Project car - 1989 75 3.0 V6 [Updated 12 November 2021]

[john m]

just put exhaust cement face to face.

Don't use exhaust cement, it will go brittle, crack and fall out. If the mating surfaces are "flat", use red RTV silicon sealant,  it wont burn or fall out. On clean surfaces smear one side and fit together, finger tighten bolts and pin them down the next day. This will give you a thicker film of sealant between surfaces.

Cheers
John

[ARQ164 Shane]

G'day mate ,
Have you thought about oil yet mate ,I know is not the first thing on your mind .
But I think you should have a look at this link:http://www.liqui-moly.com.au/?gclid=CNPD0Pmri7wCFVADvAodNw8ABA

I am going for the 10w-60 race tech GT1 oil .

Ok and now back to normal transmissions sorry about that .

cheers

[jazig.k]

Why are you choosing that oil? What's the ZDDP content?
I use pennzoil race oils for higher ZDDP

[ARQ164 Shane]

g'day jazig,
I have used the pennzoil  and found that liqui moly hold's better oil pressure in my v6.
it is a little quieter when running .

[shiny_car]

I posted an oil topic some time ago, so I might resurrect that for further discussion in the future.

This month's update is all about the central propeller shaft. It's a deceptively complex piece of engineering, yet elegant. For the power/torque of the standard engine, it's obviously fine; when people up the performance, weaknesses can arise, particularly in the rubber 'flex joints' ('donuts'). Not an issue for me in the short-medium term, so I am happy to use 'standard' replacement parts without modification.

Comparing schematics in the workshop manual versus ePer parts schematic versus the actual prop shaft, I discovered a number of differences. I attribute these to simplification and upgrades over time and possibly the Australian market.

Simplistically, the prop shaft is a 2-piece shaft connecting the engine to the rear gearbox, with rubber flex joints at each junction. Compared with 'solid' universal joints, rubber ones provide damping properties against vibration, noise, and harshness. In more detail, the flex joints transmit the rotational/twisting forces but through the central hole of each donut is an 'alignment bush', which interlock the prop shaft at each joint: front, centre, rear. The alignment bushes are spherical bearings that keep the shaft in line, working against the up/down, left/right forces. In the schematic below (taken from ePer), the alignment bushes are labelled 3 and 11 (same part number for centre and rear bushes). Pictures tell a thousand words, so more below.



I was surprised to learn that flex joints are not confined to old school cars. They continue to be used in many modern vehicles (albeit more robust), including BMWs and Commodores. I notice some people modify their cars to accommodate the stronger BMW versions.

Much emphasis is made on keeping the prop shaft balanced because the shaft spins at engine speed. It seems unclear how much balancing was performed during manufacture at the factory; there are balancing plates spot-welded onto my shaft. Some people advocate marking every bolt, nut, and washer, to ensure they are refitted in the same locations; this is easy enough to perform, but I don't personally believe this is critical. More importantly, the front and rear prop shaft sections need to maintain the same rotational orientation. Required or not, I marked every part accordingly.

I noticed some vibration during acceleration when I bought the car, the cause unclear at the time. Outlined later, I anticipate this is due to a perished centre support, so hopefully a new one cures the issue.

Referring to the workshop manual and various forums I prepared myself for the task at hand. Though, I found very few photos of the procedure, so hopefully the following will be helpful to some people.

Firstly, tilted the car on stands to access the length of the prop shaft.



Access to the front flex joint was through a 'window' in the engine bell housing. Peering through the hole, you can make out the front flex joint (left, in photo). The 3 nuts fastening the flex joint to the flywheel bolts were removed. * Flywheel marked with position of each nut.





Marking every part. Again, returning every bolt, nut, and washer to the same position seems unnecessary because there's unlikely to be significant weight differences. Yet, easy to do. Some people apply coloured paint, but because this is not permanent, and because I will clean and repaint, I used a hammer and 'punch' to mark pieces. Six bolts per flex joint, so each marked with 1 to 6 'holes'.





Next, unbolted the centre support from the chassis, just forward of the centre flex joint. The gearshift rod runs parallel from this area. Access required removal of the centre crossmember.





Then, unbolted the rear flex joint from the transaxle. 3 nuts and bolts to contend with. * Prop shaft and transaxle forks marked for correct orientation when refitted, and nuts and bolts.



Removed the gearshift rod. A nut and bolt attached the front end to the bottom of the gearshift lever. The original protective rubber boot badly torn and will be replaced. The rear end slid onto a linkage, secured by a roll-pin that was punched out.









To uncouple the rear joint from the transaxle, and enable sliding the prop shaft rearwards and out, the front of the transaxle needed tipping downwards from the chassis. As such, changed the position of the stands to raise the rear of the car.



Removed 6 bolts fastening the transaxle crossmember to the chassis.





A hydraulic jack lifted the De Dion tube, pivoting and tilting the crossmember down.



There's numerous 'attachments' to the transaxle: speedometer pulse generator, reverse light switch, clutch hydraulic line, brake hydraulic line, and handbrake cable. At this stage, only the speedo pulse generator wiring prevented the transaxle from tilting adequately, so this required removal. No external plug, so it was quickest to remove the device from the side of the transaxle. However, this opened directly into the gearbox, so oil was drained accordingly.







With transaxle tilted sufficiently, the prop shaft was disconnected at the rear joint.



Transaxle tilted back to original position for clearance to move the prop shaft rearwards. At the front, the engine bell housing required tilting downwards to allow the front flex joint to pass out. The hydraulic jack lifted the front of the engine, pivoting the rear down. With the rear of the car raised, the front was too low to slide the jack underneath, so repositioned the car again with stands under the left side.



After some jiggling, finally able to pull the prop shaft out. Hurrah!





Next stage was disassembling the prop shaft.

This is the front alignment bush, attached to the tip of the prop shaft. The 'barrel' slots into a hole in the flywheel.



Not all 75s feature this pinch bolt and adjustable front fork, though I suspect all 3.0L V6 do. During reinstallation, it allows some fore-aft adjustment.



Unbolted the front flex joint. The amount of tension evident when the donut recoiled. This one was in good condition, with only minor superficial cracks in the rubber, though it was no longer perfectly 'round'. All flex joints will be replaced. * Nuts, bolts, washers were marked for correct locations.







Front alignment bush being removed. Inside was a coil spring to hold the barrel in position. There was a 'special tool' described in the workshop manual, but of course I improvised using a balljoint remover and small socket piece to lever the bush off the shaft. Very, very tightly fitted; heat from a blow torch proved useful.





The barrel rotates over a spherical bearing, which was press-fitted onto the prop shaft.



Adjustable fork loosened and slid off the splined prop shaft, then degreased.



I originally marked the splines to ensure the fork was refitted in the correct position. However, discovered a 'flat spot' on the shaft lines-up with an area on the fork; thus, they can only be fitted in one orientation anyway.





Onto the centre support and flex joint.





I confirmed the centre support was badly perished.



Joint unbolted. Centre alignment bush at the rear of the front prop shaft slots into the hole in the rear prop shaft. * Prop shaft forks, nuts, bolts, and washers, were marked for correct orientation.





Struggled to remove the alignment bush. Again, used the balljoint remover, though it's opening was broader than ideal, limiting purchase on the back of the bush. Also, the outer ring is 'split' rather than solid; applied force favoured pushing the ring off the internal bearing rather than removing together. Next trick involved a hose clamp around the ring to keep it closed and in position.





With persuasion of the blow torch, finally removed the bush.



Removed the fork, secured by 32mm double-nuts. As described in forums, a 'thin walled' 32mm socket piece required, to fit within the recess of the fork. The socket piece I bought fitted without issues, but people have needed to 'turn down' the outer edge on a lathe.





Air impact wrench made easy work of nut removal.





Fork slid off easily using a puller. Partway, * marked the fork and prop shaft with the hole punch to ensure correct orientation when refitted.







Easy method to remove the shaft from the centre support and bearing was with the hydraulic press. The front prop shaft was short enough to fit within the press.





Centre support and cup (bearing guard) removed. Note how the bearing sat offset within the support due to the perished and distorted rubber. Normally, it should be centred.



All parts to be reused were degreased and cleaned.



Centre flex joint unbolted from the rear prop shaft, then degreased/cleaned. The alignment bush slots into the hole within this end of the rear shaft. The flex joint was in excellent condition, but will still be replaced and kept spare. * Nuts, bolts, washers, were marked for correct locations.





Finally, the rear flex joint. This was unbolted from the rear prop shaft. Rear alignment bush slots into hole in the transaxle fork. * Nuts, bolts, washers, were marked for correct locations.





Different technique used to remove this alignment bush. Firstly, the outer split ring was removed with the balljoint remover. Then, heated the spherical bearing with the blow torch, and punched the bearing off the shaft. Much easier than my effort with the centre bush!



Cleaned and reassembled, the design of the alignment bush as a spherical bearing is evident.





Lastly, I commenced refurbishing the main prop shaft pieces, which had paint chips and areas of corrosion.







A 120 grit sanding flap disc on the angle grinder made very quick and easy work of stripping the paint on the prop shafts. A finer grade would have sufficed. Notice the balancing weight plates on the shafts.
Brass wire brush on the drill worked on finer areas. Forks and cup cleaned with the wire brush.











Sprayed with Etch Primer then Enamel Primer, waiting to fully dry before I respray black...next month.



That was lots of photos, but hard to describe the details of the prop shaft without them. Next month I will respray the shaft, make a list of replacement parts, and clean the tunnel under the chassis.

[Nate Dog]

Thoughts on having those shafts rebalanced before putting them back on?
Your sanding might have thrown it out. Probably talking shit, but as far as i know, those things need to be pretty precisely weighted, else you'll set up and amazing frequency wave of vibration throw engine one end and gearbox on the other.

[shiny_car]

Hey Nate

I'm going to chance it, without having it checked, presuming it was 'balanced' before I touched it (again, there was vibration since I bought it, hopefully only due to the broken centre support).

I might be talking shit too, but I'm presuming a gram here, a gram there, isn't going to make a difference at all, for what will be a street car that isn't spending most of it's time at the top end of the rev range. Could be different if there's slight vibration at 6000 rpm and it's a track car.

So I'm taking a chance here, but somewhat calculated risk.

[VeeSix]

Nice work Richard, enjoy your thought processes re parts management, you remind me of me, i too would just chance it, you will know if its way out, just do not forget to run the engine and let it settle before the final nut tighten, there will always be some form of vibration, it just depends how noticeble it is, too low a idle can cause a bad vibration if donuts slightly worn 

[Duk]

Something worth mentioning, Greg Gordon has had a very high success rate with standard rubber couplings/donuts on his various supercharged Alfa V6's.
Our local track Alfetta demon MD, has broken clutch housings on his cars. Maybe as a result of insufficient damping from vibration due to only having 1 rubber coupling, or maybe other factors???

Either way, if you plan reasonable power upgrades and drive the car like a sane person (or 1 who has to pay for the damages), then the factory couplings should be fine for a road car. Thought that's not to say that things can't be improved upon.
The front mounts of the transaxle can be cross bolted  to help add vertical and horizontal support for the TA. The rear engine mount can have its top and bottom voids filled with silicon or Sikaflex to help give the engine more resistance to for and aft pitching. Both of these will probably result in a bit more noise transfer, but by reducing the amount of angular change the rubber couplings are subjected to, they should be able to do a better and longer lasting job of transferring torque.

[Nate Dog]

Hey Nate

I'm going to chance it, without having it checked, presuming it was 'balanced' before I touched it (again, there was vibration since I bought it, hopefully only due to the broken centre support).

I might be talking shit too, but I'm presuming a gram here, a gram there, isn't going to make a difference at all, for what will be a street car that isn't spending most of it's time at the top end of the rev range. Could be different if there's slight vibration at 6000 rpm and it's a track car.

So I'm taking a chance here, but somewhat calculated risk.

Cool cool,
Best of luck, you definitely know what you're doing
As to my post, please accept my apologies, no idea how you understood me at all, must've been drunk when i posted that.
My grammar and spelling have never been so poor!

Yes, those drive shafts have been previously balanced, just by looking at your pics you can see where weights have been glued on to balance them previously.
As to thinking a few grams here and there wont't make much of a difference, well a few kilogram piece of metal spinning at 3000rpm letting go is a sight to see
I'm sure you'll be fine!!

[aggie57]

Shiny - your detailed descriptions, photo's and attention to detail are tremendous.  There is a world of experience on this forum and others with these cars but I don't recall anyone ever documenting their work like this before.  So well done and on behalf of all who follow, thank you!

[GeeTV]

^ Totally agree!  Excellent work on the car but more importantly [for us  ], superb documentation of your works!
It's so inspiring that you make a novice like me want to go out to the garage and,.... well,.... uummmm,...maybe try & change a spark plug?
If you don't mind me asking, you must be some kind of mechanical engineer - yes?  Please don't say accountant!

[shiny_car]

Nice work Richard, enjoy your thought processes re parts management, you remind me of me, i too would just chance it, you will know if its way out, just do not forget to run the engine and let it settle before the final nut tighten

Cheers David. I think the prop shaft should turn out ok. I've read about leaving the pinch bolt slack until after a few revs to make things settled.

Something worth mentioning, Greg Gordon has had a very high success rate with standard rubber couplings/donuts on his various supercharged Alfa V6's.

That's encouraging.
I haven't decided about firming up the rear engine mount, or the rear TA mount. Probably not at this stage, mostly because I won't be driving the car much, so things should still last as long enough. I'll probably wait until I've gone through one set of rubbers, then try it for the next.

As to my post, please accept my apologies, no idea how you understood me at all, must've been drunk when i posted that.

Ha ha. No issues. In fact, didn't even notice!

Shiny - your detailed descriptions, photo's and attention to detail are tremendous.  There is a world of experience on this forum and others with these cars but I don't recall anyone ever documenting their work like this before.  So well done and on behalf of all who follow, thank you!

^ Totally agree!  Excellent work on the car but more importantly [for us  ], superb documentation of your works!
It's so inspiring that you make a novice like me want to go out to the garage and,.... well,.... uummmm,...maybe try & change a spark plug?
If you don't mind me asking, you must be some kind of mechanical engineer - yes?  Please don't say accountant!

Thanks guys. I enjoying documenting it, and everyone's encouragement helps. Particularly - as you say aggie57 - a lot of procedures haven't been documented as photos before. I've read plenty of tips and descriptions, but a picture can clarify things much better.

@ GeeTV: perhaps be even more encouraged that I'm in no way a trained mechanic or engineer, let alone a mechanical engineer! My background is totally unrelated, so it's purely putting my interest into action. OK, I grew up being a decent handyman around the place, learning from my dad to use basic tools. But this car is my first proper overhaul of a vehicle (I don't consider this a restoration as such, because the car is in decent condition). So, get to it! 

My skills just don't stretch as far as welding and structural bodywork. Nor at fully cracking open an engine to port heads and rebuild bottom ends. Maybe one day, when I can invest in more tools.  'Bolt on' stuff I can deal with.

[aggie57]

Actually I think engines would be well within your capability, from what you've shown so far.  There are no shortcuts with them, you have to do it properly, and the devil is in the detail but its very satisfying the first time you turn the key and it fires

But that's for later.....

[ALF750]

hi shiny, great job you are doing.  I had a 75TS with anaemic aircon and I was wondering what yours is like?   What have others on this forum done to fix/improve/upgrade the old gas system in the 75's??