Couldn't post the photo on the other rotary thread, but this is the engine in the rotary Sprite that Tony was thinking about at LotO last year. There is a rotary down under that blower.

Yeah TD, I'm trying to get'er done before winter. It's getting cold here in the northeast. Dave

Oh man that is cool! That thing must fly. I'd love to hear that run. Thanks for the pic. Wondering If I could get one of the to fit? Dave.

Hey Bill thanks for all the kind words. I'd be happy to on the British V8 site once I'm done. As for the half shaft, I'm have a custom shaft being made to mate the RX tranny to the diff. They say it should hold and my problem will be getting the tires to hold the road. I'm trying to keep the build as clean as I can because this car deserve the attention. Thanks again. Dave.

This weekends efforts. Polishing aluminum.

Wow, I don't like the color but that is just me. I like the idea so much.

Bill is referring to the axle shafts (half shafts), not the drive shaft. The axle shafts (which connect the differential to the wheel) are very weak on the bugeye and I've broken a few with a stock 948 cc motor, so you can imagine what your extra power will do to them. They make hardened axles for racing, but by the time you get into them, you'd be better off doing a rear axle conversion from the RX3/4. Very nice build, by the way. Good luck with it!

Thanks for the clarification on the half shafts Rick, and that is worry some. I'm finding the RX3/4 axles are to wide. I may have to go with the hardened axles you suggested. Is it difficult to do? Thanks for the help, Dave

Dave,

If you're determined to keep your stock rear end, I'd give Winner's Circle a call: Winner's Circle and tell them what you're planning. They sell all the parts to make a competition rear. I still think you'd be better off finding an 83-84 RX7 rear with disc brakes and limited slip and having a local hot rod shop shorten the axle case for you. Take a look at the RX7 diff in the Mite site mentioned above: The Mite

Rick

here's an even lazier link to The Mite that'll take you directly to the rear axle page

I second that, you can get more goodies for the Spridget rear end than you can even the Mazda rear end, hardened race axles, double bearing hubs and several limited slip choices. Fiquire a good SCCA/Vintage car are putting out 140-150 hp, and this stuff is bullit proof in those applications, so it will probably work fin in anyhting putting out 200hp or under.

That's good stuff thanks for the links. What do you think it cost to modify that Mazda rear-end. They stated the upgrade to the existing axle would be $2500. Looks like a lots of work.

Hi Rick I'm not committed to any specific setup yet. I just want to do the most economical thing. That Mazda setup looked labor intensive and I'm wonder if an upgrade is easier on me than the swap out. I'll look around tonight and see if I can get an idea of what a swap out would cost me. Thanks for the help and info as I need all I can use all the help I can get to finish this build right. Dave

Hi Hap, what do you think the most economical thing to do is? Does the $2500 quoted in the Mite web page make sense. I'm just trying to get a feel for what I should do, thanks for the help. Dave.

Or just BUY The Mite!!!

On eBay:

http://tinyurl.com/y8h5zah

Or Item # 190350536792

You can use almost any rear axle you want, depends on the eventual purpose you intend to use the car for. If you're going to drag race it then go strong and heavy, if you just want a good road car then stay with a bit lighter unit. Either way I recommend looking at the gear ratios available for the axle you select. That's one of the down sides for the original Spridget axle, very limited ratios for a street car, basically either 3.9:1 or 3.7:1 and that's it. I don't know what ratios are available for the Mazda rear axle. I used a narrowed Chevrolet 10 bolt from a Chevy Monza in my car. It's strong enough for a small V8 and there are litteraly dozens of ratios available for it as well as inexpensive limited slip differentials. I used the Monza because the lug pattern is the same as the Spridget and my existing wheels would work, but almost any rear axle can be redrilled to match the wheel lug pattern you want. You can expect to spend around a thousand bucks on the rear axle depending on where you can get the work done to narrow the housing and respline the axles or have new axles made. If you're lucky as I was the original axles will be large enough in diameter to just cut down and respline, if not you'll have to have custom axles machined. Check with the dirt track racers and hot rodders in your area, they'll know of any machine shops that do that sort of work or you can go to such nationall known shops such as Currie Enterprises.

3.7:1 3.9:1 4.22:1 4.55:1 4.875:1 5.12:1

Donn, which of those ratios do you think would work best with a modern rotary conversion and 5 speed overdrive? I found that my V6 conversion would be best with about a 3.28:1 ratio for both best low gear performance and good economy cruising at about 2500rpm at 75 mph. With a 3.7 you'll still be winding it a lot tighter than necessary and have almost a useless first gear. Use a gear ratio calculator to figure out what ratios would work best for your applicaton and then chose the rear axle that fits your needs. Here's one that works very easily. http://www.f-body.org/gears/

LOL I think the $1500 swap out my be more economical as the reserve is not met yet and its at $8500 but thanks for the option.

Hey Bill thanks for the response. I'm going use the car on the street. I don't plan on drag racing but I may want to flex its muscle now and then. So, I'm going to look around for a new axle to swap in and see if I can find a local shop to do any axle/housing work. If I can do it for $1500 I should be able to stay on budget. Anymore and something else will suffer. I'm sure those Monza axles are not easy to come buy, but if I can come close to a 3-2 ratio you think I'd be ok?