help required mk1 front brakes

[gldgti]

I just had a look at my cars. They are both originally GLDS and both had 10mm discs on them when I got them. They each had the different styles of callipers though. I fitted DB-105 pads to both of them and have been stopping happily ever since.

I seem to remember returning a set of pads once because they were too thick, these could have been the DB-128s I suppose, which kind of makes me wonder what's going on here.

One car has since been upgraded to GTI vented rotors which use DB-401 pads.

The other has new 10mm discs and is definitely running DB-105 pads.

I had a look at the Bendix catalog and a few others and got more confused.

They claim the DB-128 is the one for a diesel and is 18mm thick.
Likewise they say the DB-105 is for petrol and is 14.8mm thick.

In any case the DB-105 could be considered as a partially worn down DB-128 because they're they same shape just thinner.



When I fittted the brand new 10mm discs, the DB-105s were quite a snug fit, I don't think I could have gotten another 6.4mm of pad in there. I made sure the piston was fully pressed back beforehand too.

Pete

the thick pads are (i think) for machined down disks (9mm). i also had these once, and the bench grinder made them fit for me

[gtimk5]

Take it from someone in the trade.
128s are for petol, 105s are for deisel. The part number for deisel discs is
811 615 301 or 823 615 301. Definate!!
Andrew

[Peter Jones]

Thanks Andrew I was sure the DB-105s were for Diesels!!

Pete

[gtimk5]

No problems Pete! The 105s are 15m/m thick and the 128s are 18.5 m/m thick
You cannot put 128s in the deisel carriers. The difference in the discs themselves is the offset. Not interchangable without changing the caliper to suit.
Cheers, Andrew

[Peter Jones]

Ahh , but which is better?

What was the thinking at the time? There can't have been much of a price difference.

Do you think that they were aiming to keep the discs in their ideal operating temperature range or were thay just trying to save a dollar?

Given that a 12mm disc can be machined down to 10mm and a 10mm disc can be machined down to 8 what are the implications?

As they're the same diameter and swept area the braking effect should be the same so it must have something to do with heat dissapation and generation.

Was the theory that the petrol cars went harder and that they'd heat their brakes up more?

Did the diesels go so slow their brakes never got up to temp?

The diesels had slightly heavier motors and different front springs, does this come into the equation?


Arggh so many questions


Pete

[gtimk5]

Not sure what the thinking was Pete. I dont think heat would be different. Maybe they expected the petrol ones to be harder on pads thus the thicker pads? On the 1500 Passats it was the same. The sedans had the thin pads whereas the wagons had the thicker ones.

[deskpotato]

thanks again pete

well, you were a great help there pete, got the pads in and definitely db105's, there was a bee's **** in it, no way would larger pads fit... however, i did manage to screw up with the disc rotors, the rotor screw on the first one i tried was apparently made out of silly putty and burred when i tried to unscrew it... gonna have to take it in somewhere and get it tapped out when i can find a replacement screw. must have rusted in or something like that. anyway, the brakes work great now even with the old discs, no more grinding metal sound... cheers mate...

p.s. and yes, they are 15mm bolts, which is weird, had to go buy a socket for them....

[gldgti]

well, you were a great help there pete, got the pads in and definitely db105's, there was a bee's **** in it, no way would larger pads fit... however, i did manage to screw up with the disc rotors, the rotor screw on the first one i tried was apparently made out of silly putty and burred when i tried to unscrew it... gonna have to take it in somewhere and get it tapped out when i can find a replacement screw. must have rusted in or something like that. anyway, the brakes work great now even with the old discs, no more grinding metal sound... cheers mate...

p.s. and yes, they are 15mm bolts, which is weird, had to go buy a socket for them....

if you get an old, large screwdriver and hammer it into the screw, you might get it out.

[gldgti]

Ahh , but which is better?

What was the thinking at the time? There can't have been much of a price difference.

Do you think that they were aiming to keep the discs in their ideal operating temperature range or were thay just trying to save a dollar?

Given that a 12mm disc can be machined down to 10mm and a 10mm disc can be machined down to 8 what are the implications?

As they're the same diameter and swept area the braking effect should be the same so it must have something to do with heat dissapation and generation.

Was the theory that the petrol cars went harder and that they'd heat their brakes up more?

Did the diesels go so slow their brakes never got up to temp?

The diesels had slightly heavier motors and different front springs, does this come into the equation?


Arggh so many questions


Pete

hmmm

i dont think the engine weight would make much of a difference - we're talking 10-20kg's. i doubt it would be a dollar saving thing.... there would be some engineering reason - but as to what that is, i think we could only speculate.... maybe because the petrol model had more potential to be hotted up and go faster? nah...

i dunno.

[deskpotato]

good idea gld.. i'll try that. couldnt 'f it up much more and getting a place to drill and tap it will be expen$ive....

[Peter Jones]

An impact screwdriver will get it out. You can pick them up pretty cheap these days, try supercheap auto. They look like this.



And you use it like this



Or just drill the head off. Once the disc is off they usually came out easily.

Pete

[Golf Loon]

Plus the fixing screw is only to make putting the wheel on easier. Once the 4 wheel studs are on, the disk aint moving.

[deskpotato]

cheers once again guys, mitre 10 wants $40 for the impact s/d, so i'll head up to supercheap and see what they want for one... will update ....

[Peter Jones]

You can always drill it out. It isn't required to make the car operate.

As Matt said it's only there as a convenience so the disc doesn't move around when the wheel is off.

There's plenty of Golfs running around without that screw.

Pete