I have been toying with the idea of putting a trans axle in my spitfire, and with the history of BV8 members (you know how we are) this is the place to think it through. So, here's what I know, think and the why.
1) I wanted the engine in my car completely behind the steering rack, that caused a lot of cutting down the middle of the frame,I don't mind cutting-I'm a BV8 member, that's what we do. I don't like the giant trans cover I ended up with, its only slightly wider, maybe a couple inches, but is to tall for the factory radio/dash support.
2) Weight distribution. The M5 I'm using now weighs around 70 lbs, a trans axle weighs around 125lbs but would replace the rear diff moving maybe 80 or 90lbs to the back.
3) I have to replace the diff anyway, I think mounting a trans axle back there would be about the same as any other independent rear setup.
4) I was planning on putting the heater/defrost system behind the seats running the ducting up front through the rockers due to the big trans cover, moving the trans to the back would let me put the heater in the front.
The Porsche trans axles from 924,944 and several other numbers is used in big HP lambo, gt40 type kit cars, so it should be strong enough for my 2.3 in its final form (shooting for 400HP), the rebuild on a Porsche trans Axle, even if you do it yourself, has to be paid for in extra large Porsche dollars. One of those has 1st and reverse on the left of the shift pattern leaving 2nd through 5th in an H pattern on the right, of course that's the one with the worst parts availability($$$), and from the pics I've found the one that would require the least cutting to get it mounted.
The Alfa Romeo Malano/75 trans axle has inboard disc brakes, that would be awesome. Maybe other trans axle could be converted to inboard brakes.
There are basically 2 styles of trans axle one with the diff in the front and one with the diff in the rear of the case. I think the diff in the front style would fit best, but the diff in the rear should fit with a little more frame modification.
A few links to trans axle info:
http://www.924.org/techsection/7transaxle.htm
http://www.alfabb.com/bb/forums/search.php?searchid=2662873
http://www.gt40s.com/forum/how-engines-transaxles/23996-g31-transaxles-audi-016-083-transaxles-pete-tinucci.html
http://bridgetogantry.com/2/index.php?option=com_content&view=article&id=67:the-mighty-transaxle&catid=35:ringside-seat&Itemid=300056
Great idea! I like the idea of keeping everything between the axles. Just makes good sense. Looks like it will be a tight fit but as long as you clear the bulkhead behind the seats you should be OK. No problem cutting them, just not a lot of extra space for the driver in a Spit! I've attached the best shot that I have of the area in front of the diff (BMW) just to give an idea of the actual area. Should be very well balanced and with 400 HP!.......................
Bill
IMG_2404spaceinfrontofdiff.JPG
You might want to look outside the STATES and maybe electronic shift to avoid the shift pattern issue.
What type of HP/Torque are we talking?
http://www.hansen-motorsport.se/kenneth_sadev_transmission.asp#Rear%20WD%20-%20SL90-20
Reference: Gearbox SL90-20 Rear Wheel Drive >> PDF-file
TECHNICAL DETAILS :
· 6, 5 or 4 speed dog ring gearbox with sequential gearing
· SADEV final drive 9x35, 10x31
· Variable ratios
· Maxi engine torque : 550 N.m (398 Ibs/ft)
· Gear teeth are 20 wide, straight cut on 90mm centres
· Self-locking diff with a choice of ramp angles and preload settings
· Tripods output or lobro Ø 108 mm
· Specific aluminium housing
· Specific clutch shaft
· Splash lubrication
· Weight : 60kg
OPTIONAL :
· Bell housing
· Gear display and switch for cut off system
· Hydraulic release clutch
SadevRearWDSL90-20.jpg
Iceman,
Thanks for the pic. looks like a diff in front will fit without cutting the frame, maybe the trunk floor, but I was going to flatten that with foam and hardboard.
dwtr,
Its hard to look at that site, my A.D.D. kicks in and I'm turned into a kid on his first trip to a toy store. As much fun as 6 gears, elect. shift would be I'm almost afraid to know what they cost, but I will find out. Plus the cost of one of those car storage lifts-so I can look at it from time to time.
Thanks for the input
I read your weight for an M5, 70 pounds and thought, "Gee, am I that weak?" as it is a real tussle to lift it waist high. So I weighed mine, 90 pounds with a home made remote shifter (2 or 3 pounds) and no oil.
I would like to see the hp rating on them, they really have some HD parts, considering the intended application.
Bill
IMHO, a Boxter ,in ready to use condition, may be a better value. "Kennedy Engineering" rates the "901", as used in 914's as a "5" in strength,(no drag racing using 1st gear). Audi is usually a good value. Lot's of oem. designs out there, without breaking the bank.Motor in front-right? What about a torque tube ? Is that why 924-944 ? Good Luck, roverman.
Orange Alpine,
Thanks for the weight, I was estimating it a bit low. I don't know anything about the M5 hp rating, mine was in a extended cab Ranger so I figured it would be alright in a Spitfire. I'm still using the stock size tires, they let go before torque get's a chance to damage anything.
Roverman,
I hadn't thought about the Boxter or 914 as they are rear engine but I'll look into them, they are probable used in kitcars. I'll look into the Audi also. I want to leave the motor in the front. I wasn't thinking about a torque tube to start with, so I'm not locked into it at this point, I don't know alot about them, yet. I think I like 'em I'm just not sure why.
Richard
Roverman,
I've been looking into the 914 and boxster, it never occurred to me that those cars are mid-engine. So, thanks for pointing me in that direction. I'm going to check out Kennedy Engineering, also.
Richard
Richard,
I think you have a great idea in the works. I have a little Porsche experience (enough to be dangerous). I believe transaxles that have the shift pattern with reverse in the left up position and first in the left back position are true Porsche transaxles, all others are actually Audi. The 924 was designed as an entry level "parts bin" car that used as many existing parts as possible, including an Audi engine and transaxle. If you are looking for parts, I have a 1987 924S that suffered an engine fire (not uncommon for these cars, I found out). I was driving the car when it caught fire, I think the clutch line or slave cylinder popped. I have yet to determine the actual cause. The car is for sale (cheap to a V8 member). You should be able to use the complete trailing link suspension, brakes, torque tube and driveshaft. I live near the Toledo Express Airport which is about 4 hours from you. If you're interested, I'm sure we can work something out.
Phil
Richard D., how goes the project ? Ther are many t-axles on ebay, at good value prices,(Not an endorsement). If you've been following the eng./trans forum, you may notice I've decided to follow my own medicine, for "Hemi Healey". I will be installing 2003' Boxter S, (6) speed t-axle. I'm considering clutch at the t-axle, similar to Alpha Romeo GTV 6. A Vette C5 torque tube coupled to Mopar Gen 3 hemi, in front, is planned.This rigid torque tube will impart considerable beam and torsion strenth to unit body, JH tub. Good Luck, roverman.