Jack Sprat

I am a NOOB to Miatas, so much so that I have never even driven a Miata - not even the one I just bought. Since it had a blown engine and I have a rebuilt 5.0, I figured that I would make it a good strip & track car.

I have done a few conversions (Bronco II to V8 4x4, SVX to 5 spd, etc) so I have some skills but I honestly don't know what all I'm getting in to. I am planning on doing cardboard templates to Autocad to CNC Plasma cutter and think I can get a lot of it done this way.

Over the last few days, I have seen a lot of pictures of others' builds. The detailed images have given me a really good idea of what I need to do. I wouldn't even dream of taking this on if I hadn't found this forum. You guys rock!

So far, the build threads I have seen the builder used a kit. Has anyone done it by fabbing all their own parts (mounts, drive axles, etc)?

Thanks
JS

rick

Welcome to the site Jack Sprat



Enjoy the stay!

charchri4

Hey Jack welcome to the nut house! Yes there are guys that have done all their own fab work around here and if I was to do it again so would I. About the only thing you can't do on your own is broach the axle shafts and balance the drive shaft. I had my driveshaft made all new front to back for $150 and Martin can sell you just the axle shafts and spacers easy enough. Everything else is just meatball surgery that is no big deal to do.

Building the sub frame is not hard but you do need to be careful to keep the suspension points right. So you have to weld up a frame to hold the K member mounting and suspension points in place then cut and paste it to fit the engine. The nice thing about doing it yourself is you can set the engine where you want it and I would have shoved mine back farther and to the pass side more. There are some guys that make full frames themselves but for a Ford you can just mod the existing K member.

The trans brace is easy and you can see mine HERE.

For the diff I would have done mine different and not used the stock ford rear mount. It's too soft and too expensive to replace with poly. I would have basically built 2 front mounts using 2 sets of poly bushings but left them both about 1/2 shorter so you can tuck it up high and adjust your pinion angle right. To see how I did mine click HERE. I have some photos of how I fixed it and how I would have done it now that I know what I know that will go in a post pretty soon.

There is a guy that is doing an all DIY build but he is posting on the wrong forum. He is a little ahead of where you are at now and building his frame so it would be a good thread to follow. Go HERE

Can't wait to see what you are doing!!!

MRM331

Hi Jack,
There are a lot of people who have done Ford conversion making their own parts or using only components of the Monster Miata kit. Personally, I'd recommend looking into the kit parts for some of the less modifiable areas such as the rear. There really is not much that can be changed over the kit design and Monster Miata will sell you the whole system for $1000 last I checked. For the front end moving the engine to the passenger side a bit eliminates a lot of steering shaft header issues. The kit uses a custom set of headers that exit through the wheel wells. It works and the parts are good but if I had the ability and time i think I'd like to try using off the shelf headers that could be routed more traditionally and not reduce ground clearance.

That said, the kit is still a bargain at $4000 for those who do not want to make their own parts up and want everything delivered in one box (me).

Welcome and good luck with your project!

-Jason

WolfGT

Just a note, that $1000 for the rear end kit does not include the diff. But they do offer one, but it's an additional $2000 totally built.

MRM331

I was not sure of that. I figured as much though.

7.5 differentials with factory limited slips can be found in yards for under $50. I paid $35 for the one in my car currently.

-Jason

Jack Sprat

It's good to be part of a group that makes you feel welcome.

Charcri4
I checked out your build blog and you have inspired me to do something different from the norm. I like the extra chassis bracing and using the pipe for the exhaust tunnels. Great idea.
You mentioned poly bushing to support the front of the diff to adjust pinion angle. Will this prevent wheel hop or vibrations in the drive train?

MRM331
I emailed Monster Miata about buying the headers and other components but they never emailed me back. I expect I'll have to buy rear axles but I lengthended my SVX (5spd conversion) driveshaft by splicing and sleeving dom tubing then rewelding. Amazingly, no vibrations.
I'll try MM again.

Thanks Again!

cvx_20

Several have. Miata.net engine conversions forum has been around a little longer and has some good stuff in the archives. I built pretty much everything for my conversion except the exhaust, then I went back and redid what the incompetent exhaust guy did. Axles are tough to fabricate reliably, but Factory Five Roadsters has just the right axles for an 8.8 installation into a Miata.

I originally did a Cardomain site

http://www.cardomain.com/ride/2308228

that has some info on it, but recently I started a feeble attempt at a blog/picture site to document some of what I've done. Here's a start on that:

MiataV8 Conversion: Rear subframe

More to come.

Mike

charchri4

Wow Mike I wish I would have seen that diff mount post a year ago! That is epic and going in my blog as a book mark for sure. That is a much better set up than Martins IMO. Well done! Yet another time I have said OK on my next build I'm going to...

Jack the poly bushings do help with wheel hop because they flex less than the factory Ford rubber ones do. For drive line vibration see this video and you will see why being able to adjust the diff is super important.

Jack Sprat

Thanks Mike,

Your write up and pictures are very helpful, especially all the measurements. I was very concerned that I would not have the pinion angle correct but your measurements will help me get it right.

Jack Sprat

Jim,

That video is awesome I didn't know this. I heard that keeping the phase the same was important so I marked the driveshaft on the SVX before lengthening it but I didn't know why.

In my web travels, I haven't seen it yet but do people made their own drive shafts?

charchri4

Yep a friend of mine made his for his rat rod but that was only to prove a point to build the entire car for next to nothing.

I had my drive shaft done at a drive shaft shop in Sioux Falls that does really good work. My point of mentioning SF is if a city that size has a good shop any larger city will too. Anyway I set the trans and diff in the car to mark my Camaro drive shaft where the Tbird yoke should be. I figured they would just cut the Camaro shaft and put the tbird yoke on it but they did not like the looks of that. So they made a new tube, welded the ends on, put new U joints in, balanced and painted it while I waited for 150 bucks. I'm as cheap as anyone and will DIY anything but for that kind of money to know it's right I wouldn't try it on my own.

Jack Sprat

That is an awesome deal!

The driveSHAFT (emphasis on shaft) shop that I took my SVX driveshaft to gave me an estimate of between $900 and $1200 to add 1" to it. They also told me that they couldn't guarantee it since it was a two piece shaft. I was floored so I did it myself and it turned out great.

I have since found a better place that is reasonable, I'll probably take it to them. I just don't know if they do AL driveshafts like the one I plan to use. It is from an Aerostar and will need to be shortened A LOT.

Jack Sprat

Are most people running 7.5 with good success? I want to drag race the car and would like to add a 75 shot of nitrous with drag radials. I would think that excessive power on a light car would just spin the tires and not break stuff.

Thanks
Jack

charchri4

7.5s are suppose to be good to 400 hp. Martin says he has guys running in the 10s with them. For what it's worth I went with the 8.8 because I destroyed 3 rear ends in one summer with my donor Camaro and was not going to take any chances.

I'm sure an aluminum drive shaft would be much more expensive. I went with steel because it's cheap and I doubt it weighs more than a pound or 2 more.

Jack Sprat

Thanks Jim.

I'm not going over 400hp. I'm going to have to dig up a GT driveshaft.