MGB Rear Axle to Fender Clearance

harv8 · September 11, 2012, 09:11:42 PM

The rear axle on my BGT is offset towards the driver side a considerable amount. I thought perhaps it was a bent leaf spring.
I have replaced the stock MGB axle with a Ford 8.8" and a Guzman 4-link suspension set up. I still have the offset problem and now my new wide rims and tires accentuate the problem even more! Was my car welded together on a Friday afternoon or a Monday morning? Hopefully there is some adjustment in Bill's 4 -link rear set up........but I don't think so.
I know I'm not the only one with this problem. Anybody have a fix?

Martyn

mstemp · September 11, 2012, 09:44:17 PM

Martyn,

Peter O. did a write up on mg experience page. It involved machining the joint on the lower link alowing a slight shiming to one side to compensate a slight offset. How much is the offset you have?

harv8 · September 11, 2012, 09:59:36 PM

There is a solid 3/4" offset to the driver's side. See pics below.

ex-tyke · September 11, 2012, 10:47:52 PM

Had to do some creative shimming to my 4-link too (although it was perhaps only 1/8") The other 1/4" was compensated for when I welded the spring perches off symetrical to the axle. The photo is of the original link and spacers before modification but you can visualize what is required.
Modification to correct will require machining the ends of all four lower rod end link spacers and adding equivalent spacer shims to the opposite side - in your case you'll machine 3/8" off the spacers and add 3/8" shims to gain back the 3/4" difference (although it might not be possible to remove that much material and still retain the pilot for the bushes.) .
The other issue is that If you shift the lower links too much, the upper links will end up with some misalignment to the welded-on axle brkts

100_5011 (1152 x 864).jpg

harv8 · September 11, 2012, 11:00:38 PM

Thanks Graham. I was considering this option. I'm glad I'm not the only one in this boat.
I guess I could go with skinnier tires...............no, I don't think so!!!

pspeaks · September 12, 2012, 01:51:37 AM

No Martyn, you're not the only one. Before my present GT, I had a 71 Convertible and it was off ¾" toward the driver as well. I thought the chassis was bent, but it measured to be straight. After acquiring my GT I gave it to a friend who knew of the defect and the last I heard it was still in Virginia setting behind his garage.

Paul

bsa_m21 · September 12, 2012, 09:32:55 AM

Martyn,

Before you start modifying anything, verify the 4 wheel alignment. If the front and rear's are not aligned, the vehicle will "crab" when driving (front wheels will be offset to one side from the rears). If not, then the body is off.

An easy way to check is to have someone drive behind you and eyeball along a rear wheel towards the front. It should be easy to see if there is an offset to one side (fronts sticking out on one side and not visible on the other side).

Martin

mowog1 · September 12, 2012, 10:51:15 AM

Seems to me one could also locate the axle THEN weld the top link tabs into place (as I suggested to Martyn yesterday) The lower links can be shifted by relocating the lower mounts/u-bolts. Shimming may or may not be necessary at that point.

Martyn, you could also try the baseball bat method of pushing the fenders outboard a bit if you still need clearance.

I think you already rolled the inner fender lip, right?

Question...is 1/4" to 3/8" offset really going to create crabbing?!
Undercarriage 6-4-11.jpg

BlownMGB-V8 · September 12, 2012, 10:53:43 AM

My understanding is that this was a factory defect. I think Curtis knows as much about the origin of the problem as anyone, and I was of the mistaken opinion that it was fairly widely known. Something about a defective jig I think, and I have no idea how many cars were affected or what years. Mine was though. '71 RD. I fixed it with the IRS.

Jim

Jim Stabe · September 12, 2012, 11:08:38 AM

There are lots of articles on the net about stringing a car to check alignment. Basically you set up parallel strings between jack stands on each side of the car at hub height about 6" away from the tires, it doesn't matter if each side is the same exact distance from the tire. Measure from the pinch weld at the front and back to make sure they are parallel with the centerline of the car and measure between the strings at the front and back to make sure they are the same distance apart.

You now have the ability to accurately check toe of each wheel individually, wheelbase on each side of the car, side to side offset of each wheel. I think the way you measure each of these is fairly obvious once you have the strings set up. You can find out a lot about your car for an hour's worth of work.

mowog1 · September 12, 2012, 11:47:42 AM

Yes, Jim...it was a factory defect that was known, but never corrected (to my knowledge).

ex-tyke · September 12, 2012, 01:50:52 PM

Just for the record, here's a shot of the current lower link with the 1/8" spacer shift
lower link spacing.jpg

harv8 · September 12, 2012, 04:46:58 PM

Thanks for all the input.
I guess another solution is to remove the spring perches and the upper tabs and then relocate them where needed to centre the axle in the car. I've got lots to check out here.
Thanks guys!

flitner · September 13, 2012, 05:40:32 PM

I had to narrow my diff housing 5/8 total due to this, when I mocked up for the rear flares I located off of the passenger side for my jigs and patterns. Had I'd have known this issue then it would have been mocked from the driver side.
Luckily I had just enough spline on the axles to give me the room I needed, plus using 265/50/15 as a guide gave plenty of room for error on the 225/50/15.
I measured for a full day to make sure that the back half of the car was reinstalled correctly by me.

flitner · September 13, 2012, 05:46:21 PM

Splitting the 3/4" you have, will 3/8" be sufficient clearance to the sidewalls/wheel wells?

harv8 · September 13, 2012, 10:47:46 PM

It's gonna be real close!!!

mgbreis · September 14, 2012, 02:26:41 PM

It's a delicate balance, isn't it? There's almost nothing that looks better than a gt with nice wheels and tires tucked ever so slightly into the wheelwhell -- but you miss it by just "that much" and you've got a rubbing problem. I know what I'd do - cut and re-weld the brackets on the rear end housing. What a pain.