SUBARU TRANSAXLE ORDERED

Cool build, man. Polished transaxle and engine-turned stainless firewall is gonna be some next-level Spyder bling!

If you apply the same detail and creativity to this Spyder as you did to your Speedster, man, that is going to be one seriously bad-a$$ Spyder! 

Will enjoy watching your build progress.

Any idea on which gear ratios and R&P your going with?

I understand the temptation to polish the transaxle case because it is seen, but do the people at Rancho have any words on the matter? I'm asking because a cast surface has up to 10 times the surface area of something polished (it's of course why we don't polish the engine case), and since most transaxles don't have oil pumps or coolers (until you get into higher end road racing) I would be concerned about heat dissipation when driving the thing hard. What about painting the case a thin coat of flat black and polishing the ribs?

Now I will also qualify this with the fact that I've never seen anything written on this, nor do I know anyone who's ever had issues with trans temps on the street- just thinking out loud here and maybe trying to make something out of nothing. I wonder if my friend Bruce has anything to say about this...

Howzabout just polishing the transaxle case ribs?  That way you get some bling while leaving the surface area.

A shiny polished Subbi transaxle would be great.  I've tried to clean a couple VW magnesium transaxles in past.  They were encased in 1/2" of baked on grease and sand.  Meticulously scraped and pressure-washed that off then wire brushed the case.  Even tried caustic oven cleaner.  It came fairly clean but was that dark mat grey finish.  I did take a sanding wheel to some of the rough case casting flashings - boy, does that create pretty white sparks. I'll probably spray the case a flat or semi-flat color and then sand/polish the ribs for contrast.  Even painted it has to radiate more heat than that 1/2" grease coating.

Polish the $#!+ out of it, Bruce.  How much heat is a transaxle going to generate in the first place?  Unless you're tracking the snot out of it, it's never gonna get that hot.

That, plus the fact that you'll blow the spectators (and Ferrari owners) away at your local Cars and Coffee whenever you flip up the rear of the car will make it positively worth it.  I would like to be there to see their (the Ferrari pukes) faces, too.

I'm curious to see Greg's suspension design. Plus I'd like to hear more about the the axle shafts. Subaru cv by the trans and VW outboard?

Do whatever you want with the trans, Bruce. Just don't polish the ribs(IMHO is passé). I went Henry Ford, and bead-blasted the outside then painted it gloss black. Easy to keep clean, no polishing.

SG makes axle stubs to add vw or 930 axles FyI

you need to have them shortened as it is critical that they are not too long to not damage the R&P you don’t need any sudden stops

Great comments guys, Thanks !  Originally, I was thinking to just highlight the ribs by polishing but after looking at the case, the ribs aren't as radical and pronounced as a VW, much less, a Rhino case. So now I'm looking at doing the whole case. I have seen a magnesium VW case polished and it just didn't look all the good. The Subaru aluminum one will though. When I get it home I guess I'll make the final decision. Rib-tops only or total case.  

I had all the gear ratios written down but lost the list out of my sweater somewhere so next week I'l get them again. Memory says the R&P will be 3:46. I could be off by a 10th or 2 .  Holy Crap !   I'm gonna get a 5 speed !    Jeez !   With up to 7000 RPM and more gears to select this could be real nice.  To have a "Freeway Flyer" (a term I really don't like much) it's possible I may have a.  "Freeway Finesse" set of gears. One thing I did learn is that I don't have a lot of gearing choices using a Subaru trans. Also that there are 3 manufacturers of LSD's for this trans and none of them are cheap. They cost almost 1/3 the cost of a transmission.

I haven't discussed what axles Greg will use but will soon. Also I'm very curious about how he will build the IRS.  When I was at Rancho by the way, they said that the new JPS Suby cars will have Suby transmissions and IRS. It wasn't clear if that was for Speedsters or Spyders or both.  I'm also anxious about what type of shifter mechanism will be installed by Rancho. A while back I believe they had some issues with this. Now they seem very pleased and confident with what they offer.

This is already getting fun !...................Bruce

Lsd's are a specialty piece of machining and materials, so they're never cheap. How much does an lsd cost for a subie trans, and what is the gearing?

aircooled posted:

Great comments guys, Thanks !  Originally, I was thinking to just highlight the ribs by polishing but after looking at the case, the ribs aren't as radical and pronounced as a VW, much less, a Rhino case. So now I'm looking at doing the whole case. I have seen a magnesium VW case polished and it just didn't look all the good. The Subaru aluminum one will though. When I get it home I guess I'll make the final decision. Rib-tops only or total case.  

I had all the gear ratios written down but lost the list out of my sweater somewhere so next week I'l get them again. Memory says the R&P will be 3:46. I could be off by a 10th or 2 .  Holy Crap !   I'm gonna get a 5 speed !    Jeez !   With up to 7000 RPM and more gears to select this could be real nice.  To have a "Freeway Flyer" (a term I really don't like much) it's possible I may have a.  "Freeway Finesse" set of gears. One thing I did learn is that I don't have a lot of gearing choices using a Subaru trans. Also that there are 3 manufacturers of LSD's for this trans and none of them are cheap. They cost almost 1/3 the cost of a transmission.

I haven't discussed what axles Greg will use but will soon. Also I'm very curious about how he will build the IRS.  When I was at Rancho by the way, they said that the new JPS Suby cars will have Suby transmissions and IRS. It wasn't clear if that was for Speedsters or Spyders or both.  I'm also anxious about what type of shifter mechanism will be installed by Rancho. A while back I believe they had some issues with this. Now they seem very pleased and confident with what they offer.

This is already getting fun !...................Bruce

Sounds like you're having great fun, Bruce and nice to hear / watch the progress. An outside guess might be I'll go Soob again next winter and a very outside guess I might consider a "modern" Soob 5 speed. Please though, what does LSD mean now in these modern days ? I do remember ( hearing of )  Lucy in the Sky with Diamonds...........

I’m going with Limited Slip Differential. 

Yup ......Limited Slip Differential in this case is what I meant. The other LSD,  David, was a lot of fun (so I'm told), and very expensive because you only got one trip out of it !

Sorry about that. I try not to use acronyms n stuff. The Subaru "ECU" had me going for a while.  

LSD Cost...$1800.00 for a new one. This week I'll try and see if they can install a used/rebuilt unit for less.

I'll have all the ratios again this week and will post them. Speaking of which.....I ran into a dead end trying to find Vredestein Sportrax 5  tires  sizes 175 and 205 65 R15 out here in So Cal. Anyone have a source ?...............Bruce

Bruce as far as I know the lowest R&P is 3.91 and the gear sets are not close to the VW sets but on the other hand the torque band is not as well.  

On my car the R&P is 4.11 and my close ratio gear set is quite nice it is only the 5th cruising speed of 3100-3200 at 70mph that I would prefer to be lower.  I posted my gear ratios previously and had talks with Todd at SGears about changing my ratios to get the cruising cpeed lower.  

For all the agravation it would take a 3.91R&P, (rest in peace ) _ which is the lowest made, and a very low 5th gear which only gets you down to 2700 rpm at 70mph with 16 inch tires on my car.   The close ratio gears in my tranny are awesome 

FYI, a reversed position transmission also is filled with more oil due to the possible movement of fluid to prevent oil starvation of the 5th gear.  They how have an inspection window to make sure your oil is up to the top. 

Update:    Have you looked here subarugears LSD..  

aircooled posted:

Yup ......Limited Slip Differential in this case is what I meant. The other LSD,  David, was a lot of fun (so I'm told), and very expensive because you only got one trip out of it !

Sorry about that. I try not to use acronyms n stuff. The Subaru "ECU" had me going for a while.  

LSD Cost...$1800.00 for a new one. This week I'll try and see if they can install a used/rebuilt unit for less.

I'll have all the ratios again this week and will post them. Speaking of which.....I ran into a dead end trying to find Vredestein Sportrax 5  tires  sizes 175 and 205 65 R15 out here in So Cal. Anyone have a source ?...............Bruce

  I know it sounds insane, Bruce, but that's not out of line. LSD's are expensive (there's way more to them than open diff's), especially when made for small markets with quality materials and precision machining (there's no economies of scale) . Paul from http://www.guardtransmissionll...-slip-differentials/ has talked on the Samba about doing a run of irs lsd's- the bodies will probably be 4340 billet (even stronger than the ZF steel casing) and I'm sure will run up around $2,000.

  I watched my friend Bruce disassemble, clean and reassemble the irs ZF out of his own car last night- 60,000 hard (his description) km's and I measured virtually no wear on any of the plates or his custom hardened thrust washers (the stock thrust washers are not of hardened material and are all but destroyed in most of the lsd's he sees, so he makes his own). You gotta pay if you wanna play...

  I talked to a Canadian supplier back east just before Christmas about Sportrac 5's for my car (hoping to find 185/60's and 205/60's in a summer tread) and was told to try again late winter/early spring.  Al

PS- I just looked at http://www.subarugears.com/Pricing/Pricing.html and that is not an lsd but a gear driven closed differential (same principle as a Quaife). They do act similarly (applying power to both wheels under acceleration) but there are some differences- the thing that comes to mind is that an lsd applies force to both wheels under braking as well while the other does not. I've read about Porsche road racers replacing the gear driven units with true plate style lsd's for better lap times.

Looks like I'll be down at Rancho this week for an education..Love the comments and advise from you guys !   Got out all my sanding/grinding cones and cratex bits today. Oiled up my air grinders. Need to make up a 3/8" whip hose to get a little more air to the tools. I'll probably take off the casting chafe before it goes to the polisher.

Haven't decided where I'll put the fuse box yet but I'm a little pissed that the cool box I made is too big to cut into the firewall in the frunk. I do sorta like the idea of the hinged fuse block. 

Bought a couple 24 tooth metal cutting blades for my bandsaw to start cutting the stainless for the rear firewall. I sure wish I could weld stainless like others I have seen where there isn't even any discoloration in the metal surrounding the weld beads.

Got all the wires sorted and tagged that are coming off the engine.

Working on a really bizarre air cleaner silencer. If I'm successful with the help of my CNC guy, it will be pretty comical.  Pictures to come later if it comes out OK.....Bruce

I too am interested in what the rear suspension design will be for the Spyder.  We've done custom trailing arm using modified 944 parts as well as a DeDion suspension, and both were outperformed by a properly set up swing axle with z bars.  Not that they didn't work mind you, just not as well as Dr Porsche's original design.  

As for the Suby gearbox, I suspect we'll see that as a transition for many more companies.  Our new coupe is complete Suby drivetrain and our new Speedster chassis uses the Suby box with a reverse cut R&P.  Considering the cost of a Sub Spec Rancho box it only makes sense to utilize the original Subaru gearbox where possible...

As for Rancho, I can't say enough good things about them.  They have, literally, built us over 2000 VW gearboxes in the last 30 years and I wouldn't go elsewhere.  In the last few years they have been rebuilding our 901 and 915 Porsche boxes and we are just starting to use them for Subaru boxes now also.  Top notch company.

Great stuff Carey, with the amount of available parts the subie gear set might be able to be expanded as well.

Thanks for taking time out of your day to comment Carey. As we move along a little more in the immediate future I will be sure to post photos of my build for yours and others perusal. I was unaware that a reverse cut R&P gear set was available for a Subaru transaxle to be installed in a Speedster or any other similar rear engine layout. I just assumed that the R & P was "flipped". Who makes this gear set ? That, in itself, is a significant offering and suggests that a trend change is in the offing. That of moving away from a VW to a Subaru for a transaxle assembly. My guess is that other gearing will become available as well.

Speaking of gearing, I tried using the gear ratio tool on the Subarugears.com site and found it a little cumbersome. I came up with some pretty wild speed calculations using my expected tire size.  Who else has a decent gearing chart ?

Last thing. I need to refresh on the modern concept of "close ratio" gearing and if anything has changed on this over the last 25 years.  In other words, with the advent of all the new engine and trans. designs, higher RPMs, wider power bands, lighter cars and higher horsepower,  is there more to consider ?

Back to school ??..........................Bruce

Bruce, the R&P that is reversed so that the tranny works like a VW tranny in a rear engine speedster setup, is made by Subarugears.  

I have one.  Using the ratio calculator on their site is best done IMO using the crusing rpm you want to achieve.  So if you try 3000rpm as the shift point you will get the MPH on each gear that will give you a very close idea.  

Since Subaru has done so many of these trannies, why reinvent the wheel?   I feel the same about the ECU.  Why not just modify it slightly so that is why the 3.91 R&P and dropping the 5th could give you 2700rpm at 70mph.  This is what I recently discussed with Todd at SG.   

Since it completely slipped my mind when I built my car, I did not get this setup so I am turning at 3100-3200 at 70mph. Just saying. 

Bruce, as I understand it, you can't just flip the ring and pinion on a Subaru gearbox because the case constraints won't allow it - no room.  That's why the Aussies came up with their reversed ring and pinion set.

aircooled posted:

 Who else has a decent gearing chart ?

 

http://www.teammfactory.com/ca...48/0/6000/8400/0/0/1

@ALB  just in passing as Bruce is evaluating ratios the nicest thing i liked about my old 356 was the length of the 2nd gear.  I mean everyone who drives a P car always says they like the 2nd gear length.  I wonder how it would look in a full subaru set up with the tranny geared similarly but of course as Bruce mentioned taking into account the differences in the engines outputs.... I'm curious. ... 

BTW as long as you didn't forget about basic chemistry or should I say being  twitterpated  your ok ....  

Using the 3.91 R&P with the .73 5th @2700RPM =71MPH

Using the 4.10 R&P with the .78 5th @ 3000RPM = 71MPH

Both in the power band sufficiently. Looks like the choice would be the 3:91 R&P and .73 5th..................What do you think Ray ??.............Bruce

Bruce I just checked my notes and you are correct.  

Now I have not tried it, a problem with our hobby, but Todd says due to the car being so light he does not think the lower 5th will be an issue at all nor the intervals.  

I love the close ratio of the rest of the gearing. Actually the 5th being at 3000,3100 means your always in the powerband I really do not have to goto 4th to overtake any car. 

Best of luck on your decisions. 

Ray

Notes here: >>>>>>>>>>>

Presently I have  Oct 2018 

4.1  R&P 

1st gear 3.454 

2nd gear 2.062 

3rd gear 1.448 

4th gear 1.088 

5th gear 0.78     my tires are 24.88 inches   as they are 16 inches

What I plan to do in the future is to change the R&P 3.9   and  the fifth gear to 0.73.5     

This would give you 2700 rpm at 70mph.   

Yup....That's what I think too. I think Rancho will be calling me tomorrow about picking up the trans case for polishing. I will talk to them about this gear set selection.

Al......I liked the "team factory" gear set selection matrix.... Simple, and incl. tire diameter selections too !...................Bruce

IaM-Ray posted:

@ALB  just in passing as Bruce is evaluating ratios the nicest thing i liked about my old 356 was the length of the 2nd gear.  I mean everyone who drives a P car always says they like the 2nd gear length.  I wonder how it would look in a full subaru set up with the tranny geared similarly but of course as Bruce mentioned taking into account the differences in the engines outputs.... I'm curious. ... 

BTW as long as you didn't forget about basic chemistry or should I say being  twitterpated  your ok ....  

I've heard that before as well, Ray; I have some data on 356 gear ratios written down, so if I get energetic later I might do some sort of comparison with the type 1 gearing most of us are saddled with. 

See: http://forum.porsche356registr....php?f=1&t=29263

The first graph (BBAB aka "Normal gears") corresponds closely to a late VW Beetle box (.93 4th) with a 3.44 R&P, although that option gets you 100 mph in 3rd and 140 in 4th with 25.4-inch tires. Run slightly shorter tires (as most do) and you'll be right in the zone.

edsnova posted:

See: http://forum.porsche356registr....php?f=1&t=29263

The first graph (BBAB aka "Normal gears") corresponds closely to a late VW Beetle box (.93 4th) with a 3.44 R&P, although that option gets you 100 mph in 3rd and 140 in 4th with 25.4-inch tires. Run slightly shorter tires (as most do) and you'll be right in the zone.

 

You all know I've had about 4 or 5 different transaxles in my car. For reasons I won't get into, fitting a Berg 5-speed in a tube-frame IM is not impossible, but requires no small amount of cutting and welding.

If I had one more time to do a 4-speed, this is exactly what I'd do-- standard beetle 1-3, with a .93 4th, and a 3.44 R/P. 

That works Stan, but the space between the gears sometimes makes you feel that the engine is at the shift point and you should shift then when you do the rpm drop is too low.  This is when the posted speed is 40mph and your doing in the range or 40-50.  At least in a 2110cc engine which I had that is how it felt.  At cruising speed there was no problem.  Now with that dry sump rocket ship you might have a better time. 

I'm with you Stan, except I'd shorten 3rd and 4th. I want a canyon-carver. The car needs to squirt HARD from one corner to the next.

Down in NC, 3rd was too low and second too high in some places. This with a 6500 redline, which I hit often when we were really hoofing it. My motor pulls great, but sometimes it felt not quite what it could be. I have all stock gears, so 1.26 3rd and .89 4th with 3.44 final. Absolutely PERFECT for interstate cruising.