[Healeys] Overdrive pressure or clutch slip

[Michael Salter]

*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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