Sorting out the transmission angles

Adding a transmission tunnel and raising the prop shaft has done wonders for the ground clearance but it has severely affected the prop shaft angles. To sort this out both the engine and the back axle will have to be relocated. Thius is turing into a fairly major modification.


FrontCVAngle.jpgAs the prop is a lot higher than it was originally the engine will have to be tilted forwards to reduce the angle on the engine CV joint. The rear gearbox mount can be raised quite a bit but the front mounts will also have to be relocated as the gearchange linkages foul the steering rack. First job is to cut off all of the mounts and start again.

OrigEngMount.jpg   This is the original front engine mount. It is simply a piece of 3mm plate held on with three small welds. This car is amazing. Some parts of it are unbelievebly overbuilt and others are dangerously weak. I wonder how many of these cars had the mount fail. Mind you, it made life easier for me as it took no time to remove...


ShockMount.jpg  Just above the engine mount we go to the other extreme. This amazing construction is the front shock mount. I know the front suspension takes some fairly heavy loads but do you really need to take a piece of large diameter 6mm thick steel pipe then wrap it in 40mm square, 3mm wall box section?? It would survive a nuclear bomb blast with minor bubbling of the paint. To put this into context the front suspension on the  Locost attaches to 25mm square 1.5mm wall steel box. There is a Locost racing series and in an impact the suspension wishbones usually fail, not the mounts.


EngMountNew.jpg This is the new, repositioned engine mount. It is still made out of 3mm plate but it now has a reinforcing gusset which greatly adds to the strength. Actually this is the Mk2 bracket. I had the Mk1 bracket and rear gearbox mount in place when Rick (default_user on the Fiat Forum) warned me to check the front driveshaft clearances. It is a good thing he did because they were way out and could have resulted in some nasty damage to the shafts and gearbox. Rick is rebuilding an NCF Road Rat (dubbed Satan's Rodent), the predecessor to the Torino. You can see his site here.


GearboxMount.jpg This is the front gearbox mount. It is made from two pieces of angle welded to the chassis. Simple and strong. The hole in the chassis rail is part of the original mount. As in many other places the bolt goes straight through the box section. The box should have a reinforcing tube to stop it collapsing when the bolt is tightened. Without this it is impossible to tighten up the bolt properly. The front suspension tie bars are bolted on in the same way. I will be fitting crush tubes in them.


RearGearboxMount.jpg  This is the gearbox rear mount bracket. The original bracket placed the mount below the chassis rail, this one places it above the chassis rail.


RearPropBefore.jpg The rear prop shaft angle was so bad that the diff joint jammed solid before I could raise the prop into the correct position.


RaisedSpring1.jpg As the front leaf spring mount was very low, my first idea was to simply redrill the holes as high as they would go. This was nowhere near enough so more drastic action was required.


RaisedSpring2.jpg All of the original spring mount bracketry was cut off so the spring could sit just behing the seat well. This raised the spring mount something like 100mm above it's previous position. Cutting off the bracketry was interesting. The previous owner filled all of the box section with Waxoyl to stop rust. Mix Waxoyl and a plasma cutter and you get... a flame thrower! I couldn't see all of the flames but apparently at one point while I was cutting off the left hand mount, flames could be seen coming out the right hand wheel well! You will probably be reieved to hear I had a couple of fire extinguishers handy and someone to watch for fires.


PropMounts.jpg With the axle roughly in position I needed to make the centre bearing mounts so I could finalise the exact position of the axle. Although these brackets don't look much they took about a day each to make. To improve the angles, the centre prop is angled down a bit. This allows me to angle the front of the diff up and further reduce the joint angles. Due to the way that universal joints work it is important that the diff flange and the centre prop are parallel. If they are not parallel there will be a lot of prop shaft vibration. The centre prop is not parallel with the gearbox, which is why Fiat used CV joints for the front.


NewPropAngle.jpg Although the prop angle doesn't look much different in this pic it is actually much better. I have fitted wedges between the axle and springs to tip the front of the diff upwards which helps. The lighter grey marks on the floor above the axle are actually soot from the flamethrower episode. Before welding in the new brackets I checked the wheel alignment and was horrified to find the wheels were 10mm closer together on the left hand side. On further investigation it appears the left hand front wheel is 10mm further back than the right hand wheel. This is probably not a problem but it still seems an awful lot to me. I need to play around with the front suspension geometry so at the same time I will see if I can move the wheel forwards.


FrontSpringMount.jpg The new spring mounts are welded in place and sprayed with cold galvanizing paint. This is about the best primer I have found for preventing rust. It tends to chip fairly easily but this area will be well protected with plenty of underseal. I will be adding a brace going up to the chassis rail directly above the spring but I started running out of light and it had started raining (again).


SpaceForSpring.jpg The prop shaft length defines the position of the back axle. Unfortunately this means that the spring ends up hard against the step in the floor. Obviously this is a problem as the spring needs to move. I had a choice - cut out a section and weld in a box or beat the cr*p out of it with a large hammer. As you can see the large hammer option won. It looks a bit rough but once it is undersealed it will look a lot better. Once the seats are in you won't be able to see it inside.


Underneath.jpg Another view of the underside. As you can see the car is now nearly flat underneath. It is a major improvement from when I started. The exhaust will of course be relocated as well.


RearShackleFlat.jpg Relocating the front mounts upwards and backwards has had a disastrous effect on the ride height and rear shackle geometry. As you can see the rear shocks are almost fully compressed and the shackles are nearly hitting the chassis. The car is currently sitting about 75mm lower at the back than it did when I started. To a certain extent, lowering the ride height is good because it lowers the centre of gravity. As I removed so much junk from under the floor, ground clearance is still considerably better than it was when I started. Moving the shackle mounts backwards and downwards will restore the correct geometry and increase the ride height a bit. More importantly it will increase the clearance between the axle and chassis. The shock mounts will have to be relocated above the chassis rail. This will result in two bumps in the floor but I can't see any other solution to the problem.


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