[Healeys] Overdrive pressure or clutch slip Step 2!

Fri Apr 26 15:09:58 MDT 2024

I’ve determined this much:-

After, say, 5 miles the car started slipping in/out of OD. It was a slower in/out than one would obtain with the dashboard switch. Sort of slipping in/out. Not “dropping out” so far as I can determine.

Per Michael’s advice, I removed the operating valve and charged up/down hills and along a Motorway. No slippage. At all. I concluded that the clutch on the flywheel was not slipping. (TG, as it’s practically brand new).

I then replaced the all the valve components under a gauge, jacked the car up/wheels off the ground and spun up the engine..into gear and switched on the OD. A steady 500psi which remained steady with the engine off until I engaged/disengaged the OD a few times. Which, from memory, is what one would expect. At this stage I cleaned out the rod. No dirt detected in little hole but could easily miss a flake of paint or a piece of swarf……

The solenoid makes a healthy click and visibly lifts the lever, say, ¼”. Appears(!) healthy. OD seems to go in and out as it should and not slip but wheels are off the ground so not a fair test for slippage. 

The whole OD was rebuilt, by OD spares about 15 years ago since when it’s had a fairly relaxed time and about 15,000 miles. Very seldom more than 80mph and usually cruising at 65mph on Motorway. The front, pump end, was rebuilt by ODSpares in late 2021. Car has a 28% OD and a 3:54 diff so 65mph is fairly relaxed rev wise.

Have not delved into Throttle Switch, Relay or Solenoid yet. Will do so, in that order, when weather permits test drives.

Thank you everyone for your help and attention in this matter,

Simon

From: Healeys <healeys-bounces at autox.team.net> On Behalf Of Bob Spidell
Sent: Friday, April 26, 2024 7:17 PM
To: gradea1 at charter.net; healeys at autox.team.net
Subject: Re: [Healeys] Overdrive pressure or clutch slip Step 2!

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"  <mailto:bspidell at comcast.net> <bspidell at comcast.net> 
To:  <mailto: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 <mailto: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 <mailto:michaelsalter at gmail.com> > 
Sent: Friday, April 26, 2024 12:14 AM
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: 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 <mailto:simon.lachlan at alexarevel.plus.com> > wrote:

Of course. Isn’t that how I got the 520psi?

From: Michael Salter <michaelsalter at gmail.com <mailto:michaelsalter at gmail.com> > 
Sent: Thursday, April 25, 2024 6:19 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: 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

_______________________________________________
Support Team.Net http://www.team.net/donate.html
Suggested annual donation  $12.75

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archive/healeys

Healeys at autox.team.net <mailto:Healeys at autox.team.net> 
http://autox.team.net/mailman/listinfo/healeys

Unsubscribe/Manage: http://autox.team.net/mailman/options/healeys/bspidell@comcast.net

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20240426/8b48bb3d/attachment.htm>