[Healeys] Overdrive non return valve Question

gradea1 at charter.net gradea1 at charter.net
Mon May 25 11:43:47 MDT 2020


Overdrive engagement is controlled by having enough pressure to
overcome the 8 springs keeping the clutch from engaging the annulus.
(Direct drive). There has to be sufficient pressure to keep the clutch
attached to the annulus ring. (Overdrive position) This requires about
600lbs. Steady pressure from the pump.
I would sit down with the Moss catalog and make a list of all the
pressure parts and get new ones. Shoving washers in place is a make do
and may not last long under road loads.
After you get a parts list, contact Overdrive Spares, UK and buy them
from this company. They are the original engineers of Laycock and know
what you need to make good pressure. Best regards, Hank

	-----------------------------------------From: jpaynepbr at cox.net
To: gradea1 at charter.net
Cc: healeys at autox.team.net
Sent: Sunday May 24 2020 7:21:56PM
Subject: RE: [Healeys] Overdrive non return valve Question

	Shimmed the spring on the pump check valve by .08”. 

	Shope let me borrow an accumulator spring that was 3/64” longer.

	Up to over 450+ psi now. OD will engage with the rear jacked up, but
not while driving. On jack stands, when OD is engaged, drops to +/-
410 psi then quickly comes back up to 450+.

	Did not change out accumulator piston/rings/sleeve or O-Rings yet,
was hoping to avoid that.

	Thinking about trying a 1/16” washer to shim the accumulator spring
or is it a lost cause? 

	FROM: gradea1 at charter.net  
SENT: Sunday, May 24, 2020 10:26 AM
TO: 'jpaynepbr at cox.net' 
CC: 'healeys at autox.team.net' 
SUBJECT: RE: [Healeys] Overdrive non return valve Question

	OD Pressure should be much higher-could be 600 PSI. As I previously
stated, be sure that the ball in the operating valve is the correct
size- 1/4" OD in pump valve. The upper valve uses a 5/16" OD ball and
you cannot mix them up, our your pressure will not be there. Too large
or small a ball will not seat in the valve chamber. Also, if replacing
with a new ball and spring, take a brass drift and "seat" the ball in
its position. What is the condition of the piston rings and O
rings...they must be up to the task as well for them to hold that huge
pressure. Use sealant on all gaskets and in addition the brake ring
seal to each side of the case (ignore the passage in the workshop book
that says no sealant there-just be careful when applying it). Hank

	-----------------------------------------

	From: jpaynepbr at cox.net
To: healeys at autox.team.net
Cc: 
Sent: Saturday May 23 2020 5:36:24PM
Subject: [Healeys] Overdrive non return valve Question

	So I pressure tested the OD at the operating valve plug – 370 PSI
at 1,000 RPM in 4th. Drops to about 340 PSI when I attempt to engage
the OD. OD did not engage.

	This is with the back end on jack stands (not the recalled ones!), so
it is under no load.

	Held 150 PSI for about 20 minutes after being shut off and then took
about 2 hours to drop below 100 PSI. At least I now have a better
understanding of why these things leak so badly. Who in their right
mind would design something to hold that sort of residual oil
pressure?

	Based on all the reading, pressure is too low, but nothing appears
way off?

	I’m using the Team.Net Tech site. 
[1]http://www.team.net/www/healey/tech/big_hly/od/delborder_od.html
[2]

	Next step is to check the non return valve spring. 

	 Question, why would I take it to a machinist to add .084” to the
head of the little plunger instead of just putting a washer on the
back side of the head of the plunger? 

	If the stem length/ insertion length into spring is that important,
couldn’t I could add length to that at home with my mig welder and
file it so that the spring moves freely and doesn’t hang up? 

	From the team.net site :

	psi, but for proper operation, the pressure should be at 470 to 490
psi.

	Now, finally... the OD low oil pressure cause and fix. A fatigued
spring in the non-return valve portion of the OD (see Fig. 6.19).
What? Is that it? You must be kidding - I waited two months for this?
Yes, it does seem sort of anti-climactic, but this spring can cause
major frustration. Springs are like people - as they age, they get
shorter and weaker. As you can see in Fig. 6.19, the spring pushes
against a ball and plunger. The purpose of this spring is to allow the
ball to lift from its seat at each power stroke of the OD pump,
allowing oil to flow into the pressurized accumulating chamber, 

	 

Links:
------
[1] http://www.team.net/www/healey/tech/big_hly/od/delborder_od.html
[2] http://www.team.net/www/healey/tech/big_hly/od/delborder_od.html

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