Turbocharged 79' GTV - Track Car Build

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Re: Turbocharged 79' GTV - Track Car Build

Post by GTV27 » Tue Dec 20, 2011 8:56 pm

Good call.

The de dion is a better rear end option - it will allow for easy roll centre ajustments and it will drift like a live axle but without the disadv of lots of unsprung weight to control. Its also simple to convert to adj coilovers.

Your main task will be what to do about the rear brakes - if you are using an R200 diff you prob don't want inboard, so need to adapt the de dion for outboard brake calipers.
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Re: Turbocharged 79' GTV - Track Car Build

Post by 75evo » Wed Dec 21, 2011 12:33 am

The DeDion is good enough for anything but the top end of motor sports. Only the 75 IMSA had the fake DeDion which was actually a very complicated IRS. The evo race cars had modified DeDions.

I suggest that you max out the DeDion's capability first (widened, cambered, adjusted roll center), then when you find that it can no longer cope with your needs go with a super custom setup.

I just had my DeDion cambered, and I will modify the watts linkage (needs shortening) the widen the rear track with spacers.

My 3.0 is now with 11:1 static comp with a 13lb front and lightened rear flywheel. Ready for Laguna Seca to battle with the 3.7 24v :mrgreen: ok not really, the 3.7 will roast me.
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Fri Dec 23, 2011 2:41 pm

couple pics of basic set up of the s13 diff centre in the dedion, easier than i thought to do this as the driveshafts are perfect lenght when stretched, but they need and adapter which i machine to 10mm allowing the driveshafts to sit 'relaxed'. the craddle i need to make is a bit more difficult then remco's because i only 2 mountings in the front of the diff so need to pick up on the front mount and the rear to stop sideways movement.

yesterday i picked up a set of vx ss front calipers and rotors (300 x 30? mm) (lightweights, 2 piston calipers with a huge pad area) to my amazment the calipers bolt on :D and the rotors fit in no worries ( not sure of offset yet, need to test with hub), any ozzies heard about these in racing situations? do they flex much ect..?

im thinking of using these on the front and vs calipers with gtv6 discs on the back. thoughts?
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Re: Turbocharged 79' GTV - Track Car Build

Post by MD » Fri Dec 23, 2011 2:49 pm

I take it you plan to use outboard brakes?
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Fri Dec 23, 2011 3:02 pm

yes
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Fri Jan 06, 2012 10:07 pm

made the adapters to use the s13 diff centre with alfa driveshafts. took longer than expected cause i had to go buy a m8 x 1.00 mm tap :roll: but they worked out spot on. next step is to set up the diff center to clear the dedion, centred and at the right height / so tail shaft is parrallel to ground then start making the craddle up.
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Re: Turbocharged 79' GTV - Track Car Build

Post by Giuliettaevo2 » Sat Jan 07, 2012 10:55 am

:shock: That 's an easy solution... :D

I wish mine was as easy to fit...

The cradle won't be a problem i think.. Just use the bolts around the axle-flanges. :wink:

Looking forward to seeing this finished. :)

For the rear outboard brakes i used rear discs from a 2007 Alfa GT. They're not ventilated but they're almost a direct fit. Only thing that needed doing for them to fit was to grind a bit of the hub-diameter so the disc will slide over it. I used some cheap BMW callippers on them and welded brackets to the triangle. I cooled constantely while welding, trying to keep the temp in the wheelbearings low... :)
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Sun Jan 08, 2012 2:04 am

the other option was to cut a nissan driveshaft and a alfa one, sleeve them, plug weld and weld around the ends of the sleeve then have balanced. a lot of work required so glad it turned out so simple. how do u plan to do urs?

using the bolts on the axle flange would be easier, would require longer bolts but thats is no issue. i will look into it :)

yer im still unsure what i want to use for rear brakes, i want to use a farily low weight caliper, so thinking the holden vs front caliper might do the trick, i can get them for nothing and a decent choice on pads, just unsure what there like in racing situations so will have to do some reaserch! other option is r33 gtr calipers and rotors but a bit more expensive...

hopefully tommrow i will start on the craddle and get some pics up
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Re: Turbocharged 79' GTV - Track Car Build

Post by Giuliettaevo2 » Sun Jan 08, 2012 3:15 am

BradGTV wrote:the other option was to cut a nissan driveshaft and a alfa one, sleeve them, plug weld and weld around the ends of the sleeve then have balanced. a lot of work required so glad it turned out so simple. how do u plan to do urs?

using the bolts on the axle flange would be easier, would require longer bolts but thats is no issue. i will look into it :)

yer im still unsure what i want to use for rear brakes, i want to use a farily low weight caliper, so thinking the holden vs front caliper might do the trick, i can get them for nothing and a decent choice on pads, just unsure what there like in racing situations so will have to do some reaserch! other option is r33 gtr calipers and rotors but a bit more expensive...

hopefully tommrow i will start on the craddle and get some pics up
That's how i need to do it i guess... :( Except the balancing-part i think.

You could also use the bolts from the rear lid(?) I have seen a nice conversio with a diff once, the guy lasercut a thick late and placed that between lid and diff. The thick plate enabled him to weld a nice pair of ears onto it that his diff would hang off. :)

How is the ratio on a S13 200SX diff? plenty of those around here and i'm always looking for new options.. :wink:
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Sun Jan 08, 2012 11:14 pm

unless your shafts fit? then adapter with spacers can be made, otheiwse i can only think of sleeving and joining the two halves...

i plan to join the front mounting points with the rear making it all part and mounted by 3 rubber points. in the pics u can see the start of the craddle, took a while setting it up but is square, level and centred to 1mm. next i will make the rear plate join up the front mounts using rhs as well. i used 25x25 thick wall rhs with the bosses for extra strenght and will add a couple of braces over the driveshaft.

my diff i have now is the r200 with 4.1 (i think) ratio its a open wheeler, but for now i plan to leave it that way or weld it if traction is a problem, untill i can save up for a mechanical 2 way lsd. u can get viscous lsd but they arnt very good. there is a pretty decent choice on factory ratios but i have the 4.1 now so might aswell use it :wink:

did a quick tally up of cost of this project so far, for what i have at the moment - sr20de, 5 speed, r200 diff, 79 gtv, simmons fr16s, extractors, fuel system, fibreglass hatch just to name a few bits and peices im at $750 :mrgreen: 8) cost is low because i wrecked a silvia selling of parts so ended up with the running gear for $250 and i sold the orginal engine, carbies, gearbox and a few other bits and peices for what i payed for the whole car.
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Re: Turbocharged 79' GTV - Track Car Build

Post by Duk » Mon Jan 09, 2012 3:00 pm

Looking awesome Brad!
Gunna make the suggestion that you add 2 more pieces of square steel tube to keep the subframe strong and durable over time. Especially considering its a track car with strong turbo engine torque (that is multiplied in gears lower than 4th by the gearbox).
This will mean the load on the original front TA mounts and the front diff mounts will only be vertical. The way they are at in your pictures, there will be a lot of bending forces at those points when the subframe is trying to resist the torque from the diff.
If/when you have the car on a dyno and it spits out a rear wheel tractive effort (wheel torque), that same amount of torque is being opposed by the subframe and will be trying to push the nose of the diff up towards the floor of the body.
Cross drilling square tube can get some decent weight out of it too, without compromising much of its strength.
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Re: Turbocharged 79' GTV - Track Car Build

Post by MD » Mon Jan 09, 2012 6:07 pm

Agree with Duk in principle.
My solution is much simpler.

Get rid of the original front mounts from the crossmember altogether.
Install a captive nut in its place to take a 10mm bolt.
Fit a tube with rose joints either end to a bar like the watts links bewteen the captive nut on the crossmember and the underside of your diff. housing.
Adjust each leg to have diff. perpendicular to crossmember.

Done and dusted.
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Re: Turbocharged 79' GTV - Track Car Build

Post by BradGTV » Mon Jan 09, 2012 10:52 pm

correct you are duk, good point, is fixed now :mrgreen:
i did think about drilling 20mm holes every 50mm or so but then i would need to get it powdercoated to stop rust, the weight of the frame really isnt much so im going to leave it, thanks for the feedback :wink:

your idea is good MD, maybe in the long run would have been a better solution but after seeing remco and the rear end set up that was on ebay (the pics u sent me) i just used the rubber mounts, i will drill them and put a bolt through to stiffen them up a bit aswell.

today added other braces and welded it up, still need to weld the front mounts and oxy cut the rear plate to shape then add a brace over the driveshaft, it will then be mounted under the car and the rear mount made up to suit where ever it sits.
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Re: Turbocharged 79' GTV - Track Car Build

Post by MD » Mon Jan 09, 2012 11:41 pm

Brad, those two extra braces serve no purpose whatsoever because the diff housing is just being duplicated.Its got all the stiffness it needs.
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Re: Turbocharged 79' GTV - Track Car Build

Post by Giuliettaevo2 » Tue Jan 10, 2012 4:33 am

They protect those 'mounting eyes' on the front off the diff from being ripped off as the torque tries to pull the nose of the diff up. :wink:
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