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MrJoshua
MrJoshua PowerDork
2/19/13 7:52 p.m.
Curmudgeon wrote: In reply to MKI_GT6: Checked out your build, that's pretty cool! That motor was on the short list for this project. I would recommend that you not try to adapt the Miata subframe in the rear, it's way big in every dimension compared to the GT6 stuff and would involve massive body surgery. That's why I am building another homebrew IRS like I put under the Abomination, my rotary Spitfire.

It is not nearly as bad as you would think. Miata wheel/tires are pretty tucked into the body. I don't have a great picture of of the Miata rear suspension and subframe from my old spit project(didn't complete and cut it up) but I can post the best I have:

The tires are 195/45/14 on stock Daisies. At zero camber they only stuck out an inch or so on each side. Well within the range of an aggressive roll or tack on lip flare.

Here is the subframe in the spit frame. It could easily have been done with way smaller tubing and would end up looking more like what mudge did.

If I were to try again I would probably fab up A-arms and use a Ford diff.

MKI_GT6
MKI_GT6 New Reader
2/19/13 9:06 p.m.

Curmudgeon

I like the idea. I look forward to seeing how you do it this go around.

Curmudgeon
Curmudgeon MegaDork
2/20/13 7:28 a.m.

One of the criteria for this project is that 15x7's with 205/50-15's fit under the stock fenders, we don't want to flare the fenders. That has a lot to do with the suspension layout and design. Also, the fuel tank position on a GT6 does not lend itself to easy repositioning, unlike a Spitfire.

Ian F
Ian F PowerDork
2/20/13 7:48 a.m.

In reply to Curmudgeon:

BTW - I'm still interested in the front brakes & spindles if you still have them.

Curmudgeon
Curmudgeon MegaDork
2/20/13 7:58 a.m.

In reply to Ian F:

I do, sorry that I forgot to get back to you. Plase PM me your Email addy and I'll get you some pics.

Giant Purple Snorklewacker
Giant Purple Snorklewacker MegaDork
2/20/13 9:12 a.m.

In reply to MrJoshua:

Did you mill or waterjet the aluminum rocker arms for the push/pull rods to the dampers or were those available somewhere for purchase?

I am building an IRS for my race car and need to do something similar except... no milling machine so I have to pay someone either way.

Ian F
Ian F PowerDork
2/20/13 9:23 a.m.

In reply to Curmudgeon:

Message sent

Curmudgeon
Curmudgeon MegaDork
2/20/13 11:08 a.m.

In reply to Giant Purple Snorklewacker:

Those are stock Yamaha monoshock linkage pieces, you can get them on eBay for peanuts. Just one of many:

http://www.ebay.com/itm/A-04-05-06-2005-YAMAHA-YZF-R1-1000-RAVEN-LOWERING-LINK-DOGBONES-REAR-SHOCK-LINK-/121043345214?pt=Motorcycles_Parts_Accessories&hash=item1c2ebedf3e&vxp=mtr

Not mine, no affiliation, take only with water, may cause dizziness, etc

Curmudgeon
Curmudgeon MegaDork
2/20/13 11:08 a.m.

In reply to Ian F:

Will shoot you some pics/specs tonight or tomorrow.

gkabbt
gkabbt
2/27/13 2:09 p.m.
Curmudgeon wrote: As I work on this I keep thinking I might see if I can come up with a sorta bolt on kit for doing this. I would think there would be a market for it, seeing how many Spitfires and GT6's are out there. But that's a ways in the future.

I am slowly (very slowly) in the process of doing an engine, trans and rear end swap on my 72 GT6. I am also wanting to do the Miata suspension like you are doing here and what you did on the Abomination. If you do make a bolt on kit for the front and rear suspension bits in the relatively near future, I would be extremely interested.

Winston
Winston Reader
2/27/13 3:01 p.m.

Curmudgeon, I think that my message/email to you got lost or sent to a Spam folder somewhere in the ether... so here's a rehash of my question:

In one of my earlier Spitfire-Miata threads, you said that a TR6 upper ball joint would fit a Miata spindle. Well, I have them both now and that's certainly not true... did you mean after reaming out the hole in the spindle? The taper is the same (7 degrees, as is pretty standard), so I could get a 7 degree taper reamer and get the hole where I need it to be. I just want to be sure that I didn't get sent the wrong ball joint (or 4) by Victoria British before I go hacking up the Miata spindles I have. Thanks in advance.

Any progress on the GT6 project?

Curmudgeon
Curmudgeon MegaDork
3/1/13 7:37 a.m.

Winston, there must be a spam filter or something. Sorry about that. I had to use a tapered reamer to get the Spit/GT6 upper ball joint to fit the Miata knuckle. One of my co workers loaned me his, it's made by Hanson.

http://www.shoplet.com/Irwin-hanson-Reamers-11214/SEPTLS58511214/spdv It says hand use only, you will die of old age trying to do that. Chuck it in a 1/2" drill, then spray it with cutting oil or similar as you spin it. Warning: it cuts QUICK. Do a small amount at a time and keep checking.

I have the rear lower control arms 'roughed in' and will be posting pics of that soon. Would have done it sooner, but the Jensen needed a transmission tailshaft bushing replacement (drawn out process, that; looked so simple when I started ) and some house stuff took center stage.

Winston
Winston Reader
3/1/13 8:22 a.m.

I understand... life and other projects often get in the way of my best laid plans, too.

Thanks for the clarification on the reamer. I wonder if this would last long enough to do both spindles:

http://www.sears.com/skill-tech-t-bevel-tapered-reamer/p-00940884000P?prdNo=2&blockNo=2&blockType=G2

Hard to beat it for $7. Of course, it can't just be thrown in a chuck -- which probably makes it not worth the cost savings.

Curmudgeon
Curmudgeon MegaDork
3/1/13 3:18 p.m.

It might. For $7 if it's the right diameter I'd say buy it, put on some safety glasses, whack the handle off with a whizz wheel, chuck it in a drill and keep your fingers crossed.

Winston
Winston Reader
3/1/13 3:29 p.m.

In reply to Curmudgeon:

Eh, I already ponied up the $22+shipping for the one you linked to. When I actually sit down to perform this task I want to be able to complete it with minimal fuss. The right tool for the job works wonders in lowering my frustration level and increasing my productivity, I've found. Thanks for the link.

Curmudgeon
Curmudgeon MegaDork
3/9/13 6:03 p.m.

Okay, to the rear we go. Rear lower control arm rough assemblies: Tubing cut out to allow bushing etc installation: Mostly completed arm test fit: The washers are for shimming the knuckles front/back for wheelbase adjustment if needed.

MKI_GT6
MKI_GT6 New Reader
3/9/13 6:38 p.m.

Looks good. What bushings did you use? What size tubing?

Curmudgeon
Curmudgeon MegaDork
3/9/13 7:15 p.m.

The outer bushings are Energy Suspension stuff, their P/N is 9.9108G. The inners are Spit/GT6 urethanes from Victoria British. The inner pivot tube is 1.125 x .156 wall, the outer pivot tube is 1.625 x .187 wall, the rest of it is 1.125 x .120 wall. The thicker wall allows me to really crank the heat up for a good solid weld. These are 7.250 center to center, keep in mind that's to work with the wheels and tires we picked to keep the rear tires inside the fenders.

Winston
Winston HalfDork
3/11/13 8:35 a.m.

They look good! I'm also using the Victoria British Spit/GT6 urethane bushings, but on the front end.

MKI_GT6
MKI_GT6 New Reader
4/16/13 7:05 p.m.

Any up dates Curmudgeon?

Curmudgeon
Curmudgeon MegaDork
7/21/13 8:50 a.m.

At long last an update; life and tweaked race cars got in the way for a while. Got cracking on the rear suspension, got the rear lower control arm mounts in. This involves placing the holes properly, drilling the frame, then welding in tubes for the CA mount studs to slide into. In this pic, you can see the front CA mount hole. Caution: that's REAL close to an internal frame brace Triumph added at the factory, don't go too far forward! The other hole is inside the vertical rail which goes to the upper rear shock mount.

When placing these holes it's easiest to level the frame front/rear/side to side, verify the floor is level, then measure from the floor up. I used the body mount bolt points ahead of the rear axle as a reference point to measure back from, I used large flat washers to clamp a piece of 1/8" steel to the frame so I'd have a solid point to measure from.

The tubing added will be the upper C/A mount point. Yeah, I know it needs cross bracing, more on that in a minute. Speaking of control arms...

The eccentric cam rear camber adjusters are at the outer end of the upper control arm, I got the kits from A&A. I can get 4 degrees of negative camber if needed! The toe is set by shimming the lower control arm mounts as needed. I added enough space on the upper C/A mount to be able to shim it front/rear like the bottom, to fine tune the wheelbase. I've added a lot more adjustability to this setup than the Abomination had.

Next will be the rear shock mounts. Have to get the shocks first, though!

There's another change in the wind too. I mentioned it in another thread, the original powerplant was going to be a Dodge 2.2 turbo. My bud has ADHD worse than me and has decided he wants something newer under the snoot, it looks like we will be going 2.0T Ecotec. The original plan was also to use a Miata diff, now it's looking like Sky/Solstice. I have not added the cross brace to the upper C/A mounts, don't want to do that until the diff is sourced and installed.

Stay tuned!

Curmudgeon
Curmudgeon MegaDork
7/28/13 6:56 a.m.

The shock fairy paid a visit.

All_talk
All_talk
8/4/13 9:14 p.m.

Hello Curmudgeon,

Great looking project, I have thought of doing something similar with the ā€™70 spit I have I the shed.

But currently I am working on another project and have a question about your shortened steering rack. Based on your experience how short do you think you could get a spit rack? How much did you cut out of yours and how much do you think you could cut out? Iā€™m hoping to get down to something between 14ā€ and 16ā€ center to center on the inner tie rod ends.

Thanks,

Curmudgeon
Curmudgeon MegaDork
8/11/13 8:32 p.m.

14 to 16" center to center is easily doable, just be careful you don't have rack teeth running on the right side bushing. IIRC the piece I cut out was 4.25 inches, I'll have to look at my notes to be sure. Out of immense curiosity: What in the world are you building that is THAT narrow?

I did build the lower rear control arm shock mounts today 8/11, pics will be posted soon.

corytate
corytate SuperDork
8/11/13 10:41 p.m.

sooo.... since I'm still not working during the week... can I just come down and work for you? lol

I love this. gt6's are lovely cars, glad you're going to fix all the wonky suspension engineering those men in sheds did to it lol

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