MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Suspension Replacing bushings?

Good morning,

Question.... I have a 1979 mgb roadster that I would like to replace the suspension bushings. Currently they are probably the original rubber type. They look very old, cracked. The "B" has 75,700 original miles.

I only have just basic tools, is this a "project" that could be done over the winter by taking apart one part.... replace bushing(s) and then reinstall before removing another part? How difficult is this project? Any special tools required to do this project?

My MGB is only used for fun driving, plans are to install basic bushings.... or is there an advantage to upgrading to a better set of bushings?

Looking for your "tips" of advice.

Don 1979 MGB
Don

Hey Don...it's easy...and kinda fun...I did em all within the last year...and the improvement is obviuos...I used the red bushings...much better and more durable than the rubber...remember to keep the anti-seize handy...
pete

Don, you can do one side at a time. The tools you will need are shown in this link.
http://www.chicagolandmgclub.com/photos/mgb_susp/
Here is another link.
http://www.mgexperience.net/article/front-suspension.html
When you start post any specific questions may have on the BBS for a quick answer.

Clifton
Clifton Gordon

Don-
Obviously, there is no single “Magic Cure-all” for any car’s handling. Only in fantasy are things that simple. However, a simple modification involving nothing more than a change of parts can produce worthwhile results. The rubber front suspension bushings from an RV8 model produce significantly less longitudinal flex, endowing the steering with greater precision. Be aware that these bushings are not a press-fit onto the inner fulcrum pin. Should the fit seem to be tight, clean the fulcrum pin to bare metal. The inner end of the stainless steel bushing sleeve should be mounted with its chamfered end matching the radiused inner end by the flange of the fulcrum pin. The large flat washers must fit over the outside diameter of the pin so that they will clamp the stainless steel bushing sleeve tight on the fulcrum pin. Should the hole in the flat washer prove to be too small to permit this, both rapid failure of the bushings and rapid wear of the fulcrum pin will result.

Firmer bushings, such as those made from nylon, will reduce compressibility in the suspension component mounting points and make small steering inputs result in correspondingly small reactions in the steering. In other words, the steering will become more precise, but the greater reactivity will also demand that you pay closer attention to what you are doing. Unfortunately, hard bushings are also not only unnecessary for either the mountings or the attachment points of Stabilizer Bars, Panhard Rod ends, and Antitramp Bars as they offer no benefit in handling, but are actually undesirable as they will fail to damp out vibration and road shock. Because they are harder, you will feel more vibration emanating from the suspension and steering wheel, hear more road noise emanating throughout the body of the car, and your hands will feel smaller pavement imperfections through the steering wheel. Hit a big pothole and you will know it! Even worse, the greater transmission of these forces means that associated load-bearing components (Steering rack and column components, tie rods, ball joints, kingpins, swivel axle bushings, dampers, etc.) will wear more quickly. The purpose of the original soft bushings at the top trunnion, the bottom of the swivel pin, and at both attachment points of the lower A-arms (wishbones) is to absorb energy. By absorbing energy, they prevent it from being transmitted elsewhere. In reality, there are better options for increasing steering response while avoiding most of these drawbacks. Sudden, outright failure of these components is highly unlikely unless they are of defective manufacture, but longevity is always desirable.

This is not to say that you should resign yourself to the use of rubber bushings. Whereas rubber bushings wear rapidly and rot, polyurethane bushings take a long time to wear and never rot. Sadly, almost all of the aftermarket suppliers in the USA offer only the harder varieties, being either of the “Racing & Competition” or of the “Fast Road & Rally” type. In terms of their quality, some of these bushings are real “bargain basement” items. In my opinion, SuperFlex makes the best, and the price is quite reasonable for the quality of their product. They do not produce them in molds (a sure sign of an El Cheapo bushing), instead they start life as a solid rod that is actually precision machined to size and shape on computerized machines. As a result, they will slip-fit into place. This is not often the case with molded bushings. Sometimes you have to pound them into place with a mallet, which will result in their bores being distorted or compressed, which in turn will cause them to squeak. SuperFlex bushings are self-lubricating once installed. They even include stainless steel sleeves so that rust cannot abrade them. If you want to purchase a softer set (like rubber) for use in a daily driver, go to http://www.racecar.co.uk/SuperFlex/ and specify 80 Shore-A bushing material for the A-arm (wishbone) bushings (Original Equipment Part# AHH 7933 *, BHH 1123 **, SuperFlex Part# SPF0012) and 90 Shore-A bushing material when you order the trunnion (Original Equipment Part# 8G 621, SuperFlex Part# SPF0282), leaf spring (Front- Original Equipment Part# AHH 644, SuperFlex Part# SPF0181: Rear- Original Equipment Part# 2A 5176, SuperFlex Part# SPF0014 ), and stabilizer bar bushings. SuperFlex makes a product line that even includes stabilizer bar bushings for 1” (SuperFlex Part# SPF0063/25), 7/8” (SuperFlex Part# SPF0063/22), ¾” (Original Equipment Part# AHH 7927, SuperFlex Part# SPF0063/19), 11/16” (Original Equipment Part# AHH 7921, SuperFlex Part# SPF0063/17.5), 5/8” (Original Equipment Part# IB 4526, SuperFlex Part# SPF0063/16), and 9/16” (Original Equipment Part# AHH 6541, SuperFlex Part# SPF0063/14). I would recommend 70 Shore-A material for both the lipped upper and flat lower crossmember pads (Original Equipment Part# AHH 6204, AHH 6206, respectively; SuperFlex Part# SPF0015A, SPF0015, respectively) and the stabilizer bars.
*(MGB bushing) **(V8 bushing)

Prior to fitting any suspension bushing, remove all dust, previous paint, old grease, or bushing residue from all of the surfaces that can come into contact with the bushing. Be sure that any original outer shell is not inadvertently left in place. This is a common mistake whenever an old rubber bushing has unbonded from its shell. Do not fit new bushings to worn, rusty, or distorted fittings. All such worn components must be replaced. When preparing to install a bushing, lightly coat both it and the contact surfaces with assembly lubricant (where supplied) prior to fitting. In a very cold climate, immersing high-interference fit bushings into boiling water can facilitate fitting. Insert the stainless steel tubes (where applicable) after the bushings are installed into their housing. Before the final tightening, all of the suspension arms must be normally weighted at normal ride height and the car bounced up and down. When replacing original components, ensure that all nuts and bolts are torqued to original manufacturer’s specifications. Note that polyurethane bushings must not come into contact with alcohol-based solvents such as MEK, methanol, or methylated spirit.

Rebuilding the front suspension is very straightforward affair once you know the proper procedures: Always think in terms of safety before starting any project. Chock the rear wheels, set the parking brake, and place two jackstands under the sill/frame rails.

Because you are working on the underside of the car, expect several, if not all, of the bolts/nuts to be rusted in place. Stock up on penetrating fluid and keep a large 4-lb hammer close at hand. A Dremel tool with some cutting wheels will also prove to be useful. Remove the bump stops and their distance pieces for replacement and disconnect the stabilizer bar link from the lower A-frame.

Remove the wheels, detach the brake calipers by removing the two studs that secure the brake caliper to the swivel hub, and then disconnect the front brake hoses from the brake calipers.

Next, remove the hubs by pulling out the grease retainers, removing the cotter pins, and then removing the nut. Now, pull off the hubs and remove the rotor assemblies and their splashguards (dust covers), and then unscrew the steering rack tie-rod ends from their ball joints.

To remove the springs of the front suspension, place a hydraulic bottle jack under the spring pan to contain the pressure of the spring. Loop a strong rope through a coil of the spring and tie it to the upper suspension arm to prevent the spring from jumping out as this can occur quite violently. Remove the cotter pins from both the top of the king pin and the fulcrum pin, then loosen both of the castle nuts. Make sure that you do not remove the upper fulcrum pin before you have loosened the castle nut that secures the upper trunnion to the kingpin as the upper fulcrum pin secures the kingpin and thus prevents it from turning. Next, unscrew the nuts on both fulcrum pins until they are flush with the end of the bolt and strike them with a hammer to determine if either of them is rusted in place. The lower fulcrum pin has a steel bushing on its shank inside the trunnion. If the bushing has rusted onto the fulcrum pin, the fulcrum pin will have to be cut off with a Dremel tool and cutting wheel. Remove the center arm bolt of the lever arm damper and the upper fulcrum pin, and then allow the swivel hub/kingpin assembly to swing away. Remove the lower fulcrum pin from the bottom of the king pin. Remove the kingpin/swivel hub assembly and place it in a pan of solvent to soak. Note that the center portion of the kingpin is protected by upper and lower spring-loaded dust shields. Next, slowly lower the jack until the spring falls free.

Once the spring has been removed, remove the A-arm (wishbone) bolts that secure the spring pan and separate the arms of the A-arms (wishbones) from the lower pivot. This will also separate the A-arms (wishbones) from the spring pan. Inspect all of the A-arms (wishbones) for oval holes and replace if you find any. Remove the Steering arm from the swivel hub. Clean and degrease everything, then repaint the components with POR-15.

Make sure that you use some emery cloth to clean up the lower wishbone pivot shafts of the A-arms (wishbones) before you attempt to install the A-arms (wishbones) with their new bushings. If they must be replaced, note that the lower wishbone pivot shafts (Original Equipment Part # AAH 4003) that bolt to cross member are symmetrical and thus are not “handed”. In other words, there is no left version or right version, and no front or back to them. Use a flap sander to clean up and polish the inside of the bushing mounting bosses of the A-arms (wishbones). This will allow the bushings to rotate freely and keep them from galling and “winding up”. Crud on these parts will play a major role in tearing up your nice, new bushings. Once you have the surfaces nice and slick, get some of that wonderful silicone grease from a Honda dealer and smear it all over the sides of the bushings. If you do not have a Honda dealership within a reasonable distance, instead lubricate them with a liquid soap solution prior to fitting. The bushings should slide right in. Do not install them in a dry state. If you choose to install rubber A-arm (wishbone) bushings, use the V-8 A-arm (wishbone) bushings, not the Original Equipment rubber ones, as they have a longer service life and produce a more positive steering response. Be sure to use antisieze compound on all of the mounting nuts.

Do not attempt to reuse the fulcrum pin thrust washers if they are grooved or ridged. Endplay upon reassembly should be between .008”and .013”. When you reinstall the swivel hub assembly, be sure that the trunnion on the bottom of the kingpin is turned inward towards the car. The upper trunnion should be turned outward away from the car.

You will probably need to replace all of the associated fulcrum pin parts. If possible, purchase a kit because you are probably going to need all of it. The kit should contain all of the parts surrounding the bolt/pin and the brass bushing that goes in the king pin fulcrum pivot. When you reassemble the mechanism, be sure to use plenty of antisieze compound on all threads and the distance tubes.

You will need to make an honest appraisal of your own shop equipment and your machining skills to decide if you can independently install the brass bushings of the swivel hubs. The old ones will have to be pressed or cut out and the new ones pressed in. Once that has been done, the bushings will have to be line-reamed with a special reamer that has been designed expressly for the task ($$$).

Be sure to use antisieze compound on all of the threads when you reassemble everything.

With the exception of the inner pivot, do not fully tighten anything until the suspension is back at riding height. Keep the A-arm (wishbone) bolts loose until the car is back on all four wheels and “bounced” up and down a few times. Have someone sit in the driver’s seat to realistically load the suspension before you crawl under the car in order to tighten up all of the bolts. If the bolts are tightened before the car is weighted, then you should expect the bushings to wear out very quickly.

The proper torque settings for the front suspension are as follows-

Brake caliper mounting bolts: 40 to 45 Ft-lbs
Disc brake rotor to hub: 40 to 45 Ft-lbs
Front crossmember to body nuts: 54 to 56 Ft-lbs
Front lever arm damper (shock absorber) bolts: 43 to 45 Ft-lbs
Hub nut, align to next hole: 40 Ft-lbs
Lower suspension arm nuts, align to next
Lower suspension arm/spring pan nuts: 22 Ft-lbs
Road wheel lug nuts (Bolt on steel disc wheels): 60 to 65 Ft-lbs
Shock absorber pinch bolt: 28 Ft-lbs
Stabilizer bar link nut: 60 Ft-lbs
Steering arm bolts: 60 to 65 Ft-lbs
Steering tie rod locknuts: 33.3 to 37.5 Ft-lbs
Steering rack to front crossmember: 30 Ft-lbs
Steering U-joint Bolt: 20 to 22 Ft-lbs
Swivel pin nut, align to next

Steve S.

hey all, thanks for the support and the links.

Steve, it appears as though I should plan on doing more than I first planned on doing. My original plan was to just replace the "Lower A Arm bushings" with a set of the V8 set from Moss. Is this possible or does everything have to come-a-part to do this?

If everything has to come apart I may go with "If it's not broke, don't fix it"... as it works ok, I just thought they should be replaced.

Don
Don

Hi Don
I replaced all my bushes with yellow poly ones, and fitted front and rear Koni's.
The ride was much tighter but much harder. In fact too hard.
I have since done as per recommendation from a V8 builder that if you are not taking it on the track use standard bushes all round (except for the V8 one) and fit uprated lever arms.
It sound as if you are on a similar track.
I am happy to replace the bushes ever year if I can have a happy wife sitting next to me with all of her fillings in tact!!
Dave
D M Tetlow

Don, Yes you can replace only the lower a frame bushings.

Clifton
Clifton Gordon

Don-
As Clifton said, yes, you can do just the lower bushings. However, If I was going to jack up the front end of the car and take the trouble to replace the lower bushings, I'd go ahead and check out the rest of the system so that I could spot trouble coming early rather than wait until I was faced with more expensive repairs.
Steve S.

In contrast to the above poster recommending rubber bushings + V8's for the inner A-arms, I'd say go for polyurethane bushings throughout - Superflex / Superpro "Blue" grade bushings are similar 'hardness' to rubber, yet are almost impervious to wear and will last MUCH longer than much of the poor quality rubber around these days.

I'd also advise that once you start getting things apart you WILL see other bits that need replacing (frozen bolts, a-arm holes elongated, worn dampers, oil the steering rack, new brake bits etc. etc.)...still once it's all done, you will have learned a lot about what makes the front end tick, and you can drive with piece of mind that it's better than new.

Good Luck!

Curtis Walker

Has anyone used the red bushings Moss supplies? Are they soft enough for a comfortable ride? Or are they more for track use?
Dave E

Good afternoon,

Sorry I was away for a while and just now received your replies. I do want to keep a good ride, but also want to use quality parts (not used for high speed or track, just normal driving). Checking out Moss's newest (Fall & Winter) page A38 they list the V8 Lower A Arm Bushings $14.95 a set.... now I need your help!

Looking underneath my MG, most of the other rubber parts are cracking very bad... See page 46 Moss: Bush sway bar #2, Rubber Mount #5, what else (part(s)) should I be looking at? I understand that if the wishbone arms have enlarged oval holes I should replace these too (front back, both sides?) or just only the one if bad?

If I am not taking the whole front suspension off from the frame do I need to replace/change Mounting pads????

Note: the steering rack seal/boot (new)was recently done.

Please remember this will be a winter project, so I can take my time and order parts as needed, if needed. But, I don't want to do any thing stupid either.


Looking forward to hearing from you,
Don 1979 MGB
Don

Wow, Steve S

Don, I'm using the blue grade poly bushes. They are very good. They are firm, but not harsh. I replaced almost new rubber bushes and poly blue was a very noticable improvement. Allot less crash and rattle and more precise. Feels like a modern suspension. They are constructed in two halves that go over a stainless centre sleeve. Nice easy job to fit, and when you do up the nut they squeeze very tight which is alot of why they are so much better than rubber. make sure you use the special lubricant that comes with them, otherwise they may squeeck.
The shocker bushes are a little less easy to fit. You need to squeeze them a little and wriggle to get them in between the shocker arms. I used a G clamp and a couple of flat bits of metal. Not hard just not as easy as the lowers, which a child could do.
Don't bother with the pads unless you really want to. I replaced them but haven't noticed any difference there.
I havn't done the rear spring bushes and can't say for sure, but I've read that some people have had trouble doing them.
P.N. Sherman

This thread was discussed between 01/08/2007 and 04/08/2007

MG MGB Technical index

This thread is from the archive. The live forum is active now.