[Healeys] Overdrive Question

Wed Nov 9 14:49:11 MST 2016

*"The internal stresses resulting from the hydraulic clamping forces might
be a more likely source."*
This statement had me wondering as it sounded like quite a plausible
explanation for the leakage issue that people are experiencing at the
overdrive clutch ring joint however, sadly, if one studies where the
hydraulic pressures are applied in the overdrive unit it becomes quite
apparent that the hydraulic forces serve to pull the clutch ring in toward
the forward casing of the overdrive during overdrive operation which makes
the joint tighter.
During "normal" non overdrive operation the 8 springs in the unit do tend
to push the rear housing away from the clutch ring but that force is not
that great as it is only required, by way of the cone clutch, to overcome
overrun loads. Probably less than 150 lbs.
All that said however I can certainly understand what Andy is saying about
the likelihood of leakage occurring when the joint is assembled dry as per
the Workshop Manual..
Installing gasket(s) between the casings and the clutch ring will affect
the sunwheel end float which is specified as 0.008" to 0.014" but adding a
thicker end float adjusting washer could take care of that, if you can find
an appropriate one.
I would imagine that sparing use of sealant alone would have little or no
effect on the end float.
Michael S
BN1 #174

On Wed, Nov 9, 2016 at 1:05 PM, WILLIAM B LAWRENCE <YNOTINK at msn.com> wrote:

> Hmmm! sorry for opening a can of worms, but I've found the responses very
> enlightening. On the topic of stress inducing the leaks due to the position
> of the hold-back link I took a look at my transmission/OD (BN1) and the
> holdback is attached to the trans to OD adapter plate. I suppose it might
> be a problem for the later models if the holdback is located on the rear OD
> housing, but there shouldn't be any stress from that source at the brake
> ring location for the BN1.
>
>
> The internal stresses resulting from the hydraulic clamping forces might
> be a more likely source.
>
>
> Bill Lawrence
>
> BN1#554
> ------------------------------
> *From:* Healeys <healeys-bounces at autox.team.net> on behalf of Roger Grace
> <roggrace at telus.net>
> *Sent:* Tuesday, November 8, 2016 4:04:24 PM
> *To:* Michael Salter; Healey List
>
> *Subject:* Re: [Healeys] Overdrive Question
>
> Tks to all for good input.
> Wondering if anyone has thoughts why factory never installed a gasket at
> this flange joint ?
> Any negatives about retro-fitting one after 50 years ?
> rg
>
>
> *From:* Michael Salter
> *Sent:* Sunday, November 6, 2016 9:38 AM
> *To:* Healey List
> *Subject:* Re: [Healeys] Overdrive Question
>
> Out of interest I just did the calculations for the change in length of
> the studs in this case.
> Assuming:
> 4 x 5/16" dia studs with an effective diameter of 0.25" each (thread root)
> and a length of 3" (in actual fact only the bottom pair are that long).
> 0.8 G of braking (which is probably way higher than our tires can
> generate)
> Young's Modulus of 30,000,000 @ 100 degrees F
> 700 lbs of engine and gearbox (which is probably very high considering
> that the the mounts are all rubber and the main engine mounts would absorb
> a fair bit as well)
> Works out to about 0.00028" of stretch.
> That's less than 10% of a human hair and only during panic braking if the
> tie rod is the only thing resisting the load.
> I think that there must be other contributing factors...
> Michael S
> BN1 #174
>
> On Sun, Nov 6, 2016 at 11:19 AM, Bluehealey <bluehealey at gmail.com> wrote:
>
>> Team.
>>
>> I can agree that a good goo between the mating faces is important and the
>> Japanese Motorcycle manufacturers will probably have the solution nailed.
>> The root cause however isn’t necessarily pressure, flange flatness, or goo
>> failure.
>>
>> It is more likely that the rear reaction strut (not sure what else to
>> call it) causes the joint to flex a little and open every time the car
>> slows under braking.  My theory and the solution I adopted can be found
>> here:
>>
>> http://www.bluehealey.com/Struts.html
>>
>> No leaks from my gearbox.
>>
>>
>>
>> AlanB
>>
>> [image: cid:image001.png at 01D18856.FC90FB60]
>>
>>
>>
>>
>>
>> *From:* Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of *Roger
>> Grace
>> *Sent:* 05 November 2016 21:02
>> *To:* David Porter; Healey List
>>
>> *Subject:* Re: [Healeys] Overdrive Question
>>
>>
>>
>> Sorry to reopen this, but have this same leak in my BJ8 OD and fixing it
>> is one of my Winter projects.
>>
>> Given that the black sealant stuff that was used before didn’t last (have
>> no idea how long ago or what it is) and that there is no oil pressure on
>> the joint, am sensitive to using what is the appropriate goo that will last
>> and contain the oil.
>>
>> Have done some checking around and the Hylomar universal blue is used by
>> some shops that fix OD’s.
>>
>> Overdrive Services (ex Laycock people in UK) tell me that the originals
>> were sealed with a product called Wellseal.
>>
>> Nowadays they use a Wurth sealant that mentions flange mating in its
>> website blurb.
>>
>> BTW they said that they could supply me with a gasket for this joint that
>> seems like a good idea ?
>>
>>
>>
>> The reality is that these are 2 Al flanges that are mated without a
>> gasket. I wonder why ?. Plan to do some careful flatness checking when have
>> my hands on them.  Has anyone had a problem with the mating flatness ?  do
>> they have a tendency to warp over the years and maybe abuse too ? given the
>> shape not easy to machine flat - why do they leak ?
>>
>>
>>
>> Comments/ideas please.
>>
>> rg
>>
>>
>>
>>
>>
>> *From:* David Porter
>>
>> *Sent:* Wednesday, October 26, 2016 7:15 AM
>>
>> *To:* Bob Spidell ; John Spaur
>>
>> *Cc:* healeys
>>
>> *Subject:* Re: [Healeys] Overdrive Question
>>
>>
>>
>> seems like any RTV that is oil compliant will work. There is no internal
>> pressure that will force oil out. The oil level in the OD is just above the
>> operating shaft level, hence the need for the o-rings on the shaft.
>>
>> DaveP adding to the wisdom....
>>
>>
>>
>> On 10/26/2016 7:40 AM, Bob Spidell wrote:
>>
>> Soooooooo ... both types of Hylomar WILL seal the joint?
>>
>>
>>
>>
>> ------------------------------
>>
>> *From: *"John Spaur" mailto:jmsdarch at sbcglobal.net
>> *To: *"WILLIAM B LAWRENCE" mailto:YNOTINK at msn.com, "healeys"
>> mailto:healeys at autox.team.net
>> *Sent: *Tuesday, October 25, 2016 8:27:53 PM
>> *Subject: *Re: [Healeys] Overdrive Question
>>
>>
>>
>> In my experiences neither of the two types Hylomar will not seal that
>> joint.
>>
>>
>>
>> John Spaur
>>
>> San Jose
>>
>>
>>
>> *From:* Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of *WILLIAM
>> B LAWRENCE
>> *Sent:* Sunday, October 23, 2016 8:26 PM
>> *To:* healeys at autox.team.net
>> *Subject:* [Healeys] Overdrive Question
>>
>>
>>
>> …disassembly of the OD because it is seeping oil at the clutch ring.
>> There are no gaskets, but I would like to smear some Hylomar on the joint
>> faces to stop the leak.
>>
>>
>> _______________________________________________
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>>
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>>
>>
>>
>> --
>> Dave Porter Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM 87107
>> 505-352-1378 Go HERE: my world www.porterbikes.com/
>> ------------------------------
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>
>
> --
> *If you can't fix it with a hammer, you've got an electrical problem.*
>
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-- 
*If you can't fix it with a hammer, you've got an electrical problem.*
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