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240 Bad trailing-arm front bushing?

esmth

The member
Joined
Jul 13, 2016
Location
MA/NH
Hello!

When I accelerate or decelerate, I hear and feel a clunk in the rear suspension that I cannot narrow down. It also constantly clunks when cruising at a very low engine load and RPM. It feels almost like the diff has way too much backlash, and the pinion is slamming forward and back. (though twisting the driveshaft by hand results in a normal backlash and spider gear play.) This has been happening the past probably 3-4 months but recently its gotten worse

I am running ben's spherical main trailing arm to axle bushing, and his full heim torque and panhard rods. (installed in March-ish) The last original bushing in the rear is the front trailing arm bushing. I can wedge a screwdriver between the trailing arm and body and move the arm pretty easily making me think this bushing is bad.

posts like this also make me think its this bushing
http://www.turbobricks.com/forums/showpost.php?p=5712794&postcount=8
http://www.turbobricks.com/forums/showpost.php?p=5706038&postcount=10

Am I headed in the right direction? Should I replace this bushing with poly?
 
From reading your post you are headed in the right direction. Get that bad old bushing out of there. I have used poly in that location without issue. This is also a pretty hard rubber bushing in that location so even putting in a good quality rubber one should fix the problem.
 
I concur. I thought I had pictures of mine when I replaced them but I do not; They were pretty bad... and if not original, had not been changed in a good, long while.

I replaced mine with the rubber type. I don't see any large issues with using poly bushes in that location, but others might as there is a piece of bracketry that will need removed somehow. See http://forums.turbobricks.com/showthread.php?p=5146724#post5146724

Best Regards

PV
 
The only real negative observation about poly I've heard, was from a mechanic who said he's seen poly shatter in extreme winter temps (I'm guessing -10f, -20f, -30f, colder ??). However I didn't hear enough of the details to know if newer or older poly, how old, miles, brand/product, etc..

* Maybe a good question to pose to John V or some snow/ice racers if concerned ?
 
I have used poly in that location without issue. This is also a pretty hard rubber bushing in that location so even putting in a good quality rubber one should fix the problem.
I may be mistaken but I think because the axle can articulate more with the spherical joints, it is pushing more wear on this bushing and is why I was thinking of replacing it with poly.

I replaced mine with the rubber type. I don't see any large issues with using poly bushes in that location, but others might as there is a piece of bracketry that will need removed somehow.
I took a look at that bracket on my car, and I honestly have no idea why that user removed the reinforcement. it's on the outside where the bolt head sits and I don't see how it'll interfere with poly bushings. I'd rather trim the bushings than the mount anyway.

The only real negative observation about poly I've heard, was from a mechanic who said he's seen poly shatter in extreme winter temps (I'm guessing -10f, -20f, -30f, colder ??).
It does occasionally hit -10f here in the winter, and I have other poly bushings in the front end and they survive the winter just fine, so i'm not too worried. Plus I love to snow-drift in parking lots so they see 'extreme temperature' with abuse
 
I replaced those, using rubber bushings. Poly needs lube once in a while and with the damp conditions here I had a few poly bushings go bad when the pivot rusted.
Also using spherical bearings in the tab-axle bushings and torque rods with spherical/poly.
 
I replaced those, using rubber bushings. Poly needs lube once in a while and with the damp conditions here I had a few poly bushings go bad when the pivot rusted.
Also using spherical bearings in the tab-axle bushings and torque rods with spherical/poly.

Poly in this location would be easier to replace then pressing out the rubber bushing and sleeve, yes?

Can i just burn the worn bushing out, leaving the sleeve for the poly ones, Or does the whole sleeve need to come out? I bought this: https://www.ipdusa.com/products/6876/109354-front-trailing-rod-bushing-kit-poly
The instruction PDF seems to push the whole sleeve out.

i realized i just answered my own question, lol
 
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so an update, new trailing arms with new poly front bushings didn't do jack squat. I did a little more sleuthing under the car and the rearmost u-joint has a bunch of play in it :oops: should have checked that before tearing apart the rear suspension

Will an aw70 rear driveshaft fit on the car with my 1986 M46 front shaft? May have to try the original shaft as that had good joints
 
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It should but you'll still have to have the whole thing balanced so it's not a swap and done job. Failure to do so will put you back in the same predicament.


so an update, new trailing arms with new poly front bushings didn't do jack squat. I did a little more sleuthing under the car and the rearmost u-joint has a bunch of play in it :oops: should have checked that before tearing apart the rear suspension

Will an aw70 rear driveshaft fit on the car with my 1986 M46 front shaft? May have to try the original shaft as that had good joints
 
Glad to see you have narrowed it down and found a defective ujoint. I still feel it was a good idea to have a 30 year old bushings replaced.

Definitely want to balance the driveshaft since a rear half from an M46 is different than the rear half of an automatic but they will interchange.
 
It should but you'll still have to have the whole thing balanced so it's not a swap and done job. Failure to do so will put you back in the same predicament.
Definitely want to balance the driveshaft since a rear half from an M46 is different than the rear half of an automatic but they will interchange.

I took this into consideration, so i marked the M46 front and rear shafts to keep them balanced together, But I really wanted to try my aw70 rear shaft to see if it solved my issue. (and it did!) I will be replacing the 2 u-joints in the m46 rear shaft to put it back in the car in the coming weeks. Though, I have not noticed any significant change in vibration with the aw70 rear shaft. Maybe I got lucky

On another note, should I spring for the Volvo u-joints, or are aftermarket joints equivalent? I read Volvo joints have a larger number of smaller needle bearings which is better for longevity, but I was wondering if there is any aftermarket brand of the same durability.

Glad to see you have narrowed it down and found a defective ujoint. I still feel it was a good idea to have a 30 year old bushings replaced.
I'm happy that bushing was replaced as it was the last bushing in the rear that was original!
 
Good work figuring that out. I did not see this before, but the first post includes a pretty good description of a bad U-joint.

I have not noticed any significant change in vibration with the aw70 rear shaft. Maybe I got lucky

I don't think you got all that lucky. You put in a good driveshaft half with good u-joints. I personally don't believe that the halves need to be balanced together. I think it is an old wive's tale. Maybe someone here can point out what I am missing.


dl242gt said:
Definitely want to balance the driveshaft since a rear half from an M46 is different than the rear half of an automatic but they will interchange.

Dave, if the shaft half has the same size flange at the diff, and has the same spline at the front end, and it interchanges with the other shaft, please explain what is different between them. I am having a hard time seeing it.
 
On another note, should I spring for the Volvo u-joints, or are aftermarket joints equivalent? I read Volvo joints have a larger number of smaller needle bearings which is better for longevity, but I was wondering if there is any aftermarket brand of the same durability.

Homer has some good information on the ujoint type in his build thread. Indeed Volvo used the heavy duty variant, also found in land rover for example.

https://forums.tbforums.com/showpost.php?p=5794824&postcount=2986
 
The only real negative observation about poly I've heard, was from a mechanic who said he's seen poly shatter in extreme winter temps (I'm guessing -10f, -20f, -30f, colder ??). However I didn't hear enough of the details to know if newer or older poly, how old, miles, brand/product, etc..

* Maybe a good question to pose to John V or some snow/ice racers if concerned ?

This is a big problem depending on the poly and its age..All poly is not the same..Last snow even I did with my Saab the car had 10 year old "Rancho" shock eyelet pushings upper and lower front and lower rear, pin mount bushings upper rear..Less than 100 miles on them.

A Arm bushings were from a now defunct "Duecue Factory" , also at least 10 years old or more and lots of miles..

Wasn't that cold..about 15-20F.

200 miles of mostly easy smooth roads and ALL the Raunch-oh bushings were GONE, shattered and disappeared...A Arm bushes were perfectly fine..

In the past there was a place in Bellingham, WA called "NW Offroad" who actually cast their own bushings..Amazingly, considering the guys were total thick headed knuckle scraper red-neck idiots, those bushings were amazing and lasted 30-40 events including -40 in Ontario and Quebec.

Long and short: you never can tell..
But it can be a major problem if you experience freezing temps or below.

I guess make sure they are free range, virgin, first pressing Poly, low fat, artisinal craft bushings..
 
so an update, new trailing arms with new poly front bushings didn't do jack squat. I did a little more sleuthing under the car and the rearmost u-joint has a bunch of play in it :oops: should have checked that before tearing apart the rear suspension

Will an aw70 rear driveshaft fit on the car with my 1986 M46 front shaft? May have to try the original shaft as that had good joints

This is why written descrptions of sounds are hard..I have a dead as doornail dead front bush and i say it goes CLUNK! hard and lower pitch..Dead propshaft u-joints i say do more of a "clang"..
maybe help next time.
 
The rear section of the driveshaft on an M46 is two pieces with a rubber damper sleeve inside the drveshaft. You can tell by looking at the middle of the driveshaft section. If it has a lip with the other section slid inside it has the rubber damper and is from an M46. The M47 and I believe automatics have a solid lenght of driveshaft tube from the rear to the center u joint. But they all can interchange since they are the same length.
 
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The rear section of the driveshaft on an M46 is two pieces with a rubber damper sleeve inside the drveshaft. You can tell by looking at the middle of the driveshaft section. If it has a lip with the other section slid inside it has the rubber damper and is from an M46. The M47 and I believe automatics have a solid lenght of driveshaft tube from the rear to the center u joint. But they all can interchange since they are the same length.

Given you're not mixing large and small diameter props.
 
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