LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently Mon Sep 22, 2014 4:15 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 36 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: Subaru transaxles
PostPosted: Mon Jun 15, 2009 3:31 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
We just had some pictures posted and I can't find them...

I'm wondering does the Subaru transaxle have a bolt on bell housing?

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 4:38 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
Found the pics. Bell housing looks fixed. I'll try to collect some info about these in this thread, to make this useful.

My next question is if this unit can be run upside down, like some VW or Porsche units? I suppose that means can the ring gear be flipped and would it lube OK?

Image

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 5:01 pm 
Offline
Always Moore!
User avatar

Joined: Fri Nov 09, 2007 3:40 pm
Posts: 3329
Location: Pittsburgh, PA
My head hurts just from looking at that.

Is the lower gear set in the transmission eccentric to the center diff? Or is there an eccentric shaft that runs between the center diff (through that lower gear set) and to the front diff?

If you ran it upside down, would you have to run more oil in the transmission to keep everything lubed?

Also, on my 2.5i, there is a dipstick on the top of the transmission. You would have to seal it off somehow or relocate it (unless the WRX or STI gearboxes don't have this...I'm not that familiar with the other models).

_________________
-Andrew
Build Log
Youtube


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 5:40 pm 
Offline

Joined: Sat Aug 09, 2008 2:55 pm
Posts: 72
Location: Lake Elsinore, CA
The bellhousing is fixed. To the best of my knowledge, the differential cannot be flipped.

Are you thinking mid-engined or rear engined?

As they sit, they are setup for mid-engined used just fine as the engine sits if front of the wheels in a normal FWD/AWD Subaru.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 6:37 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
My head hurts a bit too. THese things make sense when I see the pieces laying out on a bench, but if I haven't worked on one, they can be a mystery to me.

You can see the front diff. It seems that the rear diff is in a bolt on housing at the back. It is driven off the lower shaft, but the drive to the reas comes out the top. ( ? )

The reason to turn it upside down is that it might allow the motor to be much lower. That is the setup commonly used on track cars. You do need to plug the original filler hole and add another one. Maybe on a Locost, you could tilt the drive shaft a bit and not worry about turning it upside down. For a street car it would be OK not to turn it upside down. I wonder if the R&P are bigger on a VW/Porsche, my memory is that they fill the case.

Image

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 6:42 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
Quote:
Are you thinking mid-engined or rear engined?


For a Locost actually. I've seen it done a couple of times now, which is to say it's very rare, but shows it's hard to have an original idea. I'm also looking at a Hewland, but the idea is a little more attractive if there is a similar plan B.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 7:00 pm 
Offline
User avatar

Joined: Tue May 08, 2007 9:50 am
Posts: 601
Location: Minnesota
I must have missed something, with a front (or mid) engine and an upside down transaxle you will have 5 reverse and 1 forward gear. Are you thinking you would flip the front diff ring gear to the other side of the housing to counteract this?


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 7:30 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
Quote:
Are you thinking you would flip the front diff ring gear to the other side of the housing to counteract this?


That was one of my questions above. I'm not sure this transaxle looks like it could do it though. On the VW, and I think Porsche units, the ring gear takes up most of the middle of the case, so it would splash lube. On this unit it looks like it might not. I also can't tell if the input shaft is higher then other transaxles or the ring gear is smaller...

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 7:54 pm 
Offline
Toyotaphobe
User avatar

Joined: Sat Apr 05, 2008 2:25 am
Posts: 3207
Location: Fort Worth, Texas
I talked to Saker about the tranny since they unbolt the center diff section and run the tranny in their cars and they said you can't run them level as you'll have oil related failures. You must have them a little lower in the rear. That makes me believe turning it over would present even more problems.

Here's their post back to me about the tranny failures they had:

"The transaxle angle was only an issue due to the nature of installation. We had
it installed almost level, whereas in the road vehicle, it is typically
pointing down toward to rear. Subtle difference, but one worth noting anyway."

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 8:53 pm 
Offline
User avatar

Joined: Sun Sep 10, 2006 11:29 pm
Posts: 378
horizenjob wrote:
Quote:
Are you thinking mid-engined or rear engined?


For a Locost actually. I've seen it done a couple of times now, which is to say it's very rare, but shows it's hard to have an original idea. I'm also looking at a Hewland, but the idea is a little more attractive if there is a similar plan B.


Well, I should keep my mouth shut, since I'm the Hewland owner, but for low powered, mid-engined cars there are really only three inexpensive transmissions to work with. The aircooled VW-Porsche based units (including the Hewland Mk9), Renault units (Fuego, Lotus Europa), and the Audi-Porsche944 units.

All of them have issues and strengths depending on what you want for the final outcome. Is it a track vehicle? Do you want to change gearing? Do you need to stand up to 11" slicks and turbocharged 4-banger power? Is overall length, length from axles to bellhousing, or weight an issue? Cue me into what you're hoping to end up with and I'll steer you to the right choices. I've had a number of these behind different vehicles - and LOTS of experience with VW car, Hewland, VW Bus and 901/914. If you are building from scratch, you may also want to put some thought into the rear uprights and axles DURING the transaxle selection. I.E., Renault Europa transaxles will suck mainly because you end up running crappy u-joint axles or making a lot of custom parts.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 10:16 pm 
Offline
Toyotaphobe
User avatar

Joined: Sat Apr 05, 2008 2:25 am
Posts: 3207
Location: Fort Worth, Texas
Do you know enough to be able to compare and contrast the Subie tranny and the Audi/Porsche/VW tranny?

Also where can you find the Audi/Porsche/VW tranny at a reasonable price. I recently looked for them and couldn't find them at any price except from a few of the Porsche forums where they wanted megabucks for them.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Mon Jun 15, 2009 10:40 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
It's sounding like the Subaru transaxle is good for behind a Subaru engine, but not always in other places...

Quote:
Well, I should keep my mouth shut, since I'm the Hewland owner,


If my ideas for the Locost are senseless, I still have a FF frame in the basement which need a new front bulkhead and a transaxle, so not all is lost...

This is for a Seven/Locost type car. My original thought was putting in the transaxle and also moving the flywheel, clutch and starter motor to the rear for space and weight distribution reasons. More room in the footwell and a more rear mounted motor, probably an xflow with a dry sump. I think now though that moving the flywheel etc. back is probably too much of a reach for me. There could be some downsides to getting that stuff wrong. It seems doable, but...

I would like the car to be fast on the track, for time trials with a local club. Street use too, so long as it's safe I don't mind if the suspension is non-optimal on the street. Figuring 13" rims with slicks for the track 15" for the street, hoping to work the offsets on the rims to be useable both places.

With the xflow maybe about 140 - 150 HP. Someday maybe a Duratech 180HP, but I don't see how people fit them. With the xflow I am thinking a really low hood and nose, no windshield on the track, a seating position a little more reclined, formula car style. Cycle fenders in the rear, smaller, tapered tail. Floor pan raised in the back a bit.

I wondered about the Subaru transaxle, because I wanted a low cost Hewland alternative if I got tired of using the dog box on the street, and in case anyone thought what I was doing was a good idea. It would solve some issues people have matching engines and transmissions, even including items like snowmobile engines...

I really miss using the Hewland. Maybe I will get tired of using it on the street after a couple of years, but my work commute is mostly highway and I can avoid driving it in city traffic in general. It's just a rewarding experience when you get it right, and I like the sound of the straight cut gears. Again maybe not as much a plus as I imagine in daily use.

If I give up on moving the flywheel etc. an LD200 might be better, Westfield used one on the FW400, I think.

Quote:
you may also want to put some thought into the rear uprights and axles


I remember your advice on "Micro Stub axles". This week I'll visit my mechanic friend and ask about building uprights with them...

Thanks

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Tue Jun 16, 2009 12:42 am 
Offline
User avatar

Joined: Sun Sep 10, 2006 11:29 pm
Posts: 378
I think you should look at Porsche 944 transaxles and torque tubes. They are almost exactly what you're looking for. When shortening the torque tube, you may lose the bearing in the middle, but it should be easy to adapt. The starter and flywheel will remain in front, but there's a lot of issues having the torque tube between the crank and flywheel.

The C5/C6 Corvettes have a similar setup, but the trans is in front of the diff, which makes it really long, and not much of a savings in a Locost with the normal set-back engine position. It would also cut into your hip area.

I'm glad you've already had experience with a dog box. When I try to explain it to most people, I have to tell them it's like a motorcycle box. You have to shift it with authority. It's easy once you have a feel for it.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Tue Jun 16, 2009 9:55 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
I originally thought the 944 was like the Corvette, in front of the diff so didn't look into it.

I thought you were suggesting it because it didn't have a bell housing, but it seems they do? Sorry for my confusion - searching the internet is producing as many questions as answers. I found one Audi diagram which didn't have a bell housing ( some are similar to 944 they say ). But the pictures do. Sigh...

I think weight is an issue here, sorry didn't mention it. I am seeing weights of about 75 lbs. for VW / Hewland transaxle, which is attractive. All the other choices seem another 30-50 lbs. more.

In the 944, could one use the drive tunnel as the torque tube? Seems redundant to have both. Again, it's hard to tell with out good pictures. I know we had a 944 based build here on our site, but searching both ascending and descending by date is pulling up so much stuff I haven't found it in the first few dozen posts I've read.

Routing the shift mechanism will be a bit of a pain with the VW/Hewland. Perhaps a hole thru the bellhousing, Ouch...

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
 
 Post subject: Re: Subaru transaxles
PostPosted: Tue Jun 16, 2009 10:06 pm 
Offline
The voice of reason
User avatar

Joined: Thu Jan 10, 2008 4:47 pm
Posts: 5680
Location: Massachusetts
Here's a picture of an Audi 016, Maybe this means they have bolt on bell housing or maybe it's just not included in the picture. Something like this would be great for those high power snow mobile engines or anything that is hard to bolt up to a RWD transmission...


Attachments:
016 SIZE1.jpg
016 SIZE1.jpg [ 28.87 KiB | Viewed 3775 times ]

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 36 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY