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MG MGF Technical - Experience with Rear Tie-bar bushes

Following on from the mostly successful fitting of the Polyflex damper bushes, I tackled the rear tie-bar bush. As guidance I had a couple of old threads, including Roger Parker's instructions for fitting compliance washers, and Dieter's pictorial guide. It was not as easy as all that for this amateur, so here are some notes for those interested:

1) You need a deep 18mm socket for the rear nut and plenty of elbow grease. These are hard to come by, but Teng Tools do one that is stocked by the larger Halfords.

2) The recommendation from Dieter to hold the tie-bar whilst undoing this nut cannot be emphasised enough. When I had to resort to a garage, their air-tool could not shift the nut because the flex in the bushes absorbed all the torque.

3) Dieter talks about using a "Cardan" spanner for the 13mm bolt that holds the tie-bar to the subframe. I bought a "deep-offset" ring spanner from Halfords for the job, because there is not enough room to get a socket and ratchet head onto the bolt. The garage used a socket with a long allen key as the handle - good idea, though the deep offset spanner will do the job.

4) The 13mm bolt is harder to reach on the right-hand side of the car because of two fuel hoses that have to be gently pushed out of the way. On both sides, the lip of metal running underneath the bolt and the lack of space between the bolt and neighbouring bodywork, made it impossible to get a torque-wrench to the bolt. Unless anyone else has a bright idea and posts it here, forget about torquing this to 45Nm.

5) I started on the left-hand side of the car because of those fuel lines and was able to remove the 18mm nut and 13mm bolt without too much difficulty. The head of the tie-bar needs to be wiggled out by pulling down on the bar (which needs movement in the bush), turning it 90 degrees and then pulling forward to get the bar out of the lower suspension arm.

6) This is where I came unstuck. Although I cleaned out rust from the socket in the lower suspension arm, I could not push either half of the Polyflex bush all the way in by hand. I tried to use a G-clamp but the sloping washers made this impossible. The result was that I could not get the front of the tie-bar into its subframe mount or the rear nut onto the tie-bar so as to squeeze the bushes into the arm.

7) The garage suggested (though in the end did not use) threading a bolt through the bush and tightening a nut on the end to force it into place. But you would then have to fit the tie-bar through the bush without dislodging the bush, which would be difficult (see removal method above).

8) I suspect that even if I had got the front half of the bush in all the way, the thickness of the bit of bush that does not go into the socket would have meant that the head of the tie-bar would not line up with its the subframe mount, until the bush had been compressed. If you can get this far, then I think you would have to put the rear 18mm nut on first, tighten it until the head of the tie-bar lines up with the mount and then put in the 13mm bolt. This is a variation on the compliance washer instructions and is what the garage did for me.

9) Finally, after putting the old bushing back together and lowering the car, I found that there is not enough room underneath to move the torque wrench arm sufficiently to click, at 80Nm or even a lower setting. Again, as with the rear damper nut, I cannot see how you do this without a pit.

The good news is that the mod certainly works a treat, with the cornering security much improved. The bushes compress into a shape that I can only call beautiful (you'll see!) and hold the rear wheel toe-setting much better. The garage recommended that I come back in 200 miles for tracking since the bushes will take a few miles to settle in.

The other good news is that I found Maidstone Sports Cars. They are not as far away as I had thought, compete(successfully) in the MGF Cup Cars series, had 5 cup car-modified F's in for repairs from a corporate-day organiser and clearly know and love F's. Famously they modified an MGB to a 4-wheel drive mud-plugger, built the MG RV8 GT and are currently completing a cream MGB, which has been cut in half along its length to show the re-trimming, but will run with engine and LH side suspension exposed. To be seen at an MG show near you this year!

YMMV, but I hope this info helps those undertaking this work themselves.

Chaz
C Golvala

These are fantastic instructions. I was about to tackle this job yesterday but I'm glad I waited for pearls of wisdom. Where abouts in 'Greater London' are you....?
tim woolcott

Wow, great comments there Chaz. I know that Tim will shortly be finding them very useful! :o)
Rob Bell

Actually, I work in the City (near Moorgate) and live on the Kent/Sussex border south of Tunbridge Wells. Tim, if you found pearls in this lot, then your experience with oysters is better than mine!

Chaz
C Golvala

Chaz, did you take any picture when carrying out the work...
tim woolcott

Guys,

just out of interest - if these tie bar bushes were worn what effect would you be having when driving.

Regards,
Mike
Mike Gibson

Mike, the rear wheels steer of there own accord, The worrying thing is that this is how they are when they leave the factory.....8-O
tim woolcott

Yeah these are what I have just had replaced on my F, but my friend did mine for me - he said that the worn ones were put on back to front as well..

This solved most of the handling problems I had but still get a slight snake when I apply breaks under engine power, I mean if I apply breaks when with clutch down I don't have the snake!.

Regards,
Mike
Mike Gibson

Tim, sorry no pics, since I have no digicam and my Contax won't do under the car! However, the pics on Diter's site are very helpful and this one is really obvious (even to this novice) since it is really a rod that goes through a big hole in the suspension arm.

Mike, my experience was of less controlled steering and less "contact" on bends. I also experienced some change of turning angle when backing off or braking in a corner (not adviseable I know, but sometimes unavoidable). See Rob's site for a proper explanation of why the bushes when worn will allow too much movement of the rear wheels and how this produces just the effects you and I experienced. There is also a thread from a few years ago when someone (a John, I think) explains why the rear toe-in angles change when braking or backing off accelerator quickly, particularly in mid-bend.

Chaz
C Golvala

Pix of the replaced PU bushes art at Rob's.
http://www.mgf.ultimatemg.com/upgrading_bushes.htm
Some other showing the subjet due to compliance washers are here.
http://www.mgfcar.de/lowering1/compliance_washer.htm

I'm on the washers since the first mile and I'll go for PU-bushes soon at the other locations. Mine has done now 40k miles and if bushes start to fail they get replaced.

HTH
Dieter
Dieter K.

This thread was discussed on 28/04/2003

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