Standard Parts

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Re: Standard Parts

Postby Martin Kemp » Sat May 16, 2020 8:15 pm

Making new manifolds?
It has taken a bit of time in the present circumstances but I have now had a batch of inlet and exhaust manifold flanges LASER cut.
The inlet manifold flanges locate on the outer 2 studs with larger clearance for the other studs which makes them easier to fit. I have allowed plenty of clearance for access o the spark plugs. It doesn't include a cover for the water jacket hole at the rear of the cylinder head.

To go with it there is also a carburettor flange to suit a Weber DCOE. It has a full set of mounting holes and mountings for a throttle cable bracket.

The exhaust manifold flanges are individual for each cylinder, because it makes it much easier to fit the exhaust system, especially where access is restricted.
All the flanges are 5mm thick.

If I could, I would have posted a picture but my computer won't open files any more,

Martin
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Re: Standard Parts

Postby Martin Kemp » Wed Aug 25, 2021 6:00 pm

I have had a few conversations recently about steering racks.
Here is a cheap and easy and well tested way to make a steering rack to suit many 750 cars.

Starting with a standard Seicento rack (about £60 on the internet) remove the standard track control arms and then fit the rack extensions shown in the drawing below. This shows the version for the Falcon but the dimensions can be altered to suit other cars.

Item 1 - the Rack Extension is a piece of bar with a M12x1.25 pitch thread right through, spanner flats and a shoulder to suit item 2 - the Rack Stop which is just a bit of tube to limit the rack travel . The Rack extension screws onto the thread on the end of the Seicento rack and is held with Loctite - we use High Strength Retainer.
Item 2 the Rack Stop will later be kept in position with Locktite, brazing or a spirol pin.
Item 3 is the Steering Clevis which we make by welding lugs onto an M12x1.25 pitch bolt. The holes in the lugs are to suit the rod end for your new track control arm. We use 5/16 UNF rod ends.
To customize the design for different cars alter the length of the Rack Extension and adjust the Steering Clevis to get the required rack width and tailor the rack stop tube to limit the rack travel. Not shown on the drawing is an M12x1.25 locknut for the Steering Clevis.

One important thing to note is that the rack is quite low geared and the steering arms on the upright will have to be quite short. We have 50mm steering arms. I was a bit concerned about the affects of play and wear in the system with such short arms but it has proved not be a problem and our secondhand rack has now done 8 seasons with only 2 replacement rod ends. To help scale off the drawing the rack stop tube is 1 1/4" OD

The Falcon rack is behind the steering axis and uses a RHD drive rack. For cars with the rack ahead of the steering axis use a LHD rack upside down

Martin
RK 113 RACK EXTENSION ASSY.JPG
RK 113 RACK EXTENSION ASSY.JPG (176.29 KiB) Viewed 2184 times
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Re: Standard Parts

Postby geofff » Thu Aug 26, 2021 11:01 am

Hi Martin,

Looking at Mark's blog, is this the same design used on his car or did you use a machined one piece part there?

Also what would you say to using go kart hexagonal track rod's? I think these are quite light weight ali but are they man enough for the job?

Thanks again for the standard parts and guidance in this post.

I will be pulling the Seicento rack apart tonight to see how part 2 in your drawing below attaches. Also because I've never had one apart and what the heck...

Geoff
:)
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Re: Standard Parts

Postby Martin Kemp » Thu Aug 26, 2021 12:16 pm

On the early Falcons I used a one piece machined part but because they screw onto the rack the clevis had to be machined to suit the individual rack in order to get the clevis angle correct. The new design gets over that problem and is interchangeable.

When taking the standard track control arms off the Seicento rack, some have the end of the screw on ball joint peened over the thread and some don't. You should be able to see it.
The peened bit can be ground, sawn or filed away so the joint can be unscrewed. Heating up the joint will free up any Loctite that may have been used to stop it unscrewing.
I would be a bit wary of ally track arms principally because of the puny threads We use thick walled 1/2" CDS steel tube tapped for 5/16" UNF rod ends but thinner walled tube with welded on threaded ends will also be OK. If kart ones are steel and 1/2" AF or more with 5/16" or 8mm rod ends then they would probably be OK. I wouldn't fancy 6mm or 1/4" rod ends - although theoretically strong enough.
Buckling is the most likely failure mode and the buckling strength reduces with the square of the length but this isn't going to happen while you are holding the wheel only when the steering knocked onto full lock. Our track arms are about 300mm long.
We use the same design for the front push rods which have a harder life and they have been OK so far.

Martin
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Re: Standard Parts

Postby geofff » Sat Sep 04, 2021 8:20 am

Hi Martin,

Screw on ball joints came off nice and easy, no heating or grinding required in the end, used an adjustable spanner:

Seicento rack disassemble3.1.jpg
Seicento rack disassemble3.1.jpg (50.8 KiB) Viewed 2033 times


Geoff
:)
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Re: Standard Parts

Postby Martin Kemp » Sat Sep 04, 2021 10:26 am

Anyone buying a new rack should beware of Autodoc. They have previously provided me with good service but it is not obvious from their website that they are based in Germany and they supplied me with a left hand drive rack by default - despite me being a UK customer. The problem now is that their returns process is just not responding,

Martin
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Re: Standard Parts

Postby Baggers » Sat Sep 04, 2021 1:41 pm

Yep, can second that having bought wipers from them. They were absolutely insistent that what they had sent me was right. There are other site like buycarparts.co.uk which masquerade as being UK but I think are still autodoc with the same problems.
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Re: Standard Parts

Postby ChrisDavies1 » Sun Sep 05, 2021 9:03 am

[quote="Martin Kemp"]Anyone buying a new rack should beware of Autodoc. They have previously provided me with good service but it is not obvious from their website that they are based in Germany and they supplied me with a left hand drive rack by default - despite me being a UK customer. The problem now is that their returns process is just not responding,

I believe that I will need a left hand drive rack for my build Martin so if you’re stuck, I’d be happy to purchase it off you my friend
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Re: Standard Parts

Postby Martin Kemp » Sun Sep 05, 2021 10:45 am

Would you like it with or without the standard track arms

Martin
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Re: Standard Parts

Postby Martin Kemp » Mon Nov 29, 2021 6:05 pm

While I am wandering about on the forum I ought to update the story of Autodoc and the left hand drive steering rack they sent me. They are the same as buycarparts.co.uk

After a couple of reminders they did contact me and paid the postage for returning the rack and included the several pages of post-brexit customs paperwork already filled in for me. Later they refunded the original cost and postage. So, with a little nudging and after a couple of weeks they honoured their consumer promises.

However Chris I do have another brand new left-hand drive steering (without track control arms) available.

Martin
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