Clay
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| posted on 6/5/05 at 03:53 AM |
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mid engine setup with Porsche tranny?
Has anyone on this board made a mid engine locost by taking a porsche transmission and turning around and flipping it upside down?
I know factory five does this with their new GTM Supercar Link to Factory Five GTM
Supercar using a porsche tranny flipped over and turned around with an adapter plate to mount to a corvette motor.
I believe they use a new porsche transmission that is very pricey, but older porsche transmissions can be had on ebay for fairly reasonable prices. I
was wondering if anyone has done this here, or seen of it done other than the v8 powered mid engine porsche 914.
Also is anyone familiar with the way older porsche transmissions shift? would turning it around and flipping it over like factory five did make it
impossible to use a manual five speed? like if it were shifter cables you could route them around to the back, but if it were some kind of rod that
goes into the tranny like a miata or something i cant see how it would be done.
[Edited on 6/5/05 by Clay]
Clay Marsh
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NS Dev
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| posted on 6/5/05 at 10:07 AM |
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My mate at Ultima uses this setup with no problems. They sell a good few cars in the USA too.
Ultima Sports
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ERP
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| posted on 6/5/05 at 06:16 PM |
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The primary choices for longitudinally mounted mid engined cars seem to be either the porsche unit, audi (016 and 01e 2WD) units or the renault
box.
In addition to ultima and Factor five a number of manufacturers use the porsche unit inverted. From Lambo clones to GT40 and Lola copies.
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Clay
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| posted on 6/5/05 at 07:27 PM |
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questions:
Are all the companies using porsche trannys using the automatic tiptronic porsche trannys or are some using the manual transmissions?
If manual transmissions are being used, does anone have any idea how the shifter setup looks? is it 2 cables?
also is anyone using the older porsche transmissions, and if not, does anyone know if they can be used?
also does anyone know if any of the older porsche transmissions have the same bell housing bolt pattern as the new ones, so the currently available
adapter plate could just be purchased and used?
Clay Marsh
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40inches
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| posted on 6/5/05 at 09:04 PM |
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Try here http://www.gt40s.com/ubbthreads/postlist.php/Cat/0/Board/UBB6
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chrism
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| posted on 6/5/05 at 09:48 PM |
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All of the Ultimas I have seen with Porsche boxes have been manuals.
From what Ive seen the shifting is down via a rod cominf out of the front of the box when its in the porsche when turned around it ends up at the back
of the box/car.
Ultima use a rod setup to link to it.
Take a look at the attached picture
 
Rescued attachment GTR47.JPG
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A little hard work never killed anyone, but why take the risk!
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Clay
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| posted on 6/5/05 at 10:21 PM |
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Chrism thanks thats exactly what i was looking for, and also exactly what i was hoping it was not. Here is another question...does that rod coming out
the back only have 2 positions forward and backward, and the rest of the gear selection is done by a cable driven lever like on the side of the
tranny?
how could that one rod select 5 or 6 gears?
Clay Marsh
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Clay
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| posted on 6/5/05 at 10:22 PM |
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quote:
Originally posted by 40inches
Try here http://www.gt40s.com/ubbthreads/postlist.php/Cat/0/Board/UBB6
thanks ill ask over there
Clay Marsh
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ned
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| posted on 6/5/05 at 10:55 PM |
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a standard h pattern box motion on the linkage is forwad/back and twist at 3 stages to pickup the selector fingers on the baclk of the box.
i don't quite understand your problem. if you think its goig to be going the wrong way can't you just pivot the gearstick from either
behind or infront of the linkage to change the way the rod moves in relation to the location/layout of the gears at the gearstick end?
what am i missng?
Ned.
beware, I've got yellow skin
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Clay
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| posted on 6/5/05 at 11:59 PM |
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quote:
Originally posted by ned
a standard h pattern box motion on the linkage is forwad/back and twist at 3 stages to pickup the selector fingers on the baclk of the box.
i don't quite understand your problem. if you think its goig to be going the wrong way can't you just pivot the gearstick from either
behind or infront of the linkage to change the way the rod moves in relation to the location/layout of the gears at the gearstick end?
what am i missng?
Ned.
The main reason im having trouble visualizing how to setup the shifter is because i wasnt sure how the rod in the back of the tranny selected the
gears, but i guess it twists radially left to right, and goes in and out right?
if this is the case, i could imagine a way to do it, but it would require a solid rod that would start at the shifter handle and go straight back, and
meet at the back of the rod in the transmission, but this rod that goes straight back would have to be under the car so it wouldnt have to bend around
the engine, and would require the chassis to be extended lower underneath it to protect it from being damaged by road imperfections, and prohibit me
from lowering the chassis as low as it could be..
I dont see how the shifter arm shown in the ultima picture works and i think my confusion comes from not knowing the behavior of the rod. Looking at
the piture, does that ultima made rod twist radially? like stays in its same line of axis but spins? And if so, would that actually turn the rod that
enters the transmission? I guess the ultima made shifter rod must have some kind of ujoint further up stream that i cant see that lets it move up and
down when twisted right?
this whole thing could easily be explained if i could see an unabstructed picture of the shifter setup in the ultima or gt40, or even off the car.
[Edited on 7/5/05 by Clay]
Edit: ive looked at some more pictures, and if im understanding the setup in the picture correctly, there are a couple of u joints in that shifter
rod right? to bend it around the engine? And when you tilt the shifter handle, it twists the rod, which turns the lever and consequently the gear
selector at the back of the transmission right?
assuming all that is correct, the gear selector still has to move in and out of the transmission right? how does it do this if the shifter rod is bent
around the engine with u joints?
am i anywhere near the right idea here?
[Edited on 7/5/05 by Clay]
Clay Marsh
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timsta
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| posted on 7/5/05 at 01:46 PM |
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I thint there is only the one u-joint after the gearlever. As you push the gear lever across to the left to select 1st/2nd the rod at the gear lever
will twist the rod anti-clockwise, after the u-joint that will then cause a up/down motion (on the black part of the rod near where it joins the back
of the box in the pic above.) This will then rotate the shaft on the back of the box.
When you then push it forwards to select 1st gear: the gear lever pushes the rod back. This causes the whole rod to move back and pull on the shaft
at the back of the box, popping it into gear.
(Or, at least, that's the way I see it.)
There's a few pics here: http://www.ultima-gtr.info/ubuild004.htm
[Edited on 7/5/05 by timsta]
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ned
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| posted on 7/5/05 at 06:12 PM |
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please see badly drawn attache pic!
the gearstick is currently in neutral. when you move the gearstick to either side whilst still in neutral the selector rotates at the back of the
car/gearbox between the different selector fingers on the gearbox casing. when you push forward ie to go into 1st gear on the stick, the finger is
then pushed/pulled which moves the selector fork inside the gearbx putting the car into gear.
the type of linkage/location of he pivot on the lever ie A or B will denote whether the selector fingers are pushing or pulling at the gearbox end.
hope this makes sense/explains everything?!
Ned.
 
Rescued attachment linkage.JPG
beware, I've got yellow skin
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chrism
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| posted on 8/5/05 at 09:45 PM |
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This might help.
The shifter on the Ultima is on the right hand side of the driver on the outside sill of the car.
The gear lever is attached to the side using a rose joint. There is a universal joint near the bottom of the gearstick and then this goes down and is
attached to a horizontal tube.
I have a picture of it but don't have it to hand.
To help you understand it, when push the gear lever to the left the universal joint moves to the right causing the connection to the horizontal tube
to turn it to the right, and when you puch the gear lever forward it in turn moves the horizontal tube backwards.
This tube is routed along the side of the chassis with one or two universal joints, and then attaches to the gearbox like the picture above.
He is a picture of the gear linkage parts, its not a very good one though.
 
Rescued attachment gearlink.jpg
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A little hard work never killed anyone, but why take the risk!
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NS Dev
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| posted on 9/5/05 at 08:36 AM |
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Well done that man, was about to ask my mate if he could email me a pic but you have beaten me to it!
It really isn't that difficult!
Just to confuse further, most new builds now are using the 6 speed getrag box from the new porches (tricky to get new G50 boxes now) and these ARE
cable shift, ultima use the complete cable system straight from Porsche.
The RH gearshift is good though, certainly never seemed a probem in the ones that I have been in.
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ned
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| posted on 9/5/05 at 09:02 AM |
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RH gearshift takes a little getting used to, but most formula/race cars have this setup of course. i have driven a rh gearshift car ruond goodwood and
apart from missing a gear out of the chicane it was easy to get to grips with 
Ned.
beware, I've got yellow skin
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