Big Drum Conversion... **UPDATE Page 2**

Some of you might have seen me post a week or two ago about doing a "Big Drum" conversion on my car. Well, I fianally got some work done on this yesterday!

Only really wanted to do it as my drums are knackered and got offered these in good cond. much cheaper than buying new drums and back-plates (Drums were not a matching pair - I think one was off a Mk2???). Kind of keeps it period too, by keeping drums instead of adding disks!

Drums are off a Passat - Not sure which year/model, but it was an estate ! (I'll check the details if anyone else is interested).

Main concern was that the passat had 6 bolts holding the drum and stub axle to the car and the Golf only has 4. Turns out the top and bottom sets of holes line up perfectly with the Mk1 Axle!
Even better was that the brake pipe fittment is the same size and also the handbrake cable fits straight on - The hole where it enters the drum is in the same place as the Mk1 drum - Dead easy!

Drums should give between 25 and 50% better braking at the rear as the contact area between the shoe and drum is much greater! Hope it isn't too great though as I have no compensator to adjust it at all!

I think these have spaced the rear wheel out a couple of MM - I'll have to measure when I do the other side as the two drums (Mk1 and Passat) sat next to each other on the floor were obviously different heights…

I only got one done yesterday, though I'll take some picture when I do the other side so people can see the difference!

I think the works cars ran these. There's an article I downloaded where it mentions 200mm drums.

200mm Sounds about right for the diameter of the actual breaking surface…

You still got the article?

the same drums are standard fit on mk1 caddy

animal said

the same drums are standard fit on mk1 caddy

Ah - right…

I have heard of these being used before!

i seem to remember one of the mags ferturing this convertion, but they didn't think it did much, so let us know  what there like!

I'm doing it more out of necessity than to improve breaking, though I will be sure to report back my findings!

volkswarren said

i seem to remember one of the mags ferturing this convertion, but they didn't think it did much, so let us know  what there like!

I remember that - think it was VW Motoring on the black Gti they did up. Seem to remember they used Caddy drums and stubs, but that the stubs needed to be redrilled to fit (?)

If you don't know what year, do you know what 'shape' Passat they were from (ie, one of the rounded front ones - about G plate onwards - or earlier ?).

Cheers,

Mark

Yes - the rounded front one…

Not sure what plate it was as the front end had already been removed as my mate had it for the TDI engine…

Ta - I've bought new std. drums for the Gti already, but worth remembering that one for the future. I reckon they would be a good upgrade when using 256mm disks up front.
Top tip !
Thanks,
Mark

I did this mod a few years back when I converted my mates mk1 to 16v,used audi 90 calipers,16v 256 discs and audi coupe rear drum brake assembly,all bolted straight up,the coupe was a 5cyl 83 model

OK - did the passenger side tonight. Didn't take any pics though I'm affraid as I was in a rush to do it before I lost the light!

Old drums measured 185mm across the actual breaking part (Not including the extended rim).
New drums measured 250mm, not the 200mm posted earlier! So - a BIG difference!

I adjusted the automatic sliders a little to account for the wear and tear on the drums and pads as they were not new. Once all bolted up with wheels on, I adjusted the cables at the handbrake end then took it for a drive down the road.

At first they made a horrible grinding noise as the shoes settled into the drums again then, once the grinding stopped, I gave the pedal a couple of sharp shoves…
Lets just say that they work better than the old ones!  8O

The rear wheels actually locked up pretty easily. I was only going about 20 to 30 mph. I need to take it out on the road and do a test with a bit more speed to see if this is likely to occur under normal driving conditions. If so, then I think I'll have to fit some kind of proportioning valve. I don't mind this too much as it kind of goes with the theme of the car, its just a matter of cost!

Anyway, should be good for the MOT at the end of the month. Lucky they dont actually check brake balance between front and rear eh!!!  

If you could find out the details of the reg on the car it would be nice to see if that year car also came with rear disc brakes as the caddies have a 6 bolt stub axle and would be nice to see if they fit etc

I believe it was a '94 - Spoke to my mate yesterday…

It seems I can correct me problem by putting my old wheel cylinders in. The passat ones have 22mm internals where as my old ones were only 14mm. All that extra hydraulic power - no wonder they were locking up!
Gti versions have 17mm internals apparently so there is an "in-between" for me too!

GSF lists wheel cylinders for this model passat as 3/88>

Also lists these for rear disks:
BRAKE DISC-REAR(4 STUD) B  PA Ex. VR6 3/88>96  15.60  
60342 BRAKE DISC-REAR(5 STUD) B  PA VR6  16.50   
60355 BRAKE DISC-REAR SOLID BR  PA inc. Syncro 97>  16.50  
60392 BRAKE DISC-REAR SOLID BR  PASSAT SYNCRO 98>  21.50  



The four stud hubs will probably fit the six hole caddy axle though, with the middle pair of bolts being left out!?!  :dontknow: