[Healeys] Overdrive pressure or clutch slip Step 2!
Bob Spidell
bspidell at comcast.net
Fri Apr 26 12:16:43 MDT 2024
I lost the plot (not unusual): Have we determined, for sure, that the
problem is 'slippage,' which would most likely be due to wear in the O/D
cone clutch? Or have we determined that Simon's O/D is 'dropping out'
which, to my thinking, would be caused by the 8 strong springs
overcoming hydraulic pressure (and causing the brake ring to slip or
disengage, no?).
On 4/26/2024 10:03 AM, Hank Leach wrote:
> Ok the pressure gauge implies that the hydraulic system is in good
> condition and that will effectively produce overdrive when the cone
> clutch is pushed forward in the box. When OD is *not required* the
> solenoid is inactive and the 8 springs in the unit have to keep the
> cone clutch in the rearward or in direct drive position.
> These are stout springs and normally are strong enough to engage and
> hold the clutch without slipping, overcoming the hydraulic
> influence-which should be draining at this point..However if the
> springs are misinstalled in the wrong position or not properly mounted
> on their tabs upon assembly or previously "coil bound" from that
> procedure or wear, they will not function to keep direct drive solid
> without slipping.
> The clutch material should outlive all of us and is not normally, or
> easily, replaced. All you have to keep the car in direct drive are
> those 8 springs and their pressure.
> -Hate to say it but if the re-assembly was defective, the gearbox
> needs to come out and OD removed and checked for correct spring fit-at
> that time I would replace the 8 springs (about $100 from Moss) as a
> routine repair. (photos from my article in AH Mag) Hank
>
> From: "Bob Spidell" <bspidell at comcast.net>
> To: <healeys at autox.team.net>
> Sent: April 26, 2024 at 9:37 AM PDT
> Subject: Re: [Healeys] Overdrive pressure or clutch slip Step 2!
> Spitballing ...
>
> I went through my BJ8's O/D a few years ago. The car had 64K miles on
> it when I bought it (approx. 1984), and about 215K* miles on it when I
> did the overhaul. The O/D cone clutch was serviceable--and AFAIK
> didn't slip--and I reinstalled it. If new cone clutches were readily
> available I /might/ have bought new, on principle, depending on cost,
> but all I could find was a re-manned one from DWM. To me this implied
> they didn't often need replacement, whereas known wear items like the
> accumulator are offered by several vendors (I would have installed one
> with an O-ring if I'd known about it).
>
> All this to say, unless the car has extremely high mileage and/or the
> O/D has been abused somehow I'd be surprised if the clutch is worn 'to
> the bone.' Obviously, slippage in the cone clutch would cause Simon's
> car's symptoms; if so, the problem will get progressively worse (and
> more consistent). I think one way to test an O/D clutch would be to
> really lug the car pulling an uphill grade in 4th-O/D, if the clutch
> is going to slip it would do it then (as would a worn engine clutch).
> There's also a (remote) possibility that, for some reason, O/D
> pressure fluctuates during driving.
>
>
> * Anyone else have this many or more known miles on a Healey?
>
> bs
>
>
>
> On 4/26/2024 4:51 AM, Michael Salter wrote:
>
> "What I can’t do is understand the leap to the OD cone clutch?"
> Fair question.
> Between the flywheel and the rear wheels there are only 2 places
> where "slippage" can occur these are the clutch and the
> overdrive's cone clutch.
> The gearbox, other than the cone clutch in the overdrive, is a
> go/no go arrangement, i.e. no "slippage".
> The rear wheel splines, believe it or not, can also produce
> "slippage " if they are in really bad condition but I presume that
> isn't the case here.
> The test that you just completed resulted in no driveline slippage
> when the overdrive was disabled.
> You are reporting slippage when the overdrive operating system is
> enabled so it follows that further diagnosis of that is required.
> Yes, your next step would be the same test drive, i.e. full engine
> torque on an uphill grade, to confirm that the slippage issue has
> returned now that the overdriveoperating valvehasbe re-installed.
> I would do this test drive BEFORE making any adjustments to the
> overdrive valve or solenoid in order to confirm that meerly
> installing the overdrive operating valve resulted in the slippage
> issue returning.
> Hope the weather improves, beautiful day here.
> M
>
> On Fri., Apr. 26, 2024, 7:24 a.m. Simon Lachlan,
> <simon.lachlan at alexarevel.plus.com> wrote:
>
> Hi, Thanks for this.
>
> Not sure I understand fully.
>
> Once I’d finished the test drive with the OD operating valve
> out of the car, I returned the rod, ball, spring etc and put
> in the gauge rather than the nut. And got 500+ psi.
>
> What I can’t do is understand the leap to the OD cone clutch.
> Not arguing…just saying no comprende. As I sat in the car, I
> was thinking that the function of the OD seems OK and that
> it’s being interfered with by something in its
> circuitry……relay, solenoid or throttle switch. That’s probably
> wishful thinking as I really don’t want to be swimming in
> those waters.
>
> I did, as a matter of course, clean out the tiny hole in the
> rod but didn’t detect any blockage….which doesn’t mean much as
> something minute could have been inside and been washed away
> by the detergent/hot water then WD40…..
>
> After someone’s advice – some time back – I’ve got another rod
> whose aperture has been drilled out to 1.5mm. This was “to
> allow the OD to disengage faster”. Don’t recall if I tried it.
> Could that rod be any help here?
>
> The ball seems to be sitting square on its seat and the tip of
> the rod, where the ball sits, is not worn or chipped.
>
> Residual pressure….. goes to 500+ when I switch OD ON and
> stays there until, engine and switch OFF, I energize the
> solenoid a few times whereupon it drops to zero.
>
> Another test drive(s) seems called for. But the hood is off to
> enable access and the forecast is grim for the next week.
>
> Very open to more suggestions. Thanks,
>
> Simon
>
> *From:*Michael Salter <michaelsalter at gmail.com>
> *Sent:* Friday, April 26, 2024 12:14 AM
> *To:* Simon Lachlan <simon.lachlan at alexarevel.plus.com>
> *Cc:* Healeys <healeys at autox.team.net>
> *Subject:* Re: Overdrive pressure or clutch slip Step 2!
>
> Okay, then it is confirmed that neither the clutch (on the
> flywheel) nor the overdrive cone clutch (in it's normal drive
> condition) are producing the slippage.
>
> From this we can conclude that even when the overdrive
> solenoid is *_not_* energized the slippage is occurring at the
> overdrive cone clutch and that for some reason hydraulic
> pressure is finding its way into the overdrive operating
> cylinders even when the overdrive operating valve is closed.
>
> This can be caused by leakage past operating the valve or
> residual pressure.
>
> The question of residual pressure can be resolved by checking
> that the bleed hole in the bottom of the long overdrive valve
> push rod is not blocked.
>
> Whether or not hydraulic pressure is leaking past the
> operating valve ball can be checked by ensuring that the ball
> is clearly on its seat when the operating valve is *_not
> _* energized.
>
> M
>
> On Thu., Apr. 25, 2024, 3:38 p.m. Simon Lachlan,
> <simon.lachlan at alexarevel.plus.com> wrote:
>
> Of course. Isn’t that how I got the 520psi?
>
> *From:*Michael Salter <michaelsalter at gmail.com>
> *Sent:* Thursday, April 25, 2024 6:19 PM
> *To:* Simon Lachlan <simon.lachlan at alexarevel.plus.com>
> *Cc:* Healeys <healeys at autox.team.net>
> *Subject:* Re: Overdrive pressure or clutch slip Step 2!
>
> Question ... when you got home and did the pressure test
> I presume that was AFTER you had put the valve with the
> "top hat", ball, spring and valve rod cap and washer back
> into position?
>
> M
>
> On Thu., Apr. 25, 2024, 12:29 p.m. Simon Lachlan,
> <simon.lachlan at alexarevel.plus.com> wrote:
>
> So, here is Michael’s “Step 1” completed. (See his
> email, below).
>
> 1. Removed the operating valve and, just for luck,
> disconnected the two wires into 3^rd /4^th switch.
> Took the car for a spin. Up/down longish/steepish
> hills, 10 miles on motorway. Various rpm…..no
> slippage at all.
> 2. Had a puncture…..nail in tyre. Rear RHS. Flat as a
> pancake at once. Nearly onto rim. Nail! I imagine
> the inner tube is shredded and the tyre may be a
> write-off. (Usually are!). Anyhow, I bore you with
> this as I’m convinced that I’d never have got the
> wheel off without the little scissors jack which I
> carry to get the car up the first few inches until
> the Healey jack comes into play. Just a suggestion…….
> 3. Got home and jacked car up to test pressure.
> Steady at 520psi which, I recall, is plenty.
> Stayed at 520 across rev range. Dropped very
> slowly once engine was off and dropped to zero as
> I engaged/disengaged OD a few times. Which is
> normal I think?
> 4. Solenoid makes a robust “click” when it should and
> engages the OD when activated.
>
> So what’s a sensible “Step 2”??
>
> I have been urged to check the setting of the Throttle
> Switch (TS). Assuming that the slippage returns (and
> why wouldn’t it?), I’ll short the TS out to see if
> that fixes it. If it does, I’ll check the adjustment.
>
> Suggestions would be more than welcome……I do dread
> having to take that box out again. I’ve got a very
> adequate ramp and a very strong volunteer(?) but,
> regardless of all that, it’s still quite a task. And,
> like a few of us, I’m not as young as I once was. I’ve
> always enjoyed the lines from the manual which I
> reproduce, below. ���Gently ease”!?!
>
> Thanks, Simon
>
> *From:*Michael Salter <michaelsalter at gmail.com>
> *Sent:* Monday, April 22, 2024 3:21 PM
> *To:* Simon Lachlan <simon.lachlan at alexarevel.plus.com>
> *Cc:* Healeys <healeys at autox.team.net>
> *Subject:* Re: [Healeys] Overdrive pressure or clutch slip
>
> *_Correct diagnosis is 1/2 the repair!!_*
>
> First you need to confirm whether the clutch (on the
> flywheel) or the overdrive is causing the slippage.
>
> To do this you ABSOLUTELY MUST disable the overdrive
> as a badly misadjuster overdrive operating valve can
> produce similar symptoms.
>
> To do this I would remove the overdrive operating
> valve completely. (There are other ways but this is
> absolutely definitive).
>
> Now drive the car up a long hill where you are amle to
> use full throttle at around 3000 RPM (maximum torque)
> for a few seconds. If it is the clutch (on the
> flywheel) that is causing the slippage these operating
> conditions. Test this a few times to be sure.
>
> If there is no slippage we have confirmed that the
> overdrive clutch is at fault.
>
> Step 1 completed. Please report results. MS.
>
> On Mon., Apr. 22, 2024, 8:08 a.m. Simon Lachlan
> via Healeys, <healeys at autox.team.net> wrote:
>
> You may recall the very extended overdrive and
> clutch saga last year. Long story short(ish)…
>
> OD was slipping in and out depending on oil
> temperature.
>
> Correctly diagnosed pressure. Checked with gauge.
>
> Attempted rebuild…going only so far as
> accumulator and related seals.
>
> Stymied as could not get pump out. Turned out
> to have been “fixed” at some stage with some
> form of “chemical metal” which was coming
> loose/apart.
>
> Took it up to OD Spares who fixed it..new
> housing etcetc
>
> Why not a new clutch I thought? Sensible while
> you’re in the area looking at a 30+ yr old item.
>
> New clutch…no good. Noisy, wouldn’t
> engage/disengage/play at all.
>
> Gearbox out again.
>
> Refit clutch. Presumed I’d made some
> beginner’s mistake.
>
> Refit gearbox…no good. Same
>
> Can’t recall whether I tried again. Lost count
> and enthusiasm by now.
>
> Turned out that the new clutch kit was
> defective. (Thanks Mirek) (Genuine B&B from
> AHSpares).
>
> New one did work.
>
> Saga over until yesterday.
>
> Same sort of symptoms…..
>
> All’s well for first 10 or so miles. Then the
> dreaded slippage(?) starts. But it’s not quite
> the same. Reminds me more of a slipping
> clutch. (But NO smell)
>
> Symptoms continue if it’s in or out of OD.
>
> Symptoms reduce at speed.
>
> Yes, plenty of oil. Over the full mark. Looks
> very clean. Pretty sure it’s 40wt
> non-detergent topped up with 30wt
> non-detergent. (Or vice-versa). Am confident
> in state of the filter, magnets etc.
>
> No, I have not pressure tested it yet and yes,
> I dread restarting the whole bloody process
> all over again. I’m not sure I can face taking
> the box out again once, let alone multiple times.
>
> What I want and experience tells me I’m
> unlikely to get is a miracle cure!
>
> One initial question…..do OD relays either
> work or not work? ie, can the relay hover
> between on and off which might lead to the OD
> coming in and out? I think that could happen
> if the switch is off but the unit still hasn’t
> got the message to disengage from the bulkhead
> switch.
>
> And a supplementary….how do I bench test the
> relay?
>
> Simon
>
>
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