1969 SE5 Alfa V6 conversion: Lowering the Throne.

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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by DARK STAR » Fri Jan 27, 2017 11:55 am

I have 'only' 210 bhp that passes by the 7HA back axle, but it doesn't often get abused nowadays.
It is an LSD, are they stronger?
The only problem with the excess power I had was, first time out at Harewood, the 2 litre Sierra 'box disintegrated.
I still had second gear so got home ok :mrgreen:
That was cured by fitting an RS gearbox which is reputed to handle 500 bhp.


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by turbster » Fri Jan 27, 2017 12:27 pm

Roger Pennington wrote:Paul, my note, as you will have seen, didn't mention absolute power handling figures (do such figures actually exist?). The point was a general, relative, one - I doubt that there are many people who would disagree that "the 4HA is a more robust axle than the 7HA". :)
It was more of a general comment related to the lack of figures to back up the 7 being so weak.. I'd have fitted a 4 to my car to be safe, but the weight disadvantage of doing so makes it worth the risk! Fingers crossed mine can handle the power and my sympathetic driving style!! :wink: :lol:


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by DARK STAR » Fri Jan 27, 2017 5:20 pm

Paul, if it can handle that then I've no worries :lol:


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by roymck » Sat Jan 28, 2017 8:41 am

Another thing Gavin the rear end ratio is different 7HA is 3.58-1 the normal 4HA is 3.31-1 unless you get a 3.07-1 that was fitted to some autos and 4 speed non overdrive cars so hope you haven't had the speedo recalibrated yet.
On the axles I have changed the problem with the 7HA always seems to be not the crown wheel and pinion but the planet gears in the diff. So running a lsd 7HA should be more reliable option.



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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by Coupe Racing » Sat Jan 28, 2017 9:08 am

The planet gears in my 7HA with LSD still disintegrated


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by CNHSS1 » Sat Jan 28, 2017 9:46 am

Do they do a quaife diff for the 7HA? They are almost impossible to break as they don't have the normal design sun and planets


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by turbster » Sat Jan 28, 2017 10:02 am

They do Craig, it's listed for the V8 Morgan...


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by DARK STAR » Sat Jan 28, 2017 11:40 am

My 7HA LSD is 3,31:1 according to the tags.
I managed to break the (normal) 7HA on my Daimler SP250 ...


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by Old and Slow » Sat Jan 28, 2017 12:08 pm

My 7HA LSD is 4.1:1, I assume it was set up for hillclimbs by Richard Prosser. JB Sports Engineering (www.jb-engineering.co.uk/) had lots of diff bits - for Morgans.


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by Nick » Sat Jan 28, 2017 12:12 pm

My 68 Coupe has a 331 diff and a Salisbury LSd. I presume this is a 7HA? Runs lowish profile 14 in wheels so gearing is back to standard. Richard Carter seems to know about fitting Quaife's to Coupe's.

Having had both I much prefer the Quaife to a clutch type diff.


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by efi_sprintgte » Sat Jan 28, 2017 1:28 pm

Yea dads done quite a few quaiffes, everything we've done has been 4HA


Personally I would be fitting a quaiffe to your existing axle and all will be fine I'm sure. Should be noted your not exactly putting the extra stress cut slicks but through the car...


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by DARK STAR » Sat Jan 28, 2017 5:15 pm

Does a Quaife feel different to drive?
The only other LSD I know is Porsche's intelligent active diff which is amazing if you let it act.
If you don't you finish in the earth bank at Curborough - saw that once and when I had my 928 I understood why.
Best switched off for racing ...


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by efi_sprintgte » Sat Jan 28, 2017 6:14 pm

My own racer has a ramped up plate LSD which is great for traction but does act abit welded and makes the back step out in the wet very easily.

IMHO the ATBs make the car far better(read faster) to drive in the wet.


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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by fightingtorque » Wed Feb 15, 2017 11:56 am

Hi guys. Interested to see all your comments. I've not done much yet, just got the 4HA axle and started to prepare it for stripping down to put new seals in and check it over. Need to make up the famous "pipe flange tool".

In the meantime, I've acquired a 3D printer.

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Not sure how useful it will turn out to be for actual car parts, but in the build I used some 3D printed parts as mock ups. One of the things I was considering doing for improving my instrumentation was to transfer the Alfa speedo and rev counter into the Scimitar dash, and for this I would need to make some special bezels.

So far we've just done a few bits for the kids like dinosaur skulls, and I have made some wheel centres for my T4 "Bub Van" which has got some 17" wheels on it that came without centre caps. Can print in ABS or PLA so far. PLA is a very brittle plastic that I think is pretty much only used in 3D printing market. ABS is a step up , a bit more difficult to work with in the printer, and still quite brittle as you can see - the mark one version of the wheel centre cap broke, but the second version worked ok. A big limitation with this type of filament printer is that it is not very strong in the Z plane so you need to bear this in mind in the part design and orientation in the machine.



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Re: 1969 SE5 Alfa V6 conversion:7HA axle "no strong enough"

Post by scimmy_man » Wed Feb 15, 2017 12:24 pm

hmm se6 mirror plinths in black?


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