Hydraulic gearbox linkage.
Hydraulic gearbox linkage.
(OP)
Hi, I hope someone can help me.
I want to build a mid engined car for fast road or sprinting. The engine must be mounted inline not transverse and will sit in the middle of the car. The gearbox will have to sit over the rear wheels and will also have to be a transaxle gearbox from a Renault 25/30 or similar. It would be possible to make a solid gear linkage to change gear but this would be very difficult to use and fit. I have seen in a magazine artical a hydraulic linkage used on a similar car. I have also found on the web an electronic gear changer but this is only for sequential gearboxes. My buget is not very big for this project so any help anyone could pass on to me would be great. Thanks
I want to build a mid engined car for fast road or sprinting. The engine must be mounted inline not transverse and will sit in the middle of the car. The gearbox will have to sit over the rear wheels and will also have to be a transaxle gearbox from a Renault 25/30 or similar. It would be possible to make a solid gear linkage to change gear but this would be very difficult to use and fit. I have seen in a magazine artical a hydraulic linkage used on a similar car. I have also found on the web an electronic gear changer but this is only for sequential gearboxes. My buget is not very big for this project so any help anyone could pass on to me would be great. Thanks





RE: Hydraulic gearbox linkage.
Have you considered using two Bowden cables? For compactness you would want to use a 90 degree bellcrank at both ends for the lateral motion so both cables can run side by side.
RE: Hydraulic gearbox linkage.
RE: Hydraulic gearbox linkage.
If I was going to build a mid engined car today, I think I would adapt one of the electronic automatic transmissions and replace the torque converter with a clutch. The gear lever or paddles on the steering wheel would with simple electrical contacts painlessly and VERY QUICKLY change gear. Lots of possibilities, but eliminating the clumsy mechanical linkages would sure simplify things a lot.
RE: Hydraulic gearbox linkage.
I found after removing the engine/gearbox unit for a rebuild that the universal joint was binding. Since I was able to realign the cross by holding it a vice and tweeking the shaft I suspect the metal has too low a yield point.
RE: Hydraulic gearbox linkage.
Getting the gear linkage from the very rear of the gearbox around the engine is never going to be easy in the usually very limited space available. It is the very high penalty you pay for using an engine and gearbox that were never originally designed for the mid engined configuration.
It is easy for Porsche, Ferrari, or Honda (NSX) to make beautiful linkages because the gearbox was originally designed for the mid engined configuration. Building a home made special car that uses a low cost FWD gearbox, or something like a VW, Porsche, or Renault transaxle turned around, you will be in real trouble fabricating something that works really well. It sounds like a very simple mechanical problem, until you try it for yourself.............
Fabricating something that changes gear is easy. Making something that works superbly is far more difficult. A fun little sports car will not be much fun if it has a really horrible gearchange.
RE: Hydraulic gearbox linkage.
An electric shifter will take out all of the feel which is not a problem if you are not worried about the syncros.
RE: Hydraulic gearbox linkage.
Thanks.
RE: Hydraulic gearbox linkage.
RE: Hydraulic gearbox linkage.
there are several Truck manufacturers in Europe who use a hydraulic gearshift system. It has an hydraulic four-piston manual actuator under the gearlever connected with four hydraulic pipes to two double-acting hydraulic cylinders on the gearbox. This system might well work for your installation if it doesn't need too much space or weight.
RE: Hydraulic gearbox linkage.
Wilwood make a hydraulic actuator, originally for converting the old VW Beetle and Bus cable clutches to hydraulic. They would be ideal for your situation.
You might also want to take a look at motorcycle rear brake master cylinders for possible candidates for the actuators. I have used them before in just such a setup. You can replace the feed with a bleeder.
RE: Hydraulic gearbox linkage.
RE: Hydraulic gearbox linkage.
E 350. It’s a nice 1986 Van body and is stretched for two great bucket seats in the back. I’ll be using a Hyd, linkage or push pull cables. It was great running across this mid engine discussion and has given me a different out look on the problem. My address is flydeep@bellsouth.net and I’d be happy to get more points of view on this subject. The bell cranks and push pull cables are used every where in the air craft industry and have been developed to work great. I know that they use quite a few flat cables that actually run through small bearing surfaces on the inside of the stationary cable component. But the inside cable is very very tight and extremely predictable. Dave .
RE: Hydraulic gearbox linkage.