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Learning how to build Lotus Seven replicas...together!
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 Post subject: Re: sprite into locost
PostPosted: Sun Jan 08, 2012 6:23 pm 
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Joined: Sat Dec 29, 2007 10:41 pm
Posts: 585
Location: Vancouver, BC
Chuck,
In this shot you can see the triangulated link:
Image

I never did measure the amount of lateral movement when i put the car together, but i can say it does move quite a bit. In the spring, if i still have the car, i'm planning on remaking the lower mount brackets as one has the wrong thread on it and the other i want to build slightly offset to move the pinion slightly as its very close to the trans tunnel.

On the Westy, the rear set up is basically the same as a book chassis locost, with a full width panhard rod.

And to anwser Johns question, the gas tank is hung off the LH side of the chassis, just aft of the firewall.

Cheers,
Rod


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 Post subject: Re: sprite into locost
PostPosted: Mon Jan 09, 2012 6:41 pm 
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Joined: Thu Jan 31, 2008 5:34 pm
Posts: 464
Location: SW West Consin
Rod
So how are the rear ends of the trailing arms attached to the axle ?
Tim


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 Post subject: Re: sprite into locost
PostPosted: Mon Jan 09, 2012 7:13 pm 
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Posts: 585
Location: Vancouver, BC
Tim,
All the axle connections are in single shear (though with 1/2" hardware). The uppers are indeed through the brake backing plate, the lowers attach to a bracket which is bolted to the existing leaf spring pads. Its a neat idea, as it requires no welding to the axle casing, but it places the upper trailing links very close to the tires, and thats with the bolt on wire wheel adapters. It wouldnt work at all with steel wheels.

The later Elevens and Series 1 Sevens had a fabricated bracket welded to the axle casing, but again everything was in single shear.

I was thinking about the triangluated link, and the only reason it gives side to side movement through suspension travel, it due to the chassis pick up points not being inline. The inner pivot is roughly 4" aft of the outer pivot, all the missalignment is taken up by the rubber bushings. On my current build, i'm plagiarizing the Ginetta method, with the pivots in line with each other and the axle connection closer to the center of the car.


Rod


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 Post subject: Re: sprite into locost
PostPosted: Mon Jan 09, 2012 7:50 pm 
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Joined: Sat Aug 28, 2010 7:53 am
Posts: 97
I sheared a 1/2" bolt mounted in single shear on my Legends car while autocrossing. SIngle shear also elongates the holes with time


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 Post subject: Re: sprite into locost
PostPosted: Tue Jan 10, 2012 3:13 pm 
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Joined: Thu Jan 31, 2008 5:34 pm
Posts: 464
Location: SW West Consin
Rod
Do you have a picture of the Ginetta set up? It sounds kind of like a Satchell link which is four trailing arms with the two lower front joints angled toward the center of the car. This is supposed to be the best solid axle set up according to Herb Adams but I can't figure out how it works without some compliance in the joints. I am tempted to make a model as I have never been fond of the high roll center and behind the axle structure you get with a Panhard rod.
Sean
Got a pic of that failure? Failures are the best teachers and I know I don't know much. :!:
Tim


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 Post subject: Re: sprite into locost
PostPosted: Thu Jan 12, 2012 1:20 pm 
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Posts: 464
Location: SW West Consin
Does anyone know of an engine builder in the upper midwest that could rebuild my AH Sprite 1275 A engine??


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 Post subject: Re: sprite into locost
PostPosted: Thu Jan 12, 2012 3:05 pm 
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Joined: Sat Dec 29, 2007 10:41 pm
Posts: 585
Location: Vancouver, BC
Tim,
I've been going through all my pics and i cant seem to find a good picture of the later type G4 rear axle arrangement. All i seem to have is a pic off the web of the early type which is very similar to the stock Lotus 7 S2/3 arrangement with a wide based A-frame picking up on the center of the axle. The later G4 type had it basically cut in half, and it picks up towards the side of the center diff housing. Both arrangements use just two upper trailing links and the single lower A-frame.

As for the engine, you might want to join the MG Experience forums. There's bound to be someone on there in your neck of the woods who could rebuild your A-series engine. Or, you could do it yourself. Any good machine shop should be able to do the machining for you and assembling them is a piece of cake. They are a very basic engine.

Cheers,
Rod


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 Post subject: Re: sprite into locost
PostPosted: Thu Jan 12, 2012 8:45 pm 
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Joined: Thu Jan 07, 2010 5:39 pm
Posts: 157
Location: hopkinsville KY
Does anyone know of an engine builder in the upper midwest that could rebuild my AH Sprite 1275 A engine??

call rick haynes
http://www.sportsandimports.biz/
he also crews for craig chima who races a g4 so you might be able to get more pics thru him or craig

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 Post subject: Re: sprite into locost
PostPosted: Thu Jan 12, 2012 9:58 pm 
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Joined: Mon Apr 12, 2010 5:40 pm
Posts: 1858
Location: san francisco bay area
A 1275 engine? Dude it takes longer to calibrate a pair of SU's than to rebuild one of them.
Those are soooo easy, you'll kick yourself if you pay for someone to do the work and then figure out just how easy it really is with just access to a decent local machine shop for the milling work.
Key hint, make note of which way the big end of the connecting rod is oriented. ..
And make sure the valve stem tips are even (within an acceptable variance) after the head gets built, I see a lot of shops not bothering to check and some pretty wild variances across the head (actually that applies now matter who does the work).
And spend the few extra bucks to fit some decent valve springs, otherwise valve float occurs somewhere around 56-5800 rpm.
As I recall, the Ford 170 CID 6 pot exhaust valves that are pretty close as far as diameter with a longer stem, just a little machining is needed to fit. I don't remember which intake valve I ended up using, I'll see if I can find it in my notes.

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 Post subject: Re: sprite into locost
PostPosted: Fri Jan 13, 2012 3:13 pm 
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Posts: 464
Location: SW West Consin
Oldejack
Actually I rebuilt an A series once. In the car, me on my back in the street in front of my house, in January, no snow. It wouldn't hold oil pressure. I should have known it should not have needed 50 wt. The previous owner had put the connecting rods in backward. As for now it would be a way to shorten up the project.
Tim


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 Post subject: Re: sprite into locost
PostPosted: Thu Mar 01, 2012 3:17 pm 
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Joined: Thu Jan 31, 2008 5:34 pm
Posts: 464
Location: SW West Consin
Calling all ace suspension gurus.
I have been trying to fit the standard Sprite suspension parts into something that gives optimum camber gain, minimum scrub and minimum roll center height variation. I did this using my cad system thinking it would be easier then learning to use Windows XP and a specialized program. Ten hours later I am not so sure. At any rate here it is, a front view in 2d. Please comment. There is a lot published out there about this stuff but not so much about what numbers people have used and how well it worked.


Attachments:
File comment: locost into sprite front view
nsfrtsusp9.dwg [30.01 KiB]
Downloaded 68 times
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 Post subject: Re: sprite into locost
PostPosted: Thu Mar 01, 2012 4:27 pm 
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Joined: Fri Jan 02, 2009 1:45 pm
Posts: 913
Location: Halifax, Nova Scotia
Earlier you were looking for a photo of Ginetta lower suspension links: like this? It doesn't show much I'm afraid.


Attachments:
GinettaG4-DE - Lower Link.jpg
GinettaG4-DE - Lower Link.jpg [ 47.83 KiB | Viewed 698 times ]

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601
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 Post subject: Re: sprite into locost
PostPosted: Thu Mar 01, 2012 5:17 pm 
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Joined: Thu Jan 31, 2008 5:34 pm
Posts: 464
Location: SW West Consin
Actually quite a lot. It looks like an early 7 with the A arm attached to the bottom of the axle.

I think I might have found a way to put up drawings by converting them to JPEGs with my scanner, now if I can rotate it.


Attachments:
Scan.jpeg
Scan.jpeg [ 643.87 KiB | Viewed 692 times ]
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 Post subject: Re: sprite into locost
PostPosted: Thu Mar 01, 2012 6:53 pm 
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Joined: Thu Jan 31, 2008 5:34 pm
Posts: 464
Location: SW West Consin
Series 2 actually.


Attachments:
Series Two Rear Suspension.jpg
Series Two Rear Suspension.jpg [ 54.39 KiB | Viewed 677 times ]
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 Post subject: Re: sprite into locost
PostPosted: Thu Mar 01, 2012 7:25 pm 
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Joined: Fri Jan 02, 2009 1:45 pm
Posts: 913
Location: Halifax, Nova Scotia
Rod's point was that the Ginetta A-frame was narrower than the 7's, which was almost the width of the frame. What diference it makes, I don't know.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


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