1969 SE5 Alfa V6 conversion: My LSD trip.

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fightingtorque
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1969 SE5 Alfa V6 conversion: My LSD trip.

Post by fightingtorque » Mon Oct 30, 2017 10:06 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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1969 SE5 Alfa V6 conversion: My LSD trip.

Post by GavinR » Fri Nov 03, 2017 2:38 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 » Mon Dec 18, 2017 12:14 am

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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1969 SE5 Alfa V6 conversion: My LSD trip.

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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1969 SE5 Alfa V6 conversion: My LSD trip.

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:
Image

This caused it to give up and move off when prompted by Mr Chisel.

Image

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.

Image

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

Image

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:

Image

Image

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:

Image

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:

Image

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.

Image

Image

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.

Image

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.

Image

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.

Image

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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1969 SE5 Alfa V6 conversion: My LSD trip.

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

Image

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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1969 SE5 Alfa V6 conversion: My LSD trip.

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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