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Learning how to build Lotus Seven replicas...together!
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PostPosted: June 28, 2021, 10:17 pm 
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OK, thanks for the input. I'll probably keep going the way I was, but make the primaries as long as the stock ones. I don't want to link to Ebay, but a seemingly popular cheap muffler is "db killer" and there seems to be support for or comes with an adjustable baffle.

I like quiet, I put a "streetable" pipe on a 600 way back in the day and didn't like it. It almost seemed slower, I assume because even at small throttle increases it was way too loud. I put the stock pipe back on and silently accelerated away.

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PostPosted: July 1, 2021, 8:25 am 
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I see they sell a few different designs. Consider that a muffler is going to be less restrictive for the amount of db reduction but I see the market for these inserts; folsk who want the look of open pipes but not quite so loud. They probably work ok for that but some of the designs I saw are extremely restrictive. You might try making your own insert or welding a washer to the end of the pipe. The results would be similar.

I made a copper insert a few years ago that worked well. I posted testing under various conditions with and without. Not so pretty though! Get a cheap noise meter. I think they have noise meter apps too though I don't know how accurate they are.

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Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
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Champion/Book:114x42x11
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PostPosted: July 3, 2021, 3:55 am 
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2 on order, we'll see.

Back to another topic, a possible drive (throttle) by wire solution. I forgot I had gotten the exhaust valve "servo" for the 1000RR. It has a pulley that has two slots for cables (pull pull) which might work perfectly for the throttle control. Almost like it was designed to control a butterfly valve with 2 cables!

Although it's not quite a "servo", it's really a motor/gearbox with a pot imbeded like a servo, but there's no control board. Well, the ECU is what controls it.

But just futzing around with it, I think I could put a pot (variable resistor) on the throttle pedal and using an arduino board for servo control, I could get it to work. It's got gobs of torque and runs at about 60 RPM. But that should be plenty fast enough really, 0-90 degrees in 1/4 sec or so.

The question is will it work for long? And safely? The dc motor inside is just a little 180 or 280 mabuchi, it's designed for 12 volts and the "servo" is rubber mounted. It may not like the duty cycle of a throttle. Mounting it on the lower part of the airbox seems the best place, since that's where the throttle body cables come out.

The main safety "override" I'm planning is 1 or 2 big "kill" switches I can access. I saw a youtube video of guy doing a hill climb, I forget what engine was, but the throttle stuck wide open and the ending wasn't pretty. I hope I would be alert enough to put the brakes on and push in the clutch.

The throttle body has at least 2 coil springs for return and I think they would be able to back drive the servo (to idle) in case it lost power. And I think I could also tap into the stock TPS for a secondary check on where the throttle is at. If there is a certain size discrepancy you could have it light a warning light.

Also looking at that exhaust servo, it could probably drive the shift drum directly, which could allow paddle shifting.

I'm gonna order a few arduino parts and see if I can get the throttle part working reliably on a bench.

Probably dreaming again, but I think auto throttle blip downshifts on a paddle shifter would be sweet, for a homebuilt car.

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PostPosted: July 3, 2021, 8:04 am 
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I would not retrofit an oem system, much less design around a cheap dc motor with no feedback and fail safe programming. It sounds like you want to stall a dc motor to hold a throttle position with an amp load. Not good.

Then there is blowing the motor “safety” by pressing the clutch where a rod can end up in your back or head, or the fuel tank/fire. Best not to try cornering at all when you can go WOT at any time. How well will it work in a few years after it gets wet and corroded?

The oems took a while to get theirs “right”. Some oems made it about performance but mostly it is a cost saving measure for emission limits and transmission loading that can result in warranty repair or building the trans light for cost, emission, and mpg then limiting driver input, ramping up loads gradually, etc. Then there is the damage you may cause. Nobody is going to blame the dc motor.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: July 3, 2021, 4:11 pm 
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I appreciate the concern. I would be/am leery of a DIY system. Just a couple points to clear up.

I won't push the clutch in, just brakes and kill switch.

There would be no connection to the stock ECU.

It's hot out so, I'm stuck indoors thinking of stupid things to do.

If I take the throttle springs out of the throttle body there will be practically no load on the motor at steady state. I've done some tests with it and the internal gear ratio is so extreme that you can apply a fair amount of torque to the pulley and it won't even activate a response from the motor (before you actually turn the pulley).

I just did a quick hook up to an old broken hobby servo controller board and it works as expected. You weren't thinking I was going to hook it up some how to just the motor without feedback did you? It would be working as an actual servo not a dc motor, as it did to control the exhaust valve (in the exhaust pipe) on the original bike.

By using an arduino board, I'll be able to program end points and I would think, like I said before, check the TPS and throw an error if there is a difference between that and the servo. I'd be able to adjust the throttle curve also and even make a "valet" setting for, you know, when I go to a fancy restaurant with it.

I'll see if I can mechanically hook it all up and test it. I could imagine the motor might get hotter than in it's original application and addition cooling might be good.

Pic of the motor and the temporary servo setup.


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PostPosted: July 3, 2021, 7:14 pm 
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Sorry to come across preachy from my arm chair. Seriously, do whatever you want. Just my thoughts on it. :cheers:

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: July 3, 2021, 9:56 pm 
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I will add that getting a throttle-by-wire system to do what you need to, is relatively simple task. The hard part is to make it do what you want (safely return to idle) under all conceivable failure modes. I will emphasize this later point. Being 100% certain that the design of the parts and software are fault tolerant. For example, I read a patent some years back, at least one iteration the pedal has both an increasing pot and a decreasing pot actuated by the pedal. The CPU looks at both signals to determine that they match expected results. If not the CPU sets the actuator to zero. This works to verify the pedal assembly and its wiring integrity are operating properly. This works only if the system software and drivers are working properly. There are so many various considerations with DBW systems that I have shied away from a DIY solution in my build and selected a cable operated engine & TB for my MGB build.

BTW check out the GM Blend door actuator for a similar, relatively inexpensive automotive actuator. It comes with the motor and the internal POT. However it was designed for in-cabin applications where the environment is way less stressful than under-hood operations. I have a good, used blend door actuator from a 2000 GMC Jimmy on the shelf if you want to experiment with it. Just pay postage from 60185.

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PostPosted: July 4, 2021, 4:27 am 
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"It might be easy to make work, but hard to make reliable." That's a good way to put it.

I saw the concept of 2 pots on the throttle pedal when I went to look up throttle pedals like that. Certainly that could be programmed.

My 2004 300C has a servo on the thottle body. I think it closes with no power, I'll check tomorrow.

I think programming fail safes should not be a huge deal. But I think it really needs a mechanical fail safe. I say "mechanical" meaning if power goes out to the servo it should return to idle. I'm trying to think of a electro-mechanical device that while under power would allow the servo to freely move the throttle plates. Like a solenoid maybe that when power is lost it releases a spring strong enough to overcome the servo motor and pull the throttle shut.

Or maybe if the servo controller detects a discrepancy it could cut the spark.

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PostPosted: July 8, 2021, 4:10 am 
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You'll be glad to hear I've got some nice throttle cables coming. (also an arduino :oops: )

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PostPosted: July 15, 2021, 2:34 am 
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Some less controversial work, making headers, kind of fun. I had to wire wheel the silly polished finish off of the tubes. I think I'm supposed to back purge the tubes for finish welding.


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PostPosted: July 15, 2021, 9:39 pm 
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Yes, purge your SS welds...


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PostPosted: July 15, 2021, 9:39 pm 
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Yes, purge your SS welds...


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PostPosted: July 22, 2021, 10:37 pm 
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I couldn't find the Kleen-Strip but Ace had something similar, it's main ingredient I think was some kind of phosphate acid. I tried it on a small section of the frame. It started turning black in just a few minutes. The instructions said to leave it on for about 30 minutes and wash it off. Even after washing it off with water it didn't flash rust, this pic is from the next day.

It seems like there is something left on the surface, kind of a grey dust that shows up when I wire brush it. I guess I'll experiment with my primer to see what works.

I jerry rigged a back purge set-up for welding the headers. I don't think I had it regulated very well cause I used a third of a 40lb bottle. bah.


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PostPosted: July 23, 2021, 8:12 am 
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Looks similar to the end result of Ospho.
Ospho says to wait 24 hours, but ends with a similar result. Nice flat gray finish, sometimes with some black scale from the rust conversion. Brushes off pretty easily, luckily.

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PostPosted: July 23, 2021, 1:31 pm 
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Yeah, I think we are all talking about different recipes of the same stuff. I water mine down for light surface, let it dry, then scuff, wipe dust, and spray. More care of course for body finishing.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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