Slipping Clutch

I've been having dramas with a slipping clutch in my Baja.
The story goes like this.

Started slipping while I was down in Brisbane for TAFE.
That was fine, the clutch was very old and I guess it was well past it.
So I put a new clutch plate,a good second hand pressure plate, a new throw out arm and a new throw out bearing in the day before I left to come home.

On my way over the gateway the next day the clutch started slipping. Did this the whole way home, which made overtaking a PITA because every overtaking lane seemed to be on the uphill stretches.

That's ok. Must be the flywheel that's the problem. I took the flywheel out of my dad's deregistered Baja, it was recently machined about a month before we took it off the road.

Was fine for a day or two but working her hard at 100kph in forth up a hill coming out of Rocky the clutch started slipping again. I figured I might have an oil leak.

Pulled the engine again, installed a new rear main (wasn't actually leaking). Cleaned everything up again and put it all back together again. But on the way home from work today the bastard started slipping again!!!😬

So to recap I have a new clutch plate (over 8mm thick), new pressure plate, machined flywheel and a new throwout bearing. Everytime I've done it the clutch has been adjusted correctly and is not riding on the throwout bearing.

Can people please tell me what the hell is going on cause at this stage I'm completely stumped.


Also, does anyone know what the depth measurement for the flywheel should be between the face where the clutch runs and the face where the pressure plate bolts on.

Cheers in advance.


Smiley 😎

If it was ok before and its just worn out because of old age and wear and tear , you must have some mixed up replacement parts.
I would back thr cable right off, so that you can just get it into gear and then try it again,
But sounds like out she comes again🥲

ian.mezz wrote:If it was ok before and its just worn out because of old age and wear and tear , you must have some mixed up replacement parts.
I would back thr cable right off, so that you can just get it into gear and then try it again,
But sounds like out she comes again🥲

What do you mean by mixed up parts?

Pulling the engine out of a Baja is easy anyway! I actually enjoy how quickly it happens.


Smiley 😎

ian.mezz wrote:If it was ok before and its just worn out because of old age and wear and tear , you must have some mixed up replacement parts.
I would back thr cable right off, so that you can just get it into gear and then try it again,
But sounds like out she comes again🥲

There aren't many pieces to go wrong in a clutch,if the correct pressure plate is fitted along with a machined flywheel,new clutch plate & correct thrust race,free travel adjusted it should work.

Are you sure the problem is the clutch? Maybe check the rest of the drivetrain - I don't know what - splines on the brake drum maybe (although I think that would be noisy and stop working althogether straight away).

Just a thought.

beetleboyjeff wrote:Are you sure the problem is the clutch? Maybe check the rest of the drivetrain - I don't know what - splines on the brake drum maybe (although I think that would be noisy and stop working althogether straight away).

Just a thought.

The LHS drum was stripped. I also replaced this on the weekend. But the problem continues. It was only stripped halfway down the spline though.
I have a picture somewhere.


Smiley 😎

It wasn't stripped all the way down though. Seemed a little unusual to me. The spline still engaged on the good portion and there was no slipping of the spline.
Besides, when a spline fails they usually just go and don't grab again. Either that or it would be very notchy as it slipped over the splines. When the car slips it is very smooth, not notchy at all.



Smiley 😎

Maybe you're just spinning the tyres in every gear?! I have to say that I can't think of anything you seem to have done wrong. Are you sure that there is enough spring tension in the pressure plate?

I had the same thing happen to me in my beetle, it turned out to be the return spring for the throwout fork had broken, destroyed two good secondhand clutches before I found it

Is it a 6volt flywheel and clutch (early style) ? do you have BIG wheels ?

What size is the motor ?

Pressure plate was second hand....how much tension did it have??

Flywheel depth is 22mm I think, I may stand corrected as now I write it down 23mm sounds good too !!! DB should know for sure!

Pauld wrote:I had the same thing happen to me in my beetle, it turned out to be the return spring for the throwout fork had broken, destroyed two good secondhand clutches before I found it

Has a brand new return spring too.



Smiley 😎

Craig Torrens wrote:Is it a 6volt flywheel and clutch (early style) ? do you have BIG wheels ?

What size is the motor ?

Yes. It's a 180 6V one.

Running 30s at the moment. Has a 1300 6V swingaxle gearbox, with a 1600 single port with a stock 31PICT carb.



Smiley 😎

matberry wrote:Pressure plate was second hand....how much tension did it have??

Flywheel depth is 22mm I think, I may stand corrected as now I write it down 23mm sounds good too !!! DB should know for sure!

When I got home and put the flywheel in I also put a brand new pressure plate in too. Sorry, I forgot that in the little story above.


Smiley 😎

Gotta be the flywheel depth or major oil leak, (which of course you'd see), if the driven plate checks out ok, rivets on the clutch hub??🤪

matberry wrote:rivets on the clutch hub??🤪

What about them?



Smiley 😎

The only things that havn't been mentioned or changed maybe bowmans tube or cable, maybe binding.

It'll be somthing simple, it always is

I once had a bowman tube that the clutch cable had worn quite a groove in the top of, and the cable was starting to have trouble sliding through it. Could be something to check.

with a 1600 engine and bigger tyres a 180mm jobbie is sending a boy to do a mans job.
If you got a 200mm flywheel and clutch I'd be making the switch

Smiley wrote:

Craig Torrens wrote:Is it a 6volt flywheel and clutch (early style) ? do you have BIG wheels ?

What size is the motor ?

Yes. It's a 180 6V one.

Running 30s at the moment. Has a 1300 6V swingaxle gearbox, with a 1600 single port with a stock 31PICT carb.



Smiley 😎

That maybe your problem..........just to much load for the clutch. I know when I had my Baja (1989!) with a 6volt clutch, as soon as I went to 1600 (from1300) it started to slip......I then had to get the pressure plate springs "beefed" up. That helped, but as soon as I increased it to 1640 with Kadrons it let go again...just a thought.

Yeah. I might have a 12V one somewhere.
It's just that I ran the same engine, gearbox and wheels on my old Baja and it never had a single problem. And it got royally flogged every single time I drove it, never ever had the clutch slip once.

BTW, the bowden tube is also new and correctly adjusted.

I'm beginning to think that it has to be the depth of the flywheel. I had it done at work, the guy did it in the lathe, aren't they normally ground or something? If the surface of the flywheel was too smooth would this cause slipping?

Does anyone know the depth specs?


If I can't fix the problem I'm definitely going to change to 200mm clutch /flywheel. Seems a shame to waste all these new parts.

At least my bellhousing on the gearbox has already been clearanced.


Thanks to everyone for their input so far, and keep the ideas flowing. As I've said I'm completely stumped.



Smiley 😎

matberry wrote:Pressure plate was second hand....how much tension did it have??

Flywheel depth is 22mm I think, I may stand corrected as now I write it down 23mm sounds good too !!! DB should know for sure!

21mm.

Craig Torrens wrote:

matberry wrote:Pressure plate was second hand....how much tension did it have??

Flywheel depth is 22mm I think, I may stand corrected as now I write it down 23mm sounds good too !!! DB should know for sure!

21mm.

Ok thanks. I will measure on the weekend when i have the cage off to weld my new muffler on. It's not much more work after that to pull the engine 😂


Smiley 😎

Didn't notice the 180mm post....there's the problem definately not up to the job with a 1600 and big offroad rubber.

Gday all just a quick thought when they did the machine on flywheel did they take the same amount of the area that p/plate bolt holes are this has to be done other wise you are decreasing the pressure applied by increasing the tollerance between fwheel c/plate & p/plate
Ernie

ernie norley wrote:Gday all just a quick thought when they did the machine on flywheel did they take the same amount of the area that p/plate bolt holes are this has to be done other wise you are decreasing the pressure applied by increasing the tollerance between fwheel c/plate & p/plate
Ernie

Yeah. He machined both surfaces the same amount. Not sure if they are in spec though.



Smiley 😎

I ran a 180mm Clutch for years with 31's and it was fine. then it started to slip one day and i replaced it with another 180mm clutch kit which was brand new. engine was out and in for about 6 months slipping or shuddering etc. when i got my gearbox rebuilt. Customveedub fitted a 200mm clutch and flywheel. No problems since.

odd.

I cant help but think that you need a bigger clutch.

Anthiron wrote:I cant help but think that you need a bigger clutch.

It's now in the pipeline.


Smiley 😎

Hey Daniel, when you got the flywheel machined, was it machined to perfect mirror finish?

The usual mechanics shop make it almost like that, but rather than a smooth surface like what a 'well used' flywheel surface looks like, they have a very fine gritty swirl texture the whole way around, gritty enough that if you press the clutch plate into the flywheel with ur hands, u won't be able to slip it around. A mirror finish will slip if u press the clutch disck into it with ur hand (vw flywheel did).

Like... its got to be evenly rough enough to 'grab', but no where near mirror finish so it doesn't slip and of course, doesn't eat ur clutch plate much. I would send a photo of mine done at my mates mechanic shop (sent up the road), but i just fitted it and assembled the box back on my ricer.

the machine job should be rough enough to see concentric fine circles all the way around, and rough enough to slide ur finger nail across and feel a 'very' slight roughness. and still be fine enough of a machining job to see a shine to it but not necessarily see ur own reflection lol.

again, maybe the flywheel hasn't got enough meet, and its too old/ been too machined. 🙁

ok so the gearbox has been out did you fit a new seal and o ring in6o th4 flywheel it dont take much oil to tart the lip we all love not

OY!

Daniel, just thought, if u have a dirty amount of crankshaft END FLOAT, that will cause clutch issues. particularly up hills (crank slides back), or if u power on (crank gets thrown back).

Its one thing you haven't checked yet!!

http://www.vw-resource.com/endplay.html

bajachris88 wrote:Hey Daniel, when you got the flywheel machined, was it machined to perfect mirror finish?

The usual mechanics shop make it almost like that, but rather than a smooth surface like what a 'well used' flywheel surface looks like, they have a very fine gritty swirl texture the whole way around, gritty enough that if you press the clutch plate into the flywheel with ur hands, u won't be able to slip it around. A mirror finish will slip if u press the clutch disck into it with ur hand (vw flywheel did).

Like... its got to be evenly rough enough to 'grab', but no where near mirror finish so it doesn't slip and of course, doesn't eat ur clutch plate much. I would send a photo of mine done at my mates mechanic shop (sent up the road), but i just fitted it and assembled the box back on my ricer.

the machine job should be rough enough to see concentric fine circles all the way around, and rough enough to slide ur finger nail across and feel a 'very' slight roughness. and still be fine enough of a machining job to see a shine to it but not necessarily see ur own reflection lol.

again, maybe the flywheel hasn't got enough meet, and its too old/ been too machined. 🙁

I am suspecting this Chris.
When it was done at work it was done with a lathe and tool steel, so to a mirror finish.

I'm going to dig around my bits and see if I can find a 200mm flywheel and a starter to suit then have it ground properly and buy a new clutch kit.

Greedy, when I pulled the flywheel it's the type with no O-ring so I didn't replace it. Just the lip seal.


Smiley 😎

I was just out in the carport and saw the old flywheel out of the Baja sitting there. I grabbed the verniers and measured the depth.

24mm!!!

No wonder it was slipping.

I'll have to check the one that's presently in the car too and see if there's any variation from spec.



Smiley 😎

Smiley wrote:24mm!!!


Smiley 😎

Bingo

Sorry if its been said... whats the minimum thickness spec? take it thats the thickness of the flesh on the flywheel from the friction surface to the other side? (nuffin like a stupid question hey? cough cough 🙂 )

bajachris88 wrote:Sorry if its been said... whats the minimum thickness spec? take it thats the thickness of the flesh on the flywheel from the friction surface to the other side? (nuffin like a stupid question hey? cough cough 🙂 )

It's the distance from the surface where the pressure plate bolts on to the surface where the friction material of the clutch plate bears.

Matt posted somewhere earlier that it should be 21mm.

Thanks Matt by the way.



Smiley 😎