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> 914Rubber Rear Trailing Arm Bushings, did I get the wrong ones?
bbrock
post Jan 25 2021, 08:54 PM
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@Mikey914

I bought a set of the rubber rear trailing arm bushings in the 914Rubber GB when they first came out (can't remember when that was). I am just now getting around to installing them and ran into a problem. I did a test fit to see how hard they would be to install and was shocked to find I could easily slide them into the trailing arms by hand AND could slide the pivot shaft in by hand. In fact, I'm not seeing much difference from the polygraphite bushings they are meant to replace. If anything, these fit even looser. I'm wondering I was sent the wrong ones. My understanding is the rubber bushings should be a tight fit and require a press or similar to install as seen in Ian's video. Is there a good way to know what I have? These are stamped "WDG" on the flange side which is different from the stamping on the first set of bushings I bought.
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914Sixer
post Jan 25 2021, 09:39 PM
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Sounds like the rubber shrank. Yous should not be able to do either with the bushings.
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Mikey914
post Jan 25 2021, 11:14 PM
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They are not so easy to actually install. The OD of the bushing compresses it onto the shaft.

Give that a shot. I'm sure you will see why we designed them the way we did.
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bbrock
post Jan 25 2021, 11:44 PM
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QUOTE(Mikey914 @ Jan 25 2021, 10:14 PM) *

They are not so easy to actually install. The OD of the bushing compresses it onto the shaft.

Give that a shot. I'm sure you will see why we designed them the way we did.


Yeah, what I'm saying is that I can easily slide the bushings into the trailing arm and THEN slide the shafts in by hand with surprisingly little effort so something seems amiss. I'll play with them a little more tomorrow.
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Arno914
post Jan 26 2021, 01:49 AM
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As far as I have learned, suspension rubber bushings are designed to be press fit on the shaft and the tube. Movement is only within the rubber itself. (Thats why you must lower the car on ist wheels before tightening the lock nuts.) Any movement between the bushing and the corresponding parts will eventually lead to (rapid) detoriation. Never use grease or oil for assembly. Turpentine works.
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BeatNavy
post Jan 26 2021, 06:26 AM
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QUOTE(bbrock @ Jan 26 2021, 01:44 AM) *

QUOTE(Mikey914 @ Jan 25 2021, 10:14 PM) *

They are not so easy to actually install. The OD of the bushing compresses it onto the shaft.

Give that a shot. I'm sure you will see why we designed them the way we did.


Yeah, what I'm saying is that I can easily slide the bushings into the trailing arm and THEN slide the shafts in by hand with surprisingly little effort so something seems amiss. I'll play with them a little more tomorrow.

Yeah, that doesn't sound right Brent. I installed a set of 914Rubber TA bushings / new shafts about 6 months ago, and I had to use a press. I have not installed them on a car yet.

I will say it was significantly easier than the previous pair of bushings I had done. Those also required a press...and about 8 hands.
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Superhawk996
post Jan 26 2021, 06:39 AM
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Rut Roh!

Could it be that you're using the 914Rubber bushings with the OEM pivot shafts rather than the heavy 914Rubber SS pivots? Maybe the SS pivot shafts are larger OD than OEM?
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bbrock
post Jan 26 2021, 09:22 AM
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QUOTE(Superhawk996 @ Jan 26 2021, 05:39 AM) *

Rut Roh!

Could it be that you're using the 914Rubber bushings with the OEM pivot shafts rather than the heavy 914Rubber SS pivots? Maybe the SS pivot shafts are larger OD than OEM?


Exactly my next question. I just rechecked all the bushings and there is something seriously wrong here. I checked all of the bushings and all are a snug, hand-press fit into the trailing arm bores. Then the shafts either slide right in with no effort (as in, they will drop in with gravity alone) or require only moderate hand pressure to press them in without lubrication. In the worst case, there is even noticeable play after the shaft is installed.

The only things I can think are that either the rubber shrank, or the bushings were designed for the SS pivots and those have a larger OD than stock. I just swapped my SS pivots with another member for a set of pristine OE shafts because I couldn't justify the extra weight for a street ride so I can't check. (IMG:style_emoticons/default/headbang.gif)
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bdstone914
post Jan 26 2021, 09:28 AM
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QUOTE(bbrock @ Jan 25 2021, 08:54 PM) *

@Mikey914

I bought a set of the rubber rear trailing arm bushings in the 914Rubber GB when they first came out (can't remember when that was). I am just now getting around to installing them and ran into a problem. I did a test fit to see how hard they would be to install and was shocked to find I could easily slide them into the trailing arms by hand AND could slide the pivot shaft in by hand. In fact, I'm not seeing much difference from the polygraphite bushings they are meant to replace. If anything, these fit even looser. I'm wondering I was sent the wrong ones. My understanding is the rubber bushings should be a tight fit and require a press or similar to install as seen in Ian's video. Is there a good way to know what I have? These are stamped "WDG" on the flange side which is different from the stamping on the first set of bushings I bought.


@bbrock

The problem is that the trailing arm holes can get expanded from normal use. I have installed several sets and had several sets of trailing arms in a side by side test. The bushing in one arm can be loose in another. I never liked the poly bushings and now use the rubber bushings which are more difficult to install but account for the variation on trailing arms.



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76-914
post Jan 26 2021, 10:28 AM
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They're not the torsion bar bushings are they? (IMG:style_emoticons/default/beerchug.gif)
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Montreal914
post Jan 26 2021, 11:59 AM
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QUOTE(bdstone914 @ Jan 26 2021, 07:28 AM) *

QUOTE(bbrock @ Jan 25 2021, 08:54 PM) *

@Mikey914

I bought a set of the rubber rear trailing arm bushings in the 914Rubber GB when they first came out (can't remember when that was). I am just now getting around to installing them and ran into a problem. I did a test fit to see how hard they would be to install and was shocked to find I could easily slide them into the trailing arms by hand AND could slide the pivot shaft in by hand. In fact, I'm not seeing much difference from the polygraphite bushings they are meant to replace. If anything, these fit even looser. I'm wondering I was sent the wrong ones. My understanding is the rubber bushings should be a tight fit and require a press or similar to install as seen in Ian's video. Is there a good way to know what I have? These are stamped "WDG" on the flange side which is different from the stamping on the first set of bushings I bought.


@bbrock

The problem is that the trailing arm holes can get expanded from normal use. I have installed several sets and had several sets of trailing arms in a side by side test. The bushing in one arm can be loose in another. I never liked the poly bushings and now use the rubber bushings which are more difficult to install but account for the variation on trailing arms.



Bruce, I believe he is using the rubber bushings not poly.

(IMG:style_emoticons/default/popcorn[1].gif) with great interest since I have this job ahead with 914 rubber bushings, refreshed trailing arms and replated stock shaft, not SS new 914 rubber.
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bbrock
post Jan 26 2021, 01:00 PM
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QUOTE(Montreal914 @ Jan 26 2021, 10:59 AM) *

QUOTE(bdstone914 @ Jan 26 2021, 07:28 AM) *


The problem is that the trailing arm holes can get expanded from normal use. I have installed several sets and had several sets of trailing arms in a side by side test. The bushing in one arm can be loose in another. I never liked the poly bushings and now use the rubber bushings which are more difficult to install but account for the variation on trailing arms.



Bruce, I believe he is using the rubber bushings not poly.

(IMG:style_emoticons/default/popcorn[1].gif) with great interest since I have this job ahead with 914 rubber bushings, refreshed trailing arms and replated stock shaft, not SS new 914 rubber.


Yep, installing rubber bushings. And yeah, the are definitely trailing arm bushings and not for the front torsion bars.
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bdstone914
post Jan 26 2021, 02:29 PM
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QUOTE(bbrock @ Jan 26 2021, 01:00 PM) *

QUOTE(Montreal914 @ Jan 26 2021, 10:59 AM) *

QUOTE(bdstone914 @ Jan 26 2021, 07:28 AM) *


The problem is that the trailing arm holes can get expanded from normal use. I have installed several sets and had several sets of trailing arms in a side by side test. The bushing in one arm can be loose in another. I never liked the poly bushings and now use the rubber bushings which are more difficult to install but account for the variation on trailing arms.



Bruce, I believe he is using the rubber bushings not poly.

(IMG:style_emoticons/default/popcorn[1].gif) with great interest since I have this job ahead with 914 rubber bushings, refreshed trailing arms and replated stock shaft, not SS new 914 rubber.


Yep, installing rubber bushings. And yeah, the are definitely trailing arm bushings and not for the front torsion bars.


I do not find rubber bushing listed on the 914 Rubber site. I bought these and they are definitely poly, not rubber. They give no description of the material. Is that what you bought?
The problem is that the arms get over sized holes from the leverage exerted on the bushings from cornering.
You can JB weld them into the arms.
The 914 SS shafts measure 1.105" as do the original shafts at the larger diameter. The original shafts have a .010" step. I do not know why it is there as it make the installation more difficult with rubber bushings.


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Mikey914
post Jan 26 2021, 02:40 PM
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Very interesting, I have never been able to slide a shaft in without quite a bit of pressure being required. I would suspect there may be some variation on the trailing arm side.
Mark
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Montreal914
post Jan 26 2021, 03:04 PM
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QUOTE(bdstone914 @ Jan 26 2021, 12:29 PM) *

QUOTE(bbrock @ Jan 26 2021, 01:00 PM) *

QUOTE(Montreal914 @ Jan 26 2021, 10:59 AM) *

QUOTE(bdstone914 @ Jan 26 2021, 07:28 AM) *


The problem is that the trailing arm holes can get expanded from normal use. I have installed several sets and had several sets of trailing arms in a side by side test. The bushing in one arm can be loose in another. I never liked the poly bushings and now use the rubber bushings which are more difficult to install but account for the variation on trailing arms.



Bruce, I believe he is using the rubber bushings not poly.

(IMG:style_emoticons/default/popcorn[1].gif) with great interest since I have this job ahead with 914 rubber bushings, refreshed trailing arms and replated stock shaft, not SS new 914 rubber.


Yep, installing rubber bushings. And yeah, the are definitely trailing arm bushings and not for the front torsion bars.


I do not find rubber bushing listed on the 914 Rubber site. I bought these and they are definitely poly, not rubber. They give no description of the material. Is that what you bought?
The problem is that the arms get over sized holes from the leverage exerted on the bushings from cornering.
You can JB weld them into the arms.
The 914 SS shafts measure 1.105" as do the original shafts at the larger diameter. The original shafts have a .010" step. I do not know why it is there as it make the installation more difficult with rubber bushings.



Yes, the ones on the 914Rubber screen shot are rubber per the two pictures below (IMG:style_emoticons/default/smile.gif)
Although the part number doesn't seem to match... (IMG:style_emoticons/default/idea.gif)

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Mikey914
post Jan 26 2021, 03:29 PM
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Yes those are mine I recognize the taper at the bottom. Can you take a pic of exactly what's happening? I'm most curious as to the ID on the trailing arm. We have sold used and installed these and have never been able to easily install them without some pressure.
-Mark
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bbrock
post Jan 26 2021, 07:31 PM
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Okay, I have some pics and numbers. But first, my bushings are packaged exactly like what @Montreal914 shows. That part # matches the poly graphite Daystar bushings 914R also sells but those Daystar bushings are what I pulled out to install these rubber bushings and they are not the same (as Mark already confirmeed).

For grins, I decided to try a full install without press or clamps. I couldn't find my bottle of liquid soap and didn't want to risk getting caught using the wife's froofy stuff so did this WITHOUT LUBE of any kind. The bushings press into the trailing arms with moderately firm pressure with the heel of the hand. I think that is normal. The pivot shaft fits more snugly in the inner side but still didn't fight me as much as I would expect based on reading other's experiences. I was able to drive the shaft into the inner side fairly easily with a rubber deadblow. Again - no lube. There is enough squish on that side that I cannot twist the shaft by hand but judging by the ease it drove in, I couldn't be sure it wouldn't spin under driving conditions.

Attached Image

Now here is the shocking part. Once the shaft was installed, I was able to press the outer bushing in with the shaft in place by hand - no lube. With the outer bushing installed, I could easily spin the bushing by hand. And of course, I can also pull the bushing out by hand.

Attached Image

Now for the ID of the trailing arm, my caliper only reaches about 3/4" into the bore so I can't measure the ID through the whole depth that the bushings reach but I measured across four direction on each bore and here are the numbers:

Inner
1.494"
1.493"
1.479"
1.496"

Outer
1.509"
1.490"
1.514"
1.4985"

So the outer does average a tad larger than the inner which kind of makes sense because I expect that side gets more force to stretch the metal.

I haven't measured or tried to do a full install on the other trailing arm, but based on my tests fitting the bushings one side at a time, I expect it to be the same. The shaft is has a more snug fit in the inner side but not an extraordinary amount of difficulty to try to get it to slide in. The shaft on the outer side is quite loose.
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Montreal914
post Jan 26 2021, 08:46 PM
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I believe we have a very similar setup. My trailing arms were rebuilt by Bruce Stone after powder painting. The bushings are from 914Rubber (I think from the group buy) and the shafts are re-plated by Bruce.

Here is some data showing the ranges measured at various angles around (~4-5) using a Mitutoyo 12" digital caliper:

Stock shaft as mentioned by Bruce earlier have a small step down close to each end.

Shaft 1, first end step: 1.0980 to 1.1000
Shaft 1, first end: 1.1015 to 1.1020 (27.978 to 27.991mm)
Shaft 1, second end step: 1.0990 to 1.1000
Shaft 1, second end: 1.1020 to 1.1035 (27.991 to 28.029mm)

Shaft 2, first end step: 1.0965 to 1.0985
Shaft 2, first end: 1.1020 to 1.1050 (27.991 to 28.067mm)
Shaft 2, second end step: 1.0995 to 1.0990
Shaft 2, second end: 1.1030 to 1.1050 (28.016 to 28.067mm)

Trailing arms dimensions vary more on the inside bushing since the weld is right there and has deformed the tube. Again ranges from a few measurement around.

Right side inner: 1.4930 to 1.5070
Right Side outer: 1.5060 to 1.5090

Left side inner: 1.4850 to 1.5100
Left Side outer: 1.5005 to 1.5025

I haven't tried to fit the bushings yet...
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pete000
post Jan 26 2021, 08:52 PM
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Well at least they were easy to install by hand with out special tools, clamps, presses, lubes ! Hope it all works properly for you !
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Montreal914
post Jan 26 2021, 08:54 PM
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QUOTE(pete000 @ Jan 26 2021, 06:52 PM) *

Well at least they were easy to install by hand with out special tools, clamps, presses, lubes ! Hope it all works properly for you !


They shouldn't be loose... (IMG:style_emoticons/default/dry.gif)
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