Questions about mid-engine and transmission
Discussion
This might an easy question for Ultima builders.
Till now, I always drove, front engine, RWD cars. There we have the transmission sitting in between 2 front seats, and a 1.5-2.0meter long shaft, turning the differential, differential turning two rear wheels. Easy? Thats what I saw for years.
But when it comes the Ultima, the engine is in the middle, so where is the transmission? And differential? How are they connected?
Till now, I always drove, front engine, RWD cars. There we have the transmission sitting in between 2 front seats, and a 1.5-2.0meter long shaft, turning the differential, differential turning two rear wheels. Easy? Thats what I saw for years.
But when it comes the Ultima, the engine is in the middle, so where is the transmission? And differential? How are they connected?
Most mid engined cars use things called transaxles which combine the gearbox with the differential in one casing. Ultimas tend to use the Porsche G50 tranmission from late model 911s, 964 or 993. You can also use the Getrag tranmission (which Ultima can supply brand new) which is what is fitted to the Porsche 996 C2 Turbo (I think).
If you have a lot of cash lying around you can look at fitting more exotic transmissions like a Hewland Sequential...which will set you back £27k or thereabouts!
If you have a lot of cash lying around you can look at fitting more exotic transmissions like a Hewland Sequential...which will set you back £27k or thereabouts!
In terms of where things are positioned, which I think is one of the things you were unsure of, start with the engine.
Engine faces forward with its pulleys and drive belts at the back of the drivers head.
Flywheel and clutch are fairly conventional and housed in a bell housing which is the front of the transaxle.
The first part of the transaxle immediately behind the bell housing is the diff. The driveshafts come out of the sides at this point.
The gearbox input shaft which picks up it’s drive from the clutch passes though the diff and into the gear clusters which are sitting behind the diff.
The resultant drive from the gear clusters comes forward again to the diff.
In most but not all these transaxles the gear selector shafts are at the very back. You may remember that this was the most vulnerable part of very early Grand Prix cars where a light punt into the back end would smash the gear selector and put the car out of the race.
Steve
Engine faces forward with its pulleys and drive belts at the back of the drivers head.
Flywheel and clutch are fairly conventional and housed in a bell housing which is the front of the transaxle.
The first part of the transaxle immediately behind the bell housing is the diff. The driveshafts come out of the sides at this point.
The gearbox input shaft which picks up it’s drive from the clutch passes though the diff and into the gear clusters which are sitting behind the diff.
The resultant drive from the gear clusters comes forward again to the diff.
In most but not all these transaxles the gear selector shafts are at the very back. You may remember that this was the most vulnerable part of very early Grand Prix cars where a light punt into the back end would smash the gear selector and put the car out of the race.
Steve
Steve_D said:
In most but not all these transaxles the gear selector shafts are at the very back. You may remember that this was the most vulnerable part of very early Grand Prix cars where a light punt into the back end would smash the gear selector and put the car out of the race.
Steve
You say that is the one of the weak parts of Ultima? You can easily loose your gear selector also on Ultima?
Just for a visual, here are 2 pictures of my engine trans set up. Just went in this past weekend. Actually starting to look like a car now.
larger image
larger image
You can see in the second picture the Trans sticks out the back of the frame. The gear linkage connects to the shaft on the back. Mine Trans is a short g50/50, the long box would stick out more. Since it's outside the frame if someone hits you hard enough to smash the fiberglass rear you gear linkage is the next thing to take a hit.
Mark
larger image 
larger image 
You can see in the second picture the Trans sticks out the back of the frame. The gear linkage connects to the shaft on the back. Mine Trans is a short g50/50, the long box would stick out more. Since it's outside the frame if someone hits you hard enough to smash the fiberglass rear you gear linkage is the next thing to take a hit.
Mark
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