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New clutch. Flywheel grind?


hohocc

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Gidday, my old corolla needs a new clutch and I'm told by BNT that no clutch manufacturer will guarantee their clutch unless the flywheel is ground. First I've heard of this as it's a long time since I changed a clutch.

Is the flywheel grind a significant issue, or is it one of those stupid things that are put in place to give the maker an out if their product is no good? A bit like if you cross the road down the road from a pedestrian crossing and get hit by a tourist ACC will tell you you've been reckless and maybe you should shoulder the blame, when really the tourist was an idiot on the wrong side of the road and you didn't see them coming because they were going the wrong way?

I've got no objection to getting the grind done if it's likely to be a problem by not doing it, but if it's a case of there was this one clutch in 1975 that failed due to no grind with no other failures recorded since then I'll not bother.

Cheers.

 

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AFAIK it's always been the case that the flywheel needs to be ground for warranty and more so as it's just normal practice to have the flywheel ground when fitting a new clutch.

BNT here grind them for free when you buy a clutch kit from them.

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It's been that way for a while.  When I last got a clutch-kit from BNT I just said "yep, all good I don't give a fuck though as it's me doing it all so I don't care and then if it fails it's my problem and I'll buy a new one"

 

It's still going OK.  

If you're happy with the state of your flywheel (no crack or grooves or heat spots) and you're happy with no warranty on the clutch-kit.  Don't worry about the grind.  If you're at all apprehensive, get it done simply for warranty purposes.  Liability maaaaaaaaaan.

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FWIW, there's VERY VERY rarely such a thing as a warranty on a clutch (if it's a quality brand at least). I've sold well over a thousand by now surely and never had a signle one come back and bite me in the arse. it's almost always down to fitment errors that clutches give issue, so proceed with your own gut instinct etc IMO.

 

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Organics dont seem to mind too much about not getting a grind. ive replaced a few brass button ones without resurfecing and they havent shat themsleves or anything, its still something id recommend  giving the flywheel a nice flat surface instead of a worn sunked one.

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This is in trucks, same diff. the brass button also tends to be jammed on if you dont resurface due to the edge of the buttons not being worn some gentle persusion with revs,brakes and clutch usually beds it right in though.

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Yeah that sounds about like I thought, I'll see what I find when it's apart and probably just bolt it all together with fingers crossed.

Thinking waaaay back I can recall trouble with a new clutch release bearing that disintegrated into a pile of carbon straight after fitting (manufacturing defect), it's the only occasion I experienced any fault in a new clutch. 

Thanks for the responses.

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47 minutes ago, flyingbrick said:

Also, it doesn't necessarily have to be ground- a skim in a lathe with good tooling will also suffice (have done a few at work)

 

You'd be amazed how warped and worn the surface can become even especially on an old ladies daily.

fixed

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49 minutes ago, Seedy Al said:

BNT here do flywheel grounds for free when you buy a kit from them.

this maybe a trade only thing tho.........

 

however, the real question, is why wouldnt you?

Well, the car is my second car, which will become my daughters car when she gets her restricted. So if I put a clutch in it and it's not flash I have plenty of time, and another car to use while I pull it apart, possibly buy another new clutch (2 clutches from rockauto is still cheaper than 1 at trade from bnt, and for me at least the grind wasn't free), get a grind done, and put it together again. The car is probably only going to do another 20000km in our ownership so if by not grinding I risk it lasting less than the 100000km it may last by doing the whole job it's still more than likely to last longer than I need. It is also going to be driven by a young woman driver, so maybe it will last another 100000km, or it may have a high likelihood of giving someone a shunt at the lights in a couple of months which would write it off since it's of low value. The guts of it is that by doing it cheap it will probably do the job, the downside of doing it cheap is not that big, and if doing it "right" is unlikely to gain anything I won't take that route. If doing it right is more than likely to gain something then I'd do it right.

42 minutes ago, smokin'joe said:

would you install a new set of rings without honing the bores ?

Well, if I asked that question in a thread most of the responses would be "shit no", from people who had always honed, and there would be very few responses from people who had successfully done rings without honing from which I could make a decision! However there seem to be a lot of people out there who have done clutches, and it's about 50/50 as to if they grind or not. So no I wouldn't do rings without a hone, because I've got no experience of it and don't know of anybody that has, but I do have some (past) experience of doing a clutch without grinding, and there seem to be many others that do.

Really it's all about the job I expect the car to do once it's done, and the length of ownership that I foresee.

Thanks! 

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I didn't grind the Starlet flywheel when I did the clutch. No problems so far.

 

Then again the original clutch was still like new and doesn't appear to have ever caused the flywheel to have gotten hot.

 

With the forces/friction in a normal clutch, it will bed into the flywheel pretty quickly unless the flywheel is in serious need of a refinishing.

 

But if you can get it done for cheap/free and/or the flywheel is visually degraded then definitely go for it. A few dollars spent now can save hours of headache/wasted time down the road.
 

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I have had mixed experience with NOT skimming them, first one was ok but slipped under load and when trying to do skids. Second one was second hand everything and it was mint. 3rd the flywheel looked good so we didn't,mrs drove it to work and it was good, gave the car some beans on the on ramp and the flywheel side of clutch evaporated. 

Every other I've skimmed. So for the sake of $30 get it done,better than gearbox back out etc 

Edited by chris r
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I agree.

I'd seriously consider replacing any frost plugs in the back of the block at the same time too. And if the rear main looks even remotely wet and isn't rope I'd do that too. A little bit more coin, and a tiny bit more effort can pay dividends in the long run.

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