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240 Suspension Bushings

C

crozek

New member
Joined
May 29, 2024
Location
Chicago, IL
I recently bought my first 240, 1992 with the B230F.

I did some searching on the forum but lots of the information seems to be a bit old and varies. I also come from the miata and formula car world, where everything is fully independent double wishbone, so forgive my lack of solid axle knowledge.

All of the bushings on my car are in poor shape, and I would like to overhaul them, but I want to make sure I upgrade the weak points I understand are in the rear trailing arms.

This car is just my daily driver, so I am not looking for anything performance driving oriented, the car does see some rough roads though. Ride quality and stable ride are most important. The car feels extremely sloppy right now, I'm sure part of that is due to the bad shocks, but that's already in the works.

Curious for all of your advice on a bushing setup. Thanks.
 
I have only heard bad things about poly in the rear. Poly doesn't articulate along more than 1 axis well, so the rear axle won't want to articulate. It'll act like it has a massive rear sway bar. Poly for front control arms and panhard bar. Spherical for the rear trailing arm bushing, rubber everywhere else. This will make the ride worse though.

For a DD what I've done is NOS W. German Volvo or Boge rubber only replaced in pairs where it has failed. Along with springs, shocks, front swaybar, and 15a plates the car feels compliant and responsive for a 240.
 
OVERDRIVE said:
I have only heard bad things about poly in the rear. Poly doesn't articulate along more than 1 axis well, so the rear axle won't want to articulate. It'll act like it has a massive rear sway bar. Poly for front control arms and panhard bar. Spherical for the rear trailing arm bushing, rubber everywhere else. This will make the ride worse though.
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That hasn’t been my experience

I got maybe 250k miles on poly bushings on various 240s
 
For DD poly rear is fine, plus the added ease of install compared to rubber or spherical, no fancy tools needed.
 
I think where poly in the rear becomes an issue is when you add in stiffer shocks, springs, and sway bars. Those or a subset of them can probably lead to an overly stiff rear axle.

I do run poly in the front. My steering feels really nice and precise when combined with the chassis braces.
 
Aren't the rear poly bushings solid where the rubber ones are supposed to have holes to allow some flex?

Kaplhenke sells spherical bearing replacements for that location, which is probably the most robust option. Rubber should be fine for most people though.
 
Khrrck said:
Aren't the rear poly bushings solid where the rubber ones are supposed to have holes to allow some flex?
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Was just about to say that. OEM axle and torque rod bushings have voids that allow the axle to twist. They do not exist in poly bushings, poly bushings are also much stiffer. It isn't going to articulate as intended. I'd bet it doesn't matter in 9/10 cars for owners intended proposes.

I use a mix of poly and rubber depending where it is.
 
Rubber everywhere is not difficult and nice for a dd. U can rent the tool at a parts store or buy a shit one at fright harbor for $60. The one that looks like a giant c clamp. Did the whole rear with a coworkers snap on set last weekend.
 
h(iroll)er said:
Rubber everywhere is not difficult and nice for a dd. U can rent the tool at a parts store or buy a shit one at fright harbor for $60. The one that looks like a giant c clamp. Did the whole rear with a coworkers snap on set last weekend.
Click to expand...
Gregervin on here also makes a tool for the large axle bushing, has a spacer so that you don't bend the ears.
 
Worse how
Better how

Poly will transfer more noise and vibrations
Positive of that is the car will feel more responsive

It’s a crap shoot with rubber these days as even the Volvo stuff tends not to last

were getting a new generation of drivers on here, not everyone is experiencing hemorrhoids and limp dick backs
 
Jack said:
Worse how
Better how

Poly will transfer more noise and vibrations
Positive of that is the car will feel more responsive

It’s a crap shoot with rubber these days as even the Volvo stuff tends not to last

were getting a new generation of drivers on here, not everyone is experiencing hemorrhoids and limp dick backs
Click to expand...
nailed it, do you just want to argue?

... or more likely, talk about dicks?>
 
crozek said:
I recently bought my first 240, 1992 with the B230F.

I did some searching on the forum but lots of the information seems to be a bit old and varies. I also come from the miata and formula car world, where everything is fully independent double wishbone, so forgive my lack of solid axle knowledge.

All of the bushings on my car are in poor shape, and I would like to overhaul them, but I want to make sure I upgrade the weak points I understand are in the rear trailing arms.

This car is just my daily driver, so I am not looking for anything performance driving oriented, the car does see some rough roads though. Ride quality and stable ride are most important. The car feels extremely sloppy right now, I'm sure part of that is due to the bad shocks, but that's already in the works.

Curious for all of your advice on a bushing setup. Thanks.
Click to expand...
I just did this job on the same year, same engine. Here's what I did and what I advise you to do differently. 1. admitted the trailing arms should come off, too, in changing the rear shocks. 2. Met the Big Fat Challenge that is the bushings 3. Bought the $80 tool from Greg Ervin to have a chance at them. 4. Fought with them for almost 7 hours with Patience, Kroil, Fire in rotation X 4. 5. Put in Ipd poly where Rubber had been. A mistake for two reasons: almost as hard to put in as get out and b. very hard ride. I've heard it said: Rubber for the rear, poly up front. I suggest that is true. I'd squeeze back rubber for the rear trailing arms. OR pay for the anodized metal BNE bushings, if only for the ease of re-entry. See Longbow's video on attempting to take the "sword from the stone." Basically great video. I also used the biggest, baddest C-clamp in addition to the Greg Ervin tool. Be SURE to use the spacer to protect the "ears" or you will crush and destroy them. Good luck.
 
I prefer rubber OEM style in the trailing arms and poly in the torque rods. Or spherical ends in the torque rods.

OEM style rubber (Volvo brand might be impossible to find, I think Boge might be decent?) works well in the trailing arms and has lasted a very long time in my experience. It doesn't transmit noise/vibration like poly, and it allows the pivoting to occur between the chassis & axle.

OEM style rubber torque rod bushings probably last a while in a calmly-driven car, or with an auto trans. With a manual and with hard launches, etc., they lasted me about a year, many many years ago. I replaced with the red poly available at the time and those lasted much longer. The mode of failure was splitting of the poly bushing due to the ends of the torque rod elongating into ovals and they pinched the bushings. Cracks formed in the poly and then the steel sleeve around the bolt torque through the poly.

After that, I used pre-81 ORIGINAL-BUSHING torque rods. These hour glass bushings are solid, unlike the '81+ with voids. They seem to last forever.

I've also used this type when I needed an adjustable torque rod: https://www.bneshop.com/collections/240/products/240-adjustable-torque-rods

My theory was that the torque rod bushings would go first, then the excessive twisting at the axle connection to the trailing arm would rip up the trailing arm bushings. In all the years I autocrossed, occasionally tracked, and occasionally drag raced my '87 240, I always had original type rubber trailing arm bushings.

When I swapped in a '79 1030 axle, I left these original (?) bushings alone, and they seemed just fine. This axle came from a car with the old hourglass torque rods, and they were fine. Probably superior to the later stuff as far as durability, but maybe transmitted more noise???

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For a near-stock car with normal driving, I'd stick with rubber bushings.
 
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