Mazda BT-50 Clutch Issues

Submitted: Tuesday, Sep 08, 2015 at 15:26
ThreadID: 130231 Views:7413 Replies:3 FollowUps:6
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Hi. I know there have been previous threads on the topic, but I don't think this particular "issue" has been discussed. I refer to replacement of the dual-mass flywheel with a solid flywheel. Everything I have read seems to suggest that this conversion, along with a heavy duty clutch kit, is a good thing.

I need to have 5th gear replaced in the gearbox, so while the box is out I am thinking about having the clutch replaced, as it seems to be getting a little low and now that I am towing a camper trailer the heavy duty option seems to be the way to go. (Obviously this will be more readily apparent once the box is removed.)

However, when I mentioned this to the local Ford dealer that services my vehicle it was suggested that this is NOT a good idea due to the added strain placed on the engine - particularly the crank shaft. He indicated that the heavy duty clutch & solid flywheel option would actually cause more trouble & expense than sticking with the standard components that the vehicle was manufactured with (either OEM or after-market, but replacing like with like rather than going the heavy duty route). So if anyone has any knowledge of issues caused by installing heavy duty replacement parts as per above I would be extremely interested to hear what you have to say. And just for the purposes of clarity the vehicle is a 2007 model with the 3 litre diesel motor, now sporting a 3" exhaust & a steinbauer chip.

Thanks,

Shane
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Reply By: TomH - Tuesday, Sep 08, 2015 at 15:33

Tuesday, Sep 08, 2015 at 15:33
Is the fifth gear failing a result of towing in it.
If so the best result would be to get the heavy duty clutch and tow in 4th in the future
AnswerID: 590138

Follow Up By: Member - shane r1 - Tuesday, Sep 08, 2015 at 18:16

Tuesday, Sep 08, 2015 at 18:16
I had 2 bt50's that were popping out of fifth, this was a recognised warranty issue and the whole box was changed under warranty.
Also Does the heavier clutch also make this model easier to start off from stopped?
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Follow Up By: Lockie - Tuesday, Sep 08, 2015 at 21:11

Tuesday, Sep 08, 2015 at 21:11
Thanks for the response Tom, but my query is not about the reason 5th gear failed - I already know why, and yes it was operator error. I am simply inquiring if anyone has any knowledge regarding possible adverse ramifications to the motor if I do fit a solid flywheel and heavy duty clutch system. From what I have been told, you can't fit a heavy duty clutch if you have a dual-mass flywheel, so a change to a solid (single mass) flywheel is required as part of the "upgrade". However, I have been told that this will cause problems with the crank shaft and other connected components as they were not designed to operate with anything other than the dual-mass flywheel.

Cheers,

Shane
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FollowupID: 858161

Follow Up By: TomH - Tuesday, Sep 08, 2015 at 22:04

Tuesday, Sep 08, 2015 at 22:04
Yes the Dual mass is designed to take the shocks from starting and transmits less shock to the crankshaft and other engine components.

Lots of Patrol owners have changed them and seem to keep going but dont know about the Mazda.

Perhaps there are Mazda forums that may help
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Follow Up By: GREG T11 - Tuesday, Sep 08, 2015 at 22:19

Tuesday, Sep 08, 2015 at 22:19
Have a look at Wikpedia explanation, seems to match what the dealer is saying, but being more likely the most expensive replacement (and no doubt more frequent ) I would approach a PROFFESSIONAL gearbox repair shop and get a second opinion .
Gabba Gearboxes in Brisbane is good place to start if you live up this way.
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FollowupID: 858166

Reply By: 671 - Tuesday, Sep 08, 2015 at 22:56

Tuesday, Sep 08, 2015 at 22:56
Shane

During the years that I worked in the motor industry, I saw a couple of crankshaft thrust bearings worn out by clutches with heavier than standard springs. The problem is when the clutch bearing moves forward and pushes on the clutch diaphragm, it also pushes the flywheel and crankshaft forward. The crankshaft bearing is only designed to take a certain amount of pressure and exceeding it can lead to excessive wear.

It is the same old story, when you change something on a car it will always have some effect on something else.
AnswerID: 590165

Reply By: Ron N - Thursday, Sep 10, 2015 at 20:59

Thursday, Sep 10, 2015 at 20:59
Lockie, you have to weigh up the risk of going to a heavier duty clutch and possibly developing crankshaft issues - as compared to the ongoing costs of maintaining the DMF - which are nearly always noted as an expensive and complex answer to the relatively low possibility of crankshaft damage.
As a previous poster mentioned, a talk to a professional clutch crowd who have installed multiple numbers of HD clutches in Mazdas/Fords would be in order.

As general rule, manufacturers appear to be producing poorer quality OE clutches today than they did in the past.
Part of the problem has been the total elimination of asbestos (in itself, a necessary thing for health and safety) - but the replacement clutch materials of standard clutches seem to fall far short of the satisfactory service life of most of the old standard asbestos clutches.

As a result, HD clutches seem to be a good investment, particularly when engine power has been increased - off-road work is becoming a regular feature of your vehicles useage pattern - and towing is also a regular feature of that useage pattern.

Cheers, Ron.
AnswerID: 590231

Follow Up By: Lockie - Friday, Sep 11, 2015 at 11:47

Friday, Sep 11, 2015 at 11:47
Thanks for that Ron. I actually had a chat with the local brake & clutch guy yesterday - I got on to him via Google through an advert for a Solid Mass clutch kit. It turns out he runs the same vehicle as me and tows a horse float on a regular basis. He basically said that a solid mass fly wheel is not worth the hassle as they send vibrations throughout the entire car at low revs & require changing down to lower gears more frequently. His opinion was basically that people need to learn how to use the clutch properly (especially when towing) and that the dual mass flywheel was not the monster that most people think it is, it's just poor clutch technique that causes most issues.

On that basis I think I'm going to stick to the original set-up, as I really don't want to be spending a heap of money having the motor reconditioned anytime in the near future as a result of making the change. As they say "Act in haste, repent at leisure". I'll just have to investigate the availability of better a better clutch & pressure plate that is compatible with the Dual Mass flywheel (if there is such a thing :-) ).

Cheers,

Shane
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FollowupID: 858241

Follow Up By: Ron N - Friday, Sep 11, 2015 at 12:42

Friday, Sep 11, 2015 at 12:42
Thanks for the feedback, that is interesting. Essentially, there are only three ways (well, four, because two are related) that drivetrain vibrations can be produced from a clutch, flywheel and crankshaft combination.

One way is from flywheel and clutch imbalance, which can be cured by removal and proper balancing of the complete clutch and flywheel assembly when imbalance is suspected or noted.

The second way is from a flywheel that is not running true (wobbling). Measurement of flywheel runout is a critical feature of engine building and overhaul - and one measurement that is often ignored during overhauls. A flywheel with excessive runout can be caused by either a buckle in the flywheel or a bend in the end of the crankshaft.

The third way is torsional whip in a crankshaft - a very common source of low-frequency drivetrain vibration. It is caused by poor crankshaft design with inadequate resistance to varying torsional stresses, and it can also be amplified by the material the crankshaft is made from.

The fourth way is less common today and is caused by longitudinal whip in a crankshaft. This is caused by inadequate crankshaft support and was more common in the days of inadequate numbers of main bearings - as in 3 bearing mains in 4 cylinder engines.

I can see where the clutch bloke is coming from, by talking about vibrations created by heavier solid flywheels.
Nearly all engines and crankshafts today are quite high-tech in their design and materials, and they are much much lighter than they ever used to be.
As a result, altering the weight of a component such as a flywheel can immediately create torsional whip problems in a crankshaft that is lighter than ever, and which has narrow design parameters than never considered a heavier flywheel.

I'm not sure about the 2.5L Mazda engine in your vehicle, but I know the new Ford Duratorq engines now utilise a forged steel crankshaft (which Ford claim is "lighter than previous models" - as always!).
A cast iron crankshaft has more weight and rigidity as compared to a lightweight forged steel crankshaft, and the steel crankshaft has a tendency to be "springy", thus creating the potential for introduced crankshaft torsional whip, if a much heavier flywheel is fitted than the original design intended.

Cheers, Ron.
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FollowupID: 858244

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