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Re-assembling rear suspension

7K views 53 replies 8 participants last post by  richardbradford 
#1 ·
Ok so I finally (I think) have ALL my parts together. I've now tried to put it together twice, but I want to make sure 100% that I am doing this right.



Specifically I am asking about the long bolts marked 14 and 16 in this photo.

When I removed them there were various thickness washers in between each part. I have all those washers I removed. As well I have some extras of the thin ones too.

In putting it back together I assumed it would be possible to bottom out the nut on the small amount of threads on the ends of the top bolt. Despite every combination of washers this is just not possible. However of course if I tighten the nut then the suspension arms only move within the range of the deflection of the rubber bushings. This doesn't seem right.

Then of course there are the plastic caps that go on the ends of Bolt #14. If I pop that cap on the end over a thin washer, and snug the nut up I still get movement without deflection, and I can keep the nut attached using red loctite. Is this what is expected? Or should I just leave everything loose a bit till its all in and then tighten down fully and allow deflection to happen?

On the bottom it seems I would be able to bottom the nut out even with washers so it would move freely, or should i do the same on the bottom too?
 
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#2 ·
Interesting questions and would love to know the answers. I know the rear nut on the back of the front suspension arms seems to lock the bush so the only flex is in the rubber itself - which seemed odd but have heard of it on other cars. Begs the question of what position the arms should be in when fully tightened? Loaded or unloaded?

Can I ask what grade steel your long bolts are? 8.8 or 10.9? Galvanised?
 
#3 ·
The front bushing on the front control arms flex like that as well which I thought was strange but they only go in one possible way so it is what it is. As far as i could tell as well my nearly 30 year old control arms that i removed the bushings were not damaged, so I guess there is enough flex in them. As well my rear bushings while worn were not spinning in their mount or anything so they haven't torn either.

You bring up a good question, should they be loaded up when tightened?

I'll have to check the bolts when I get home to see the grade. The long bolts were not galvanized, but some other bolts were. I wirewheeled all of them to get the crud/rust/whatever off so the galvanization is gone now anyway. I figured since I won't be driving the car in the winter, a regular diet of silicone spray on all bolts will keep them nice.
 
#4 ·
Page 21-25 of the 1991 ARDONA shop manual shows three spacers denoted "a" "b" and "c" to be included on those long bolts.

Spacer "a" fits between the inboard ends of each control arm and the subframe, for spacer "a" there are two for each bolt. These are number 17 on your diagram.

Spacer "b" fits between the forward control arm and the strut mounting hole and spacer "c" fits between the aft (adjustable) control arm and the strut mounting hole. Spacer "b" is numbered 17 also on your diagram and spacer "c" is numbered 12.

These spacers should prevent the bolts from bottoming out and jamming the bushes as far as I can see.
 
#5 ·
Even if I install thin washers in each position, putting the nut on locks the whole deal solidly together. The only way to not do it is to use the plastic cap over the end as a spacer of sorts and snug the nut to that. However that seems flimsy, but maybe thats the way. Someone here has done this before right?
 
#9 ·
Yup. If not done this way, you will wear out bushings much quicker placing unnecessary torque on the bushings. If they are tightened either up on a jack or off the car they they will not be set in level driving position which is basically set at 0.

This is the right way to do it.
 
#12 ·
As you know the standard rubber bushing has an inner and outer metal sleeve with the rubber vulcanized to the sleeves. In the case of a basic control unit (wishbone), the outer sleeve is pressed into the wishbone, making that part rigid; when you tighten the bolt, ca 45 foot pounds, it's the inner sleeve that becomes rigid to the body part. The only flexing of the component is via the rubber itself, a few degrees in one direction, a few degrees in the other direction. Thus if you were to tighten the bolt with suspension parts hanging, when you lower the car, all the flex on the poor rubber is in one direction. On the other hand tightening (properly) at road level, which represents the average height of the car, this is the 0 stress position of the rubber. So as Jason pointed out, doing it the wrong way leads to premature failure of the rubber bushing (especially when you are reassembling the suspension without the bushing renewed). On a super light car like a Lotus, tightening in a jacked position will actually change the ride height of the car when you lower it, not to mention making the suspension quirky, as the rubber of the bushes themselves create unequal resistance to the suspension's movement.

I think that this thread shows, that no matter how experienced a mechanic you are, when working an a component that is unfamiliar to you, you need to carefully examine and catalog the parts as you remove them so you can reassemble them in the right order. There are lots of situations where shims are used to compensate for irregularities in the build; surprise surprise, not all 164s are the same. Something as simple as the AC compressor bracket is a case in point, where a shim might be added on one car at the factory to help align the serpentine belt, a shim here, a shim there, basta. Next car, please, oh, no shims needed, basta.
 
#13 ·
Ok so let me see if I get this straight:

Assemble to rear cradle without torquing bolts so the parts can move.

Install all parts, leaving bolts loose as well.

Get car on ground to level driving height.

Torque all bolts which means the bushings WILL be deflecting just like the ones in the front A arms, but that deflection of rubber is ok (this was my main question as that did not seem right).

Do i have it right? if so, anyone know the torque values?
 
#14 · (Edited)
How does the inner steel sleeve bind on the mounting bolt?

The shop manual specifies moly grease on the rear mount for the lower control arm. That indicates that the mounting stud (the rear mount comes with the double ended threaded "bolt" already inserted into the bushing) rotates within the clamping bracket. The bush remains unloaded from a torque perspective.

There is no way the rubber in these bushes can become locked in a particular orientation to suspension movement. That's a lot of rotation to accommodate.

Plus if you substitute polyurethane bushings these need to be greased on the outside where they adjoin the steel sleeve or they squeak.

I say this is one of those mechanics myths.
 
#15 · (Edited)
How does the inner steel sleeve bind on the mounting bolt?
Mechanic's myth?, oh please.

Well, let's start with bolt #16. This bolt along with two thick washers cinch against the inner steel sleeve of the bushing of the link #2, then the other side of the steel sleeve of the bushing is squashed against the strut bracket with another thick washer in between, metal against metal. Follow the bolt through the strut bracket and the same occurs on the other end. The bolt kills two birds with one stone. When you torque this bolt to 45 ft lbs, it locks both bushings (inner sleeves) from turning. The movement of the links is entirely due to the flex in the rubber, the bushing itself does not rotate. If anything is greased here it would be the the bolt and the nut, as it is very prone to getting oxidized. (I've spend up to two hours removing the lower bolt and the car was not even rusty) I can't explain how polyurethane aftermarket bushings work, I personally prefer the original design.

Tightening the suspension bolts on the Lotus 7, it's also crucial to do this at ride level; just like the Alfa, the flex in the links is due to the flex of the rubber, inner and outer sleeves are fixed.

How much flexing in degrees? Hard to say, and it depends on the length of the links, maybe 2° in each direction.
 

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#16 ·
To add to my post above (sequence... did I get the sequence right?) then in theory I could also drop the car on to 4 jack stands mounted under the hubs which would then basically have the weight of the car on the points it should be, while still giving me room to work.and then torque all bolts.
 
#20 ·
Basically yes. as long as the suspension is at ride level and those forces on the suspension are in place. You could also loosen the rear front control arm at this time and re-set that as well. No other bushing on front needs to be set in this manner.

I will tell you, once I made this mistake. I installed new bushings on a car, did not set it at ride level but instead up in the air. Car sat 1" higher and wore the bushings within a few months. This was when I was much younger and ignorant to this.
Learned my lesson.
 
#17 ·
When I replaced the rear trailing arms in my 91S, I installed them but not really tightening the forward bolts, and then set the rear hubs on blocks to load them into road height position, then tightened the forward bolts, thus reducing the movement stresses in the bushings. The rear long bolts I didn't worry about (lol, lazy).

However, I did slather the long bolts with plenty of anti-seize goop, still pristine from new.
 
#25 ·
If the spacers fit over the ends of the inner steel sleeve of the bushing there is no need to load the suspension before torquing up the bolts. The diagram indicates this is how the spacers fit. Do they? Looking at the thread I linked you to it certainly looks that way. If that's not the purpose of these spacers it's hard to see why they are there at all.
 
#27 ·
Michael, what I don't think you're taking into account is the fact that this is not a model car sitting on your desk. It's a 3000lb vehicle designed for speeds well in excess of 100 MPH. A metal sleeve sliding over a bolt with no lubrication beyond initial greasing is not a feasible bearing design for (at least) three reasons:

1) Going down the road at highway speeds the suspension is in constant motion. The friction would quickly overheat the surfaces.

2) When a bump is hit at these speeds there is a tremendous twisting force on the suspension members due to the force vectors involved - hitting a bump produces both an upward force on the wheel as well a backward force. This would cause the sleeve to bind on the bolt unpredictably.

3) Even if the first two were not true, a sleeve sliding on a bolt would wear out extremely quickly.

Therefore the metal sleeves of a rubber bushing MUST be held rigid on both the inner and outer sleeves. The rubber provides the range of motion necessary. This is a pretty universal suspension bushing design and it's well understood in an engineering sense. The rubber thickness and durometer are carefully chosen to accommodate the designed range of motion.
 
#28 ·
Therefore the metal sleeves of a rubber bushing MUST be held rigid on both the inner and outer sleeves. The rubber provides the range of motion necessary. This is a pretty universal suspension bushing design and it's well understood in an engineering sense. The rubber thickness and durometer are carefully chosen to accommodate the designed range of motion.
Exactly! Exact reason why you cannot torque them down up in the air, they will be set or rigid in their positions. Place the car on the ground at ride level and you have twisting to the rubber occurring without anything happening, just sitting at ride level. This causes many issues from quickly wearing out the bushing by maxing it out when it encounters any motion, sometimes ride height change, alignment issues, handling issues and so on.
 
#29 ·
My initial view resulted from the absence in the ARDONA shop manual of any reference to torquing the suspension bolts only after compressing the suspension to normal ride height. Perhaps this is because ARDONA presumes all mechanics would know to do this.

I have no vested interest in being right or wrong, only in understanding the suspension design and the repair process.
 
#33 ·
Just an idea.

Could not the inner arm ends, against the subframe, be held at the correct angle and tightened before the outer bolts are fitted, and then, with the car slightly raised from the ground just enough to fit the outer bolts, the car could then be lowered to the ground and outer bolts tightened on the deck, in the correct position/loading?

As for getting the right arm angles at the subframe end, they could be measured/photgraphed before dismantling.

Any thoughts?
 
#34 ·
In theory sure, but that sounds a bit too much like a guesstimate that may be somewhat off. Also if the old bushings are trashed your measurements won't be good.
 
#39 ·
As someone who has used a spring compressor this is a terrible idea.

First off once you compress the spring you would still need to jack up the corner you're working on to the spring as the damper doesn't compress with a spring. Secondly external spring compressors which is what you'd need to use are ultra dangerous and can result in serious gruesome injuries should it slip off. I say this because I have actually seen this happen more than once. There are some better ones out there these days but its not a quick simple tool to use inside the strut tower.

This is a problem that can be solved by driving the car up on 4 double wood planks, or hitting a local shop, or 4 jack stands under the hubs, all of which are faster and significantly safer.
 
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#40 ·
Rougue Leader, you are right. I totally missed the element that the damper will remain fully extended. Glad you pointed it out before I tried it and had one of those 'Duh' realisations. Would be confident the compressors wouldn't slip off as they would hook around the curved bottom of the strut and the spring coils but the exercise itself would be totally pointless, as you have correctly pointed out - unless something like a bottle jack was used to squash the damper too - wouldn't lift the car with the spring compressed.

Personally not too keen on the plank idea stability wise so have got round it here by buying a pair of wide car ramps to safely raise the rear wheels enough to gain bolt access, while the front can be raised with a trolly jack and axle stands. Problem solved, at last.
 
#41 ·
That's a low pressure gas strut just btw. You can lift those by hand. Even high pressure gas struts exert very little pressure.

As for the spring compressor slipping well so can a jack. The spring is restrained anyway. It's not as if you'd be dealing with a compressed but otherwise totally free spring.

The main reason not to use a spring compressor is that an ordinary jack could be used instead. The key element either way would be to know the ride height you need to simulate.

Easiest would be to torque everything up and then have the suspension loosened and retorqued while the car was on the type of lift that lifts the car by the wheels.
 
#42 ·
Easiest would be to torque everything up and then have the suspension loosened and retorqued while the car was on the type of lift that lifts the car by the wheels.
Agreed, unfortunately since most of us don't have that its more of a how much money do you want to spend to do that part?

Or just had another idea, I have a car trailer with an open deck, can drive the car up on it and do it that way as well.
 
#43 ·
No need to make it difficult.

Put it all back together, keep bolts just enough loose. Either jack up rear end (from middle of rear) and put jack stands under hubs to compress suspension like it is on the ground (be careful though), tighten up everything to spec. Or put wheels on, put blocks under wheels and tighten up on the ground.

No fancy lifts etc...
 
#46 ·
They will but you also don't want to load up your suspension with those bushings way off, you can damage them if they are far enough off to begin with. Its only supposed to deflect within a small range. This was the basic concern of my initial question, because clearly doing it that way would quickly damage the bushing.

Why tighten the crap out of them when you are going to need to loosen them and retorque anyway. Just leave them lightly attached so they will 0 out when the suspension loads up, and then tighten them properly.
 
#48 ·
Just to say, found the rear clearance of my 164 on the ground is high enough for me to slide underneath with spanners in hand and tighten the rear suspension bolts, now in their natural position. How did I miss this before? It totally answers all previous ideas of spring compressors or jacks or wheel ramps.

By the way, also found that the lower rear strut suspension bolts, the 105mm and 200mm (205mm) M10s, are (EU/UK) grade 10 steel, not sure what the US equivalent is, with special zinc coating. Think it is thicker than even passivated yellow zinc. As temporary measure, have grade 8.8 (UK/EU) 110mm bolts in the top holes of the bottom struts. This is still really strong steel and probably strong enough to rip through the strut itself before breaking. Not managed to free up the long lower bolts yet - still spraying them with variety of rust penetrating stuff and got some emery paper strips to clean up their exposed shafts.

Hope this helps.
 
#49 · (Edited)
Help!
Today got the car up on a friends ramps and managed to bang out the 8" long bolt on the bottom struts on one side, after about an hour of freeing the lateral arms up. On the other side - zero joy. Hammering it hard (club hammer), breaker bar adding torque on the head end - nothing. Took out the 5" bolt above it and moved the stub axle in/out a bit relative to the strut so the bae of the strut is free - just nothing else.
With a longer breaker bar had the head turning a bit, though zero visible movement in the rest of the bolt. Not even in the open middle section between the stub axle sides.
Considered using butane/propane to apply heat but the strut/shock is too close and it would burn the bush in the stub axle, possibly the ABS sensor too.
Another option am considering is just dropping the rear subframe, stub axle/trailing arm and that strut as one then trying to get the bolt out. While it is on the car the rubber bushings take the jarring out of the hammering, reducing the ability to break the corrosion on the bolt.

Any suggestions would be really very welcome.

A final though: has anyone tried snapping the bolt head off and then using the nut on the other end to pull the remains out?
 
#50 ·
Wow yours are worse than mine.

I used VERY liberal amounts of pb blaster which I sprayed on multiple times over the period of days. And once I got the bolt in somewhat i used a screwdriver to drive it out through the hole.
 
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#52 ·
Thanks Guys.

Steve, am pretty much heading your route now. Bought a 6mm cobalt drill bit in case have to drill final bolt out, after angle grinding off long bits.

How did you access the 3 nuts on top of the struts? Through the boot with something like a swan neck spanner or from above via the parcel shelf?

Did you manage to leave the rear brake balancer cylinder in situ? I.e. was it possible to slide it off the subframe without having to undo the hydraulics?

Great posts/pics by the way.

Thanks again,

Richard
 
#53 ·
I accessed three 13mm nuts on top of strut going in trunk/boot area under rear speaker area with a socket and ratchet. Pull out sound deadening material on top of strut tower first.

You maybe able to unbolt brake valve from rear cross member but long brake lines go over top of gas tank and shorter lines go out to brake calibers. So you probably will have to disconnect short lines from hoses in wheel well.

Parking brake wire cables may have to be disconnected from calipers, too.

I ended up removing and replacing everything in both front and rear suspension and brake system as well as gas tank and gas lines/brake line all the way to engine bay.
 
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