Andrew Skopp asks a number of front suspension questions:

>I have a relatively low mileage 1988 M5 that is just beginning
>to show signs of front end shimmy... <my mechanic> tells me, I
>need to replace, "the left and right thrust arms and bushings,
>the left and right tie rods and the centerlink."
>Is a thrust arm also known as a control arm? Is there an upgrade
>option? Is upgrading necessary? Are the thrust arms/controls for
>an M5 the same for those for other E28s?

The upper thrust arm and lower control arm together form the equivalent of an "A" arm or "wishbone". For example, the left front suspension looks like this from above:

     ^
     |

fwd

(left front tire)
[]
||----- (left, lower control arm)
[] \

\ (left, upper thrust arm)

The arms are called "upper" and "lower" because that's how they are oriented where they attach below the strut housing at the wheel. All the front end parts, including the bushings, for the E28 M5 are the same as any E28 535i.

>Isn't there a commonly accepted bushing upgrade for the E28?
>I have heard conflicting reports of using the liquid bushing from
>the 750 versus using them from the 850?

Yes, modified 750/850 bushings (same part number for both cars) have been discussed a number of times on this list. Check the archives for all the details. I also reposted some information about the bushings to Mformation yesterday.

E28 (E24) Front End Rebuild Part Numbers

• same parts as any E28 535i. The only upgrade option is to purchase correctly modified 750/850 thrust arm bushings (31 12 1 136 607 in place of stock 31 12 9 058 819 bushing). Thanks to Charles Karnati for providing me this list of part numbers when I first looked into rebuilding my front end.

Quan Part Number      Description                    Price
---- ---------------  ---------------               -------
 1   31 12 1 139 991  Left lower control arm       $ 98.46
 1   31 12 1 139 992  Right lower control arm        98.46
 1   31 12 1 132 353  Left upper thrust arm         151.07
 1   31 12 1 132 354  Right upper thrust arm        151.07
 2   31 12 9 058 819  Bushing, upper thrust arm      36.43
 2   32 21 1 135 666  Tie rod                        36.39
 1   32 21 1 136 450  Idler arm                      34.09
 1   32 21 1 129 014  Center link                    64.45
                                                    ------
                                             Total $743.24

Notes:

1. p/n 32 21 1 134 277 Drop arm $113.43 is not included

   because it doesn't wear like the other front end parts.

2. Lower control arms include the bushings. Upper thrust

   arms do not include bushings, so they are listed as separate items above.

Pete Read
'88 M5
Arlington, VA