Project London Bridge

Restoring or fettling your ride ? Show us your progress.
KiwiDave
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Re: Project London Bridge

Post by KiwiDave » Sat Jul 14, 2018 9:58 pm

A7RXY wrote:
Sat Jul 14, 2018 9:48 pm
biznatch wrote:
Sat Jul 14, 2018 9:13 pm
Last week's event definitely added some motivation to update my build thread and move things forward again. I would have liked to have had my FB back on the road in time for the event but it wasn't to be. It was great to go along, see some fantastic cars and meet some of the regular members here :D
Likewise, good luck.... Dibs
Was good to catch up Glen. th:
1985 Sunrise Red S3 TWR
2003 Mercedes E320 CDI Estate AMG

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Hobbawobba
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Location: Worcester - UK

Re: Project London Bridge

Post by Hobbawobba » Sun Jul 15, 2018 4:56 pm

All looks pretty good aye bro! I'll have to keep an eye out on the rack conversion as it's on my to do list! :lol:

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ian65
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Re: Project London Bridge

Post by ian65 » Sun Jul 15, 2018 5:09 pm

loads of projects there Glen... subframe swap is on my to do list too. That reminds me I need to post the PAS lines to you.
1986 Series 3 13B Turbo II
http://rx7fb.com/viewtopic.php?f=2&t=2400
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

biznatch
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Location: Hornchurch, Essex

Re: Project London Bridge

Post by biznatch » Sun Jul 15, 2018 8:25 pm

Hobbawobba wrote:
Sun Jul 15, 2018 4:56 pm
All looks pretty good aye bro! I'll have to keep an eye out on the rack conversion as it's on my to do list! :lol:
Thanks Jesse,
Yeah from what i have read so far there seems there's a number of ways to go with the steering rack conversion when doing the FC subframe swap. Some of the options being:

1. Use the FC power assisted rack with the hydraulic pump. This would need a speed signal from somewhere? to reduce the powered assistance as speed increases. At the moment I'm not sure where that signal would be derived from on the FB so maybe this would just be 100% assisted at all speeds?
2. Use a manual FC rack
3. Use a powered FC rack and convert it to manual. This seems to be preferred over option 2 above, i'm not 100% sure why but maybe it has a better ratio?
4. Use an electrically assisted rack, such as Opel Corsa/Holden Barina. Shorten the rack length to suit and re-thread for FC rod ends. Apparently EAS is a common conversion for older cars and there are cheap and simple controllers readily available. Personally, I'd like to see a few successful examples on the FB before I'd be convinced to go down this route.

I'm sure there are other options too. I'm not sure if there is any particular method that that is considered to be the best but most of the threads I've read seem to opt for a depowered PAS rack. I'm keeping my options open at the moment and would be interested to hear which way you and Ian are thinking to go with it.

biznatch
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Location: Hornchurch, Essex

Re: Project London Bridge

Post by biznatch » Sun Jul 15, 2018 9:51 pm

ian65 wrote:
Sun Jul 15, 2018 5:09 pm
loads of projects there Glen... subframe swap is on my to do list too. That reminds me I need to post the PAS lines to you.
Thanks Ian. They could be needed If I manage to find a workaround for the speed sensor input I could reinstate the FC PAS, or accept it will have full assistance at all times.

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ian65
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Re: Project London Bridge

Post by ian65 » Sun Jul 15, 2018 10:03 pm

I know that PAS on 1st gens uses a speed sensor built into the speedo and I think that FC's probably do as well. You could use it on full assistance or maybe you could introduce a valve to reduce the flow of power steering fluid through the lines ( a bit like the idea of a manual boost control valve ) ... it wouldn't be speed sensitive but you could set it according to how you are using the car.... might be a solution? :?
1986 Series 3 13B Turbo II
http://rx7fb.com/viewtopic.php?f=2&t=2400
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

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KYPREO
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Re: Project London Bridge

Post by KYPREO » Mon Jul 16, 2018 2:14 am

There were 2 different kinds of power steering in the FC.

Most FCs used vehicle speed sensing power steering
Some series 5 (but not series 4) models used engine speed/RPM based power steering - generally these were in N/A models in the US and Infini turbo models in Japan. It was an inferior (but simpler) setup.

There is a separate computer which controls hydraulic pressure from the pump via a valve. Getting this computer to work in a 1st gen might be tricky without the factory FC ECU as well as I'm sure they are designed to work together.

If you ditch the controller and have the valve running in low-assist mode all the time, I dare say it will be perfect in a light car like the 1st gen RX-7 and would be lighter than the factory steering anyway.

In terms of electric power steering, yes you can try to fix a Corsa power steering column. These are easy to find in the UK and even have aftermarket controllers for them. But having a good look under the dash, there's not a lot of room for it - the column has a big motor sitting on it.

The other option is to use an electric pump to replace the mechanical one. Many cars used these so-called EHPS (electric hydraulic power steering systems), some notable examples include the Mazda 3, Toyota MR2 and Holden/Vauxhall/Opel Astra. I got one of the latter ones. There are 3 generations of pumps. The first one has an inbuilt reservoir and is self-regulating. The greater the pressure requirements, the more it ramps up. No speed control required.

The pump from the Spyder has an inbuilt reservoir and has a speed controller. To get the speed controller working, you actually need to feed it a speed signal that matches the original car and the controller can understand. Otherwise it might be possible to get an aftermarket ECU to control duty vs road speed via a PWM controlled solid-state relay. That said, I know an owner of an FC with one of these and he runs the pump full-time and it's not a problem at all.

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KYPREO
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Re: Project London Bridge

Post by KYPREO » Mon Jul 16, 2018 2:19 am

PS yeas ago Ian did a great writeup on how the 1st gen power steer works which is pretty similar to the FCs in application: http://www.ausrotary.com/viewtopic.php?t=211744

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ian65
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Re: Project London Bridge

Post by ian65 » Mon Jul 16, 2018 1:02 pm

KYPREO wrote:
Mon Jul 16, 2018 2:19 am
PS yeas ago Ian did a great writeup on how the 1st gen power steer works which is pretty similar to the FCs in application: http://www.ausrotary.com/viewtopic.php?t=211744
I’d forgotten I’d written that :shock: that was a good few years ago
1986 Series 3 13B Turbo II
http://rx7fb.com/viewtopic.php?f=2&t=2400
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

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