1969 SE5 Alfa V6 conversion: PROJECT ALFATAR.

If you have a long-term project and would like to share/document progress, this is for you.

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fightingtorque
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1969 SE5 Alfa V6 conversion: My LSD trip.

Post by fightingtorque » Mon Oct 30, 2017 9:06 am

Thanks Jim. Looking at that manual it seems the "standard" is normally 0.007" (0.18mm), which seems reasonable, and then elsewhere in the manual it shows how to interpret the contact patch found using engineers' blue.
backlash.JPG
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Post by GavinR » Fri Nov 03, 2017 1:38 pm

Hi,

The preload on the differential case bearings is achieved by fitting shims under the bearings to give the required preload
(I think the IRS units achieve preload by attaching the output shafts to the diff casing so don't need these shims)

Once you have the correct preload, you can then swap shims side to side to adjust the backlash, keeping the same total shims - make sure the pinion is at the correct depth first though

It usually takes a while and a few attempts to get it right - you also need a decent puller / press to get the bearings off and on!
I've seen 8-10 thou backlash in other manuals so it doesn't need to be exactly 7 thou

Thanks


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rossnzwpi
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1969 SE5 Alfa V6 conversion: My LSD trip.

Post by rossnzwpi » Sun Dec 17, 2017 11:14 pm

Hi, just a wee thought on that 3.0 Busso V6. The 2.5 is a sweet high-revving engine with sufficient power and torque for most people's (maybe yours???) needs. The 3.0 was used in various cars and, if I remember correctly, in the Alfa 166 it was re-tuned to favour smooth, lower rev lugging so isn't as sporty. What I'm saying is I think you have a great engine with a 2.5 Alfa 156!
Ross



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Post by fightingtorque » Thu May 24, 2018 8:48 am

Finally got my replacement axle built up, with LSD, ready to go in.......... although I need to make a new propshaft now because the diff is bigger than the old 7HA axle.

Image

I'll put details of the build in the next post, just testing the use of images from my own website rather than photobucket for now.
Thanks to all those of you who contributed info via Scimitarweb and facebook during the build of this.

Gav



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Post by fightingtorque » Thu Jun 14, 2018 1:17 pm

OK, so the job of rebuilding the axle. My first advice to anyone considering doing this would probably be, "DONT".

But if you are still reading.....

Getting the hubs off is something I already covered in earlier posts, it was pretty difficult but on reflection the one that was really hard to shift was probably difficult because it had been damaged by hammering or something.

Getting the diff out was not too bad.

Getting the old bearings off the pinion and the diff is not easy. For the pinion I cut a slit in it and beat it to death:
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This caused it to give up and move off when prompted by Mr Chisel.

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For the diff bearings, one of the facebookers alrerted me to the existence of a different type of pulling device "bearing splitter" which I hadn't met before. Still, it wasn't easy. There wasn't a good enough gap between the diff and the bearing race to get into, so the best method seemed to be to cut a couple of grooves using Sir Angle of Grind. Then, in conjunction with patience, blowtorch and WD40 and additional leverage from a specially modified chisel I eventually got them off. I know there may now be an argument about whether WD40 is a penetrating oil or not.

A useful tip is to keep a nose out for a faint smell of old gearbox oil that will be released the first time it moves even a little bit and lets you know you are getting somewhere.

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Here you can see the grooves I cut and also the aluminium piece I made in the lathe for the puller to push against.

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So, that was the thing apart. Then you have to rebuild it, and this involves measuring and adding various shims, which means you have to find a way to get the new bearings on and off a few times without destroying them.

So, first to buy the bearings. I already got the rest of the parts for the build such as the seals and wheel bearings, new bushes for the trailing arms etc. from QRG. For the diff bearings though, I bought them from Simplybearings.co.uk . I like to support the specialists but on this occasion the price differential was too great. The four bearings - one on each side of the diff and two for the pinion, run at £30-40 each even from Simply Bearings.

I got the shims from ebay, there are some sellers selling various thicknesses and diameters. The diameter was not perfect but close enough, ideal inner diameter for the diff bearings would be about 42mm and the closest was 45mm, I don't think they will move about.

I decided to modify the diff as in the picture below, to allow better access for the bearing splitter (you are looking for a "ramp" section that I have added with the help of Sir Angle of Grind:

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And the bearing splitter, which came from Machine Mart, also needed some attention. Really, it is a bit too small for the job but like this it works:

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Even with this, I decided that it would be best to leave a small gap. So I initially installed the bearings with a 0.5mm gap using shims as shown:

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Like this, I was able to remove them and fit them. For the pinion, I reassembled it using the original shims. The internet suggested that the main variation regarding the pinion distance setting is the machining of the case, so that probably you won't need to change these shims.

For checking the amount of clearance and backlash you start with a dial gauge but end up with looking at the actual contact. I tried both the yellow stuff , and also engineers' blue, both from the internet. I think the blue is better, but even so, it's not an easy thing to capture by camera.

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After a few iterations, I was happy. So then to take the diff out again and do the final assembly.

As this was an LSD, it is necessary to install a pair of "buttons" which allow the two halfshafts to work against each other without pushing on the diff. These came from a company who sell on ebay (but not always). They are tiny little things, I have to admit, I have my doubts about the long term durability of this arrangement.

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One point here, DO NOT PUT THE SEAL IN FIRST. If you do, then you can't put the oil slinger in. I made this mistake but luckily I was able to get the seal out again without damage.

To do the nut up on the pinion, it is necessary to measure the "preload" as a rotational torque. The only torque device I could find that read such low values was a beam type with 1/4" drive, it came from a USA based ebay seller. I fitted it to a bolt through one of the flange holes. After doing this I checked the meshing again....... it had changed because evidently I hadn't done it up as tightly as before, so I had to make another shim change.

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In this final build, I ran into a problem regarding the crush tube. I think it is made too hard, or with not enough profile. Anyway, I could not get it to crush - I went as far as I dared before I felt that the nut/ pinion thread was in danger of damage and then decided it wasn't working. So I re-used the original crush tube, but I was happy with this because there was still a good amount of torque required to get the nut tight enough to preload the bearings to the desired torque measurement. I think it will be ok.

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The rest of the rebuild went more or less as the book. I've now got it in the car and even put the wheels on and dropped it to the ground for the first time in over a year. Still afew things to do like connecting the (new) propshaft and making some new brake lines etc.
Last edited by fightingtorque on Thu Jun 14, 2018 2:50 pm, edited 1 time in total.



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1969 SE5 Alfa V6 conversion: My LSD trip.

Post by DARK STAR » Thu Jun 14, 2018 1:39 pm

Brilliant post ... it would certainly put me off doing the job :mrgreen:


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Post by philhoward » Thu Jun 14, 2018 1:54 pm

I’ll heed the advice in the first paragraph too :mrgreen:

Cracking write up though :D


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Post by fightingtorque » Thu Jun 14, 2018 2:54 pm

Couple more pics that might be useful. The spacer drawing came from elsewhere on scimitarweb.

Image

Image

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Image
www.simplybearings.co.uk



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Post by Oaksey » Thu Jun 14, 2018 3:00 pm

They're good fun aren't they. I didn't have an issue using a new crush tube, just a lot of force to get it to start. That was on a later axle though in fairness


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Post by fightingtorque » Thu Jun 14, 2018 3:02 pm

Tools added to collection:

Hub puller- about £70, broke it, modified it.
Thread file £15 and die nut £35 (both ebay) to restore some minor damage to one of the halfshaft threads
Hydraulic press - about £300 from Machine Mart
Bearing Splitter - about £30 from machine Mart. Best to buy the small item first, then if you are on their mailing list, about 10 days later you tend to get a 20% off voucher for a limited period to go and buy the big thing you want. It's taken me a while to identify their method, at first it always seemed an annoying coincidence that I'd get these offers shortly after I already bought a load of stuff!
Marking fluid, a few quid.
Bits of random metal to turn into tooling for the presswork.

Cost of parts:
£150 for the bearings
£275 for the LSD
£150 for the secondhand axle
About £30 for those little button thingies
A bunch of stuff bought from QRG including wheel bearings, seals, gaskets, new brake shoes and a complete set of polybushes for the trailing arms, I think was a surprising lot like £200 or more

Basically, if your axle isn't whining like hell or leaking oil everywhere, or proper broken, leave it alone!



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Post by fightingtorque » Fri Oct 05, 2018 12:25 pm

OK, so the axle went back in more or less without drama.

Propshaft was next. Previously I had used an unmodified Mazda MX5 prop with a laser cut adaptor plate to mate it to the diff, but because the 4HA diff is bigger than the 7HA, the propshaft was now a couple of inches too long.

So, I cut the back end off the MX5 prop, and also the back end of an old Scimitar prop, got a piece of tube about the right size and with some turning made an internal sleeve. Offered it up to the car, moving the suspension through it's travel to find the closest point of approach. Then marked it, took it off and tack welded it 15mm shorter to allow for movement of the various bits under things like acceleration.


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I thought about "giving this a try" but decided it would be better to get a proper welding and balancing job done.

I put a question out on an fb forum and a few prop specialists came up, one of which being Dave Mac Props near Coventry. I happened to be going that way with the family on a trip to the Lake District so we dropped it off on the way. It turned out that my own efforts were mostly pointless becuase for a very reasonably £185 +VAT they made me a 100% new propshaft to my template, so I chopped up two propshafts for nothing (the Scim one had a knackered front section anyway though).

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One other thing to do under there was to resolve the speedometer / flying magnet issue. So I 3D printed some parts to hold a pair of magnets nicely in position. You will start to see quite a lot of use of 3D printing from here on because I now have 2 machines and one of the companies I work for (my main work) has decided to start manufacturing nanodiamond-modified polymers for 3D printing.

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So with that, I should have been "on the road for summer" but for some reason I then decided to.....



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1969 SE5 Alfa V6 conversion: Lowering the Throne.

Post by fightingtorque » Fri Oct 05, 2018 12:32 pm

........ cut the floor off.
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This is to get the driving position a bit lower as it has been too high ever since fitting Ford RS Recaro recliners. Especially if helmets are involved.

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Sadly, unless you want to modify the chassis the amount to be gained isn't as much as I thought, although you can get rid of the slope.

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But, in any case the seat was just about to rip out of the old floor as the metal reinforcement had all rusted away and split the fibreglass. I used angle iron to make some solid mounts that were welded to the chassis.

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And with the help of lots of cardboard and gaffa tape from underneath, and some rubber strips inserted, I fibreglassed in a new floor.

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It's a bit alarming how much light the fibreglass allows through but it's not so bad once you paint it black.

It was not a five minute job, so I haven't bothered with the passenger side, but I will add some reinforcement back to the chassis at some point on that side.



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Post by fightingtorque » Fri Oct 05, 2018 12:35 pm

Lost quite a bit of car time over the summer, as I decided to do a "sailing boat modification project" and also some things on my VW Caravelle ready for the family holiday, then the rest of August was taken up with other sub holidays and a business trip to China which meant I missed Curborough again. Now we are suddenly in October, but I have just got it MOT'd, insured and freetaxed again and ready to start off where I got to 18 months ago before the axle broke..........



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Post by Dcrosby13 » Fri Oct 05, 2018 1:48 pm

are you aiming to attend Curborough next year?


I break stuff...... :w

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Post by fightingtorque » Tue Oct 09, 2018 11:52 pm

Yes. I aim to go every year........
Never been.
See also Le Mans.......
Been once each to classic and normal 24hr.
Been to Goodwood revival 3 times but not this year and now all I see on Facebook is amazing racing footage.



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