323 rear calipers pre/post 08/1979

[E21noob]

323 rear brake calipers are listed as different part numbers pre and post 08/1979.

Can anyone tell me the actual difference between these?

Guess there is a reason why they changed. Are the earlier models best avoided?

The calipers are no longer available new, but the repair kits are.

Thanks

[E21noob]

I have learned the early calipers have a bias valve.

I am just about to buy a set of these. Any advise much appreciated.

[3771489]

Piston size pre 27mm/post 33mm. (.. and because that,post 8/79 pressure regulator in rear brake line.)

[E21noob]

Thanks man!

So Besides the smaller piston, better or worse?

[PeteK]

Not really better or worse as such.

You need to stick to what you've got. If you don't have a pressure regulator and you go with the later model, you'll have too much rear brake pressure and lock your rear tyres first.

If you're doing disc brake conversion from drums, you're better off getting the later model and using an adjustable pressure regulator. That way, you can adjust the pressure to suit standard or larger front brakes.

Good luck

[E21noob]

Thanks Pete.

I had the impression this conversion was plug and play using 323 trailing arms, but as always the plot thickens

My 316 does have a brake pressure regulator, but it's pre-08/1979. (part number 34331116365)

The post 08/1979 has the same part number as the 323 (part number 34341151640). Part 12 on here:



From what I gather, I have two options.
1. Remove and bypass my pre 08/1979 brake pressure regulator, and use pre 08/1979 323 calipers.
2. Find a post 08/1979 brake pressure regulator, and use post 08/1979 323 calipers.

Does that sounds about right?

[Jeroen]

3rd option would be to convert to E30 rear calipers which gives you a wider choice in pads, several of us have implemented this upgrade. Later pressure regulator is mandatory otherwise the brake bias will be too much towards the rear. Also see this topic in the Top Tech Topics section: upgrade to E30 rear calipers.

[E21noob]

Thing is my best bet to get the whole thing road worthy is if I stick to 100% 323 original setup.

But I guess option 2 with a view of your option for the future is a good plan.

[E21noob]

Just going through this again..

Pre 08/1979:
- smaller piston, 27mm
- No brake pressure regulator on 323s.
- All other E21s came with 34331116365

Post 08/1979:
- larger piston, 33mm
- All E21s came with same brake pressure regulator 34341151640
- You could also use an adjustabel bias valve like this one: http://www.iemotorsport.com/bmw/2002-br ... valve.html

[PeteK]

It's up to you, but I'd leave the standard one on there for road worthy and then give it some trials. if you're locking the rears before the front, get the 323i one off Ebay (saw one for $140). If not, just leave it.