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MG MGB Technical - Suspension Rebuild
|I'm overhauling a 1979 MGB. Most of the body work is done. The engine is in the machine shop. I've purchased four new shocks, a rebuild kit for the front end, new lowering springs for the front, new rear springs and lowering blocks for the back. Two problems that I'd appreciate advice to solve.|
1. How do you get the rear shock links off of the shock? I suspect that they are a tapered fit. Do I need a tapered fork like that used on ball joints or is there another method?
2. I planned on using the guidance in the Hynes manual to remove the springs and rest of the front suspension. When I put my floor jack under the pan assemble and put a little pressure on the pan to partially compress the coil spring, the whole car lifts off the jack stands. I lowered it back on the jack stands and could discern no spring compression. Since the next step is to remove the wishbone bolts (4) and disconnect the pan from the wishbones, I'm a little concerned. With the engine and transmission out is there not enough weight in the car? Do I need to get a spring compressor or is the jack under the pan good enough?
Any suggestions or experiences would be appreciated.
|Dick, I seem to remember the same problem with the front end. Without the engine there is not enough weight to allow the springs to compress. I eventually removed the whole front suspension assy and used spring compressors. Its not a big job to remove the assy and it gives access for cleaning up the sub frame and I think makes the rebuild and fitting of the new parts easier.|
As Tony said.
I went the same way and removed the whole assembly. It was either that or find a few friends who totalled around 500lbs to sit on the front guards.....
|As stated above, take the whole unit out. Very easy. Just 4 bolts. This will also allow you to replace the rubber pads under the bolts. Something you should do anyway if you are doing a total rebuild.|
Other way is to chain it to something on the ground or a lift.
|Tony, David, and Bruce;|
Thanks for the advice. I'm off to find a spring compressor this morning and will remove the whole front assemble this weekend. One thing I've read is it is a bit of a challenge to realign the steering when reassembling the front suspension. Did you guys have any problems doing the reinstallation?
Bruce - you are right on the rubber pads. I've got the new black poly pads coming with my rebuilt King Pin assemblies.
John Twist at University Motors does a great YouTube Video on aligning the steering column shaft, although if you keep any shims in their original places when reassembling, you should be ok. If it's the tracking that you are worrying about it is worth getting a decent front end alignment anyway. So just try and get it close by counting the number of turns when you undo the track rod ends.
|As far as the rear goes the nuts on mine had corroded so turning that turned the pin in the damper arm, or bottom plate whichever it was. You shouldn't use heat as it will destroy the rubber bush between pin and link. I cut most of the way through the nut with a hacksaw, then used a chisel to open it up. If the nut is off but the pin stuck in the damper arm then the front track-rod end trick of putting one side of the damper arm eye on an anvil and belting the other side with a hammer may help. Had that problem with the front ARB links in the A-arms, but I was replacing the A-arms so hacksawed through one side then used the chisel to open it up. Had to do much the same with track-rod ends seized onto track-rods, although in that case once I had cut through to the tips of the thread I used Stilsons to open up the cut rather than hammer and chisel.|
Don't waste your money on spring compressors, you will be hard pushed to find a set that works. The best way I have found is to assemble the front end onto the car and then use a trolley jack to jack the spring pan into position after blocking up the cross member.
If you don't have enough weight just get a friend to sit in the engine bay and/or place axle stands as far back along the body rails as you can. That way most of the weight of the car is levered against the front cross member. I did mine that way without the engine.
The rack is easy if you follow John twists video. I bought the alignment tool years ago but have not used it since I saw the twist version.
The drop links should come off easily if you give them a reall sharp tap with a hammer. If they are stuborn you might need to soak them with penetrating fluid to release the rust. Same with ARB links and the steering arms. But I have never had one stick in the taper after a hard tap. Use two hammers if your concerned about the suspension arms. One each side.
|A J Ogilvie|
Thanks for the advice. I agree with everyone about John Twist's. Super guy with lots of good advice.
I got the rear shock lever arms to come off with a tie rod tool. The front end came out of the car without to much trouble today. Applying a good wack with a hammer caused the tie rod ends to pop right out.
I'll drop the rear end tomorrow and put the new springs, rubber and lowering blocks on. If I understand the lowering blocks they go under the springs on the bottom. Almost seems to simple.
|Surely the lowering blocks go between the axle and the springs?|
You are correct. Thanks, Dick
|I got my front springs out by placing a trolley jack under the spring pan and a heavy duty ratchet strap around this and the top of the crossmember. Easy to compress and easy to control decompression. This was done with the suspension removed from the car.|
|I just got through doing this yesterday (MGA with MGB suspension) with the engine out. I used the "jack-under-the-springpan" method. The first time I tried it (last weekend) I too started lifting the car up off the jack stands. This weekend, I moved the jack a little further in toward the middle of the spring pan (maybe an inch) and it worked perfectly without having to strap anything down or have someone stand in the engine bay--I don't know why--it doesn't make mechanical sense. But it worked with no car movement. |
A couple of possibilities: 1) I'm using new, well lubricated, prothane bushings at all pivot points, clamping nuts slacked off. Therefore, less binding friction to work against suspension movement (thereby lifting the car instead of the suspension) 2) I loosened all A-arm to spring pan bolts to the max possible 3) I used a larger, heavier duty jack. The first jack I used was a lightweight, aluminum "racing jack", and was at the limit of it's travel when I first tried this. I suspect there was a more radical arc of travel at it's limit causing more sideways movement rather than upward movement. The larger jack provided a more straight up linear motion.
The only thing that differed from the first attempt was the jack, and a slight inward movement of the contact point on the spring pan, and slackening the A-arm to spring pan bolts.
|A trick I use when removing/replacing tie rods is to put a layer of tape on the threads at the end of the tie rod. I also try and count the number of turns, but that way, If I loose that figure, I know very close to where it was.|
|OK, I will assure you that I have done this myself and it does work.|
The last MGB suspension I rebuilt, I dropped the crossmember and was planning to use a spring compressor. I received advice from one much wiser than me.
Don't waste your moneyor time on the compressor; chances of finding one that works on a B are slim anyways. Simply unscrew the 4 bolts that hold the shock base. You will be disappointed by the lack of potential to kinetic energy transformation.Not so much as a "Sproing"!
In order to replace with no engine in car, simply put the rear axle stands at the very rear of the frame by the bumper irons. Or ask your wife to sit on the rad support. Then proceed to jack up spring pan as is most often done.
And don't worry if you cringe as you do this the first time, I did!
|The further the jack is placed towards the fulcrum of the front suspension i.e. the inner A-arm pivots the more likely the car is to lift off its supports before you have compressed the springs enough to lift the damper arms off the rebound rubbers. If fitting new springs you may find that the position that was adequate to lift the damper arms off the rubbers for dismantling, will not work for reassembly (BT, DT) and the jack will have to be moved further outboard.|
Counting turns of the track-rod ends, wrapping tape round the track-rods, or leaving the lock-nut in position is only any use if refitting the same track-rod ends, and even then I'd recheck the tracking afterwards. If fitting new track-rod ends they are quite likely to be a different length, even slightly, so the above is not methods are not helpful. BT, DT also.
|I just replaced the (leaking) front shocks on my car by swapping them over with ones I had on a spare front cross member. I was also worried about how to remove the springs but undoing the bolts holding the shocks down does work. By the time you have all four bolts undone there is almost no tension left on the spring at all.|
|Lots of good advice. Sorry I haven't responded lately but I've been traveling w/o internet access. I have the front suspension out and will do the disassembly in about a week (more travel) and I get the rear suspension finished. |
I have gotten the rear shocks apart and put in new springs with lowering blocks. Not surprising the geometry changed a little and my sway bar is off about 1/16th to 1/8th of an inch. Pulled it today and will readjust and reinstall. I went to install the new chrome bumper rebound straps and haven't been able to compress the springs enough for them to make up. It almost looks like the rubber bumper straps would fit better.
1. Has anyone experienced this with the new springs and the lowering blocks?
2 Should I leave all the spring bolts loose until the car is on the ground again to let everything settle into position?
Once I get back from travel, I'll put the sway bar back on and the new shocks. Any tips?
|With the car complete there should be more than enough weight to compress the springs enough to get the rebound straps attached with a bow in them. If you can't then either the springs are too hard or arched (a very common complaint) or there is some other issue with positioning which can be caused by non-standard parts. The front crossmember being out shouldn't really affect that, but other missing parts with significant weight will of course.|
Damper movement is a factor of drop-link length, rebound strap length, and bump-rubber pedestal height and if you get these wrong the damper can hit one or other limit before the bump-rubber/rebound strap does.
Whilst I have noticed significant settling of the front springs in there pans after a short shake-down ride, I have never found any settling of the rear, and I've always (several times) fully tightened all the spring and U-bolt nuts with the wheels off the ground.
Not tightening the inner A-arm pivot nuts until the full weight of the car is on its wheels when using V8 bushes has long been recommended, and I can see why. More recently I've seen recommendations that the spring eye nuts should be tightened ditto, and whilst there is a possible case for that with the front eye (although I've not had any problem moving the spring up and down on it without) it will definitely make no difference as far as the rear shackle nuts are concerned. But the other week I saw a recommendation that the U-bolt nuts shouldn't be tightened until the weight of the car is on its wheels and that makes no sense to me at all, being counter-productive in fact. If you jack up the spring until it starts lifting the axle the only force on the U-bolts is when they start compressing the rubber spring-seating pads, and the axle can be wiggled around to get things seated correctly while you tighten the nuts. If you leave the nuts loose and put the car on its wheels then the weight of the car will be trying to pull the spring away from the axle i.e. tensioning the U-bolts, so when tightening the nuts not only are you having to lift the car while doing so, but the spring is pretty rigidly attached to the body and the axle pretty firmly attached to the ground via the tyres, so it is going to be harder for the axle, spring and spring-seating rubbers to take up the correct positions.
|Have an 80 LE and did similar renewal to all the suspension. I agree with Paul, can't see the sense in tightening the U-Bolt nuts with the weight of the car on the wheels. However, I do recall that the manufacturer of the poly bushings, Energy Suspension, recommended not tightening the shackle or front leaf spring bolts until the car was on the ground in its normal position. Thus, the poly bushings rotate into a normal position without stress before torquing.|
Had the same experience with the rear anti-sway not meeting up and wondered about how it was done at the factory. I just dropped the car to the ground and adjusted the anti-sway bar ends a few turns being sure to apply the same number of turns to each end and it all came together.
|Rick and Paul,|
Thanks for the input.
|It makes no difference for the shackle bushings because the nut tightens the side plates onto shoulders on the bolt and not onto any part of the bush, the sides of the bush are only relatively lightly gripped. With the front eye, like the V8 bushes, it is the spacer tube inside the bush that is clamped by the nut, and that tube is bonded to the rubber. The outer part of the rubber bush (in both cases) is pressed into the eye, so there is still the potential for that to turn, although it does need a lot more force than the shackles.|
|Along these lines, let me get this straight; I am just about to assemble all the new front suspension,onto the subframe using urathane bushes. There should be no use of grease with these, am I correct? Except the King pin assemblies. The inboard wishbone bushes are to be urathane, and the upper swivel axles bushes are to be urathane. Indeed my new lower wish bone arms have no grease nipples (inner bush housing.) Any further tips? Mike|
|I though grease was recommended for Urethane as otherwise they squeak, not being as compliant as rubber so they turn on pins/in holes.|
The grease nipples are essential for longevity of the swivel axle bushes as well as the lower spacer tube and pin, which are all metal. Originally the swivel axles had two nipples, later a third one was added for the lower spacer tube and pin, and this is recommended as a retro-fit for earlier assemblies.
If you mean the A-arms themselves have no nipples, then they never did as the bushes were always rubber. Hence the need for grease with something much stiffer.
|Thanks Paul, yes I think you are right some grease otherwise they squeak. I think in this case it is the use of silicone grease which is a hardy substance, and I only use this at the top trunnion, and the the A frame bushes. The King pins will still receive molybdenum disulphide grease via a grease gun, and yes while load is off. In fact I have installed one side. Most impressed as I got the king pin assembly from one supplier and the re-build swivel axles from another. One might guees that the king pin inner tube might not match the sleave of the distance piece seeing the inner tube needs to be reamed to a given tolerance, but guess what it fit a treat. High praise for the engineer that reamed, he must have followed the specifications and stuck to it! I got the Castor kit on too, supplied by Gammonds and something-or-other?That was tricky, as in the instructions one is not to take out the bolts that secure the subframe to the chassis rails completly, unless one is re-newing the pads as well which I was for urathane pads. so lining up the subframe with everything single handed-ly with two scissor jacks and hydraulic was challenging all good fun. Until my wife said 'I thought you were going to clean the patio door slinding channels?' Oh, Yes my dear! Mike|
|The bushings I installed came with small tubes of the proper grease. It's a non-petroleum type of grease. Since I accidentally through some of them of out, I had to find some and did so at my local Auto Zone store. It's made by Energy Suspension and I got a small container of it for about $15 USD. The instructions about application are available from their site or I've attached it here.|
|Well, didn't get the file to attach. Basically, apply a thin coat to the O.D. and I.D. of the bushings and flange. Any part of the bushing that contacts metal. I also replaced the pads on the leaf springs, but those are not supposed to be lubricated.|
|I have virtually completed the suspension rebuild but am somewhat puzzled. Paul, you say the A arm bushes never had grease nipples, I found the previous owner had drilled and installed grease nipples but the bushes were not rubber but urathane! Anyway I was installing new A arms and these do not have grease nipples, so have placed the new bushes in. They don't have inner sleeves, some urathane kits seem to is this important? ( the old original rubber ones did not have sleeves.) Also the big washer that now holds the bushes in the A arm, seats up to a small shoulder on the shaft of the A frame mounting, thus it does not compress the bush, is this correct? thanks Mike|
|An update and question. First, appreciate everyones input. I've reassembled the rear suspension and have the front cross member is refurbished and bolted into the car. I can compress the new springs by putting some weight on the front end. (Engine is done and will be back from the builder next week). |
Problem- I purchased rebuilt kingpins. I am trying to install them and am having the following problem. The trunnion (piece 59 figure 11.2 in the Haynes MGB manual) are not parallel to the swivel pin openings (piece 46). They are slanted at about 3 degrees toward the front of the car. The openings of the trunnion and the shock arms do not line up. I haven't been able to get the fulcrum pin (piece 11) to go through the trunnion and the shock arms. The pin hits the forward shock arm outside the hole. I've tried to align them using a small bar but can't keep them holes aligned.
a. Should the holes in the trunnion and swivel pins be parallel?
b. How do you get them to align? Can I back off the nut for the swivel axle and rotate the trunnion?
c. Any cautions or tricks? I used some silicon grease on the poly bearing (piece 12) and slackened the nut that holds the shock arms together.
|Dick, I can appreciate the problem having just completed the same job. I had everything quite loose. Note there is a bolt and nut which 'for want of better words' squeeze the two shock absorbers arms once the trunnion bolt is in place at the top of the swivel axle, this lies inboard of the trunnion. Now, I cannot recall whether this ran parallel or at an angle, but I fitted the top of the swivel axle first, prying the shock arms appart somewhat. to line things up. In my case, it was all straight forward and easy single handed. I cannot think, that one can have things back to front? Once the upper part was in place I lined upp the lower between the spring pan arms. This also called for the nuts and bolts to be loose, as getting this could be tight. Have another go. Mike|
Thanks. I have received advice to loosen all the bolts so everything is in place but a bit flexible. The problem is basically, everything is new or rebuilt and the tolerances all on the tight side. I guess it is a matter of patients. Did you compress your spring after making the connection on the trunnion and spring arms? I've seen two suggestions - one is to connect the lower kingpins connection to the spring arms with the pan and spring in place. Then use a floor jack to raise the assemble and compress the spring until the trunnion lines up with the shock arms. The seconds says assemble everything and then put the spring and spring pan in raising and compressing the spring with a jack under the spring pan. You then have to align the four holes holding the spring pan to the spring arms.
|Actually Dick I did the second suggestion. The upper part assembled first spring pan just left 'floppy' or dangling so to speak. Then placed the spring with a jack under the pan and slowly raised, then lined up the king pin holes, a bit tricky used some grease, and actually gently tapped the pin into place. So you see the spring pan nuts and bolts are all assembled but loose.If one had been just changing the spring, then spring pan would have had to be disassembled completely, then lining up the spring pan nuts and bolts with the jack gently and slowly lifting is quite difficult, cause it wants to go in all sorts of directions. Mike|
This thread was discussed between 13/07/2011 and 12/09/2011
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