BJ7 Flywheel Help

[BG 62AH]

Hi,

I am hoping that someone would be able to help me out with a little advice on a flywheel for a 62 BJ7. I need to resurface the flywheel as part of a clutch repair that I am doing. The flywheel displays fairly significant wear that is about .025 into the face of the flywheel. The damage was caused by a wornout clutch plate (and its rivets).

The flywheel is currently about 1.250 thick. After resurfaceing, I feel it will be approx 1.220. Is there a spec on how much can be machined/ground off before the flywheel needs to be replaced? Will the 1.220 be acceptable, it seems like it would still be very strong?

Will removing this amount change any geometery in the clutch/pressure plate/release bearing relationship that will be of a concern? Or will I have to place a shim behind the flywheel to make up for the thinner flywheel (again this seems minimal).

I asked the machine shop that I am working with if the flywheel will need to be re-balanced after being resurfaced. They have stated that this is not necessary, is this true?

Will I need to balance my new pressure plate? This is the early BJ7 pressure plate with the larger dia clutch plate.

My release bearing is also really worn. I am replacing it. I believe this is just due to wear and neglect. Any special suggestions that are not included in the Haynes manual?

I truely appreciate any suggestions. Thank you.

 

[57_BN4]

Hi Bill,

shouldn't be a problem to machine the surface. If it hasn't been done before there will be a '1' stamped near the outer edge, this is the alignment mark for #1 at TDC and it will need to be marked on the back of the flywheel as it will be ground off during resurfacing. If there is no mark then you need to note which orientation the flywheel came off in otherwise it may vibrate when reinstalled. The factory balanced the entire rotating assembly as one unit which often catches people out since the flywheel can go on any orientation.

You shouldn't need to balance anything afterwards if it was in balance before and everything is refitted in the same orientation as before.

The release bearing is a bit temperamental and can fail quickly if not done properly. The plate which it presses against on the clutch needs to be flat, smooth and even so you'll probably have to get it surface ground with the flywheel/clutch and lap it on a glass plate until it is mirror shiny. Then you have to adjust the three fulcrum points on the installed clutch so the plate is dead even when the crankshaft is rotated. I couldn't re-stake the nuts to lock them properly once adjusted so ended up fusing them with the TIG welder.

Have a look at the release fork pivot pin/bushes too and replace them if worn.

The last issue is that the reproduction release bearing/blocks are of dubious quality so have a look on Ebay for a NOS AP one, they aren't that dear. There are at least three different types used on the Healey so you might have to wait till the right version for your car comes up.

Andy.

 

[Randy Forbes]

To accomodate one of the iterations my Healey's been through, I had 1/8" (.125") shaved off the contact face of the flywheel. I fitted an all-synchromesh MGC xmsn for a while, and with the shallowest release bearing I could find, it was *just* making contact. I guesstimated that an eighth of an inch would be better than zero, and there were no ill-effects.

A couple of years ago, I refitted the side-shift xmsn, and I'm still using the same altered flywheel. Hydraulic actuating systems automatically taking up the slack, when needed.

Cutting .025" should not be any cause for concern; leastwise I wouldn't give it a second thought

 

[BG 62AH]

Thank you for the help. Reallly appreciated.

 

[EV2239]

I'd have the flywheel balance as well as ground flat and then I'd have it drilled for the BJ8 spring diaphragm clutch and balanced as an assembly. This will make the car significantly smoother, slightly more response, will make the clutch lighter and gear changes easier. You'll be amazed at just how smooth the old Healey engine is.

TBH, there is such a big difference I'd never fit a new clutch and not balance it and the flywheel together. I've done my BJ7 this way and my TR3A has a lightened flywheel with a 4A clutch and is a better car for it.

While the flywheel is off I'd also fit the oil seal conversion to the end of the crankshaft if yours is as leaky as most.

 

[bob hughes]

I'd go along with EV on the rear oil seal conversion, best thing I ever did.



Bob

 

[BG 62AH]

Thank you for making these suggestions, can you tell me where you purchased the rear oil seal conversions. I do plan on replacing this, as I have perfect access with the flywheel out? I appreciate the suggestions.

 

[bob hughes]

Not sure on your side of the pond - try Moss, otherwise spend your dollars in good old Blighty and go to AH Spares or Dennis Welch or SC Parts of course other suppliers are also available ! ! !



Bob

 

[57_BN4]

+1 on fitting the seal kit. A bit fiddly to do but well worth the improvement. Also need a gasket for the rear plate as you'll need to remove that to cut away metal around the crank.

How about lightening the flywheel while you're in there? https://www.britishcarforum.com/bcf/showthread.php?86289-Lightened-flywheel-options

 

[tonyk]

SC parts are very expensive compared to the others.

 

[bob hughes]

SC parts are very expensive compared to the others.

True, but I sometimes wonder if there isn't a glitch in their system, I have not used them now for several years, but there prices were comparable when I wanted a new clutch and rear oil seal. They are a fast hour away from me so if my local supplier ( Rawles) does not have it then I would visit them after a phone call.




Bob

 

[tonyk]

YEP. I've noticed Rawles do a lot of stuff, more than I thought.

SC parts are not too bad when they have one of their VAT free sales,normal prices include this.

(evil EU dictated sales tax).

I have bought things from them, OK quality but, for instance, I was waiting 3 months last year to get a Putzke (?) tubular shock absorber set from them. The parent is a German company and they depend on that for supplies.