Datsun 280ZX IMSA GTU replica race car build...

Restores, Revamps and Repairs

Moderators: Andy, BRONZEE, Z Club

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Wed Jan 02, 2019 4:39 pm

Ok, sketched up a diff mount.
Will use Nolathane bush around the stock mount, with a steel machined washer top and bottom. (40mm OD x 8mm thick for the top as I need a spacer on the top, and 4mm thick for the bottom).

I will make the mount out of aluminium and if that fails, steel...
One thing I did find, is the mount is a little offset to one side. I think this because of the finned cover, the studs are not central.
I loosened everything off and gave the rear end a good wobble, and did not move...
Image

Drawing of new mount.
Image
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
Baker93
Z Club Member
Posts: 313
Joined: Tue Apr 01, 2008 9:39 pm
Location: Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Baker93 » Sat Jan 05, 2019 4:07 pm

I just solid mount mine front and rear.
The front has big cap screws going up vertically through the eyes / bolt holes on the front of diff into threaded bobins welded into the cage. The rear has a large piece of 90deg angle with two vertical slots that the studs on the diff slide up into. On my car this is located by two tubes coming down on angle from each strut tower. You could just as easily utilise the existing holes in the rear cross member.

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Sat Jan 05, 2019 6:06 pm

Thanks Anthony, An Angle bracket at the back would definitely make it easier.
I got a bit paranoid after reading some horror stories on the www of broken diff casings.
Ps. What's your comments on Daniel's (DJZ) post about the location of mounting the front rotors?

Today, I put the pedal box in and out about 10 times... :(
It now all sits nicely, and the new Tilton throttle pedal is a perfect fit. I had to cut away the original mount, and give it a quick paint.
I will get some new bolts next week and remove it one more time to set up the mechanical brake bias to my best guess position (as per Tilton's set up video).
The floor plates are aluminium chequer plate that have been hard anodised grey.
Image
Image

Picked these up today from a visit to CMR, my box of missing hoses & odds & ends, well most of them.
Just need to clean them up and fit them.
Image
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Sun Jan 06, 2019 3:41 pm

Ordered a new rear hatch inner seal and the front wind shield upper & lower moulding strips from Z Car Source in the USA today.
https://zcarsource.com/weatherstrip-sea ... trip-280zx

I have the original rear seal, its not great but definitely not to bad as well. Will keep it as a spare.
I did not have any front moulding strips.
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
Baker93
Z Club Member
Posts: 313
Joined: Tue Apr 01, 2008 9:39 pm
Location: Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Baker93 » Wed Jan 09, 2019 6:48 am

Hi Grant.

I guess i should clarify the diff mount method.
Mine is solid mounted front and rear and into the cage !
If i break a rear diff housing i am in serious trouble !
Im no 280zx expert but if im seeing your photos correctly the front of the diff is mounted to the cross member which in turn is mounted on flexible bushes ? This cross member is going to move as it has suspension loadings going into it.
With this in mind i would not be solid mounting the rear of your diff.
In short solid or flexible in this case not both.

As an aside my engine is solidly mounted, but the gearbox has a flexible rear mount. Have a think about that one.

Regarding the front brakes.
I have used both methods. but for a race car and mine the hat and rotor assembly just slides over the studs. Simple easy no stress. I would not however run a floating spacer in there. Just a personal thing. Too much scope for a stuff up, when changing wheels etc.

Finally. A hydraulic proportioning valve in the rear line should not be needed with the pedal box. You may also run into brake bleeding issues with the hydraulic handbrake depending on pipe routing. Andy Mygind knows about this. I believe he may have fitted a bleed nipple in the hydraulic hand brake.
Andy jump in here anytime.

Anthony

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Wed Jan 09, 2019 4:15 pm

Thanks Anthony,
I'll go flexible at the moment on the rear since I'm half way there, and see how it goes.

As for the brakes, decided to stay with the factory mount, as the hub has a machined face to help centre it.
Though having it slip over the studs does kill two birds with one stone... Reg likes to stay with the original mount...

Thanks for the advice much appreciated.

Another big help I will need is what to do with the ignition & electrical system?

Can you suggest or let me know what I should use.
I see you have a MSD 6AL, and ? coils... also what to use for a crank angle sensor and cam timing?

Cheers again Grant.
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
Baker93
Z Club Member
Posts: 313
Joined: Tue Apr 01, 2008 9:39 pm
Location: Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Baker93 » Fri Jan 11, 2019 7:00 am

Hi Grant.

Ok. I used to run a locked out distributor ( no vacuum no mechanical ) an MSD 6AL with rev limiter and a single MSD coil. Brutal, effective, went bang, couldnt ask for more at the time.
This was a long time ago.

Then i changed to an electromotive HPV ( good name ! ) crank fired unit complete with 3 double post coils. This enabled a degree of an advance curve to be employed as well as advance back down at high RPM. This unit also has 2 stage rev limiting i think. This unit was a big step forward from the MSD unit in terms of reliability, ( although there were still issues) having an advance curve and a stable spark at high RPM without scatter. At this time time with a standard distributor and high sustained RPM distributor wear was fearsome and hence spark scatter was a constant issue.
The Electromotive unit is very period correct. If you care about these things being a replica and all.
Both these unit were used with fuel carbs.

Then finally when the car was fuel injected i changed again. I retained the crank trigger, added a cam sensor, run a Link Extreme ECU, Link igniter, and remote mounted electromotive 3 x 2 post coil pack. This obviously is wasted spark like the original Electromotive Unit. Obviously ignition curve timing and stability are not an issue. This system works fine. If i was going to change anything or do anything different i would use a Motec ECU. I run a Motec dash and have since before i purchased the Link ECU. It probably way to technical to get into here. The Link is a fine product, it just lacked a little in the ability to customize things and we had a few issues getting it to work with the Motec Dash.

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Fri Jan 11, 2019 7:15 am

Ok thanks,
I have a Motec M800 ECU, and will be changing to a Motec Dash.

I found this shop in the US that sells Electromotive stuff, example their 3x2 coil pack.
https://electromotive.com/our-products/ ... fire-unit/

this place has the best prices... :)
https://www.racetep.com/manufacturer/el ... ystem.html

Could you let me know what specifically I should look at buying in respect of the crank and cam angle sensor.
cheers grant
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
djz
Posts: 822
Joined: Thu May 04, 2006 7:10 pm
Location: Christchurch

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by djz » Fri Jan 11, 2019 7:31 pm

They are just V6 Commodore coils. You can get some nice coil on plug setups for L series now.

What are you running for a crank pulley?
Nissan 280ZX 2 seater RB26 powered.

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Fri Jan 11, 2019 8:52 pm

for the crank pulley I have one of the last Nissan Motorsports USA dampers, same as used by the works racing cars of the period.
I ordered it off Nissan Motorsports in CA before they moved.
Part number as per the "how to modify your L series OHC engine..."...
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
djz
Posts: 822
Joined: Thu May 04, 2006 7:10 pm
Location: Christchurch

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by djz » Sat Jan 12, 2019 12:34 pm

Hoke Performance in the States make a nice trigger kit but you'd have to drill the damper to mount the trigger wheel, but I guess you'll have to do that either way unless you run it off the flywheel.

There's not much to them if you have a good fabricator though and you can get generic trigger wheels and the sensors from heaps of places.

http://hokeperformance.squarespace.com/ ... sensor-kit
Nissan 280ZX 2 seater RB26 powered.

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Sat Jan 12, 2019 4:45 pm

Thanks for that link! :)

Last few days been a bit slow, but done a lot of cleaning, and spray bombing small repairs.

Got the rear hatch lock from a Z club forum member! thanks.
Got the lever and cable mounted. This will make my life much easier when fitting the rear hatch, as pins would have had to go through the rear wing...
Image

Image

I got a new rubber section from Para Rubber to seal around the oil tank. The last one had a gap...
Image

Slowly putting in some rubber bungs/plugs, some are original Datsun ones others are from Para Rubber.
Image
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

User avatar
Grunzter
Posts: 327
Joined: Mon Mar 13, 2006 4:49 pm
Location: Epsom, Auckland

Re: Datsun 280ZX IMSA GTU replica race car build...

Post by Grunzter » Thu Jan 17, 2019 7:11 pm

Some new springs today from CMI Springs in Mt Wellington, they have stock of some random sizes...

One size replaced the heavy door hinges, as the new doors a light weight fibreglass, and I would have probably bent the doors on the original springs...
Image

The other little springs are for the hatch guides. :)
Image
1981 280ZX #33 IMSA GTU Race Car ...not yet finished...
(Sold) 1984 300ZX Z31 2+2 Turbo
(Sold) 1980 280ZX 2+2

Post Reply