Massively heavy and shitty gear ratios.

 

Rebuilding a 6 speed Got to the point of trying to press on the 6th gear clutch hub. I had noticed the end of the counter shaft had threads in the end of it and figured it would be easy to come up with a tool to tread in there and press the thing on.

Couldn’t find a bolt that fit the threads though. As near as I can tell they are 9mm left hand threads. Pretty much non existent off the shelf. I called Mazdamotorsports about the SST 49-N017-2A0 Clutch Hub Installer. Said it was ~ $90 special order 4 to 6 weeks for delivery.

How are other people getting that thing on? I think I might be able to press it on by somehow supporting the other end of the shaft up in the flywheel housing as I’m pressing on it which is what I’m leaning towards trying.

 

I would think as long as the pressure needed to press the 6th gear hub on is not so great as to damage the roller bearing cage it should be fine.

 

Find a transmission shop who can do it for you and bring him a 6-pack.

 

Definitely could be done on a press with a really wide throat and an array of spacer blocks without the special AZ6 specific tool I think.

I'm going to try heating the clutch hub in the oven and whacking it on while supporting the other end of the shaft so as to not side load the roller bearings.

 

I've done all sorts of crazy stuff on my crappy 12-ton HF press I got for $20. Tried the hammer method once and messed up a bearing in the process. It's worth the time getting it pressed off. Most things aren't on very tight.

 

I have a harbor freight press. but I don't have one that is that tall.

 

dry ice from your local grocery for the shaft

 

Create a tall/long press with a largish U profile (or dual I profiles) with welded ends and a jack?

Or simply make your existing press taller.

 

went to harbor freight and bought a 20 ton press yesterday but stuck doing yardwork today.

 

I tried looking but can't find a definite answer...

Would a 1999 (3.9) torsen R&P gear set fit in a 1994 (4.1) torsen?

Thanks in advance.

 

Yes it would.

 

Thank you.

Well one/two more questions for the road.

I have a 1994 supercharged set-up. I am installing this 6-speed tranny and I also have a 4.1 Torsen. Would this be enough for a street use and spirited driving activities? Or since I'm there, a 3.9 FGR will be worth it?

Tnx again!

 

3.90 well give you a little better rpm, thus gas mileage on the highway, other then that there is no real reason to change it. The 6 spd has a really low first gear so no real need for the 4.10. But unless you're bored or can't make the end of the straight at the race track i'd leave it be for the little gain.

 

This has nothing to do with this thread. And is a very subjective question. Go to the FM gearing calculator and figure it out for yourself.

 

Was just thinking about this again and it occured to me, what exactly are the ideal gear ratios for a track driven miata. Obviously there are lots of variables such as engine power, redline, diff ratio, tire size etc and even the track in question.
But many of the higher horsepower setups are relatively similar 15 inch wheels with 225/45 tires. 3.6 or 3.9 rear end ratios, 300-350hp, shift points around 7500rpm or so depending. similar to Bob's setup.

If you got to pick the ratios for a 5 or 6 speed what would they be. Obviously they might be different for track,autocross or a street car that is occasionally tracked. Many have pointed out that most of the tranny swap options have shitty ratios, so what would your ideal ratios be? Higher first gear, how tight of a spread across the ratios?
Sorry just seemed like it would be easier to define what was desired and then look for something.

 

Tried #172 as a starting point?

 

Yep, start with this:

Then space the rest out as fits your use best.

 

I am in the same boat, i pulled my 6speed apart last night and it needs some new synchros and sliders and forks ect... the parts are gonna be over $1500, so im just gonna buy another tranny.

It doesnt make sense to spend 1k on a 75,000+ mile miata box when i can spend $800 on a 15,000 mile RX8 box. Has the internal swap actually been done?

 

That is good to know now... I bought an MSM tranny with a 3rd gear grind. I've got it torn down and have a 3rd gear, synchro and 3-4 hub sleeve on order. I had a hell of a time getting the 6th hub off and actually destroyed my HB puller. Ended up buying a Snap-on puller off of the truck to get it off. I have a feeling it will be a bear to get back on too. My parts should come in tomorrow, I'll let you know if I come up with a way to get it to go on. I have a 6ft name brand 20 ton press so I shouldn't have trouble getting the whole tranny in the press.