[Healeys] Overdrive pressure or clutch slip

Michael Salter michaelsalter at gmail.com
Mon Apr 22 15:39:51 MDT 2024


Yes the solenoids can cause all sorts of problems.
Around the time you last worked on your overdrive OD Spares were having
problems with a batch of solenoid as I recall. May want to check with them.
If the "pull" coil or points in the solenoid have burned out, usually
because the adjustment is done incorrectly,  the hold coil will have
insufficient power to move the solenoid armature to the "engaged" position
consistently.
After you have confirmed that the vehicle clutch ( the one on the flywheel)
isn't slipping it's time to move onto checking the overdrive.
You can eliminate the possibility of problems within the unit by manually
engaging overdrive by pulling up on the setting arm while on a road test
with the tunnel off (don't get caught up in the driveshaft because they
will probably have to put you into the coffin in pieces).
If there is no evidence of your "slipping " issue when the unit is manually
engaged then start looking into operating issues.
Haven't we been through this before?

M

On Mon., Apr. 22, 2024, 4:13 p.m. Simon Lachlan, <
simon.lachlan at alexarevel.plus.com> wrote:

> Alright…thanks for the replies so far. Still trying to get all my ducks in
> a row before I pick up the spanners.
>
> Next question,,,,solenoids. Do they fail 100% or can they wobble
> inbetween? Likewise, might give same symptoms. (Any straw worth  clutching?)
>
> And again, how to bench test a solenoid?
>
> Simon
>
>
>
> *From:* Roger Grace <roggrace at telus.net>
> *Sent:* Monday, April 22, 2024 4:27 PM
> *To:* Michael Salter <michaelsalter at gmail.com>
> *Cc:* Simon Lachlan <simon.lachlan at alexarevel.plus.com>; Healeys <
> healeys at autox.team.net>
> *Subject:* Re: [Healeys] Overdrive pressure or clutch slip
>
>
>
> Agree - I had to re read your note to be sure which clutch you were
> talking about.
>
> If you have the GB cover still on you, could disable the OD by
> disconnecting the solenoid - probably easier than removing the operating
> valve.
>
> Regarding testing the OD relay, yes as MS says they usually fail
> positively and usually the operating coil.
>
> To bench test:
>
> With a 12V supply on W1 and W2 you should hear a clear click for ON and OFF
>
> This would prove that the coil is OK
>
> Contacts not quite as easy to verify.
>
> Same test as above but an ohm meter on lowest scale across C1 and C2
>
> An anologue meter is preferable and you can see if there is any dithering
> when the contacts close. Operating should be positive and crisp.
>
> I would also be suspicious of the TS - they can have some weird failure
> modes and go out of adjustment,
>
> rg
>
>
>
>
>
>
>
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>
> On Mon, Apr 22, 2024 at 7:39 AM Michael Salter <michaelsalter at gmail.com>
> wrote:
>
> *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.
>
>
>
>
>
>
>
> On Mon., Apr. 22, 2024, 9:03 a.m. Michael Salter, <michaelsalter at gmail.com>
> wrote:
>
> In my experience relays are yes/no. No "maybe".
>
>
>
> 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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