Hello,

Sorry to bother you all with clutch release bearings but i have not been able to find a definate answer, i have a saab gearbox that will bolt up to a zetec, and the standard clutch cover and clutch plate can be used, however the clutch release bearing is a saab flat face one

what i want to know is the clutch cover on a 1800 XR3i zetec compatable with a flat face? i would check myself but i am nowhere near my car, if not can my saab gearbox be modified to fit a saab 900 slave cylinder? i have seen it done on type 9 but i am not sure where it would bolt to in the bellhousing on this gearbox, there is a pic below of the gearbox, it has no release bearing fitted but it is opeated by the arm in the left hand side of the bell housing. hope i can get a definate answer!

many thanks
Rescued attachment gearbox.JPG

oh and here is a pic of the release bearing, i also saw that someone had made an insert to fit to his flat faced bearing to make it a round faced one, is that posible with this bearing?

many thanks
Rescued attachment 40-137.jpg

what's the diameter of the sleeve that the bearing slides along?

just thinking aloud, you could get a saab 900 release bearing and machine a "top hat" in bronze to mount it on that replicates the front of the saab clutch slave cyl, with the right internal dia. to slide on the release bearing sleeve of your current gearbox. It would be a dead easy turning job as long as there is enough of a difference between the sleeve od and the 900 bearing ID.

I am not sure what you mean by sleeve, the bearing sits over the input shaft , the two mounting points on the outer case mount to the two arms that are above and below the input shaft which is moved by the slave cylinder mounted outside the gearbox by moving a pushrod

to be honest its abit of a strange way of doing it, if i can fit the saab 900 slave cylinder i think i would

but what does the bearing ride on. They normally ride on a sleeve over the inout shaft, even on setups like yours, otherwise the bearing tends to tip when not pressed up against the clutch

erm, thats a good question, on the car i have when i took the original engine out there was the bearing in the second photo over the shaft its sat 90 degrees to how u see it, and the fixed to the two arms that are fixed to the shaft to the left of the bell housing which is rotated by a pushrod fixed to the slave cylinder, the bearing is free to rotate about its vertical axis.

Thats it as far as i could see, there is not much else to it! I wish i had taken photos of this when i had the engine out!

[Edited on 18/1/07 by trogdor]

thats it exactly, because the bearing is free to rotate on those two pins, they "normally" have a sleeve to keep them pointing at the clutch, otherwise it would be tricky getting the bellhousing and engine bolted together without everything getting in a mess!

here is what i am talking about quickly annotated i wish i had a better photo...
Rescued attachment anno.jpg

well when i put the engine and gearbox back together i didn't have anything stopping it rotating and it all went back together ok, that said i haven't driven it since then.

hmmmm i guess the saab 900 slave is prob the way forward, as far as i can see there is no trumpet to replace allowing me to fit the cylinder, are there any other ways that to do it?

EDIT have posted on a saab 96 forum to see if that is normal for the release bearing in the saab, i have a suspicion it is but you never know

[Edited on 18/1/07 by trogdor]

hmmmm looks tricky to do on the cheap, instinct says machine an ally ring big enough to mount the slave onto, hack the back of it to sit on the profiles in the back of the bellhousing and keep the front flat to the clutch, then get it tig welded into the bellhousing and bolt the slave to it.

that sounds pretty involved and i didn't really want to have to take the gearbox out! at least until i break it! is it a real prob if you use a flat faced bearing with a zetec clutch cover?

as a quick and dirty bodge, you could run a grinder carefully round the edge of the end of the clutch springs and round the edge of the bearing.

It won't last ages but it'll stop them eating each other

i might go with that since the gearbox will need rebuilding or replacing with a different model at some point since it isn't really designed to take that much power and torque, when i get it rebuilt i could get them to modify it to fit the saab 900 slave cylinder.

so the kind of slave cylinder i should be using is the one in the photo? from a saab 900 pre 1993 model, i just need to find a way of mounting it in the bellhousing is the reach of these cylinders adjustable? as i have no idea how far the release bearing needs to travel.
Rescued attachment 51-2209.jpg

have found on ebay a clutch release bearing suitable for a escort which is where my zetec comes from, i think i may be able modify this to fit the pivot arms on my saab gearbox, possibly anyway

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280068685405#ebayphotohosting

quote:

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Originally posted by trogdor
so the kind of slave cylinder i should be using is the one in the photo? from a saab 900 pre 1993 model, i just need to find a way of mounting it in the bellhousing is the reach of these cylinders adjustable? as i have no idea how far the release bearing needs to travel.

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oooh that is useful, ta very much!

18mm stroke seems like not alot is that normal? am thinking of how to mount this in my bellhousing, is a shame i don't have a trumpet! what kinda stress is the slave cylinder subject too?ie how much torque is the mounting subject too?

guess it depends how heavy you are with the clutch?

[Edited on 18/1/07 by trogdor]

18mm is plenty, it only takes about 5mm to disengage a clutch fully. (but you want about 5mm clearance between fully compressed cyl with bearing attached and new clutch springs to allow for clutch wear)

there is little or no torque on the mounting, the release bearing is there for a reason, it spins!!

The only real force on it is compression. The slave is just held by 3 m6 bolts.

Here you go, big alloy lump is the spacer I machined up, which bolts to the front of the gearbox, trumpet is machined off basically.

slave bolts to 3 m6 threads cut in spacer:



cr1

well i am just wondering if i could fix it in some way that didn't involve bolts etc

you can get adeshives that are really strong nowadays, do you think i could expoy it into place and that would last?

not sure if it would stand vibrations etc tho

just thinking about it somemore, man i should be revising!

if i use a proper adeshive to glue the spacer the the bellhousing and then bolted the slave cylinder to that, would that be strong enough to survive?

maybe something like this?

Repair metal components - EPOXY METAL PASTE - any metal - filler/adhesive - (withstands high temperatures, can be machined)

[Edited on 18/1/07 by trogdor]

Adhesives? Don’t like the sound of that at all. If you are worried about swarf getting inside the gearbox or having to go to the bother of dismantling it, then just determine the thickness of the casing and drill and tap blind holes.

Then just fit long studs that reach through the spacer block.

I'm thinking off piece of tube over drill bit to set the depth & a flat bottom milling cutter to flatten the bottom of the hole once the ordinary drill bit had been used

[Edited on 18/1/07 by macnab]

yeah that is another possibilty, what would be the miniium sort of depth the holes would have to be? doubt its the casing is that thick!

oh and what is a flat bottom milling cutter?

[Edited on 18/1/07 by trogdor]

I'd expect the casing to be around 10mm there.

Cutter I mean is the end mill, one on the right.
Rescued attachment end_mill_types_1.gif

sure we have one of those in the aladdins cave! my dads garage is so small u can't get a car in but it has so many tools!

so if the casing is 10mm thick, how far should i go? about 80% of the casing ie 8mm?

top tap would be used to finish off the hole once the tapered ones have been used, so that you have the maximum thread depth.

Yeah 8mm would be fine...



[Edited on 18/1/07 by macnab]
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coolio, now i need to get one of these cylinders and a suitable spacer made! what materials are the best to use
i assume a chunk of ally would be best?

where can get some? is it expensive?

at least my car is already set up for hydralic clutch!

[Edited on 18/1/07 by trogdor]

allys not expensive!

Got to a scrap metal merchant and find a small block, tenner at most

shows how much i know!

cool will have to sort some out, the main prob is going to be the machining and measuring but i can prob find a machinst in runcorn there is alot of that sort of industry around here.

is the saab 900 release bearing ok with a zetec clutch or does it have to be another one? ie is it rounded, its not obvious from the pics that i have found.

You could also maybe use some other holes / bolts

for example the ones where the box join the belhousing.

If you could get 3/4/5mm sheet.
You would just cut a "gasket" wich in the middle has the hole for the gearbox input shaft.

then around that hole you could drill and shampfer the holes, weld in a shampfer bolt and to that bolt you could easyly mount your spacer. In that way you don´t need to play with the casting.

Thinking about the forces in fact the onlyy thing it should be able to survivie is the bearing resistance at max rpm.

sow any piece of sheet could do it.
or just some straps.

wy not use a normal slave cilinder wich is outside the belhousing?

With a bit of angle it should be able to build a mount and tab / screw that to the housing!! the big advantage is there that
if your clutch needs some adjustment..
you then just could make sleeves instead of holes in your support.

hope you get it and it makes sense...

also make sure while measuring the slave cilinder is fully in!!

TKs

[Edited on 18/1/07 by tks]

Looking at your first posting it doesn't look as though the bell housing is very deep. Try putting a straight edge across the BH and measure the distance to the release bearing and compare this to a type 9. You might also want to measure the distance from the flywheel mounting face on the Zetec to the gearbox flange again compare this to the Saab engine.
The combination of these measurements should give you some idea of the size spacer you will need.
You could also try using a CRB from a 1971-88 Ford Transit 2.4/2.5 diesel (Quinton Hazell part CCT303) which is a deeper bearing and is used with a T9/Zetec combo to reduce the throw.

Saab 900 bearing is indeed round nose you will be pleased to hear!!!

£15 from your local stockist, slave cyl around £40

To work out the measurements, use the AP sheet to get the compressed depth of the cylinder from rear mounting face to front face of bearing, then add 4-5mm for some free play to allow for clutch wear.

Next measure your clutch and flywheel in situ on the engine. you need the fitted height from the tips of the clutch fingers to the back of the engine block face, easiest is to put a straight edge across the clutch fingers to extend across to just outside the flywheel, then measure with a ruler from the block face to the inside of the straight edge.

Add up the slave and bearing height, the free play 5mm plus the depth you just measured, and compare it to the measurement from front of bellhousing to the face you plan to mount the cylinder on at the back of the bellhousing.

The amount that the bellhousing is greater by is the thickness of spacer needed.

ps the face of that alloy block in the piccy is not flat, front or back!

The back is machined out to allow the oil seal in there and the front is recessed behind the slave as it sits in a small recess. This machined recess also keeps it dead concentric, the bolts just pull it into the recess firmly, they don't locate it on the face at all.

ps ps I'll see if I drew it, I usually do before I set to on the lathe

would just make it external allot easier faster and more fool proof.

only thing is you need the space..

Tks

i already have an external slave cylinder, but my problem is having a clutch release bearing that is flat faced when i need it to be rounded

i am thinking the best bet is with the saab 900 slave as i can't see any obvious way of making the crb rounded, if anyone knows of a crb that is rounded that will fit that would be great but i have doubts about that since this gearbox was designed by saab and only used by them.

unfortunatly i can't use the bolts where the bellhousing joins the gearbox as there aren't any.the gearbox and bell housing are in one piece but that would of been a good way around it

damn this is harder than i hoped it would be, am asking on another forum for the casing thickness at the front of the gearbox, no answer yet tho

[Edited on 19/1/07 by trogdor]

oooh a diagram of your spacer would be great ns dev, would like ot know general diemensions and how the front needs to be machined, will have to measure the lumps and bumps on my gearbox so i can get the back of my spacer ready!