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SILENTBLOC BUSHING is Too Short -- FT-017

At 08:19 PM 6/17/04 +0200, Jørgen Hedetoft from Denmark wrote:
>"In process of renovation of the leaf spring [on MGA] I fit a new Silentbloc bush [purchased from Moss Europe, London] ...., after refitting the spring, I can now move it sideways from site to site! ....
>
>".... the old bush measure 2 , the new one only 1.907
>
>"After fitting a flat steel washer in both site of the Silentbloc I can now use it without any play, but it is not a complete satisfactorily solution."

original part = 2.000 inches long
Original part = 2.000 inches long

new part = 1.907 inches long
New part = 1.907 inches long

space left inside of front spring mount
Space left inside of front spring mount

flat washers used to take up loose space
Flat washers used to take up loose space

Moss Motors, US, notified on June 17, 2004. Moss Motors, Europe also to be notified.
------

ADDENDUM August 12, 2004:

Report from Moss Motors. Parts in inventory have been measured, and it is confirmed that they are too short. Parts from Victoria British have also been checked, and are also too short, also from the same supplier. This part is procured from "the British Motor Heritage approved supplier of leaf springs". It is also included as part of the MGA springs from the same "approved" supplier. It is not clear if there will be any correction from the supplier in the near future (but we will keep trying). Alternative source has not been found (yet).

It is also checked and confirmed that the frame brackets on the MGA will not bend inward enough to capture this foreshortened bushing, leaving the spring free to float sideways when the bolt is tightened, which is definitely not acceptable.

For an interim fix Moss Motors will measure the bushings in inventory, and also the bushings in any springs in inventory. They will then include with every part shipped an appropriate thickness hardened steel spacer washer to make up the correct length for the bushing center tube, and an instruction sheet explaining how to use the spacer.

A single spacer on one side will suffice. A lateral displacement up to 1/16" will not affect the function of the suspension. This appears to be the best and only reasonable solution at this time. If you have any of these parts in your possession, please check the length, and use an appropriate spacer for assembly. I will post any additional information here as it accrues.

ADDENDUM April, 2006:

At 12:58 AM 4/26/06, Tommy Baker in Tokyo, Japan, wrote:
"I picked up a pair of the Silentbloc bushings from Scarborough Faire and they are too short as well."

That's three for three, so the distributors.must be all using the same supplier, and it's not fixed yet.


ADDENDUM March 2016:

On 3/15/2016, Clayton Ottley wrote:
"Purchased some from Moss UK in Oct 2015. They are still too narrow, but slightly wider at 1.930-in. Now the problem is the bore size at only 0.430-in, and the 7/16-in bolt won’t fit".

On 3/16/2016, Clayton Ottley wrote:
"I sent the tech team an email and received one back tonight, here's a part of it".

"There does appear to be a problem with this bush as we sent them all back to the suppliers, we do not currently have any stock as we are waiting for the corrected bushes to come in".

ADDENDUM February, 2021:

On 2/8/2021, Richard Bennett wrote:
"I incorrectly believed Moss should have had the bushing issue resolved, so I ordered a set. Upon inspection I found that the length of the center bushing is 1.930" long where the original I removed was 2.000" long. I called Moss, and while they have notes in their system about the dimensions being incorrect their solution was for me to return the part and buy the polyurethane version".

For reference the dimensions of the bushing Moss is currently selling are:
Inner sleeve ID=0.4795". OD=0.59", Length=1.930"
Outer sleeve ID=0.78", OD=0.870", Length=1.76"

The dimension of the inner sleeve I removed from my car is:
ID=0.445, OD=0.57, Length=2.000"
I destroyed the outer sleeves during disassembly and could not take measurements.

Note that the bolt is 7/16" (0.438") diameter. Original Silentbloc bushing ID is 0.445", only 0.007" clearance (very close fit). This is good for not allowing anything to move in service, but can also account for reports of great difficulty in removing the bolt after many years in service. Otherwise normal standard practice is to make the hole 1/32" larger than the bolt, which would be 0.469" ID. So the ID of 0.4795" in the new Moss bushing seems a bit sloppy with an additional 0.010" more clearance than standard. It should work if you make the bolt very tight so nothing can move under severe shock of normal road use, but it still needs one or two shim washers to make up the 2.000" required length.

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