Questions or comments should be sent directly to Scott. (Scott (dot) Ashworth (at) aksteel (dot) com.

Well, our 4.3 conversion is complete and (knocking-wood / crossing-fingers)
everything appears to be working great. The differential is a whole lot
quieter, (mostly because the carrier bearings were shot), and I can now
travel with traffic and not think that the engine will explode. We really
couldn't be happier. 

I want to thank all of the brethren out there who offered advice and
guidance. We poured over the Cedarstrand book prior to starting the job, and
would like to give special thanks to Don Harmer and the Atlanta group who
have de-mystified the process. 

We ended up spending a fair amount of money.  It was not as much as the
often-quoted $1000 for a professional job, but buying the components and
machining the various pieces as per the Cedarstrand book can run into to
some cash.  For our part, we have offered to lend our jigs and tools to the
next local guy who wants to try the conversion. I suggest casting about in
your area to find someone who has already done the job and who may still
have the necessary apparatus.

I want to suggest a couple things that we came across that might help the
next guy. The pinion shaft bearing has to be pre-loaded to an inch-pound
specification. We have an inch-pound torque wrench, but the resolution was
not very good and it wasn't working for us at the low end. We had used a
bed-frame rail attached to the output flange to lock the pinion shaft in
order to torque and remove the nut. It was balanced on the flange. By taking
a one-pound weight (in our case a pint can of beverage) and sliding it along
the rail until it started to fall, we were able to use a tape measure to
determine exactly when we had achieved the correct inch-pounds: so many
inches away from the center, so many inch-pounds. (That "pint is a pound the
world around" quote works for those of us in the land of 16 ounce pints. Our
former oppressors with their 20 ounce imperial pints would have to do some
algebra.) 

Also, getting the old bearings off of the carrier was tricky.  We ended up
pulling them apart with a gear puller. Once you do that, there is nowhere to
get purchase on the remaining part of the bearing to press it off.  We found
that we could use the MGA inserts from the Cedarstrand jig, which fit
snuggly into the ball-bearing race.  With those pieces in place we were able
to press off the bearings. 

I am now using third gear a lot more than I had been, and am using first
gear for the first time since we've owned the car. But whatever gear I'm in,
I'm grinning. 

Safety? Fast?
Scott Ashworth - '54 TF (with a wee bit of MGA)

 

Photo Show of 4.3 Conversion by Scott Ashworth

click on images for enlarged view

 

01 MGA carrier prior to disassembly	02 Again, MGA prior tp disasembly.	03 MGA pinion shaft	04 MGA carrier	05 MGA ring disassembly
06 Frame of the Cedarstrand press	07 Cedarstrand press set-up	08 Cedarstrand press with machined plates attached, removing bearing from MGA pinion shaft	09 Same	10 Half round inserts for removing the bearing
11 Removing the carrier bearing. We pulled the carrier bearings apart with a gear puller, and then used the MGA inserts to clamp the bearing in the race. It fits with a little help from a couple washers. This was a nice discovery. Foam to help catch it.	12 Without doing this, we weren't sure how we would get the bearing off the carrier.	13 This just pulled the carrier bearing apart.	14 The carrier bearings were shot.	15 Removing the carrier bearing.
16 Pressing on the new carrier bearings.	17 Again.	18 Removing the TF pinion shaft.	19 Driving out the inner bearing race.	20 Using a brass rod to avoid damage to the case.
21 Removing the outer pinion shaft bearing race.	22 Pressing on the inner pinion shaft bearing. Since we had dry ice, we cooled the pinion shaft.	23 Another.	24 Using the Cedarstrand tool to press in the pinion shaft races. They were cooled with dry ice prior to installation.	25 View from the inside.
26 Another.	27 It was helpful to lay everything out to keep things straight.	28 Again.	29 The tool in the front is Cedarstrands design to hold the carrier still to check backlash.	30 We used a bed frame rail to lock the shaft to torque the pinion shaft nut.
31 Torquing the pinion shaft.	32 We used a lathe and a honing stone to true the ends of the MGA spacer.	33 This was our tool to determine the pinion shaft pre-load. We measurede how far away the one pound can was when the rail started to drop. So many inches away determined inch pounds.	34 Again. A little too much.	35 Tool for testing backlash. We did not end up using this method.
36 This was the method that we used for measuring backlash. Board made out of foam-core with a loose fit around the flange.	37 We used the Cedarstrand bar to lock the carrier in place in order to measure the backlash.	38 Looking into the case with the pinion shaft installed.	39 Again.	40 The carrier inserted with a spacer resting on top of the bearing.
41 Pressing the assembly together.	42 We used three inexpensive feeler gauges to set the gap on the case.	43 Again.	44 We cut the required amount of metal off the spacer on the lathe.	45 Final smoothing.
46 Again.	47 Final assembly.	48 New nuts. We did use a paper gasket.	49 Done.

 

created 6/24/2010

edited 6/25/2010