How to Know When Diff Subframe & Suspension Bushings are Bad

9

93celicaconv

Member
I see a lot of posts on here about where to get replacement rear differential subframe bushing kits, replacement bushings for other suspension components, etc. Looks like there are many putting time & money into replacing these bushings.

My question is: How do I know (and how do I determine) when some or all these bushings are at the end of their life and should be replaced?

Does one look to see if the bushings are almost completely disintegrated before starting to plan for a replacement? Is there a ride quality change or a sound/vibration that develops pointing to bushing replacements?

These cars are 25-28 years old now (ST185's, that is). Just want to know what owners are looking for when they decide to get replacement bushing kits for their vehicles.
 
9

93celicaconv

Member
Maybe I should ask this question differently. For those of you who changed many of the rubber bushings on your ST185's, what was the cause/benefit that led you to spend the time and money to replace them? And did doing just bushing replacements give you the results/benefits you were seeking?
 
8

8BitBrody

New member
I also would like to know this. I've been having some clunking from the rear end, and I'm not sure if it's the diff, the diff mount, or some of the subframe bushings.
 
underscore

underscore

Well-known member
You'll get clunking if things are really bad, but given the size of the bushings I imagine you could get under there and apply some leverage to see how much play there is in various bushings. There's a lot of rubber back there so lots of things to wear out and cause noise.
 
9

93celicaconv

Member
underscore":1jzceejm said:
You'll get clunking if things are really bad, but given the size of the bushings I imagine you could get under there and apply some leverage to see how much play there is in various bushings. There's a lot of rubber back there so lots of things to wear out and cause noise.
Click to expand...
Appreciate the response, underscore.

I'm assuming the response to mean, if there is free movement (indicative of a bushing whose ID is bigger than the pin going through it and/or smaller than the housing containing it), that is the sign of worn out bushings. Bushings just plain getting hard (like the can easily do on engine mounts) isn't an issue with suspension bushings. Do I understand correctly?

Is it fair to say that a lot of noise/vibration that comes from a car in high gear, moving slowly and lugging the engine (which is typical of manual transmissions vehicles to some extent), when it is overly loud & noticeable, is not a sign of these rear differential bushings having become loose or hardened, right?
 
K

kn0wledge185

New member
Change them when they look like this. Since your in there......you might as well change everything else.
0b8afabbee7c682a765b99300dbc1e1e.jpg
aed7677b1ee0df929846427c24b5c0ad.jpg
71428373eb327cc8a1a5d9d036d109dc.jpg
0aece6d06f34547ccfe6e3e88ca85ca1.jpg


Sent from my SM-G950U using Tapatalk
 
9

93celicaconv

Member
Okay, thanks kn0wledge185. So you changed yours based on visual ques. Were there any driving symptoms that caused you to lose look at these bushings? Also, where was your source for replacements, and what were the part numbers? Are the polyurethanes you got of similar hardness to the original rubber ones, or did you go with harder than original? Did the replacements change how the car drove/handled? If so, in what way? Are you glad you changed them?
 
9

93celicaconv

Member
Okay, thanks kn0wledge185. So you changed yours based on visual ques. Were there any driving symptoms that caused you to lose look at these bushings? Also, where was your source for replacements, and what were the part numbers? Are the polyurethanes you got of similar hardness to the original rubber ones, or did you go with harder than original? Did the replacements change how the car drove/handled? If so, in what way? Are you glad you changed them?
 
9

93celicaconv

Member
I can get you the original Toyota part numbers. But in checking, there is only one set of original Toyota cushions still available. If you need/want more than that, I would suggest getting all the bushings from a single source, since different sources likely would have different bushing materials and characteristics - I don't like mixing things like that.
 
underscore

underscore

Well-known member
There's a few threads on here about the different options for replacement bushings, I've got the GT4 Racing ones in my car and I like them. For the rear diff and subframe xiiimotorsports makes a solid kit or BRD makes a poly one.

93celicaconv":3drwzafr said:
I'm assuming the response to mean, if there is free movement (indicative of a bushing whose ID is bigger than the pin going through it and/or smaller than the housing containing it), that is the sign of worn out bushings. Bushings just plain getting hard (like the can easily do on engine mounts) isn't an issue with suspension bushings. Do I understand correctly?
Click to expand...

I've never dealt with a bushing going hard, just sloppy from wear. If it got harder without extra play then I imagine you'd get more vibration but not knocking.

93celicaconv":3drwzafr said:
Is it fair to say that a lot of noise/vibration that comes from a car in high gear, moving slowly and lugging the engine (which is typical of manual transmissions vehicles to some extent), when it is overly loud & noticeable, is not a sign of these rear differential bushings having become loose or hardened, right?
Click to expand...

If they're worn out you could get some added noise when cruising since the extra play may be allowing things to make contact and transfer more vibration.
 
K

kn0wledge185

New member
Well I'm in the process of removing all the arms & sub frame from my spare st185 and getting them prepped. Honestly a visual inspection and what underscore said.... get under and apply some leverage and see if you have any play. I'll get all my parts together later on today and post part numbers. I'm doing all this because suspension is shot and i have a broken axle. So my game plan is to take all parts off the spare get them ready..... so when I'm ready to fix the daily driver, i can just swap out parts.

Sent from my SM-G950U using Tapatalk
 
8

8BitBrody

New member
I'm personally having a hard time figuring out how many bushings there are to be replaced, and what each of them would be called. I can see, just by visual inspection, that I have some bushings on top of the rear subframe that look shot, but I'm not sure where to even begin to search for those. Does anyone have any links to complete rear end kits? My searching for the brands provided yielded little to no quality results.
 
8

8BitBrody

New member
Are Klue and Mario members on the site? I can't find them on Google. It also seems like GT4's site has been hacked, so no luck from them. =/ Is there any way to make those rear subframe mounts on your own?
 
underscore

underscore

Well-known member
Klue is the owner of xiiimotorsports, Mario I'm not sure how to get ahold of other than through the forum here. I'm not sure what's up with the website for GT4.
 
9

93celicaconv

Member
8BitBrody":1jtdygtb said:
Are Klue and Mario members on the site? I can't find them on Google. It also seems like GT4's site has been hacked, so no luck from them. =/ Is there any way to make those rear subframe mounts on your own?
Click to expand...
Hmm. The GT4 website work fine on April 30. Even sent in a question on polyurethane bushings regarding hardness specs, and got an e-mail reply from Paul there on May 2. I was glad to see they can make polyurethane bushings with a hardness spec matching that of natural rubber (which the OEM used) - not sure if that translates into equivalent ride characteristics or not for street use purposes.
 
M

mpg

New member
Suggest checking the sway bar bushings and end links for wear, mine were shot as there was clunks/rattles. Replaced all and no more of either, car rides/handles better, less understeer.
 
N

Numbchux

New member
Put some lateral pressure on them with a prybar, and if they deflect too much, they're bad. It can be a difficult thing to diagnose, as they're supposed to deflect a fair bit. The bushings I put in my car were a side-effect of other projects.

IIRC, The rear lateral links in the ST18x chassis use spherical bearings, instead of bushings. I had one of these develop a bunch of play, which caused a number of weird handling characteristics on my '92 ST. I grabbed the lateral links, knuckles, and brakes from a '94 GT, and swapped them in. I chose an ST20x chassis, because they used conventional bushings that could be easily replaced, and adjustable links, instead of cam bolts for toe adjustment. I have swapped this setup onto my '91 GT vert.


When I bought my '91 vert, it had a bent front control arm, so I bought a used control arm, and replaced the bushings while I had it apart (I then did the other side to match).


I'm replacing the rear diff on my Outback this weekend, and when I dropped the diff out, the center section of the rear mount bushings just fell out, the bushing was completely torn, and just floating in there....But 311k miles will do that. Just ordered poly for those, too. Luckily the salt is finally washed off the road so I can start driving my Celica.



IIRC the front control arm bushings I bought came from SuperPro, and the rear was a set from eBay, might have been GT4 (it had to get shipped from Europe, somewhere).
 
You must log in or register to reply here.
Top