FAQ for 7xx/9xx/90 Cars
[Symptom:] When you accelerate from a stand still or when you decelerate
suddenly, you could hear and feel a jerk from the rear. This is when the
rear suspension is beating the chassis as it is taking up the clearance
due to the worn bushing. [Diagnosis:] Try this: Jack up the rear end of
the car and first with the car in neutral and the park brake off, turn
the drive shaft back and forth quickly. You will see if there is much play
in the torque arm bushings. The rear end will actually swing back and forth.
With the weight off the rear end, you should be able to pry on various
portions of the trailing arms close to the bushings and notice if there
is excessive play. If your trailing arm bushings are bad, you'll need a
special tool to take them out and press them back in. The torque arm can
easily be taken out and the bushings pressed in and out.
"Clunk" in Rear End: Bushing Diagnosis.
[Query:] 87 740 wagon with 190k, M46 trannie, new to us. Have replaced
shocks, struts, u-joints, trannie mount and center support bearing on driveshaft,
and some front bushings. Acceleration from standstill in normal traffic
results in a "clunk" which seems to come from rear end. Trannie output
bushing and pinion bushing have no play. Wheel bearings are good. Nothing
is rolling around in rear of car or spare tire well. The only thing I can
figure is bushing(s) in rear, but which one(s)? (none are visibly broken
up, although I haven't yet given them the prybar test.) Can anyone
guide me to the most likely culprit on this one? [Response: Steve
Seekins] I would focus on the rear suspension bushings. There are 7 - two
on each of the torque rods and three on the sub frame to body mounts -
one at the front and two at the rear. I would suspect the subframe mounts,
probably got accelerated wear from soft torque rod bushings. The Haynes
manual is adequate for procedures here. Of course you should first
check for loose upper or lower shock mounts or loose sway bar mounts. If
the lower shock mount has loosened, check carefully for elongated hole
in trail arm - if so, consider replacing the trail arm if tightening the
bolt does not do the job.
from Solid Rear Axle. My 745 with a solid rear axle has a single arm
with large rubber donut bushings connecting the underside of the differential
to the frame just ahead of the diff. The lower rubber donut has gone really
soft, allowing about 15 degrees of angular rotation of the rear axle; enough
to seriously deflect the drive shaft under acceleration at low speed and
causing the U joints to grumble loudly. At speeds over 15 kmh the noise
is gone; I suspect the momentum of the drive shaft resists the deflection
and the acceleration force is lower. The side bushings are fine; also I
have a heavy IPD swar bar.
and Stuck Bolts: Removal Techniques. See the link
for more ideas.
Spring Replacement. [Query:] I am thinking about installing new springs
and shock in the rear of my 745. How do I do it?] Regarding putting together
a detailed procedure for REAR spring replacements on a 745, basically anybody
who knows which end of a ratchet is which can do it. This is one of the
easiest things I've done to that car. It pertains to 7xx wagons with "live"
(aka non-IRS) axles. Probably pertains to the sedans, too.
Chock the front wheels.
A brief note: For replacement springs on a
wagon, I recommend going with "cargo coils", which are variable rate springs.
I purchased a set of MOOGs from my local parts supply (about $70 w/tax,
as I recall) and have been quite happy with them. I have had a couple of
occasions since installing them to give them a good try-out, the most severe
being when I filled the entire wagon full of materials for a new section
of fence, including post hole mix. I figure we had loaded about 800 lb.
of stuff in the back, plus there were two of us adults. The springs handled
this extra weight with ease. Further, because they're variable rate springs,
they still offer a decent ride even when unloaded. [Contrary Note:] I recently
installed a set of Moog cargo coils on the rear of my 89 765T and while
I've been happy with the ride etc. I'm not happy with the sagging rear
end they left me with. It sags about 1.5". I've talked with the reps at
Moog and they say the cargo coils are for sedans only and do not have an
application for wagons. I've ordered a set of IPD overload springs which
incidentally list different part #s for 7xx sedans and wagons. RPR also
sells Moog cargo coils for sedans only. In speaking with them they've had
a lot of complaints of rear end sag when used on wagons
Loosen the lug nuts.
Elevate one rear quarter of the car with
the jack, and find a suitable place to locate a jack stand that will keep
weight off the spring. I found a place right in front of the trailing arm
where I was able to locate a jack stand. If it looks like it's gonna bite
into the underside of the body shell, spread the contact zone out by inserting
a piece of 4x5x.75" plywood or something similar between the jack stand
and the car.
Remove the wheel.
Loosen the lower shock mount. The Haynes
manual says to jack up the trailing arm slightly to take tension off the
nut here. I don't recall if I did this, but it seems like a good idea.
I seem to recall that I also had to loosen the upper one too, but you'll
know it if you need to.
Remove the nut holding the upper spring
seat in place. If you're replacing a Volvo spring, chances are it is not
a variable rate spring, so you can get to the nut with just a ratchet wrench
and a socket. If you're removing a variable rate spring, however, you'll
probably need a fairly long extension.
Now at this point, I was able to lightly
tug on the spring and it fell right out. I did NOT have to remove the brake
caliper on either side, and I did not find the exhaust system to inhibit
the removal or installation on the passenger's side. I began the replacement,
prepared to remove the calipers, if necessary, but I found that there was
plenty of clearance there, and I didn't have to touch them.
When you get the spring out, inspect the
rubber seats for wear or deterioration. Replace if necessary.
If you're replacing your springs with
variable rate ones (recommended), you'll need a long extension for your
socket to reattach the upper spring seat because you won't be able to get
your ratchet to fit comfortably between the coils until about halfway down
the spring's length.
Reattach the upper spring seat. This was
the most time-consuming part of the procedure -- getting that nut's threads
to start was a bit tedious.
Reverse the above steps for the remainder
of the installation.
Shock Installation. [Query:] I am thinking about replacing rear
shocks on my '89 745 Turbo Wagon (non-Nivomat) and would like to know how
difficult a job this is [Response 2: John B] The shocks ARE gas charged
and can be difficult to compress and remove...same with the new shocks.
IF the new shocks have a wire or strap to keep them compressed, try to
install them with the wire or strap unbroken...you clip the retainer device
to allow the shocks to expand and hit the stud hole for the top of the
shock. Also, the lower control arm that the shock goes into may be
tight or loose depending on the brand of shock you buy. If it's loose,
make sure you tighten the bolt sufficiently to compress the control arm
sides against the shock bushing...or the shock will clunk. If the shock
bushing is too long, making the shock impossible to install, just wedge
or expand the control arm sidewalls enough to put the new shock in. Jack
the back of car up and put it on stands. [Response 2: Bill Woesthaus]
Take wheels off. Pull the rubber bolt hole cover off the top of the inside
wheel well. Unscrew the top shock bolt. Then, put wrench and socket on
bottom shock bolt, undo it. Wrestle shock out. Compress new shock and put
it in, top bolt first then bottom. Itís a good idea to leave the retainer
wire on shock (you don't have to wrestle with live shock) Possible
trouble? Top shock cavity could be too bent in from heavy bolt pressure
to allow new shock in easily, or to get old one out!! I ground down shock
ears to allow entry. If your holes aren't squashed tight it's a pretty
Nivomat Conversion. See Volvo
760/780 Nivomat Shock Conversion for complete instructions and illustrations
showing the conversion of Nivomats to normal springs and shocks.
Maintenance FAQ for 7xx/9xx/90 Cars
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