Saturday, March 8, 2014

Front subframe mounts

The front 'tear drop' subframe mounts are fine as they were replaced last year as work needed for the first MOT. So I am concentrating on the rear ones that attach the front subframe to the car floor.

These ones.

I have been conscious of some 'play' in the front of the car during acceleration for ages. It is an unsettling feeling that the front of the car is going faster than the rest when accelerating! Not ideal. Originally I put it down to the shocking condition of the engine mounts. But replaced them and it was still there. Then I thought that it would be cured when I sorted the front suspension, but it was still there, so I concluded that the only thing it could be was the subframe mounts.

I had a look at the Haynes manual for help and it was woefully inadequate, having only 4 simple steps!! Which to make it worse, were wrong. It implied that the bolts that hold the mounts to the floor of the car would need an assistant to hold them with a spanner while I undo the mount from below.


So after I pulled the carpets and soundproofing, I discovered I had captive bolts! Not sure how common this is. Excellent I thought, this will make things way simpler as no assistant was required, but it turned out to be a bit of a nightmare later on.

So I had a search around the various forums, but didn't have much success finding a guide. The nearest thing I could find was this: How to Guide: Fitting solid front subframe mounts on The Mini Forum. Close enough!

To start, I jacked up the car from from the front subframe and supported it with axle stands under the floor of the car. I used wood to spread the load and also old towels between the wood and the car to act as a cushion. Once the car was settled on the stands, I put a little lift on the subframe with the jacks and removed the two front road wheels.

Now I can get at the job in hand, the (rear) front subframe mounts. Sprawled out on the ground with two 13mm ring spanners, I could get to work removing the bolts. The bolts were probably 1/2 inch, but the ring spanners served very well. There is a pitiful amount of room to move and some of the nuts could only be turned one sixth before having to re-position the spanner. But slow as it was, all the nuts came free without grief.

Passenger side...

It's round about now that the nightmare I mentioned earlier started to manifest. Because the bolts were captive, they were holding the mounts in place and try as I may, the mounts were not coming out without lowering the subframe a little. The guide I read had done this to get at the top mounts, so it must be possible to do the same for the lower mounts.

So out comes the BIG socket and the breaker bar as the tower bolts would need removing. Once they were out, I could gently lower the jacks a tiny bit. I was worried that if I lowered it too much, it would put undue strain on the front mounts. So I worked by trial and error, lowering a little, then checking to see if it was enough and so on.

With the subframe lowered just enough, I found I could angle the mount and get it off the lower/rear bolt and with a little wiggling and persuasion, swing it away from me to free it. It was very tight and I had to be careful not to damage the brake pipes as it came round. Once it was around, it could be lifted free from the upper/front bolt..

Round the back...
and out, shown here with its replacement.

Before I put the new mount in place, I applied a generous helping of grease on the car where the mount would sit. Hopefully this would offer some protection from corrosion. Putting the new mount back on is the reverse of taking the old one out. I hooked it on the upper/front bolt, swung it round the back and maneuvered it onto the lower/rear bolt.

In terms of the order, I secured the mount to the car first. Then jacked the subframe back up to where it should be before tightening the lower nuts and bolts. Once both sides were done, I put the tower bolts back in place and the job was done. All that was needed now was to put the road wheels back on and tidy up.

I had a look at the old mounts and flexing them in the vice, I could see that the rubber was coming away from the steel. I guess that would account for the movement.

All was good in the world again, that was until I saw the state of the rubbers covering the knuckle joints!!
There were knackered and I only fitted them last April!!!! They would need replacing, but not tonight, it was too late. That was a job for a Sunday morning.

So I don't get the joy of trying the car out with the new mounts just yet.

UPDATE: Car is much improved with the new mounts. The horrible play has gone.

<Next Post> - 'Knuckle Joint Dust Covers Knackered' 
<This Post> - 'Front subframe mounts'
<Previous Post> - 'Bleeding the rear brakes and MOT' 

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1 comment:

  1. Thank you for providing such a useful information about Tower bolts for construction. Keep posting like this.