Brake Booster Options

[btec116]

I have been scouring for threads on brake booster solutions, and found the usual E21, E32 (with MC), and E23/28 hydraulic booster solutions people have been using.

With this info I headed to the local wreckers to find something that'd fit. I ended up coming away with something I have never seen anyone else use;
An Audi "5+5" brake booster.

Vital dimensions and ID as follows:
Outer diameter: 220mm
Depth : ~90mm
(from firewall mount to MC mount)
ATE part number:
3-6140-6401-4
Audi Part number:
812 612 107 (I think)

Firewall and MC mounts identical, and the pushrod is the correct length to MC (flush with MC mount). On the pedal side, the rod with the threaded "forkhead" is slightly longer, but long enough to drill another (10mm) hole for the pedal pin through the forkhead in front of the original hole.

It was pretty cheap too, $100AUD and I was lucky enough to get a brand new one, The thing had never been mounted! Deadstock I guess.

I only have two pics (camera died), but will post some more later, particularly of the forkhead. Hope it helps some of you!
Bence

[Drew325is]

Nice find! You're having more luck than me with boosters in Oz. Scoring a brand new is pretty cool too. They don't have any other new ones sitting around???

[btec116]

Haha, yeah that was a bit of luck! No others unfortunately, I found that one by accident rummaging through rackfulls of boosters! But at least it gives us some more options. If you were really keen you could search the part number with Audi, and see if it comes up with any other models, I imagine 5+5's are pretty rare around here... There was also a VW emblem on it, so it could be shared. Hey where are you located? It'd be nice to know someone around here thats also doing the swap! I'm in Sydney, but moving to Melbourne in a few weeks...

[Mike B.]

That looks like the VW Golf II booster, which is around 9" in diameter. I came across these in my search for a booster to work with the euro intake.

Nice find! Another one to add to the list (Porsche 924/944, E21, E32, VW/Audi, Geo Metro, etc...)

[btec116]

I had a look at some golf boosters but the pushrod going into the MC was a different diameter and length. Although it was unclear which golfs they were from. But this one is sweet!

The drilled forkhead meets the pedal (-linkage for my right-hooker) fine, except for a few minor issues;
I drilled the hole so there is plenty of metal around it (half the pin diameter), even though it'll only ever be in compression. The forkhead is designed to tighten onto the pushrod, but for the current setup this can't be done, and there's not enough thread between to fit a locknut. But liberal Loctite-ing should take care of that.
The width of the forkhead is also wider than the link to the brake pedal. It needs to be spaced out with some washers.

The new booster installed beautifully, and gives plenty of clearance! I needn't have shaved the plenum, it would have cleared anyway. Oh well, at least there's extra room for OBDI manifold later.


Here are some more pics:

[btec116]

Mike,
Was that Euro intake as in OBDI intake? Did that setup clear? Its something I want to get later, since I'm runnign an M52 with all OBDII...

[e30s52]

Mike,
Was that Euro intake as in OBDI intake? Did that setup clear? Its something I want to get later, since I'm runnign an M52 with all OBDII...

same question. please get back soon!

[Drew325is]

Haha, yeah that was a bit of luck! No others unfortunately, I found that one by accident rummaging through rackfulls of boosters! But at least it gives us some more options. If you were really keen you could search the part number with Audi, and see if it comes up with any other models, I imagine 5+5's are pretty rare around here... There was also a VW emblem on it, so it could be shared. Hey where are you located? It'd be nice to know someone around here thats also doing the swap! I'm in Sydney, but moving to Melbourne in a few weeks...

I'm up in Brisbane...it's actually been tricky to find any wreckers that you just browse at. I've ended up with a 924 booster, but it's cost me like $150 and needs a rebuild ($175). Bit of a PITA. To be honest the booster issue has been a bit of a thorn in my side. MK1 Golf GTi seems to be a winner, but rare as hens teeth in Oz.
I have a write up of my swap here: http://forums.eurocca.net/showthread.php?t=12214 if you're interested.

[btec116]

I guess you're probably familiar with them, but I got my M52 from KMJ europarts in Brisbane, they were very helpful and sympathetic to my cause! I dealed with a guy called Rob. He should remember me, I have a flatmate looking at an E30 of theirs tomorrow!
At the very least they should let you have a look around to find something. Thats how I was let into wreckers here in Syd, through someone who knew someone who used to work for someone... But I know its not something they like doing.
Have you considered scouring ebay UK and Germany for boosters? If you want a golf booster, they're everywhere over there. I know a bit of broken German too if its of any use.
How did you end up going with the 944 booster? Will it work once the pushrod's threaded? The other option you have if you can't get a booster that fits is going hydraulic assist for brakes too, as done on E23's and E28's. If THAT doesn't clear your M3 manifold, it's time for Mr. Angle-grinder :crazy:
THanks for the link to on EuroCCA, thats an awesome writeup you're doing, I gave it a quick look. We're actually roughly at the same stage (I jsut got the engine and box in today)! Huge thumbs-up for posting engine weights, finally someone had a set of scales handy! I can't beleive we're 30kg in the plus! Sweeeet!!!
I have to get on that board too, you guys solved a few things I still haven't figured out.
I'll post my swap after its done, I'm in a rush (not good) to finish this, I'm supposed to move and start work in Melbourne in two weeks. That was unplanned.....
:blowup:

Bence

[Mike B.]

Mike,
Was that Euro intake as in OBDI intake? Did that setup clear? Its something I want to get later, since I'm runnign an M52 with all OBDII...

S50B32 intake.

[Drew325is]

I guess you're probably familiar with them, but I got my M52 from KMJ europarts in Brisbane, they were very helpful and sympathetic to my cause! I dealed with a guy called Rob. He should remember me, I have a flatmate looking at an E30 of theirs tomorrow!
At the very least they should let you have a look around to find something. Thats how I was let into wreckers here in Syd, through someone who knew someone who used to work for someone... But I know its not something they like doing.
Have you considered scouring ebay UK and Germany for boosters? If you want a golf booster, they're everywhere over there. I know a bit of broken German too if its of any use.
How did you end up going with the 944 booster? Will it work once the pushrod's threaded? The other option you have if you can't get a booster that fits is going hydraulic assist for brakes too, as done on E23's and E28's. If THAT doesn't clear your M3 manifold, it's time for Mr. Angle-grinder :crazy:
THanks for the link to on EuroCCA, thats an awesome writeup you're doing, I gave it a quick look. We're actually roughly at the same stage (I jsut got the engine and box in today)! Huge thumbs-up for posting engine weights, finally someone had a set of scales handy! I can't beleive we're 30kg in the plus! Sweeeet!!!
I have to get on that board too, you guys solved a few things I still haven't figured out.
I'll post my swap after its done, I'm in a rush (not good) to finish this, I'm supposed to move and start work in Melbourne in two weeks. That was unplanned.....
:blowup:

Bence

I've heard of KMJ, but never dealt with them...I'll keep them in mind in the future. Are their prices reasonable?

Yeah I have looked into Germany and the UK for boosters, but I'd already invested money into the 944 booster before finding out that Mk Golf GTi was a direct swap (all that's required is drilling out the hole in the fork a little more). I ended up swapping the 944 for 924, to get a little extra clearance for the manifold (stage 1 of the build is using a M50 manifold...stage 2 will be ITBs). I can't see any reason for the 924 booster not working once the input shaft is modified.

Yeah the weight saving with the M52 is a major bonus. I've been for a ride in an M50tu 2.5L E30, with 3 people on board and been impressed with how much quicker the M50 is than the M20...the M52 with less weight and more power should be a hoot.

I can't wait to drop the engine and tranny into the car...will be a great milestone! I've been working towards this swap for years....however it's been nice to not be in too much of a rush. I thought about getting my mechanic to do the swap, but I know he could never have put in the attention to detail that we can when going DIY. We either don't take any shortcuts, or at least know what short cuts we've taken.

[btec116]

Definately recommend KMJ!
I just called them today for an E32 airbox (I want über-stock look!), they're giving me one for $45. I cant get that price in Syd at all.
Also, after months of waiting and looking all over AUS, I got the M52B25 off them (I gave up on a B28) with basically ALL parts I needed for turnkey swap, complete with all electrics, EWS, key, barrel (with the steering shaft!), E34 sump, motor mounts, oil pump and pickup, and complete E36 325i exhaust for 2200. Delivered to my door in Syd! Basically I gave them a shopping list and they got me everything. They even remembered stuff like putting in all the bolts for sump and a few extra bits and pieces I didn't even ask for, like rad fan and extra lambda sensors. Very helpful.
I spoke to Rob again, if you ever need to hunt around for stuff, go to him.
Your ITB's are hot! I'm still a little curious wether they'll fit next to any booster. If they do, I think I'll have to start hitting ebay!!! ANyway, back to the garage...

[Drew325is]

Damn dude...$2200 is cheap as hell...will DEFINITELY have to check them out.

ITBs should be fine...the problem would be the M3 plenum...which I wouldn't use anyway as it's weighs a friggin' tonne.

[Mike B.]

Damn dude...$2200 is cheap as hell...will DEFINITELY have to check them out.

ITBs should be fine...the problem would be the M3 plenum...which I wouldn't use anyway as it's weighs a friggin' tonne.

If you come up with a nice plenum design, let me know. I'd like to see what you come up with.