UKSaabs

Early 99/c900 brake discs (the type that bolt behind the hubs - p/n 8934036) are now very hard to get hold of and expensive when you can get them.
It seems like everybody has now stopped manufacture of them and most stock left showing as available is all lost in warehouses/distribution and nobody can actually find it!

The later front handbrake c900(and 90/late 99?) brake disks that fit conventionally to the front of the hub are cheap and easy to get hold of.

Can you swap the entire later disc/hub/CV/driveshaft assembly onto an earlier car?

HELLO TOMARSE, YES YOU CAN. BUT THERE IS A TIMEFRAME OF AROUND 1982-1985 WHEN EVERYTHING BOLTS STRAIGHT ON FROM YOUR DONOR 90/99/900, STRAIGHT ONTO YOUR GEARBOX(IF ITS STILL THE 99T 4 SPEED)


AFTER THAT THE GEARBOX CUPS/TRIPOD BEARINGS WERE ENLARGED.

CURRENTLY I AM TRYING TO FIND OUT THE EXACT GEARBOX NUMBER, THAT SAAB WENT FROM THE SMALLER TRIPOD INNER BEARINGS(ON END OF DRIVESHAFT) TO THE LARGER DIAMETER TRIPOD INNER BEARINGS.

MY 1986 900 TURBO, IS SLOPEY FRONT BUT FRONT HANDBRAKE, AND AROUND THIS TIME THEY MADE THE CHANGE,SO I NEED TO CHECK IF IT HAS, SMALL OR LARGE TRIPODS... JUST AS A MATTER OF FACT.

THE LARGER LATER TRIPODS THEMSELVES ON THE END OF THE DRIVESHAFTS ARE NOT INTERCHANGEABLE, BUT THE SPLINES ON THE DRIVESHAFT CV JOINT, CAN BE USED TO ENGAGE THE HUB ASSEMBLY FLANGE, ON EITHER FRONT, OR REAR HANDBRAKE CARS.

SO ITS RATHER ESSENTIAL, WHEN FITTING A DONOR GEARBOX, TO HAVE THE MATCHING DRIVESHAFTS, NOT ONLY FOR FITMENT, BUT ALSO IN MATCHING WEAR/TOLERANCE IN THOSE GEARBOX CUPS.

AUTOMATIC GEARBOX DRIVESHAFTS, AND MANUAL GEARBOX DRIVESHAFTS ALSO DIFFER IN LENGTH...!!



THE BENEFIT FROM DUMPING YOUR ORIGINAL 99T HUBS, DISCS&DRIVESHAFTS IS NOT ONLY LACK OF PARTS AVAILABILITY FOR THE ORIGINAL DISCS&WHEEL BEARINGS, BUT A REDUCTION IN WEIGHT, AS WELL...

_________________
NEVER,SUFFER FROM INSANITY...............

ENJOY IT.

Thanks Birdie!

My 99T now has an early 5 speed box with the 'standard' 99 smaller tripods.
The other 99 that is next in my "queue" and will likely need brake parts too is a standard '80 4 speed

I excavated all my parts stash today and found 2 sets of hubs and axles - one set from a 1980 99 and a set from a 1984 900 (I think!)

I stripped them all down (in the process working out how different the outer CV assembly is) and the inner axle tripod splines are the same on both so I guess I can move the c900 complete assembly over to either 99

The 99 set of hubs was super rusty and came from a rusty car i broke for parts over 10 years ago and I had my eye on them for the scrap pile as the backplates had virtually gone and the calipers were also scrap - however upon close examination I realised that they actually had a set of totally unworn discs on them!
So I spent around 6 hours of today out in the balmy -2C weather drilling and cutting 2/4 of the caliper bolts off after one snapped and one rounded off
Looks like the discs were 'new' shortly before that 99 was parked up around 15 years ago and after a thorough wire wheeling are now on my 99T

Not a hijacking attempt, but what are the differences? Easily identifiable?
Have early 900gle but not had the wheels off yet

at first glance not that much looks different but:

[*]early discs bolt onto the back of the hub whereas the cheaper and easier to get later ones just screw onto the front of the hub (so you will see 2 screws on later ones). You have to use a puller to remove the hub to replace the discs on the early ones.
[*]on the early ones the CV joint is inside the outer hub assembly. There is just a circlip holding the driveshaft into the CV.
[*]on the later ones the CV joint is separate and simply drops out of the back of the hub, attached to the driveshaft and stub axle if you remove the big hub bolt

brake calipers, brake disks and CV boots are the same for both of them.

Thanks for that tomarse, made me dig out the haynes manual.
Familiar with the post 88 900's and assumed all front handbrake cars had just the one setup.
Looks like i will eventually have to source a later setup like yourself then. My car, being an auto, guessing will require bit more research.

Every day is a school day

I had stupidly assumed that they didn't differ this much too! (I've had lots of 1980-84 99's and 900s which were all identical and clearly spoiled me!)

Saabbits have found the early disc's in the end (because Bill is awesome!) - but they are £120/pair for aftermarket or £150 for saab original ones - vs the later ones which are £50/pair.
I've still got 2 actual orders in with some other motor factors who were advertising them at £50 ish/pair but neither of them have actually managed to physically get hold of any stock and i suspect will have to cancel my order.

I should have looked into it prior to rebuilding the rest of the early hubs and axles!

Pull a front wheel off yours and take the pads out and check what the disc surface looks like. The front of mine didn't look bad but the back side is terrible and the disc slopes from about 9.5mm on the outside edge to full thickness (12.7mm) on the inside edge! minimum thickness is given as 11.7mm.
Fingers crossed you may not need to replace your discs!

The uneven wear on the brake discs (inside and outside) may be because the outer pistons were seized but could also be because Saab used to use different pad materials for the inner and outer pads. Later on the pad material was standerdised but Saab stipulated that if the later pads were used then the inner piston dust seals had to be changed for the latest spec because of the extra heat generated by the new pad material. Inner pads used to wear about twice as fast as the outer pads because the material was much softer. Just a bit of useless information that might be of interest!

The taper on the discs might be because of wear in the calipers were the yoke slides on the caliper body. Often refurbished calipers have a bit of shim steel fitted in the groove to take up the wear. This wear can also cause a big clonk when braking in reverse, this can be reduced by bending the U pins so the yoke is biased against one side of the groove.

I'm reading this thread with interest as I have recently refurbished a set of front hubs ready to go on the car but, am now concerned I have refurbished a set that I wont be able to get discs for!

Can anyone please clarify what is meant by early disc and bolting from behind the hub?

My car is a 1972 and the discs fit onto the hub as in the pic below from the factory manual - from the front, over the hub and incorporates the front handbrake surface.

I guess its possible the hubs have been swapped somewhere in the last 49 years and before my ownership but, the main question is; are these the type that are more easily obtainable?

thanks in advance.

Think yours will be the early early set up, disc with built in drums?
This is for the front handbrake disc only cars
Here is the difference from Haynes manual discussed earlier in thread

Moving to the later front handbrake setup also has the benefit (option) of moving to the vented discs up front that were on c900 T16S's

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What we need are more people who specialise in the impossible

Definitely discs all round in my car but that doesn't mean it left the factory with them!

Anyone got photos of the difference as I'm struggling to translate the diagrams into real life

I've got the ATE calipers front and back and I don't understand what people are saying about discs bolting on from. Behind - mine have 2 retaining screws and come off without removing the hub.

The later 99 caliper looks well funky where yours will look normal.
Handbrake was built in to caliper instead of separate as per your set up.
Will take another pic for you

When said rear drum meant inside the front disc not rear of car

The first 900 (2nd 99) setup had a press fit hub that had to be removed to fit the disc to the rear of it

Easy check for newer or older front handbrake hub is:

older (pre 1980?) the hub retaining nut is proud (sticks out)
newer (1980 on?) the hub nut is recessed into the hub casting

_________________
What we need are more people who specialise in the impossible

Hi Steve,
these are my hubs without the disc fitted:


The disc bolts onto the back side of the hub - you can see some of the bolts sitting there in the photo above. You have to pull the hub to fit the discs.

You can see the proud hub nut as wrighar points out.

This type is in use on my 78 car along with the 2x W-reg cars I have owned - one of which was April 81 and the other Nov 80.

Not sure what discs your earlier car uses. would suggest you find the p/n and investigate if you need discs. Not quote unobtainable but much more expensive than the other options!

1978 front brakes...

_________________
What we need are more people who specialise in the impossible

HELLO STEVE BRIANCE,

ALL SAAB 99 CAME OUT THE FACTORY WITH BRAKE DISCS FITTED ALL ROUND.




JUST TO CLARIFY HERE, 'EARLY SEVENTIES'(POSSIBLY YOUR CAR?) SAAB 99 WITH 'DROP GEARS'(NOT CHAIN DRIVE) ON THE GEARBOX,HAD INTERNAL BRAKE SHOES FOR HANDBRAKE ON THE OUTER FRONT HUBS,CONCEALED BEHIND THE FRONT BRAKE DISC,AND ARE FITTED WITH SIMPLE TWIN PISTON BRAKE CALIPERS.
YOUR FRONT BRAKE DISC PART NUMBER,WILL DIFFER AGAIN,TO THOSE THAT 'TOMARSE' WAS ATTEMPTING TO FIND,ON HIS 1978 99 TURBO,AND YOU SHOULD INDEED HAVE TWO COUNTERSUNK EXTERNAL MACHINE SCREW,TO REMOVE THE FRONT DISC.

DIFFERING LENGTH DRIVESHAFTS ON THESE EARLIER 'DROP GEAR' GEARBOXES,COMPARED TO LATER 'CHAIN DRIVE' BOXES WILL RESULT,IN THE DRIVESHAFT TRIPOD BEARINGS DROPPING OUT THE GEARBOX DRIVE CUPS,ON FULL STEERING LOCK,OR ON FULL 'DROOP' ON THE RAMP....IF YOU TRY AND MIX&MATCH LATER HUBS/DISCS TO THE 'DROP GEAR' TYPE GEARBOX.

FOR MR.BRIANCE TO RETAIN 'A' 4 SPEED GEARBOX ON YOUR EARLY SAAB 99,YOU WOULD INDEED NEED TO FIND AROUND LATE 99 1975,ONWARDS 4 SPEED 'CHAIN DRIVE 'BOX',AND THEN FIT THE LATER( '82- 'NOW MID '86 ) DRIVESHAFTS/HUBS SET-UP ON 'YOUR' CAR,OR YOU COULD GO 5 SPEED....?
YOUR BEST BET WOULD BE COMPLETE 'DONOR' 90/99/900 WITH DRIVESHAFTS,AND HUBS FROM THAT ERA....

HOWEVER 'BE WARNED!!' THAT 99 BODY METAL PRESSINGS,HANDBRAKE SET-UP&LOCATION,GEAR LEVER MOUNTS/CHANGE/JOINTS&CLUTCH SLAVE CYLINDER,ALL DIFFER CONSIDERABLY,FROM EARLY TO LATER CARS,AND IT WOULD 'NOT!!' BE JUST A 'BOLT-ON' JOB.....

C900 GEARCHANGE SELECTOR &SELF-CENTERING DEVICE RODS ARE ALSO LONGER THAN A 99!! AND C900&99 GEARBOXES,HAVE DIFFERING FRONT ALLOY CAST MOUNTING PLATES......












REGARDS THE ORIGINAL QUERY FROM 'TOMARSE'?

SEE ATTACHMENT....GEARBOX NUMBER CHANGEOVER MID-86

BUT OF COURSE,AS WE ARE DEALING WITH CARS NOW WELL OVER 35 YEARS OLD,THE CHANCE'S OF YOUR SAAB(ESPECIALLY TURBO) HAVING THE ORIGINAL GEARBOX,CAN BE RATHER SLIM !! SO YOU COULD WELL,ALREADY HAVE A MIX&MATCH OF GEARBOX/DRIVESHAFTS IN YOUR 90/99/900

_________________
NEVER,SUFFER FROM INSANITY...............

ENJOY IT.

Might be useful to know that the early early (drum handbrake) brake discs are the same front and rear.
Rear brake discs are the the same for all years.
So rear discs from any year of 99 can also be used on the front of drum handbrake cars.