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MG MGA - Removing Pinion Nut

I have a leak at my pinion seal. I have tried to get the pinion nut off but it wont budge. Suggestions? Also, anyway to tightly lock the pinion itself in place? I have been using the brakes at the wheels but that seems to leave so much play I can't even get a good hammer smack to try to loosen the nut. Of course, working on the floor and not having a hoist does not help!
Steve
Steve

Steve - Here is how I did it on our MGB. I took a two foot length of about 1 X 1/4 strap iron, drilled two holes in it to match two of the mounting holes in the flange on the pinion shaft and bolted the strap in place. I rolled the pinion over until the end of the strap was resting on the floor of the garage and then used an impact socket on my (small) 1/2" drive impact wrench. I triggered the wrench and not much happened to loosen the nut. After talking to a local mechanic, I tried again, following his instructions of leaving the impact wrench hammer away on the nut and sure enough, after several minutes of continuous hammering, the nut finally came off. If you can rent a larger impact wrench, it might go faster. Cheers - Dave
David DuBois

As David said, make the tool. It's simple and something most of us will use one day. With this even a long breaker bar will loosen the nut enough to use a ratchet.
Bill Young

Have a helper hold the brakes and use a jack to push on the end of a breaker bar. No special tool needed.
R J Brown

An impact wrench works, also.
Bill Haglan

I have always used a homemade tool to hold the flange. I don't like the idea of using the brakes and then an impact tool on the nut. I don't believe such shock forces should be applied to the teeth of the crown wheel and pinion.
Even in a fast standing start the differential has considerable cushioning (preload) effects from the clutch and tyres.

Mick
Mick Anderson

Steve, you are about to mess up your pinion assy if you do not follow this step. You have to torque that nut exactly as the factory had set it or you will crush the pinion spacer and then your pinion will pretty much self destruct.

Before you start unscrewing that nut you must get a punch and dimple the end of the pinion, then dimple the nut beside the pinion dimple reference point and then dimple the yoke flange in a straight line thru the dimples from the center of the pinion. Then line up your socket and mark it with a sharpie to align with the dimple on the flange. Now you can use an air impact to start unscrewing the nut. Count the EXACT number of rotations as they align with the dimples each counterclockwise turn. Note the final number of turns and then remove the flange and replace your seal. Now reinstall the nut and count the exact number of rotations it took to remove it. This will set it back to factory torque and you will be okay.

Mark
M Whitt

I was not aware that the MGA used the crushable spacer system to set the pinion preload. Triumph cars use that method and you must replace the crushable spacer every time the pinion nut is removed. It is not satisfactory to just bring the nut back to the same position, the spacer must be crushed during the nut tightening process.
However, with the MGA the nut is always tightened to 140 ft/lb and the pinion preload is set with shims.
When replacing items (not just a seal) you may have to remove and replace the nut several times and change shims to get between the upper and lower preload limits.
When just replacing the seal you may be lucky and the current number of shims is OK.

Mick
Mick Anderson

The (original) banjo style MGA and early (through mid-1967) MGB carrier does not use a crushable spacer. This style has a stout solid pinion shaft spacer and uses only shims to set the pre-loading. The Salisbury tube style (later MGB)rear axle does use the collapsable spacer that must be replaced whenever the pinion nut is loosened.

Steve
Steve Brandt

I noticed in the back of the MGA Workshop Manual that there was a special tool as David and Mick described. Guess I'll take up metalworking as well as woodworking and MGAing!
Or, what the heck, what's one more drip pan in the shop anyway?
Steve

Sue a lot of Steves around here!

Steve Gyles has a picture of a pinion holder tool:

http://freespace.virgin.net/stephen.gyles/odds_and_sods.htm

Thanks Steve
Steve
Steve

Steve you did not understand my post. Have an assistant hold the brake while you loosen the nut with a socket on a breaker bar moved by a jack. A sissor jack under the car pushing up on the breaker bar should get it off easily. No impact or shock to the differential teeth. No special tool needed. Simple procedure.
R J Brown

R J - Thanks, I'll give that a try first.
Steve

Steve(1)

Steve(2) kindly referred to the picture of my breaker bar, made from instructions posted by Mick Anderson.

For me, the nut removal and replacement turned out to be the easiest part of the procedure. The fiddliest part was lying on my back under the car trying to get the new seal lined up square in the hole.

Steve(3)
Steve Gyles

Steve(3) - "The fiddliest part was lying on my back under the car trying to get the new seal lined up square in the hole."
Maybe that is because the hole is round?
(Couldn't resist.)
Steve(1)
Steve(1)

I have done this job just by tying a poly rope through a bolt hole, taking a few turns around the flanged piece and tying it off to the leaf spring near the spring mount. Reverse to reassemble. The most difficult part is getting the required force while lying on the ground with little room to manoeuvre.
John DeWolf

John

RJ touched on the way of getting enough force on the nut. Place a bottle jack under the (torque)wrench and wind it up until the nut undoes/torque wrench clicks.

Steve(1) Nice one, but you will discover what I mean! By square I was of course referring to 'square on' (right angles). I found that the seal would appear to start to slide in then tilt so that only about 180 degrees of the circumference was going in.

Steve(3)
Steve Gyles

This thread was discussed between 19/12/2006 and 21/12/2006

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