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MG MGF Technical - Sub-frame mounting bush

I know that front sub-frame mounting bush on the later Fs was FAM 9525 [Source: http://www.mgf.ultimatemg.com/group2/suspension/model_specific_suspension.htm].

Q1 - What the difference between NAM 4131 and FAM 9525?

Q2 - Where does KGE000060 fit in to the picture?

Q3 - Was this the same as the solid version that was fitted to the Trophy?
Steve Ratledge

Yes, I know NAM 4131 - are black and FAM 9525 are green.
Steve Ratledge

Q1 - the first part number is the original, Metro-based bush. As you say, the casing was painted black. I don't know the actual compliant data, but apparently it is softer than the later bush.

Q2 - I wonder whether this is the TF specification subframe mount? In which case it is blue. I thought they were solid alloy though, not rubber, so the description is confusing me. Anyone else know what's going on here?

Q3 - see above ;o)
Rob Bell

Rob - what did you have fitted was it the green FAM 9525?

Has anybody upgraded from black to green to any other version?
Steve Ratledge

Steve, I've gone from Black, to Green to Blue. The latter were bought in by Techspeed, and I don't have a copy of the part number on the invoice. It could be KGE000060 - perhaps check with Roy? Mike Satur will also know the answer to this. :o)
Rob Bell

Looking at Dave's car in the MG Enthusiast article - he has the front and rear cross bracing - I can in the picture of the front crossbrace a green sub-frame mounting bush. Although the article talks about solid sub-frame mounting bushes.

Dave which bushes do you have fitted?
Steve Ratledge

Steve,

I had the original black mounts changed to the later green ones some years ago. I plan to go to the solid (Trophy/TF) mounts in the next few weeks, as recommended by VHS to complete the stiffness kit.

In the article I report that VHS attribute 20% of the difference in torsional stiffness between an F and a TF (F is 4,500 Newton Metres compared to TF at 7,300 Newton Metres) to the sub-frame mounts. They then estimate that a further 70% comes from the THREE braces with the largest contribution coming from the brace behind the dash, followed by the rear engine-bay brace and then the least contribution (surprisingly) from the front sub-frame brace.

So, according to VHS I have currently added 70% of the difference to my F. When I install the solid sub-frame mounts that will bring it up to 90%. The final 10% is attributed to the body panel changes made by Mayflower - so that's not retrofittable!
Dave Livingstone

Q1 Were the solid (blue) mounts fitted to all TF? - I think you can guess where this thread is heading - a breakers yard!

Q2 Rob/Dave which bushes did/are you going to have replaced?
- all four at the front [ http://www.mgfcar.de/epc/422.htm ]
- All four at the rear [ http://www.mgfcar.de/epc/614.htm ]

Q3 Dave the article talks about 20% from the sub-frame mounts I take it this is derived from all 8?

Q4 Is replacement of the sub-frame mounts a DIY job or do you need specialised kit to do it?

Steve Ratledge

Steve,

My answers:

Q1 - that's my understanding from VHS
Q2 - all 8
Q3 - all 8
Q4 - pass (mine's in to Tech-Speed next week for a thorough going over before the new trackday season and they are doing this for me)

Dave
Dave Livingstone

Q1 - yes, the blue solid mounts were fitted to all TFs (to my knowledge), and also to the MGF Trophy160

Q2 - all 8 of them

Q3 - yes, you need all of them to gain the full benefit.

Q4 - DIY-able, but they can be a royal pain to get to (I recall helping Andy out with SF, and access to the front mount bolts is restricted, and I seem to recall Roy saying that replacing the rear mounts can be a pain in the posterior)
Rob Bell

Thanks Dave. It was a very interesting article. Other than in the order as stated in the article, did VHS give any indication of how the 70% improvement was split across the Centre, Engine bay and Front sub-frame brace?
Steve Ratledge

My impression on chatting to them before is that it is that hard to get to dashboard struct brace that represents the majority of the torsional rigidity - which when you consider what one is attempting to reduce the front axle flexing relative to the rear, is not all that surprising.

Frustrating from a practical point of view, but not surprising.
Rob Bell

Do you know the cost of the solid bushes or how much SF paid for the cross braces?
Steve Ratledge

No Steve, VHS gave no numerical estimate of how the 70% divided up, just their subjective judgement on relative importance. One anecdote used to support the value of the rear engine bay brace (which looks quite flimsy) was that when the nut holding this brace wasn't up to torque on some TFs, the drivers experienced a squeaking noise. This, VHS implied, showed how much movement there was in that area, as when the nut was correctly torqued the noise stopped.
Dave Livingstone

Q2: please notice, the newer TF parts were missing. I just started to update. Means *under construction*
Dieter

Would £80 be a good price for a set of 2nd hand TF Blue solid subframe mounts?
Steve Ratledge

Having just read through everything above and noting that the Trophy already has the solid type blue mounts, does anyone know if I already have any of the upgraded TF braces too?? :)

I know I don't have the rear brace but what about the front and mid (behind dash) ones?

Although I will be hopefully taking mine to VHS mid-year, I'm kind of hoping that I won't need to get all three done. (Cost cutting I know!)
Kris Ford

Fraid not Kris. These braces were introduced with the TF. At least you have the sub-frame mounts :-)
Dave Livingstone

This thread was discussed between 01/01/2006 and 07/01/2006

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