[Healeys] Overdrive pressure or clutch slip Step 2!

[Michael Salter]

Well ...  here's where I believe we are so far.
Presuming that Simon completed the "full torque" test, with the overdrive
hydraulic system totally disabled correctly, we have confirmed that neither
the flywheel clutch nor the overdrive cone clutch slip to produce the
slippage issue that he is chasing.
If the weather improves and Simon can do another road test now that he has
reinstalled the overdrive operating valve *and * the slippage returns we
can be fairly confident that the slippage issue is related to the overdrive
hydraulic system.
Simon has reported that the pump produces over 500 p.s.i. which in my
experience is quite adequate for the overdrive to operate without slippage..
My bet is that either the operating pistons are not receiving that 500
p.s.i. when the valve is opened by the solenoid or something, perhaps an
incorrectly installed spring or 2 or badly leaking piston seals is
preventing the clutch from travelling to the "engaged" position.

M

On Fri., Apr. 26, 2024, 4:05 p.m. Bob Spidell, <bspidell at comcast.net> wrote:

> 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> <bspidell at comcast.net>
> To: <healeys at autox.team.net> <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 3rd/4th 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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