Rear Differential

Rear Differential Rebuild (new thrust washers)

The process is documented well at the Chicagoland MG club website "MGB Differential Clunk Removal" so I will not repeat it here.

Symptoms in my car were:

• Loud clunking at highway speed for about 30 seconds that went away.
• Chirping rear tire when turning hard right from a stop
• Play in the rear axle with the parking brake on.

Parts

Rear Axle Parts Diagram for Late Tubed Axle at Moss Motors
At a minimum you will need:

• Two Oil seals for rear axle : #120-700 (#90 diagram)

• One gasket for the "rear pumpkin" or make your own: #296-210 (#61 diag.)
• Two thrust washers for the differential pinion #267-130 (#67 in diag.) - Copper washers
  
• Two thrust washers for the differential pinion #267-140 (#65 in diag.) - Phenol washers
  
• One Pinion Pin Peg 267-125 (#70 in diag). Say that 3 times fast! Its a good idea to replace this pin.
• Hylomar for the bearing cap
• SilGlide for the axle seals
  

Not mentioned in the article

• Pulling one axle may be difficult. I had to place the hub back on with the nut and hit sharply from the back (from middle of car toward exterior) to dislodge bearing cap and pull the axle.
• Placing the pinion gears back in is an art. Once you get it, you "get it" in how to do it.
  

1. I placed the first pinion gear the bottom and geared it in with the differential gears on the axle, then rotated the "pinion cage" so that gear was at the top.
2. Rotate a wheel so the gear goes toward the front of the car and is almost out of meshing with the differential gears.
3. Feed in the bottom pinion gear at about a 45 degree angle so it starts to mesh with the diff gears.
   
4. Now rotate the wheel so the bottom gear goes in toward the pinion pin whole (back of car to front) and the other pinion gear comes from the front of the car toward the back.
   
5. Check for alignment with the pinion hole. Back out, adjust the starting point (Step 2) and repeat until everything lines up.

When you do this, it will make sense. Trust me!

MGB GT Front End Damage Assessment

Introduction

I obtained this car from an impound lot back in Virginia approximately three years ago. The car was involved in a hit-and-run incident and sustained impact damage on the front wing and front suspension. I am currently ripping out the sills for rust replacement so its also time to assess the collision damage. I am posting these pics and descriptions for an evaluation by the good folks on the MG-Experience forum and my local car club, the NCMGCC.

I have never driven this car other than to take it to end of the driveway and back. I have no experience with the suspension or steering other than "it works at low speed."

The obvious

This picture shows the original damage to the driver's wing. I have since removed the wing and have a heritage replacement waiting installation after the sill work. The picture gives you an idea as to the force involved. Not shown is a badly damaged Rostyle wheel that I discarded. The rim was severely bent and the tire had blown on impact.

Steering

Note how the steering column rubs against the frame. When turning the steering wheel you feel the column rubbing, though the wheel turns easily.

View from the front

It may not be immediately evident from the picture, but visually you can see the wheels are no longer aligned in parallel. When the passenger wheel is turned noticeably to the right, the driver's wheel is pointing straight ahead. Arrows added to show the misalignment.
Damage to front shock

This is an interesting observation. Notice how the rear shock arm is protruding much more than the front. 3.2 mm gap in front (A) , 6.2 mm in the rear (B). Not evident from the picture but the metal tab that comes up around from the beneath the car is slightly "popped" at its apex (blue arrow.)

Now the questions...

Before seeing all this damage I had already decided to drop the suspension and rebuild it with poly bushings. Is that a waste of time? Should I instead try to locate a rebuildable suspension and chuck this one? Or just find a new shock for the driver's side? Replace all driver's side components?

What other evaluation is needed to help me make a decision?

Thanks for looking!

Tim

Hot Toddy Recipe

Where have I been? 

A lot has happened since my last post in April. During that interval I decided to spend more time working on the cars and less time blogging about working on the cars. Now I come back to post something entirely unrelated to cars! But first a recap: The 1980 MGB was back on the road for most of the summer after re-installing a rebuilt cylinder head, new radiator, tie rods, alignment...and some other stuff. Right now its parked awaiting replacement of a leaking fuel sender unit. The '73 GT is now up on stands in the garage being stripped to bare metal and the outer sills are being cut away. Now for the real reason for today's post: I can never find this recipe when I really need it:

 

The Classic Atlantic Canadian 'Hot Toddy'

A Toddy is a hot drink consisting of liquor (often rum), water, sugar, and spices. This a Maritime Canadian variation of the drink used for medicinal purposes. It is particularly effective in the early stages of a cold brought on from excessive hours out in cold Bay of Fundy. This recipe comes from Dr. Burt, a parasitologist at the University of New Brunswick in Fredericton, NB, Canada. He was one of my favorite professors - I almost majored in parasitology as a result! My parasitology training has served me well as a Systems Administrator and Application Manager ;-) Ingredients Makes one "dose"

• 2 large, fresh lemons
• Liquor (Rum, Gin, Whiskey, Brandy, Vodka - I prefer Rum or Gin)
• Honey
• Warmed mug
• Ibuprofen or Tylenol (for the next day)

Squeeze the two lemons into a pot, including as much of the pulp as you can. Some folks throw in the rinds and all, but that would require straining the hot liquid - not recommended after more than two dosings! Lemons are your source of Vitamin C. Add at least 2-3 tablespoons of honey. Dr. B's theory is that is facilitates Vitamin C transfer into your cells. My theory : it makes the lemon juice bearable,  adds antihistamine, and gives the toddy its juju. Heat the lemon juice on the stove and dissolve lots of honey into the mixture. Remove from heat and allow to cool slightly (to prevent evaporation of the alcohol). Something truly magic happens when you heat this stuff. Add a couple of shots of liquor and serve in a warmed mug. Prepare to sweat a lot and feel very warm and fuzzy all over. The treatment is best right before bed. Repeat dosing as long as you are able to serve yourself. Take Ibuprofen or Tylenol in the morning to counteract any effects of overdosing - it also helps with any lingering fever.

Off with my Head. Part 3.

Good news

The machine shop called - the cylinder head passed the pressure test!

Bad news

The machine shop called again - the cylinder head failed the pressure test!

The real news

While the head passed, the valves were not holding pressure. Not a big deal since a valve job would tighten this up. On to the valve job!

The really bad news

When polishing the head for the valve job the shop found cracks in the exhaust ports for cylinders 2 and 3. At least one of the cracks extends outside of the valve seat area into the head.
You can't really see the cracks in this pictures so I marked the locations on the head with a marker.So why didn't this show up in the pressure test? The cracks may open up when the head is hot, or the leak may have been solely from a failed gasket. Regardless, I need to find a replacement cylinder head. I'm working a couple of leads but this may take a while. The late heads have a greater tendency to crack.

I removed the remaining studs from the block. If you break one off you have to pull the lump and take the engine to a machine shop. Removing 4 stuck studs took 2 hours of gentle heat, persuasion and patience.

The quest for a replacement head begins...

Off with my Head! Part 2

What lurks beneath

With the head off its time to examine the cylinders, block and pistons. Lets start from the back and work forward. Cylinder four has a carbon buildup but looks okay.

Cylinders 2,3 are similar to 4.And now for something rather different! Cylinder 1 has carbon but has a light grey appearance. This may indicate a gasket failure resutling in coolant "steam cleaning" the top of the piston.
The location indicated by the green arrow was full of "grit" that reminded me of a hard water scale or buildup. More evidence of a failed gasket.

Here are the valves. These look okay but only a pressure test will tell definitively.
Now its off to the machine shop for pressure testing, magnafluxing and a valve job, assuming all goes well and no cracks are found in the head. Could it be that easy?

More info
This site has some excellent information about MGB head identification, etc:
http://flowspeed.com/cylinder-ident.htm

Off with my Head! Part 1

It started out innocently enough...
Doesn't it always? When I took the car off the road in November 2006 the cylinder head had developed a slow weep between cylinders 2 and 3, just above the engine block number plate. In this picture you can see the greenish coolant where the head meets the block. Trust me, its there - just above the engine number plate, below spark plug number 2. You see it. I know you do.

No problem - whip off the head, change the gasket and we're good to go, right? Not so fast. Late model heads are prone to cracking in this region. Max Fulton at Flying Circus English Cars also told me that late model blocks can sag in this area, or the block can pull up around the studs. So what could it be? Its an old British car - how could it be anything but a simple gasket failure?

I drained the cooling system, unhooked the hoses and took off the valve cover and rockers. Here we are after backing off the head nuts in a spiral pattern as described in the shop manual. Check out the stud with the nut still on. It unscrewed easily directly from the block. Interesting....

When pulling the pushrods angle them to the side so the tappets will stay aligned. Its important to remember the order so I pushed them through a box and labeled each. Wow - look at how professional I am.

With the pushrods out I unhooked the manifold and pulled it back away from the head.

At this point you can lift the head away from the block. That is what the manual says. Reality was more complicated. The head was stuck to the block at the stud indicated by the green arrow. I could rock it up and down on each end but it is stuck in the middle! Blue arrow shows the location of the weepage and red arrow the stud the screwed easily out of the block.

I repeated applications of my new favourite penetrating oil (hmm, that sounds dirty) Kroil www.kanolabs.com over a period of a few days to the top of the stud and where the head meets the block. I also applied some light heat from a propane torch and some gentle tapping with a hammer on the top of the stud. After a few days it came loose! What suprises will be found underneath?