[Engwi]

Greetings,

Where can I obtain technical data specifically around the dimensions of the clutch plate to be used in the mechanical clutch setup? Reason for asking, I had my clutch plate resurfaced and it is definitely too “thick”. Tightening the bolts on the pressure plate to fasten it to the flywheel, makes the facing area where the release bearing interfaces, “sink away” – The car will surely not clutch.

I just had the sorry case for a gearbox redone from A-Z, dog gears, syncro rings, drums, bearings, seals ext, and don’t want to put it though the abuse it had due to a bad clutch or just plain bad driving habits.

Anything I should lookout for? What must I pay careful attention to when it comes to these mechanical clutches? Any pointers will be greatly appreciated!

 

[Gordon Raymond]

Mechanical clutch disc facing

Hi Engwi,
I'm not quite sure what you refer to as "sink away", as a new disc should be thick enough that the installed pressure plate will put pressure (lots) on the disc when bolted to the flywheel. If the flywheel friction surface has been cut, the upper pressure plate mounting face in the flywheel must be cut exactly the same amount. I am not in my shop, but a new old stock GTA clutch disc here in my office is 10 mm thick. It's about 1968 vintage. I believe all the mechanical clutch Alfa discs are 9.5 to 10.5 uncompressed. That is, not installed, and without pressure from the pressure plate. This particular disc is marked Kupplungsseite, an has the older style black facing with groves. I hope this helps. Gordon Raymond

 

[Engwi]

"Travel" on clutch pedal virtually Zero

Good Day Gordon,

Thank you for replying to my very first posting on the BB.
Apologies for the "Sink away" description, but being a software developer, this is the best I could come up with

Ok, here goes, installing the new clutch plate, pressure plate fastened, gearbox installed, the amount of "travel" the clutch pedal has, is virtually zero - Hence my "sink away" comment on the interface where the release bearing meets the pressure plate. And as you can image, the clutch does not work at all. The slight bit of travel the pedal has (up until the arm moving the release bearing towards the pressure plate) touches the bell housing - does not allow for sufficient pressure to be removed from the clutch plate - So I thought this might be due to the clutch plate not being the right "size".

The clutch plate I installed now was the exact same one that worked fine before, apart from the re-surfacing and new springs fitted.

 

[Gordon Raymond]

More clutch information

Welcome to the BB! This is probably the best source for information on Alfa's, worldwide. I am about to get some sleep, it's 3 AM here, but lets see if I can help. If everything is currently assembled, have you tried adjusting the clevis on the clutch activation shaft? I would guess the clutch was replaced due to wear and slipping. If so, the clevis was probably at the limit of adjustment to get the old clutch to function. Adjusted correctly, there should be about 15 /25 mm pedal free play before the throw out bearing contacts the pressure plate ring. If this cannot be done with adjustment of the clevis, the throw out bearing may be incorrect, (too thick), or the disc too thick. It is also possible if the flywheel was resurfaced, the pressure plate mounting flange could have been cut more than the friction surface, or the pressure plate itself, if replaced, could be incorrect and thicker from the friction face to the throw out ring than the original. As you can see, there are a lot of areas here that can get one into difficulty.
I would find out exactly what was replaced, and what machine work was done. If you compare the replacement parts with new, the only area intended to wear is the disc friction facings. If the clutch really burned up, it will damage the flywheel friction surface, making it necessary to resurface the flywheel. A comprehensive job consists of replacing the pressure plate, disc and throw out bearing, though if the disc is undamaged, it may be rebuilt. The same is true for the pressure plate, though it is usually less costly to replace it as well. The throw out bearing should always be replaced, as the normal service life is about the same as a disc. Again, I hope all this helps you decide what to look at next. Keep us informed!
Now off to bed! Gordon Raymond

 

[Engwi]

Many areas to address - Which fits my scenario ?

Thank you Gordon!

With the kind of insight you supplied, this BB must be the best around - Thanks again.

Reading your response gave me allot of ideas what to look for, but my concern is the following:

Background
The reason for tending to the clutch in the first place, was because a virtually new plate's springs got broken - Still trying to understand why that happened, but then again, you cant trust others to respect your cars as much as you do.. (no further comment)

The overall surface was fine and because I wanted this car's transmission and clutch to be 110% after my rebuild (I rebuilt the machine as well), I thought of having the entire plate reconditioned.

Variables
So in my setup, the only "variable" really is the plate itself, the pressure plate was fine before hand, that "carbon" ring on the throw out bearing is still fine and the linkages, well, this is my issue, except if I am not technical enough...

No amount of adjustment on those links will do me any good, as the actual lever, that actuates the release bearing, has virtually no room to move, with the pressure plate installed, the bit of movement it can make is not sufficient at all, no pressure gets removed from the plate when the actuating lever travels that small distance.

Not sure if the pressure plate itself can be adjusted, but all in all, at this point, my hypothesis is that the plate is too thick.

I will try and post a proper photo of the scenario soon.

 

[Gordon Raymond]

Clutch questions

Hi Engwi,
You have narrowed the areas of concern. I assume no machine work was done to the flywheel, and the throw out bearing is the same, as well as the pressure plate. You mention broken disc springs, these are those in the hub, not the flat compression leaves between the friction faces. I have seen broken springs in the pressure plate spring towers, that will coil bind, preventing the pressure plate from compressing, or compressing unevenly, thus dragging on the disc {AND breaking hub springs!}. Was the pressure plates motion (or lack of) checked when apart? Since it seems a disassembly is in order, I would check the lining thickness, as suggested earlier (+- 10 mm) and the pressure plate, specifically the springs. I have used an Alfa factory tool to rebuild racing Alfa pressure plates years ago, but parts are not commonly available and this is more effort and labor intensive than buying a new pressure plate. If you end up going this route, replace the throw out bearing as well, as it is bound to fail if used again with a new pressure plate. Let us hear what you discover!
Gordon Raymond

 

[papajam]

Found this info in Alfa service manual #1008 R3.

 

[Gordon Raymond]

THE Illustration!

Papajam,
One picture IS worth 1000 words! Thanks!
Gordon Raymond

 

[Engwi]

.. Why did I never know about this forum before...

Gordon / Papajam

I must say, I don’t really know how I managed in the past without this forum. I have tons more questions to ask !

The insight given by Gordon on what to keep in mind when doing any machine work will certainly be remembered for future reference! With the info I got from the illustration posted by Papajam, I can explain my issue as follows:

When looking at the illustration from the workshop manual, you will note the two "grayed" out positions of the throw out bearing's actuation lever. As it stands now, the moment my car's throw out bearing contacts the thrust ring, and I say again, CONTACT, not even start to push the trust ring, its at the grayed out position "at the back" - i.e, the illustrated position furthest away from the driven plate's thickness indicator "B".

I will start by measuring the distance "C", look at the plates thickness "B" and take it from there !

Gordon / Papajam - Awesome! I hope to get some time to fiddle again soon - I cant wait to get this car back on the road - Of all my Alfa's I love this one the most - It's just a unique experience to drive (And even if it's a 1968 model, it still turns heads !)

Kind Regards and I will update once I rectify this mess.

 

[Engwi]

Further help needed !

Greetings Alfisti,

I finally got the time to get back to my clutch issues on my Junior and my findings are as follows.

1. Clutch plate (uncompressed) measures 10mm on the dot (uncompressed)
2. On the illustration from the workshop manual PapaJam posted, distance "C" (that is, distance from pressure plate face to thrust washer face) measures 40mm on the dot.

Looking at it, I am round about 10mm short for distance "C" according to the workshop manual. With the pressure plate fitted to the flywheel, the thrust washer face is "flush" with the rest of the pressure plate, where in the past, after assembly, it used to protrude at least a bit. (If needed I will post a photo)

What would you suggest I do? Must the pressure plate be adjusted somehow?
Must I have thinner facings fitted to the newly reconditioned clutch plate?

Let me know, because currently it does not clutch at all.

Thanks in advance.

 

[GTD]

GT 1300 Junior

Engwi
This may or may not be a factor in your problem. ALFA used two different pressure plate and throwout bearing assemblies on Juniors; exactly which was originally determined by the serial number of the chassis. After all these years and possible engine/transmission swaps - nothing can be safely assumed.
The following data is from an original GT1300 Junior spare parts catalog:

 

[papajam]

Don't have an answer on the problem (yet) but I'll add that the parts book listings for the clutch components show that up to chassis 1230000 (Series 1) are mechanical clutches, 1230001 (Series 2) and up are hydraulic.

 

[Gordon Raymond]

Typical Alfa Mechanical clutch photo's

Engwi,
This car you are working on I assume has a mechanical clutch. From GTD's information, the difference is clear. You cannot successfully mix and match the two types of clutches.
I dug around in my shop and came up with enough mechanical clutch components, mostly new, but old stock, to take pictures and give some additional measurements.
1) The first photo should be of a currently available, heavy duty F & S pressure plate.
2) Next, the top surface on this pressure plate throw out bearing surface, to the ring deck measures 20 mm with the disc relaxed.
3) This is an new, old stock, GTA throw out bearing with the carbon ring. The new ones measure the same thickness, and appear similar, but with hollow, rather than solid legs, and a ring of a more modern material. This ring, should face the throw out bearing plate on the pressure plate.

Now we need another post for the remaining photo's.

 

[Gordon Raymond]

More clutch information.

Engwi,
Here we go with part two. To begin with, a resurfaced flywheel must also have the ledge the pressure plate rests on cut the same amount as the disc bearing surface, necessary to maintain the correct relationship between components for proper function and adjustment. This is about 30.25 mm on a new mechanical clutch flywheel. The one photographed here and measured, is a custom aluminum racing flywheel with a steel facing insert. It is new, and this measurement may be a little high, as nothing has been run in. The Pressure plate itself is adjustable to some extent, but this is best left to the rebuilder, as measurements must be exact, springs correct type and tension, plus he must have the tools to do this work. As new pressure plates are available, it is not cost efficient too rebuild one unless for a special application.
4) This is a new F & S disc. It measures 10 mm thick relaxed. It only will fit in the flywheel, spring side up.
5) This is the assembled flywheel, disc, pressure plate and throw out bearing in correct relationship. The throw out bearing ring on the pressure plate now measures 10 mm from the pressure plate spring support deck, the thickness of the clutch disc.
6) This is the same assembly in side view, again showing the correct relationship between the component parts.
I hope this has been of some help.

 

[Engwi]

Greetings !

PapaJam, Gordon, GTD - Thanks allot for the input and guidance. The discussions led me to adjust the pressure plate to give the correct results as per the details you supplied. The three adjusting nuts on the pressure plate itself where used to obtain the measurements mentioned in this posting and the clutch works better than before !

If only the guy who rebuilt my gearbox did not make such a mess of it (now jumps out of 3rd which it never did... does not even go into 3rd) I would have jumped for joy.. but at least I was able to get around this clutch issue ! Thanks again guys !