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MG MGB Technical - Flat rear springs on my 73 MGB


How can I tell if the rear springs on my '73 MGB are worn out? The car sits high in the front and low in the back. It looks like it is going up small hill all the time. Some people say the front is too high, while others say the back is low? If the springs are bad in the rear and I replace them, how much higher should I expect the rear end to raise up? Is there an easy way to tell if the springs are bad? Are there any measurements I can take to check the height of the car. I have
only driven the car a total of about 300 miles, as I am restoring it, but the rear end keeps feeling like it is bottoming out. If the shocks are bad, would this cause the car to sit low in the rear?
Robert Browning

One additional item. How difficult are the rear springs to change out? Any special secrets I need to know?
Robert Browning

Bad shocks will only affect the ride height if they bind before allowing the car to reach its normal height, highly unlikely. Worn out or leaking shocks could increase the incidence of bottoming out, but bouncing more than once when hitting a bump is what generally happens. If the springs are flat and they assume an elliptical shape when the body is lifted, they need replacement.
George B.

Robert,
If the car is bottoming out it could possibly be the springs. It was on my 1970 B. I replaced the springs in January of this year. Not too hard, but for me time consuming. Getting the old ones off is the hardest - Rusted bolts, etc. Good Luck. E-mail me and I can send a detailed description of how I did it.
Gary Mills

Sounds like the rear springs need replacing. When the rear end is higher it lowers the front end. Try putting a floor jack under the rear of the gas tank. Place a 2x6 between the jack head and the tank. Jack up the rear of the car about 1" and see how it affects the overall look and "sitting" of the car.

The job is fairly easy providing the bolts are not frozen. Soak all the bolts and nuts in penetrating oil or WD40 for a least 24 hrs before trying to remove them.

Jack up the back of the car under the differential and place jack stands under the hangers at the front of the rear springs. Place wood blocks between the jack stand heads and the car hanger.

On my 74 GT CA car with no rust the front bolt on the RHS was frozen in the bushing. This is fairly common and you'll probably need to cut through the bushing and bolt with an angle grinder or reciprocating saw. Take care not to cut into the hanger.

Recommend getting springs and new hardware from The Proper MG or another good supplier. Their items are made in England and usually fit. There have been several stories about other suppliers getting their springs in far eastern countries and difficulty fitting them. Mine fit pefect.

Good Luck, Andy
Andy Preston

your back wheels should be about 1 inch above the e tops of the guards.
Peter

When re-fitting th springs attach at the front first then jack up under the spring and it will extend at the back so that you can the rear spring hanger attached.
Richard Evans

Robert-
The measured distance from the center of the wheel to the chrome strip on the side should be 15" rear, 14.5" front.
Don't make the mistake of trying to install the rear leaf springs using the procedure that?s described in the Factory Service manual. That procedure is in fact a company engineer?s description of how they were installed on the production line at Abingdon. Unfortunately, while the procedure does describe the installation itself, it fails to describe one critical element of preparation for the act of installation: The use of a Leaf Spring Compressor. This is a handy device that looks not unlike an archer?s bow with a large roller bearing mounted on a perpendicular projection on each end. The bearings are placed on top of the leaf spring, then the spring is compressed by screwing in a through-bolt that projects through the center of the bow and bears against the spring with a large rubber pad. As the bolt is tightened against the bottom of the spring, the spring compresses and its ends extend outwards as the spring flattens.
The Leaf Spring Compressor used by MG at the Abingdon plant was designed so that when the bolt reached the limit of its inward travel, the eyes of the spring were the right distance apart so that the rear leaf spring could be easily bolted in. The spring would arrive at the assembly line with the spring compressor already installed and tightened, whereupon the workers on the assembly line would attach the forward end to its rigid mount, then swivel the rear shackle forward so that the rear bolt could be easily slid through. Once the bolts were through the eyes of the spring, a pneumatic impact gun was used to loosen the bolt of the compressor. The compressor was then sent back to the spring people for reuse.
Of course, if you aren?t one of those rare people lucky enough to actually have a leaf spring compressor, the method that I describe in this article is the easy way to do it. Trying to do the installation by means of the technique described in the factory service manual when you don?t have a leaf spring compressor is a nightmare.
Many MGB owners approach the task of replacing the rear leaf springs on their car with trepidation. Actually, it's all very straightforward. Just work steadily and methodically and the work will go quickly. Try to rush the job and it'll take forever.
Lubricate and preinstall the bushings and rear shackle links on the new springs before trying to remove either of the old springs. Make sure that you?ve got the special lubricant on the outside of the tubular stainless steel bushings that go inside the polyurethane bushings. Push them into the bushings. Smear antisieze compound on the mounting bolts and inside the tubular stainless steel bushing so that the mounting bolt will slide in as easily as possible. Slide the mounting bolt through the stainless steel bushings and twist it to be sure that the antisieze compound is smeared evenly inside the stainless steel bushings.
Now, think in terms of safety. Chock the front wheels (always!), jack up and support the rear of the car on axle stands, remove the rear wheels, then adequately support the axle with either a hydraulic bottle jack placed on a hefty block of wood or (better yet) with a floor jack under the differential casing, undo the damper links, and remove the U-bolts from one side of the axle.
Having made those proper preparations, remove the rear bolt first. Hopefully the bushing sleeve on the front bolt won't be rusted to the bolt. If it is, don't bother trying to pound the bolt out because you'll risk deforming the hanger bracket. If you have a big C clamp, you can try pressing it out. If you can, you're lucky. Just cut it off with a hacksaw or, better yet, a dremel tool fitted with a cutting wheel. Cut between the flange and the bushing, on both sides, starting on the nut side so you can hold the bolt head with a pair of vice grips or a wrench so it won't try to spin on you, and toss it in the trash.
Once you get the spring off, examine the hanger brackets and the areas around them. It's not at all unusual to find rust there, especially in the area around the front bracket. Also, take a moment to examine the rear brake hoses. If they're bulged or, even worse, cracked, you really should replace them. Since the wheels are off to grant easy access to everything, pull the brake drums off and look to see if the slave cylinders or axle seals are leaking.
As you're putting it all back together, be sure to use antisieze compound, especially on the steel sleeve that goes on the front mounting bolt. Whatever you do, don't reuse any of the the old bolts, nuts, or U-bolts. Remount the rear end of the spring first (Yeah, I know that the manual says to do the front first, but let's do this the easy way, shall we?). Swivel the shackle links as far forward as they'll go and use the hydraulic jack under the axle to compress the spring so that it will extend forward into the front spring bracket until things align. As the spring extends you'll need to tap the block of wood under the hydraulic jack with a heavy hammer to move the axle forward. An alternative method is to place a hydraulic jack under the spring with the axle unattached and tap the wooden block and jack forward as the spring extends. From the front side of the bracket, slide the tip of a tire iron under the eye of the spring so that you?ll be able to use it as a wedge lever to align the height of the eye of the spring inside the bracket. When the eye of the spring is even with the mounting hole of the bracket, work the tire iron slowly to lower the eye of the spring into alignment with the mounting hole of the bracket.
Test the alignment by pushing in the mounting bolt. If it won?t go through, don?t pound it in with a hammer or you?ll damage the threads. Instead, patiently peer in there with a flashlight and adjust the alignment by compressing or decompressing the spring with the bottle jack (horizontal alignment), or by moving the tire iron (vertical alignment). Sometimes it helps to hold the flashlight against the outside of the bracket on the opposite side so that concentricity can be confirmed. When it?s aligned, install the mounting bolt using hand pressure and spin on the nut. use the floor jack to maneuver the axle so that the U-bolts can be installed. Once all of the U-bolts are in place on both ends of the axle, bolt up the new springs loosely, push the axle over to center, then torque the nuts on the U-bolts to 25-30 ft-lbs. Never tighten the front or rear spring mounting bolts until the car is back on the ground and the rear bounced up and down a few times to settle the suspension!
Drive the car in the driveway in a straight line to make sure that the front wheels are pointing straight ahead and then measure the distance between the front and rear hubs. It's supposed be equal. If it's not, put the rear end up on stands again, loosen the U-clamps, place a wood block against the rear hub that has the longest measurement, and use a big hammer to give the rear axle a shove. It may take a few tries to get the measurements equal. When you've got them equal the rear wheels will be properly aligned, so tighten the nuts on the joints until the rubber pads bulge.
You're going to be almost shocked at the improvement in the ride and handling. That, of course, will give you all the incentive that you'll need to redo the front suspension. Once that's done you'll know what an MGB is supposed to handle like and why so many people came back to the dealership right after their first test drive with a big grin on their faces and stopped their search for the right sports car! S-w-e-e-t!
Steve S.

Thank you very much. I now feel confident enough to tackle the job of replacing the rear springs. However, one question I still have is, will changing the rear springs effect the rear wheel
alignment?

To Steve S., the distance from the center of my rear wheel to the chrome strip on the side of the car, is 14" - and inch low. The front is 15.5" - an inch high. So, will new springs balance the height?

Also, to Steve S., the front suspension has already been completely rebuilt and is tight and correct. So with R&R of the rear springs, this should complete my suspension.

Thank you for taking the time to give me such a deatiled description. It will really help.

Thanks very much to everyone. I will let you know how it turns out.
Robert Browning

Robert,
Follow Steve's instructions and you won't have any problems. I just finished mine this afternoon with only one problem. The front bolt on the left side was frozen so it took some cutting to get it out. Other than that smooth sailing.

Use lots of penetrating oil and let it soak overnight.

Good luck.

John
John

Let me clarify one question. After I replace the rear spring, should I have the rear end aligned professionally?
Robert Browning

Robert
Their are holes in the center of the springs so it is hard to install them out of line. After you do the job have some one follow you and see if the car is tracking straight. If it is not it could be either front or rear alignment.
Barry
Barry Parkinson

Robert, just a couple of months ago there was a thread on the quality of the new springs, and it had lots of important information. Be sure to check the archives.
The springs that have the part number stenciled on them in white, and have thin plastic inserts between the leaves seem to be the best quality replacement springs.
I just did this project to my 74 roadster a couple of months ago and it sets just right and looks good.
You might as well replace all the bushings, bumper stops, straps--everything, and be sure to order new bolts for the front hangers/mounting.
Put your jackstands under the front hangers, just far enough forward to give you room to work but safely support the car. Put your floor jack under the differntial because you'll need to raise and lower the rear end that way. Go to your local tool rental place and rent a sawzall reciprocating saw. Use a large C clamp to push the leaf spring away from the hanger, and be very careful not to cut the hanger when you use the sawzall to cut the bolt. Like Steve S says, use anti-sieze, and it's a good idea to use talcum powder on all the rubber parts. After you have both leaf springs out and the new bolts hand tight on the front hangers, then raise and lower the floor jack to get the rear shackles to line up.
Tighten all the nuts hand-tight. Then lift the entire car with the floor jack and reposition the jackstands under the rear axle tubes where you would normally put them. Lower the floor jack, and the weight of the car will put the tension onto the new springs. The rear shackles have to be positioned with the lower end/spring bolts to the rear of the car, forming a Z shape. If one isn't lined up that way, carefully use a large pry bar and pop it into position as Steve describes. Then tighten all the bolts to the correct torque.

The bump stops are not bolted, they just slide over a metal rod that has the head spread out like an umbrella. They will pry off with a pry bar. To install new bump stops, put some talcum powder on the opening in the bumpstop. Get a 2x4 about 1 ft long, and a bottle jack. Position the bottle jack under the bumps stop and use the 2x4 as a distance piece to push the new bump stop straight up onto the metal rod.

Many people recommend using the nylon castellated nuts on the u-bolts along with flat washers.

Allow yourself 2 or 3 weekends and don't get into a hurry.

After it's all done, and your MGB is setting correctly, you'll be glad that you went to all that trouble!
Ken T
Kenneth Thompson

To everyone that helped me, I would like to offer my many thanks. I replaced the rear springs on my MGB this week. It took me three days - only because I took my time and only worked a couple hours each day. The job of replacing the springs was actually very simple. The part that took so long was cleaning and painting all the parts.
The only problem I had was taking one of the front spring bolts out. However, with a c-clamp I was able to press it out. The new spring was actually very easy to install and it lined up perfectly. The rear of my car is now almost two inches higher. During the process, I also discovered that one of my rear shocks was almost out of oil. Adding new, clean oil made a world of difference.
If anyone would additional tips, please feel free to contact me.

Thank you.
Robert Browning

You're the first and only person I know of who was able to get the front bolts out with a c-clamp!! On mine, I'd tighten the clamp as much as possible, leave it that way over night and the next morning it wouldn't budge! Did that for 2 weeks and used an entire can of WD40, but those bolts wouldn't come out! You lucky devil!!!!!
Ken T
Kenneth Thompson

Yes, I realize how lucky I was to be able to press the bolts out with a c-clamp. At first I did not think it was going to work, but then they just popped. Lucky - you better believe it!!!
Robert Browning

This thread was discussed between 01/06/2003 and 11/06/2003

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