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Discussion Starter · #1 ·
BMW 77 320I front Disk Brakes

i want to start gathering parts for the bmw brake conversion for my GT.... is there a thread on here about it?? ive decided to buy loaded rebuilt calipers and new rotors.... i need to find 2 hubs.... anyone know where i can get some used ones?? are there any additional parts needed besides the new brake lines??

has anyone else done this conversion?? how do you like the brakes?? was it worth it??

Thanks!!

Joe Van Wagnen
71 2.4L GT
 

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You will need to remember a few items.

>Track in front will be widened by approx. 3/4" total....so choose wheels carefully.

>Rotors need to be machined to a smaller diameter to fit under the calipers...the Opel mounting flange is in a different location than the BMW's. Same diameter as a 1975 rotor in fact.

>Calipers must be shimmed aprox. .030" so they are centered on rotors.

Much has been written about this conversion in the 'Blitz" newsletter over the years. Perhaps back issues are available.

Stopping power is identical to 1975 brakes, seeing how the caliper, pad and rotor surface are identical. Pad choice will determine ultimate C.F. They are however, far more fade resistant because of the ventilated rotors. I've had a set since 1985, have only replaced pads a few times, and turned rotors twice. Been on three different cars of mine.

Bob
 

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Discussion Starter · #3 ·
>Track in front will be widened by approx. 3/4" total....so choose wheels carefully.


lets see the recomended offset for 15x7 wheels should be 15-20 mm.... so which way do you add the 3/8"??? + or -??? to the offset
 

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Joe,

Here's the page you want, thanks to Otto Bartsch:

http://autos.groups.yahoo.com/group/classicopels/files/ Technical Information/Brakes/

As for the wheel offset, Otto's modification requires a spacer to allow the wheel to clear the caliper. So you can actually use a wheel with MORE offset, such as would fit a typical rice burner. Instead of a 15x7 wheel requiring a 20 mm positive offset, you can use a VERY available 38 mm offset wheel. At least at the front. If you want to use the same wheel at the rear, just use the same spacer. And longer studs at both ends, of course!
 

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Wheel stud reoval

I think that Opels use a fairly standard stud, but to be honest, I have never changed a wheel stud! I looked at the OGTS site, and Gil doesn't list wheel studs. So either they are extremely rare (I don't think so!) or they are so common that OGTS doesn't bother stocking them (I hope so). It seems to be a common suggestion to change out the wheel studs for longer ones when spacers are used, so I suspect that they are quite common. Any specific size or description from our members would be appreciated.

I have also been meaning to ask the group for instructions on replacing wheel studs. I assume that it is much easier (if not required) to remove the front hub or rear axle in order to press the old studs out. Or can they be driven out with the hubs in place, with a hammer and a drift?

I have a spare front hub that I was practicing on, but I can't seem to get the old studs out with my 4 inch bench vise (which I read somewhere was one way to do it). My next step was going to be to try my newest toy (I mean tool!), a 12 ton bearing press, but I wasn't sure if there were "tricks" to follow. Such as: should the hub be heated with a torch first to help release the stud, or does the stud just press out, or is there a shoulder that has to be ground away first? The only manual of the four that I have that mentions replacing wheel studs also talks about "peening over" the new stud after pressing it in place, which sounds a bit like a shoulder may be hammered over to hold it in place. And the illustration seems to show that the stud is removed by pressing it outwards, rather than inwards, which seems quite odd. But the picture clearly shows it being pressed by the head-end with a narrow drift, out of the hub towards the threaded end.

Can anyone help out here?
 

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Umm, no

One good smack with a hammer usually drops them right out.

Ask for studs for a chevette. The splines are either a little more or less coarse, I cant remember, but they work perfectly.
 

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Also want to put in my $.02 worth on wheel studs, there are some from the early 70's Toyota truck that are the exact same thread and pitch wise, just a bit longer for wheels with thicker center sections, like BBS BMW wheels.
Gene
 

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Discussion Starter · #10 ·
Wheel Studs

Keith

there easy to remove... just hit them with a hammer... put them back in buy pulling them in with a larger nut under the lug nut... the front ones should be no problem doing them on the car... im wondering if there is room enough behind the rear hub for the stud to come out?? and will the 20mm longer one go back in?? ide rather not pull the axels to do...

deos anyone know the dimensions on the studs??
 

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I have done the "pull through" method several times, but recommend using "junk" nuts that you're not ever going to use, as by the time you get through a few studs, the nut you're using to do the pulling is starting to "bell" at the bottom. So, I'd get several junk nuts. Another trick that was passed onto me about installing studs this way, was to rub the area that is to bite into the axle plate with a bar of soap, it helps it slide in easier. It's sounds funny, but, you have to remember, that the correct way to install a stud is to press them in with a bench press, which means removing them off the car. So, every little bit helps to get the stud in.
MTCW
Gene
 

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Discussion Starter · #13 ·
Wheel Spacers and studs

Keith

Ive found a better option than the wheel spacer.... the guys at OGTS suggested a Wheel Adapter!! and gave me the number of MC Motorsports (909-947-5115) I called and a 20mm Wheel adapter 4x100 by 4x100 with nuts is $47 and you dont have to replace the studs. the H&R Wheel spacer otto is talking about are $96 for two.... so it is about the same price. you will have to shorten the existing studs alittle or put a small conter bore in the back of your new wheels for the existing studs

the problem as dennis told me is the 20mm longer Toyota studs dont have the same spline on them and are loose until you put the wheel on... i like the wheel adapter idea better...

i think ill bolt on the adapter mark the existing studs where they need to be cut off, remove the adapter screw on a die and cut off the stud to length.... re install the adapter and bolt on my new wheels and tires.

Today i ordered the parts for the Bmw vented brake conversion and new wheels and tires.... i cant wait to get them on


Joe
 

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Discussion Starter · #18 · (Edited)
Hay.... i see there is crossdrilled rotors listed for the 77 bmw 320i... would they be better than the just vented type rotors???

i got all the parts disassembled, cleaned and painted and the parts reinstalled.... those long upper control arm bolts came out easy... i was lucky... new poly bushings installed.... i also had the hubs turned down to the right od for the calipers... and this morning i installed the braided stainless brake hoses...

i had to cancel my caliper and rotor order from carparts.com they said the rotors were discontinued and that it would take 30-40 days to get the calipers... ill look elsewhere
 

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Wheel adapter 4x100 by 4x100

Joe,
Did you (or anyone else) use the MCMotorsports wheel adapters and did they work well? I was thinking I might give them a try rather than wheel spacers.
Also what was the model number - I see several 4x100-4x100 adapters listed.

Thanks,
Bob
 

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MC Motorsport

Part # 4100-4100 (if you are still using an Opel pattern wheel)....however, you still have to tell them what thickness you need. The smallest thickness will require you to trim the studs. As I recall, those are 1" and 1 1/4" will not require any shortening of the wheel studs. I have a pair of each but am only currently using the 1" pair. They work fine and seem to be a reasonable cost versus wheel spacers.
 
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