Technical Subframe bush replacement

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Technical Subframe bush replacement

JamesAtthews

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Hi all

Just a quick update for you all regarding the fitting of the front bush which I bought for a fiat bravo, which I think is an fsm2026 part. I fitted these bushes around a year ago, and would like to add to the wealth of information on this site about fitting these bushes.

I followed the instructions to the letter about reaming the outer surface of the Bush to fit the mainframe better. I used some araldite to seat the Bush and to ensure that it is held securely in place. As many of you know this replacement bush is a bit shorter than the original, so I used a piece of 6mm rubber sheet that I bought from eBay, to sit between the mainframe and the car, the reasoning being to increase the gap between the frame and the car, and to give some noise damping between th road and car.

In addition to this rubber, I recently had to add a double rubber donut using this same rubber sheet, fitted between the bottom of the Bush, and the cup washer that sits near the bolt head, to stop the whole assembly dropping down too far. I had to do this as every time I hit a pot hole, lump etc, the mainframe would drop down and hit against this cup washer as the suspension unloaded into the hole. I think this stems from the bushing being intended for a much lighter car to the multipla, and this caused too much movement in the Bush itself. The result of the 12mm of rubber is a much quieter ride with no knocking and a much tauter feel to the back end. I notice that the old Bush at the rear has a rubber flange to the bottom of it, for I suspect the very same reason. I will try and upload some photos later to demonstrate what I have explained.

Cheers
JamesAtthews
 
The front Bushes, due to the Geometry/Layout of the Suspension Arms, are subject to both upwards and downwards loading.
They need to be a very tight fit in the Subframe.
I'm wondering if that's why Fiat don't supply spares?

One of mine (Vauxhall Vectra items) came loose after a while, resulting in a knocking over bumps/dips.
I had to make some spacers to hold it in place.
 
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Hi BikeDoc

I'm glad to read that I'm not the only one with an issue with my front bushes. It's always going to be a compromise fitting a bush from one car into a different one, but at least we've both managed to resolve our knocking issues, without having to buy a whole new subframe. I do wonder if those kits on ebay for a full set, would suffer from the same issues that we've had?

Cheers

JamesAtthews
 
The Vectra ones I used (See here...) needed a little material taking off where it fits in the Subframe, I must have taken off a few thou' too much from one of them.
At the time I didn't think too much about any downwards loading on them, only when I started to get the knocking and looked at the layout properly.

If I ever replace them again, I'll make sure they're a proper interference (shrink) fit.
 
The Vectra ones I used (See here...) needed a little material taking off where it fits in the Subframe, I must have taken off a few thou' too much from one of them.
At the time I didn't think too much about any downwards loading on them, only when I started to get the knocking and looked at the layout properly.

If I ever replace them again, I'll make sure they're a proper interference (shrink) fit.[/

QUOTE]

Hi I have to admit that the araldite was because I had made them too small for the frame, but having checked the bushes they haven't moved a millimeter looking at the rust marks around the frame and the bush.

Thanks for your reply.

Jamesatthews
 
My mechanic did it I have been using him for over 20 years there was no modification required straight fit he didn't know why he said that in description charged me £100 to fit.
 
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A good press-fit could easily be done in-situ (I had my Subframe out at the time), using the weight of the car to help press them in, or with a sleeve over the Bush, using the mounting Bolt to pull it into place.
 
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