[Healeys] Overdrive pressure or clutch slip Step 2!

[Simon Lachlan]

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 <mailto: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 <mailto:michaelsalter at gmail.com> > 
Sent: Monday, April 22, 2024 3:21 PM
To: Simon Lachlan <simon.lachlan at alexarevel.plus.com <mailto:simon.lachlan at alexarevel.plus.com> >
Cc: Healeys <healeys at autox.team.net <mailto: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 <mailto: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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