Instrument readings are simulated, we always obey speed limits

Weather conditions were suitable for road testing Tuesday, so I was able to run-in some miles on the uprated engine in this MGB.  Results for the engine were highly satisfactory.  But in direct drive I was encountering a freewheeling condition in which the engine would return to idle when I took my foot off the gas.  With the overdrive engaged in top, however, everything was fine.

Cor’ Blimey, this felt for all the world like a slipping cone clutch in the O/D.

Without getting too technical, an overdrive has a cone clutch.  When spring pressure clamps the cone clutch against the brake ring in the overdrive maincase, you effectively lock the mainshaft to the annulus (or output shaft) and have direct drive thru the TX.  Flip the overdrive switch,  and hydraulic pressure overcomes spring pressure and the cone clutch is now locked on the annulus

O/D operating valve (foreground) with solenoid assy.

This action allows the so-called “planet gears”, which are toothed to the I.D. of the annulus, to speed things up a bit giving you “overdrive”.

Now, logic tells us that there’s a short period of time when there’s no cone clutch contact at all, but this is compensated for by a “sprag” (or ‘one-way’) clutch splined on the TX mainshaft that grips a hardened ring in the center of the annulus maintaining the drive.  It works just like the pull cord in your power lawn mower.  I was guessing a bad clutch band on the direct drive side,  this is an ‘engine out’ repair, but first I thought I’d pull the operating valve and solenoid and

"Birfield" Solenoid cover & operating valve (above)

clean them.  Well, shazaam !   That did the trick.  Apparently the bleed-off from the overdrive hydraulic circuit was restricted somehow.

Always look for the simple solutions first. I had told the owner to prepare for hard & heavy tidings because it seemed like a sure bet that the overdrive was coming out.  Now I owe him money.

The reason this particular overdrive is Healey Green is because it is an MGC gearbox.  The MGC uses the same LH unit as the MGB, but with heavier clutch springs.

Early GKN "Black Lable"

Later GKN "Blue Label"

Around 1938 Birfield Industries acquired the Hardy Spicer Company, as well as  the assets of the Laycock Engineering Company.  In turn, Birfield was bought up in 1967 by Guest, Keene & Nettlefolds, aka “GKN”.  The solenoid cover plates provide a quick identification.  Early units are tagged “A.Birfield Co.”, followed shortly thereafter by a “GKN” identifier.  Late MGB overdrives have blue solenoid covers, and, I believe, a slightly increased reduction ratio.

You might have noticed that the solenoid cover plate orientation relative to the operating valve isn’t consistant in these pictures.  It’s our belief that on the MGC overdrive it’s correct, but functionally, it doesn’t make a darn bit of difference.

Your scribe about to take some simulated instrument readings

Mini Cooper subframe with hydrolastic suspension

John has reduced the 1275 Cooper to its constituent parts.  Pictured here is the front subframe on which the HYDROLASTIC  suspension hoses can be seen at the top of the housings which contain the “wet” suspension bladders.  This is a fluid medium suspension with all four wheels of of the car interconnected so that a jounce at one corner causes a rebound at the other three.

It is well known that after designing the iconic Morris Minor, it’s principal creator Sir Alec Issigonis went on to design the Mini.  Less well known is that the suspension came from the drafting of table of one Alex Moulton C.B.E.  Rubber was the Moulton family business, they were early licensees of Charles Goodyear.  Hydrolastic was the originally intended suspension system for all Minis, but it warn’t ready in time, and the solid rubber suspension used on most of them was simply a last minute lash up by Moulton as well !

What a difference..

...A day makes

Welcome to the vagaries of spring.  On Monday Steve put the gold series 1 E-type thru its paces and we’re pleased to report that it now has four forward speeds in its Moss ‘Box.  It took Patrick about 20 hours to dig it out and put it back.  Of course he took advantage of the access to fix a few other things as well.  Tuesday I was out in the GT

Five Guys: Patrick & his crew re-attach the bonnet

in a full-on winter storm that dumped 14 inches of snow in our corner of Vermont.  Let me just say for the last time, that if you’re going to be out driving in winter conditions then ditch the Three Season Radials before they ditch you.  Invest in your personal safety and buy four studded snow tires.

Now that it is spring we’re likely to get a couple of real snow storms.

Jaguar cylinder heads came in a number of different colors depending on the head and when the car was built.  The “C” type head in my XK 140  is red, and to the best of our knowledge, the later “B” type head on the Mark IX is supposed to be a metallic blue, so after taking care of the tappet guide hold downs, Butch took care of little paint job, too.

The finishing touch: "B" type metallic blue for the Mark IX cylinder head

1275 Cooper "S"

The Mini Cooper “S” pictured here is a later big valve 1275 with a nitrided, cross drilled crankshaft and all the rest of the zoot stuff.  Most interestingly of all, it’s been off the road since 1975 and as noted last week, it is showing very low miles on the odometer.

The rear subframe is a little tender in a few spots and there’s an interesting woggle in the back support for the rear seat which is baffling.  It’s as if cargo

John grinds away a door latch fastener

in the trunk was violently propelled forward, because there are no signs of impact on any of the outer panels.

Upon consultation with the owner, we all agreed that the best way forward was to pull the car completely down for measurement and repair.  John has been boxing up and cataloguing the bright work and upholstery.  Only the suspension remains to be dismantled.

Steve checks carpet fit in an MG TD

It is Steve who has been fully engaged in the soft arts this week.  Steve’s week began with pulling out the seats and giving this MG TD a thorough cleaning in preparation for re-carpeting.

Sharp-eyed readers will know by the vinyl covered dashboard (or fascia panel) that this is a later TD.  If you could see the top of the windshield, the center-mounted windshield wiper motor would give it away as a 1953 model year car.

Steve builds up a pair of TR6 seats

The TD came with a full compliment of previous license plates, three sets from New York, a set from Washington, D.C. and the original California black plates.  It’s certainly a car worthy of preservation.

That task completed, he next turned his attention to reupholstering a pair of TR6 seats.  These are much more of an undertaking than what we encounter with MG’s and Austin Healeys.  Some sense of

Patrick & Butch wrestle with an MGB windshield

this can be taken from the amount of pre-fitting that Steve is doing here and before doing any fit-up, Steve and Butch first had to weld up the broken seat frames !  O.K. this last picture here is from Windshield Week, which was the week before last when Steve & Butch also changed out the windshield from another TR6.  MGB  windshields (not MGB GT’s) are a struggle from start to finish, and in my experience the only easy part of the job is asking for your money when you’re done, because you will have earned it !

Thursday afternoon

I snapped this picture earlier today of a bench conference between  Butch and Steve, with  Patrick in the foreground.  They’re looking for a set of hog-ring pliers to use on a set of TR6 seats that Steve is reupholstering.  Patrick has just hauled the engine & transaxle out the red  Mini.  It’s a genuine Cooper “S” which was last registered in 1975 and displays an odometer reading of 32, 688.  More on that story as it develops.

Ken Booth checks Shorrock Supercharger tolerances

An ongoing project here has been the reconditioning of this C75B Shorrock supercharger, destined for Larry Perry’s MG TC.  This wasn’t the first time to the Prom for this old girl.  We pulled it down and cleaned it up, but a close inspection revealed the heavy touch of a previous unskilled hand with the result that while the vanes were individually within the range for end clearance of .010″, in practice we had a variance within the total operating plane of .010″ as well.

Patrick lines things up for Ken's hammer

That adds up to zero, which is not enough for a precision mechanism like this.  by machining the vane shaft and carefully adjusting shimming, Ken and Patrick were able to reduce the vane tolerance to .005″, a number we can live with.

For Ken Booth it’s a change of pace from the close tolerance prototyping work he spends most of his time doing.  Look him up at KNB Manufacturing and Automation.

E-type rear brake rotors with big cracks (click to enlarge for clarity)

When we’re overhauling a Jaguar independent rear suspension it is our practice to resurface or replace the brake rotors.  After washing them up we run ’em thru the bead blast cabinet and swizzle some paint on them with the result that they’re very spanky-looking when they’re done.  It also aids in the inspection process.

These cracks which radiate from the apex of the brake caliper mounting bolt access holes were not at all apparent when we cleaned them up and could have led to a very nasty failure later on down the road.  Most likely they were caused by excessive heat from the calipers which were well and truly seized, which is why we dropped the I.R.S. out of the car in the first place.

Small oopsie

Large oopsie

The Laws of Probability, as they apply to our work, state that if you only have one incident of damage every five thousand man-hours the amount of damage will be proportional to the likelihood that   it will happen under the least favorable conditions.  The broken heater fascia on the Austin Healey in the left hand picture cost us a $25.00 part and an hour’s time to fix it. The paint chip caused by a dropped wrench just behind the E-type hood catch on the driver’s side cost us a lot more.  Since it’s much easier to own your mistakes than not, I sent the owner a check to cover the damage.  He in turn endorsed it to my order, thereby taking it off his not insignificant bill.

Now that we got our steering side rods (as detailed last week) from Mike Buonanduci, the push is on to clear the Jaguar Mark IX Sedan from our work load.  We really only have one work bay that will accomodate these behemouths and a Mark VI Bentley Standard Steel Saloon is currently waiting in the barn.

Butch installs tappet guide hold downs in the Jaguar Mark IX Wednesday