RWD - How to replace the crossmember, and why you might want to (Warning bandwidth intensive)

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How to replace the crossmember, and why you might want to (Warning bandwidth intensive) 700

My 85 745 developed some front end problems,like no control in reverse, leaving black marks on concrete just from tire scrub, hideous popping noises on the highway, and of course excessive outer edge tire wear.

This is after I:
upgraded to 15" alloys
installed Tokico struts
replaced rack with known good unit
changed the weak tie rod at the same time
checked ball joints in good order
did a brake job, and repacked the nice nearly new bearings
replaced the forward strut rod bushings
Added an IPD sway bar

The car was pretty tight for a little while, and i did notice some small fractures at the inner control arm mounts. It didn't look too serious, but that metal is not as tough as I would have hoped. 6 months later, its scary to drive, the crossmember is nearly ripped in half...

How did this happen? I am somewhere between experienced and expert, and I have foud no evidence the car has ever been in a serious front end crash of any kind. The standard wearing parts are worn at 180,xxx. I know the previous owner well, and neither he nor I ever hit anything big.

I don't know if the dealer sells crossmembers, and I'm not inspired to find out what they cost. I went to Pick N Pull (they are half price next weekend), and every 700 still had the motor in it! not wanting to pull 2 motors out of the way, I agreed to haul the dead parts car from my friends work (local Volvo specialist) Being the car was mostly stripped it came out pretty easy.

Now I have 3 mini spares ;) one more and I can go drifting! The dump even took the shell for free.

But back to my car...Does the alignment look ok?

the camera is 15 feet from the bumper, and both wheels are aligned right at it!

Here are some pictuers of the damage, at both inner control arm ends, and the right rear subframe bolt:



Up under the motor mount

A bolt hole is even pulling thrugh

I forgot to take a picture of the lower sway bar end link that lost its bushing trying to make up for the lazy control arm. FIRED!

So, how do you get the crossmember out?
Raise the car to a height where you can ger comfortable under it, and support it securely. Chilton would tell you to disconnect the battery, I would rather spend my time getting a beer...

12mm........remove mud gathering plate from under rack
14&19mm.....remove sway bar
phillips....remove battery cable ties
19mm........remove front wheels
19mm........remove outer tie rods (1)
13mm........remove rack~column U joint bolts
19&22mm.....remove rack banjo bolts &drain fluid (2)
15mm........loosen forward end of track rods a few turns
17&19mm.....unbolt inner control arm ends, and pry them free
17mm........unbolt motor mounts
Jack........jack up the motor about 2" to clear mounts
16mm........unbolt 4 crossmember bots from above(3)
Hammer......knock the ends of the crossmember downward
13&17mm.....seperate rack from crossmember

(1) I use a 3' pry bar pulling down on the ball joint, and hit the end of the steering arm hard with a hammer, this distorts the taper momentarily, and the tie rod drops right out. leave the nut on a few threads for safety 2 hammers simultaneously striking the taper works better, but can be difficult to do.

(2)move on to other steps while the goo drains

(3)counterhold broke one(s) with vice grip

If you had x ray vision, this is what it would look like just before you pull the crossmember:

yep, my camera sucks in shadows, yay Photoshop 'equalize selected'

I think it took me about 2 hours, even though I spent 20 min talking on the phone...I had thought it would be longer. I used ratcheting box wrenches and my cordless impact to good advantage, it could take longer the old fashioned way.
Now I can realy see the damage!

The old part is at the bottom, note mangled control arm hoop, and bolt hole.
the rubber pads are different, as is the left (relative to car) motor mount.

starting at the right of the car, nice rear bolt hole.

under the motor mount

The fracture has passed the motor mount towards the front of the car.

The left side is starting to go the same way

And the left rear bolt hole is getting ready to folow mr. right rear hole

My analysis:
There was no accident, and I didn't screw up the car.
Somone at Volvo was trying to save $.02 in steel and .0004% fuel economy, or just faied to properly consider the effects of repeated side loading on their design. This created yet another McPherson strut suspension prone to disintegrate in an environment with corners or imperfect road surfaces. At least there are no constant maintainence axles. The chassis of the car should hold up for 200K.
That the defect is occuring on both sides of the car, in the same locations leads me to beleive it is an inherent problem. Both rear mounting bolt holes are failing, I would expect the fronts to go first if it were from hitting stuff. The bolt holes are particularly bothersome, because they are very hard to inspect without pulling the car apart.

Lets have a look at my 1987 mdel year replacement crossmember...

Sometime between 85 and 87 model years, Volvo realised their mistake, and changed the cutout(bottom) to a supported structure with an access hole(top)
Also just to the right of the rack input shaft, you can see the older crossmember has a WELDED on motor mount pad not present on my newer part. JOY!

Heres me carefuly sawing off the weld...windex makes an ok blade coolant.

A *smack* of the hammer pops the pad free.

Prepped and ready to weld, tiny screw hole at right (held L shaped bracket) realy helped me line it up just right. surfaced degreased, depainted, degreased again, and chamfered with a file.

Tacked, Lincoln 110 wirefeed using .035 flux core wire, turned up almost half way

Done!It wont come apart, but I'm not too proud. If the power strip hadn't popped every 1-2 inches, it would have been much prettier.
Why do I weld on a power strip? If the fire marshall saw all the wires the PO put up in my shed, he'd probably have a stroke. In short, a 10 outlet strip hardwired into the fuse(not breaker)box is the ONLY outlet in the parking area, and I just moved in.

Tomorow Ill find some motor mounts and write part two: Instalation is reverse of removal
If you have an 83-86?, check for cracks.


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New 1 How to replace the crossmember, and why you might want to (Warning bandwidth intensive) [700]
posted by  745 TurboGreasel  on Mon May 9 21:37 CST 2005 >

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