just use it how it is and see if i get clutch judder or not.

Unless its manufactured incorrectly it will align to the flywheel (providing you've used the correct shoulder bolts) simply because you've got three equal length straps holding it. I suggest you fit it and then working through the starter motor aperture fix a piece of welding rod adjacent to the pressure plate and rotate the flywheel by hand for a full revolution and look to see if there's any deviation between the rod and the pressure plate. It may just be the centre of the cover is not central.