1.6 Gti Drum Brakes

[clayts 9 1 Cars]

I need to replace one of the drums on my GTI.

 

The 1.6 GTI used Girling brakes for the drums. As I understand, there were different size drums across the 205 range.

 

How many different variations are there, and what size do I need for the GTI?

 

In Australia we had 2 models that used drums on the rear - base model 205 Si and early model 205 GTI.

 

Please provide more info!

 

Thanks

[welshpug 1,657]

std drums, 30x180 mm bendix.

 

gti drums 40x180 girling.

 

different backplates, different bore cylinder, base model incorporates pressure limiting ball valves, so if you have a single rear line and an inline compensator its 1.6, if its twin rear lines its base model

 

euro rallye also used 1.6 brakes/beam, plus front hubs etc.

Edited August 1, 2014 by welshpug

[clayts 9 1 Cars]

Thanks - I see many advertised on ebay (not OEM) with compatability listed for non GTI models but are 180 x 40.

 

I need the 180 x 40 for my GTI - so am I safe in any 180 x 40 drum, or is it not that simple?

 

Eg

Drum Diameter = 180mm

Internal Shoe contact width = 43mm

Hub Hole = 52mm

 

 

Problem is I don't have my old one with me to measure!

[ArthurH 7]

On 8/1/2014 at 9:00 AM, welshpug said:

std drums, 30x180 mm bendix.

 

gti drums 40x180 girling.

 

different backplates, different bore cylinder, base model incorporates pressure limiting ball valves, so if you have a single rear line and an inline compensator its 1.6, if its twin rear lines its base model

 

euro rallye also used 1.6 brakes/beam, plus front hubs etc.

 

Can anyone provide part numbers for the 40mm wide GTI drums?  Either original Girling or any make.  Are there any other cars apart from  205s that use a compatible drum?

[SRDT 180]

4247-30, many 309 have those 40mm wide drums.

As for backplates some are the same as the GTI but others aren't, you will also find Bendix ones.

[ArthurH 7]

Thank you - just what I needed.  I'm trying to balance the price of new drums against paying to have the inner races pressed out of our current ones.

[welshpug 1,657]

you'll need nee bearings in the new drums so if your current ones arent worn out or the wheel bolt threads damaged theres no need to change then

[ArthurH 7]

Thanks Mei.  Instinctively I will always attempt to repair rather than replace; I'm not keen on the 'disposable' culture.  Sadly, in this instance, I can't find anyone local that will press the old ruined inner races out for less than the price of new drums:

 

 

It might be a function of living in the South East....?

 

We have ordered the above drums, and already have the new SNR bearings.  I don't yet know how much force with be required to press the new ones in, but typically I would warm the drums and chill the bearings to minimise the mechanical stress on the new bearing.  Can anyone see any issue with that method on this bearing drum combination?

[welshpug 1,657]

can't imagine anyone charging £50 to swap 2 wheel bearings

[309SRiguy 15]

I used a molybdenum spray as recommended in Haynes 309 manual. 

 

A light application made it easy to squeeze the bearing in using a bench vice. Like a hot knife through butter as the old saying goes.

If things are tight chill the bearing in a fridge and warm the drum slightly to increase the clearance. Then apply spray and squeeze the bearings in. 

Use a socket or tube of an appropriate diameter so that the pressure is on the outer ring of the bearing.  That will avoid damage to the ball-race.

 

If there was wear in the old bearings you might find that the shoes do not square up with the new drum's friction surface. Check after assembly or sling new shoes on and bed them in on the nice true surface of the new drums.

[ArthurH 7]

Thanks Bryan.  I have included some pics of how the shoes (all4) and the set fitted before the, have worn.  All 8 of them have this step at the back of the shoe, about 1.5mm tall and 3mm wide.  What intrigues me, is there is no matching recess on the inner surface of the drum... 

 

 

 

The step could be filed off quite easily, but we have bought new shoes to see how they will wear in the new drums.

[309SRiguy 15]

Hi Arthur,

If there is slack in the bearing it allows the drum to cant over  (top-in, bottom-out). The axle stays horizontal but the drum tilts.

 

Cleaning up the wear on the one above would probably reduce the shoe beyond recommended minimum thickness.  You would have to alter the curvature as well. A tedious, if not futile, task with a file.

Your new shoes will save you all kinds of frustration. 

 

While it is all apart investing in a pair of new hydraulic cylinders will ensure that the old ones don't spew fluid all over the new shoes.  Check whether Girling or Bendix by shape of hole in backing plate. Right and Left are a mirrored pair. (side specific)

The old seals will be working in a different part of the old cylinder when they are pushed further in to fit the new shoes. Further back in the cylinder is where moisture can sit and corrode the cylinder wall if the seals have been sitting towards the outside ends with older worn shoes. Fluid can seep past the seal if the cylinder is slightly pitted. 

 

Bed the new shoes and drums using the handbrake on/off without too long periods. You don't want too much heat to build up. Drive the engine at a fairly constant speed and pull handbrake on for 5 or 10 seconds, cool for 10 to 20, then repeat as necessary. If you smell them give them some extra cooling time.

The foot brake puts most of the force to the front discs. No need to wear them in the process. 

 

When they settle in you will find a noticeable dip in the rear of the car when you apply handbrake at low to medium speed. You can also tell if they are pulling down evenly. The car will pull down more on one side if they are not adjusted and bedded-in properly. There is some discussion on shoe adjustment on this site. 

 

If you have been driving with the shoe above you will be in for a pleasant surprise in the improvement from the new ones. If your bearings were badly worn you will also notice an improvement in steering and general tracking. 

[ArthurH 7]

Thanks again Bryan.  Your suggestion that the step is caused by bearing wear is one I hadn't considered - it could well be the cause of the taper across the shoe surface, but I still struggle with the cause for the step.  On the drum, the machined surface is lower than the raw cast surface -so if anything, the step should be a recess .  It is also identical on the top and bottom shoe of each pair.

 

We are replacing the bearings as they fell apart when we removed the drums for this off-season overhaul - but hadn't shown significant play up until now.

 

As this is a race car, the handbrake doesn't get the normal use (at every junction/traffic light), but we have to keep them properly adjusted, as any play softens the pedal.  So the drum is off at least once per month while we 'override' the automatic adjusters.

 

We are replacing the cylinders as well.

[welshpug 1,657]

handbrake should not affect footbrake, you need to adjust the shoes more if that is the case.

 

 

if bearing wear was causing that shoe lip you would definitely know it, the wheel would be flapping about noticeably!

 

rear wheel bearings dont have anything to hold them together, its normal for the inner race and bearings to drop out and stay on the stub axle.

[ArthurH 7]

Thanks Mei, but when I said they fell apart, I meant I had to pick up individual rollers and bits of the race cage

 

Warming the drums and chilling the bearings worked better than expected - the bearing slid in down to its lip on its own.  When we turned the hub over to check it was fully down, it slid back out again 

We are confused by the rear oil seal.  The new SNR kit includes a passivated steel 'retainer' and a rubber seal.  When we dismantled the drums we had the retainer, but no rubber seal that matches the new ones.....

The outside edge of the rubber seals is an asymmetrical 'V' profile.  The only thing the inside diameter seems to fit is the spacer that first goes onto the stub.

We assume the retainer should be tapped into the back of the hub - but flush with the outside - or down to the bearing?  And how should the rubber be fitted?  Facing which way?

I have found a very crude schematic of the assembly, but it doesn't have enough detail to answer these questions.

TiA

 

 

 

 

[Gohn 68]

arthur, this the 'crude schematic' you've already got ? 

(I think 7 is supposed to read HUB BEARING KIT but anyway)

could you check the other side for retainer and seal assembly ? or that's already off too ?

[ArthurH 7]

Thanks Andrew, yes. it is the schematic I have seen.  It is items 1 & 2 that I am referring to.  Both sides are stripped down  - and, I'm still confident we never removed any rubber part with an OD as small as item 2 (Wheel Hub seal (internal)).  I think Item 1 should be fitted with the flange on the outside of the assembly (facing the training arm), it would look odd the other way around, but the rubber seal is asymmetric and I can't deduce what is the correct way around.