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Group C JPS tribute build.

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Mamod17
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Group C JPS tribute build.

Post by Mamod17 » Sat Feb 23, 2019 3:34 am

So an odd 40 years after laying eyes on the JPS 635csi I'm finally building my own tribute. I've been following these cars around like a groupie for a few years now, and I'm off to Philip Island Historics in a couple of weeks to see the racing JPS 6's in full flight. I currency own a series 2, 5 speed Australian delivered 635csi - previous owner Addam Smith (aka OziBimmer) of Bavarian Classics and Restorations in Brisbane. Addam's building a limited edition Group C body kit, and I was lucky enough to be invited to own a set. Then we decided to go the whole way and build a tribute form the ground up. So all things going well, this time next year I will be seated in my dream car! :D

As I'm discovering, the hardest part of all this is deciding what spec to build to, so I'd be interested in your feedback on what I'm thinking. I don't have endlessly deep pockets, so this will be a smart, neat build. If I had the money I'd buy the real thing! So we're going try to make the most of what we have in stock and buy some hero pieces.

Here's the brief.

Must be able to be road registered. Here in NSW we have historic plates allow you to drive 60 days a year plus club events.

Must be able to track in regularity events (I'm not a fast driver, and have no aspirations nor budget to race, however I would like to stretch my legs on the track now and then).

I will be driving it to race events, cars and coffees and entering it in show and shines.

On the road I would like it to have good torque, not necessarily top speed.

And sound tough.


So answering the brief rules out a full caged replica race car.

I could get away with a half cage for the road, but would turn it into a two seater. Not too interested in that.

Question is to go full race stickers, which is awesomely cool and indoor face - driving on the road certainly would be an event.

or

What if, in 1986, BMW chose to release a limited edition of Group C spec road cars? what would they spec out? (Aussie readers think Walkinshaw Commodore or road going A9X Torana )

In Australia they did release an e21 JPS special, built by the race team for the road, with these specs:

So here's the spec: plan this week (it constantly changes).

Here are the definite items.

Starting with a 1978 series one shell (it's how we can afford to get started).

Limited edition Group C body kit.

Paint Schwatrz black

Simmons wheels 16x9 front 16 x 10 rear

Lowered suspension - bilstein shocks

New bushes all round.

Custom headers.

air con delete

Audio delete.


Inspecting with view to purchase

Individual throttle Bodies plus haltech engine management system


Still to be decided:

Motor currently M90 motor B35 head.

Gearbox - early 4-speed or later 5 speed. Overdrive 5 speeds are pretty useless. I’d rather have a 4 speed if I cannot get a dogleg.

Brakes - stick with 4 pot e12 brakes?

E28 rear subframe with LSD


Nice to have -

Garagistic - shifter.

https://store.garagistic.com/Garagistic ... EsbPPWDckk

Bigger Brakes - 135i?

Extra gauges.



Front and rear strut braces - 
battery relocate to rear.

https://www.racetep.com/manufacturer/sh ... _i_7i0XGBs


Be keen to know what you would prioritise? How would you spec it out?

 Thanks for reading and look forward to sharing the progress.


Here’s some photos to get started.
Donor car.jpg
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1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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Ozibimmer
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Re: Group C JPS tribute build.

Post by Ozibimmer » Sat Feb 23, 2019 4:07 am

Going to be fun Denis.
We are stripping the car to a bare shell then taking any rust out that we find. =D>
_________________________
77 E3 3.0SI
77 E24 633CSi
78 E23 728i
79 E24 633CSi
80 E24 635CSi
82 E24 635csi Race Car Build (Schnitzer Replica) viewtopic.php?t=21792
82 E28 JPS (1 of 2 Ever Built)
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jps635
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Re: Group C JPS tribute build.

Post by jps635 » Sat Feb 23, 2019 8:42 am

Hi Denis

I wish you all the best in your project. I built my own JPS tribute - see photos below.

I guess what specs you build to is a personal thing and depends on how true to the real deal you want to be and how deep your pockets are.

A couple of comments:
- If you're building a Group C tribute you should probably be considering a 24V engine ??
- I wouldn't dismiss the overdrive box for a road car, especially with increased torque and a lower ratio diff.
- Before deciding on a stand alone ecu, consider who is going to do the tuning. The power runs are easy but is a different matter tuning for
drivability, especially getting smooth at low throttle openings. So lining up someone with the knowledge and patience to get this bit right is really important
- My engine also built for torque - viewtopic.php?f=2&t=29340&p=210630&hilit=m3

Can provide other details if required.
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'85 635csi JPS (RA2-66)

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jps635
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Re: Group C JPS tribute build.

Post by jps635 » Sat Feb 23, 2019 8:43 am

Couple more pics
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'85 635csi JPS (RA2-66)

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Sat Feb 23, 2019 12:05 pm

Thanks for the advice JPS635, I’ve admired your car for a while now!

I’ll take a good look at your engine specs.

What’s that shifter you’re running?
1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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jps635
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Re: Group C JPS tribute build.

Post by jps635 » Mon Feb 25, 2019 9:22 am

Is an Autosolutions short shift kit with a custom extension sleeve and custom delrin knob.

I felt the shift lever as supplied was too short and required too much effort - hence the mods. Being longer also falls better to the hand.

On a different note, I've always fancied a set of Simmons wheels. Which style are you thinking?
'85 635csi JPS (RA2-66)

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Fri Mar 01, 2019 7:21 am

Haven't really drilled down to that yet, basically wha looks similar to JPS. Will start doing some research.
1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Fri Jul 12, 2019 10:06 am

Update: It's been a while but we've been concentrating on getting the body kit right. Working on 3D Modelling against photos. Hard work but will be worth the effort. Ozibimmer also has some images on his post.

Heres some amazing 3D scans of a 6 for the 3D modeller to build from: Scans by https://www.3dsl.com.au
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1986 635csi 5speed Alpine White M-Tech Aust Del
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VintageRacer
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Re: Group C JPS tribute build.

Post by VintageRacer » Tue Aug 13, 2019 10:26 pm

I have the perfect 4.0L S38 sitting in my shop for this project. PM me for details but it would be epic, 425shp all motor!

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Thu Aug 15, 2019 9:38 am

Sounds mean! I'm sure I can't afford it but hit me with some details! :D
1986 635csi 5speed Alpine White M-Tech Aust Del
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CSGuy
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Re: Group C JPS tribute build.

Post by CSGuy » Fri Aug 30, 2019 4:51 pm

jps635 wrote:
Mon Feb 25, 2019 9:22 am
Is an Autosolutions short shift kit with a custom extension sleeve and custom delrin knob.

I felt the shift lever as supplied was too short and required too much effort - hence the mods. Being longer also falls better to the hand.
I'm looking at the Autosolutions complete for my car.

How has it worked for you?

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Wed Sep 04, 2019 9:46 am

Exciting times - Software sorted for CNC machining of polystyrene prototype for hand finishing and setting up moulds next week.
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TBM
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Re: Group C JPS tribute build.

Post by TBM » Thu Sep 05, 2019 6:13 pm

Glad to see some progress..
'84 M635csi
'86 Lotus esprit Turbo (sold)

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Fri Sep 06, 2019 6:54 am

Earlier CAD design



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1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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1988 635csi Auto Zinnerbot
1988 320i Convertible

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Fri Sep 06, 2019 6:55 am

Rear guard cut away - no turning back!
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turning back!
1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Sun Sep 15, 2019 8:11 am

Kit machined in for. Off to hand fishing and fitting before moulds.
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1986 635csi 5speed Alpine White M-Tech Aust Del
2001 325ci Auto Orient Blue

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1988 635csi Auto Zinnerbot
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Atomic
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Re: Group C JPS tribute build.

Post by Atomic » Fri Sep 20, 2019 3:59 am

That 3D scan is neat, good luck with the build! I look forward to seeing the progress!
1987 M6

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Sun Sep 22, 2019 10:30 am

A MORE DETAILED SUMMARY OF THE ABOVE PICS...

So it’s been a journey since I originally posted this. Like the proverbial calmly swimming duck, the paddling below has been furious.

My obvious obsession with the JPS 6s led me to working with Addam Smith on building these kits and along the way learning about CAD, 3D modelling, 3D scanning & CNC machining.

As you can see from Addam’s post, a lot of effort has gone into getting the details of the kits right. We sourced hundreds of images from the inter webs including including early group 2 variations of racing sharks.

I also flew down to Philip Island where there was an unmissable opportunity to snap the 3 racing JPS 6s in Australia together.
Dean How was very generous in letting me take some reference snaps of his original kit.

Having said that, photographs just can’t capture the precise measurements because of lens distortion and perspective changes.
So there’s a lot of finessing required to get the right overall feel of the car.

We started with 2 x 3D scans of an original 6er to ensure the base we were working to was correct. 


Then it took 60 hours over 3 months working with an Automotive CAD designer, (in Solidworks and CREO, Think3 & Fusion360) back and forth with creative interpretations of photographic reference, turning them into technical diagrams.


Addam and I constantly discussed the design, shapes, versions and fixing points, reviewing each iteration of the design.


Once we signed off the CAD, we CNC machined styrofoam to the final shape.


Now it’s off for moulds. Still plenty of work to do but looking forward to getting the kit on the car and refining from there.
Last edited by Mamod17 on Mon Sep 23, 2019 4:39 am, edited 1 time in total.
1986 635csi 5speed Alpine White M-Tech Aust Del
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hornhospital
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Re: Group C JPS tribute build.

Post by hornhospital » Sun Sep 22, 2019 9:11 pm

For some unknown reason, your pictures didn't attach. :-k
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'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"; '95 318is "Bebe"

Mamod17
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Re: Group C JPS tribute build.

Post by Mamod17 » Fri Oct 04, 2019 8:00 am

Machined Polystyrene is a delicate substance, so its being covered with resin and sanded back to protect and test fit.
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1986 635csi 5speed Alpine White M-Tech Aust Del
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Shipper 01
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Re: Group C JPS tribute build.

Post by Shipper 01 » Tue Oct 15, 2019 1:16 am

Incredible work Addam.

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