Sunday, March 12, 2023

Front Suspension Rebuild

The last remaining 'rebuild' job on Alice was the front suspension.  She drove well enough, but felt a bit loose and bobbed and weaved more than I'd like going around corners and when braking.

I decided to take a peek at the front dampers to see if there was anything I could do in the interim.  It turns out the front right damper was empty!  Well, that's an easy fix, I thought... I filled it up and the situation improved quite a bit.  Until I saw the stream of oil finding its way down the front subframe, that is... at that point, I knew why the damper was empty.

That is also a relatively easy fix.  Worldwide Auto Parts in Madison, WI is a premier rebuilder of many British car front Armstrong (lever) dampers, and I've used their stuff on Gidget.  I rang them up and soon had newly rebuilt dampers zinging their way across the country to my front door.  But that just meant I had to follow through, and rather than just replace the dampers I decided it was time to get the rebuild off my to-do list.  The challenge was that I had just one day to finish the job... or I'd have to wait a month for another free weekend.

So, here we go!  I'll describe the driver's side rebuild and let your imagination fill in the details for the passenger's side.

Here's where I started.  This doesn't look too bad, right?  There's a ton of old grease and crud hidden behind that rotor.  Those rotors and pads are almost new and the brakes work very well, so at least I didn't have to worry about that...

Disassembly was the name of the game here.  With 47 years on the clock (figuring this hadn't been done before), I was nervous but hopeful that Lady Luck would continue to smile upon me. Most things have come apart on this car with relative ease, even after being an Illinois and Virginia resident.

To start, I supported the car on a frame rail with a jack stand as I would need my jack to safely lower and decompress the spring.  I removed the tie rod end followed by the brake caliper, and suspended the caliper so it wouldn't yank on the brake hose.  Once I dismounted the hub and rotor, I then jacked up the stub axle underneath the lower trunnion (being careful not to shear off the grease fitting) and freed the upper trunnion from the damper arm.  I then lowered the unit carefully and removed the now-decompressed front spring.

That actually went pretty well.  Mmmm, look at that old grease and crud!

Once the spring was released, it was a pretty easy job to remove the lower A arm by heating up, then undoing the four bolts that hold the arm to the subframe.  My luck held and everything came loose.

Finally, I unbolted the rebound buffer and the damper.  I was less fortunate with the rebound buffer, as one bolt was chemically welded to the spacer - but who cares?  I had a replacement buffer and spacer.

Then I cleaned everything I could.  I did not do a full restoration on this, but at least it's free of grime and looks like someone cared.

Look at that lovely damper next to its fresh replacement...

I decided that in the interests of time, I would not drop the subframe.  I looked at the body mounts that join the subframe to the shell and decided they looked okay.  It would be a major effort to unbolt the steering rack and drain and remove the front brakes, and I just wasn't able to tackle that.  I have the urethane body mount pads and if I find in the future it needs doing, I'll plan accordingly.

But enough of that... on to more disassembly!

Now I had the driver's side front suspension as a unit on my workbench (which I cleaned just for this job).


I removed the dust shroud and stared at the kingpin for a bit.  I crossed my fingers and put the assembly in my trusty vise, and a miracle occurred.  The trunnion nut came loose!  I removed the nut, tapped the bolt through and removed the stub axle.  Then I removed the spring pan by undoing the four bolts that hold it to the A arms, followed by the arms themselves.  And I noticed something. 

Do you see what I see?  Those look like polyurethane bushings!

So maybe I had good reason to believe the subframe body mounts were in good shape.  Someone's been here before.  I looked again and the body mount pads look like they're urethane too.  I did note that the lower trunnion bolt and assembly did not look like they had been touched, so I suspect that to be the source of the looseness and noise I was hearing.

Well, I'm here now, so everything's getting replaced anyway.

Once I had everything apart, it was time to clean.  This is a filthy job!  But it could be worse... it could be raining.  I also had to deal with the fact that the pins on which the A arm bushings rode were not in the best shape.  I cleaned them up as best I could and they'll do, though they aren't perfect.

I cleaned and cleaned and cleaned for at least an hour.  I used a couple of different scrapers to pick the decades of grease and gunk off the stub axles and A arms, followed by brake cleaner to remove the last of the gunk.  Once clean, I hit the A arms and spring with a light coat of black semi-gloss paint.  I was going for that 'cared for' look without it being perfect.  These items would all have to be replaced to achieve a restoration quality job.  The difference is impressive.

I also did not disassemble the stub axle.  There was no appreciable play in the kingpin and my initial attempt to remove the upper trunnion nut convinced me I should leave it well enough alone.

While the parts dried in the sun, I took a trip to my favorite hardware store (Ace) and picked up a mess of replacement hardware for both sides.  I only made one trip this time.

Once painted and dry, I loosely reassembled the lower A arm with its new bushings.  Loose reassembly is important as you have to be able to jockey things around a bit for proper alignment during reassembly.

Now, the fun began!  it's always fun to put clean and new parts back together.  And good thing, too.  I had been at work for about 6 hours (minus that half hour at the hardware store).

First, I bolted the new damper and rebound buffer in place with a new spacer.  I have found that the rebound buffers need a bit of 'adjustment' (tweaking in a vise) to get them to fit properly to the subframe.

Next, the A arm went in with four new bolts to attach it to the subframe, followed by attaching the stub axle to the A arm with new kit.  (I had previously installed the new trunnion bushings and greased the stub axle.)  I inserted the spring and carefully jacked the axle up until I could attach the upper trunnion to the damper.  This was a bit of a struggle, though it was eased by the fact that you can loosen a bolt that holds the damper's arms together to give just enough clearance to insert the trunnion.  Once the lower trunnion bolt was in place, I tightened the spring pan bolts and attached the tie rod end.  I then lowered the jack and admired the view.  But not for too long - I had miles to go before I could sleep!

Finally, I installed the dust shroud and remounted the hub and rotor.  I took the opportunity to repack the front wheel bearing too.  I reinstalled the caliper, and the job was done!

Boy, that looks better.  It looks like it has some age, but was taken care of.  That's all I was after.

That was a 7-hour job.  The passenger's side went about the same, but a bit quicker as things tend to do when you have done them before.  The one thing I did fight with on the passenger's side was that lower trunnion bolt.  The nut stubbornly refused to come loose, so I cut it off and drove the pin out with a punch.  Aside from that, it was a straightforward but very messy job.

All in all, I spent 12 hours on this job from start to finish.

But was it worth it?  Oh, you betcha!

After I cleaned myself up and changed, I went for a short test drive.  The difference is remarkable!  Before, corners were a chore and it felt like I was fighting to get around a turn.  Now, Alice is happy to take them.  I won't say it's "go-kart-like handling," but it's miles better than before and is very predictable.  Stopping doesn't exhibit more than minimal brake dive.  Everything is quiet, and the annoying steering wheel shake I was getting at 60-65 MPH is gone.  Even going over heavy bumps doesn't get her unsettled.

Alice now rides and handles like the sporty car she is meant to be.  

I would have preferred to have taken the whole weekend for the job, but it was probably best to have gotten it all done at once as I was incredibly worn out the following day.  This is not a job for the faint of heart, though it is not terribly difficult given proper tools and patience.  MGB front suspensions are simple affairs and will last for years if serviced regularly.

My last major task is to swap transmissions.  But that's going to have to wait a while... 

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