H&H Model A motor thrust bearing issue
 

I've just repaired the thrust bearing on the center main of my H&H touring motor purchased in 1999. I didn't own the car at the time (1928 Model A Tudor) but the fellow before me put on a lot of miles of cross country touring. (Over 30,000+) and I've put on another eight to ten myself.

A bad knock showed up last year and I found that the crankshaft slid forward and backwards quite badly. Last Fall, I spoke with someone from H&H of La Crescenta, CA who told me the fix was simple. Basically remove the oil pan, drop the center main and send it to H&H with dimensions and they would replace the thrust bearings.

It must be stated that H&H uses a unique design in rebuilding Model A motors with replacing the rear thrust bearing with thrust bearings placed fore and aft of the center main bearing. They are pinned in place using roll pins.

A simple process which I undertook myself these past few days after some coaching over the phone by Max Sr. The parts were sent out quickly and gratis! Here are some pointers I'd like to give for those attempting to do this themselves:

After dropping the oil pan and center main; the major and minor diameters must be measured. This is needed by the folks at H&H to ensure proper fit of new thrust washer bearing.

Once the new bearing washer is received, remove the old and sand smooth the surface in preparation for the new application. (The roll pins are too hard to drill out)

Using a Bridgeport type mill, I placed the center main bearing in a table vise and using a 1/8" drill, drill ONE pin hole. Then clamp the bronze thrust washer on to the bearing side and drill through the washer in precisely the same place. After the hole is drilled, drive the roll pin in place and then locate the drill bit over the next location a hole is to be placed. Swing the bronze thrust washer out of the way and drill another hole for a second roll pin into the side of center main. Once drilled (3/8" deep) swing the bronze thrust washer back in place and drill a hole through it as well. Pin and your set.

Remove from vise and grind away excess roll pin that protrudes above the surface of the bronze washer. Be sure to grind off the roll pin below the surface of the thrust washer as it is hard and you don't want it grinding in to the side of the crank shaft surfaces. Repeat the same process on the opposite side of the center main and then your ready to install.

A tip on reinstalling: Be sure that the surface on the crank shaft where the thrust washer is riding is smooth and free of blemishes which will cause premature wear. If necessary, you might need to polish this area. You may also need to sand a bit off the bronze thrust washers if they are too tight going in. Do this carefully on an upright surface sander being sure to keep straight while doing so. There should be no more than .005" play in the thrust washer, fore and aft.

H&H Antique Motors have taken some criticism over this design from some folks but I find it a quality design although it must be addressed every so often... In my case, after more than 40,000 miles!

I'm not sure why I waited so long. This process took less than 6 hours...I didn't really need to wait so long! Over a year!


Have A Great Day!

Re: H&H Model A motor thrust bearing issue
 

My roadster has an H&H engine. I too have heard a lot of horror stories, but mine is great.

Re: H&H Model A motor thrust bearing issue
 

Question,

Looks like there a thrust bearing on the center main cap.

Is there a thrust bearing on the block side of center main also or is the bearing only on the center main cap?

Re: H&H Model A motor thrust bearing issue
 

When I bought it, my pickup had an H&H engine in it. The center main was "fixed" that way.

Long story made short, the engine was literally crap. It had just over 1,000 miles on it when I bought the pickup. After 3 catastrophic failures in the next couple thousand miles, it went to Model A heaven.

Re: H&H Model A motor thrust bearing issue
 

Benson makes a good point! Some engine builders use only the lower half of the thrust bearing, because it is much easier than making a full-circle bearing. IMO this is not adequate, and they do wear out!

Re: H&H Model A motor thrust bearing issue
 

I agree 100% with that. I wouldn't dream of using only one half of the thrust. Even as far away as this, H&H have a reputation. :( I'm being polite.
In addition, I don't think the center main is the place to put the thrust bearing. I always use the rear bearing.

Re: H&H Model A motor thrust bearing issue
 

A point of fact,...

Jaguar used this SAME think for many years, well up into the 70's! A 1/2 thrust washer
too control crank shaft end play. The BAD part of this, in the Jag, they ARE NOT pinned.
They also fall out !

So,..if there pinned I see no problem..

Re: H&H Model A motor thrust bearing issue
 

How much pressure did disengaging the clutch put on the crankshaft on those Jags? Or are you talking about an automatic transmission? What is it on a Model A?

Re: H&H Model A motor thrust bearing issue
 

Gez,..I don't know, it's hydraulic for the standard transmissions. Same block/
crank set-up for the automatics,..sedan's and E-types. As an after thought,
the Jag's weight more, so the clutch has to be stronger (heaver springs) than
the A's.

I think the big deal is taking it out of gear at stop lights, any std. transmission
cars, too save the thrust..

Re: H&H Model A motor thrust bearing issue
 

I've seen people do that and I shudder. Some even use the clutch to hold the car on an up grade. They have no clue!

Re: H&H Model A motor thrust bearing issue
 

Neither the block nor the crank were designed for center thrust, I question this modification.

Re: H&H Model A motor thrust bearing issue
 

Especially as the Model A center main is already an overworked part of the engine's power train.

Re: H&H Model A motor thrust bearing issue
 

...........................bingo.................. ..

Re: H&H Model A motor thrust bearing issue
 

Agree completely. That's why I use the rear bearing for thrust. Using the centre main is asking for trouble IMO.

Re: H&H Model A motor thrust bearing issue
 

What's wrong with putting the trans in neutral and taking your foot off the clutch at stoplights? This way you're not wearing out the thrust bearing, nor the throw out bearing, nor the pilot bearing. Plus, your left leg gets a rest!

Re: H&H Model A motor thrust bearing issue
 

I think we have different interpretations of a previous post. I took it to mean that it was important to put the car in neutral and take your foot off the clutch. (That's what I do.) I was referring to those who sit there for the whole lights cycle with their foot on the clutch, some even stopping the car rolling backwards by riding the clutch.

Re: H&H Model A motor thrust bearing issue
 

i sit at stop light in neutral hear, good thing to do. the lights are so long, when you get a green light 6 cars go through the
red

Re: H&H Model A motor thrust bearing issue
 

Same here, use that few seconds to putting the car in gear to let the red light runners through :eek:

Re: H&H Model A motor thrust bearing issue
 

Ditto as two post above. . This makes three of us.

Re: H&H Model A motor thrust bearing issue
 

It lasted 40,000 miles, not too bad IMHO.