07-26-2013, 08:57 PM | #1 |
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86 Vs 87 turbo front spindle notes
I know this has been investigated elsewhere, but I've uncovered a difference that I thought was worth mentioning. In restoring my 86 951 I decided to upgrade to the 87 spindles in order to get the thicker stub axle. In principle there are no other dimensional differences.
Except that I have the a "Big Red" Brake kit. That means I have a rotor hat that fits over the 86 hub. The hub was machined so that the same hat fits over the 86 and 87 hubs. However the 86 originally had the rotor bolted to the back of the hub, so the stock rotor hat doesn't affect the offset. The 87 on the other hand has a conventional hat that fits over the lug bolts. To keep the offset the same as the 86, the 87 hub is 6.5 mm closer to the caliper mounting plane. If an 87 rotor hat is (I'm guessing 6.5 mm) then that makes the mounting plane of wheel the same. Except that my hat was made for the 86, so I need to add a spacer under my hat now. Without the spacer the rotor is essentially touching the end of the (Fabcar) control arm. The pictures show the 87 hub (painted a cool red) on the car, and the 86 hub (in my lap). The reading for the 87 says 90 mm, but you can see it slipped a bit in the pic. It was actually more like 88.25 mm, and the 86 was more like 94.75 mm, but you get the idea. Note that this entire discussion has nothing to do with the actual wheel offset since that was changed using a longer control arm for 87. Regards, doug 86 951 (http://pcaucr.org/media/image-galler...ll&gallery=224) 01 E320 (W210) 4matic Wagon (http://www.benzworld.org/forums/w210...body-do-2.html) 00 540i-6 (http://forums.bimmerforums.com/forum...hp?albumid=976) 94 855 turbo Wagon (sold in 09) 85 535i-5 (sold in 07) 76 300D (sold in 92) 83 944 (sold in 86) I apparently only buy cars designated by numbers |
07-28-2013, 02:26 PM | #2 |
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Update: I got the spacer OD turned so it fits inside the hat, now I need to get another 50 thou off the thickness and its Sunday. Feh.
The inner surface of the outside part of the caliper (that's clear, isn't it) is just touching the rotor and the difference between the rotor thickness and the caliper opening is 2.5 mm. So half of that is 1.25 mm or about 50 thou. Easy enough on a lathe since the center needn't be machined, as it can poke up into the hole in the hat. Regards, doug 86 951 (http://pcaucr.org/media/image-galler...ll&gallery=224) 01 E320 (W210) 4matic Wagon (http://www.benzworld.org/forums/w210...body-do-2.html) 00 540i-6 (http://forums.bimmerforums.com/forum...hp?albumid=976) 94 855 turbo Wagon (sold in 09) 85 535i-5 (sold in 07) 76 300D (sold in 92) 83 944 (sold in 86) I apparently only buy cars designated by numbers |
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