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(83 votes) Published: Nov 19, 2007 4:52 p.m. In 2 Favorites Lists Viewed 499 times
A common issue with cars today is the difference in wheel hp and engine hp. Hp and Torque is only useful if it makes it to the wheels. A car can be 300 hp out of the engine but only making 250 hp at the wheels due to resistance in the transmission, engine rock, differential resistance and strain as well as clutch slippage. There are ways of decreasing this percentage reduction with less money than people realize.
If you ever do a burnout in a luxury car or a street car with no serious performance mods, you will notice "wheel hop". This is basically when the wheel hops/skips over the ground and the suspension loads/unloads rapidfire. Its rather annoying. If you do alot of burnouts with a Town and Country minivan or an old bonneville, you will break CV joints, ruin axles and have transmission/synchro problems pretty quickly. Wheel hop is generally inevitable if you want the car to ride nicely and have no dashboard vibrations or rattles.
But if your car is a stick-shift and the transmission is designed for strain, than you can feel free to start making serious modifications. Heres where you can feel it...
This is the stick shift and shift linkage of a Volkswagen Corrado. The shift linkage is how you know that the engine and transmission are both on a suspension system. Most people think that the wheels are the only thing on a suspension system but this is very wrong. Start up your car with the hood open, does the car shake simultaneously while the engine shakes? No, this is because the engine is mounted to fluid filled pieces of rubber (similar to a fruit gusher) which gives cushioning between the engine and the car chassis. This is why the wheels hop. Although the suspension can move up and down, the engine can move up and down at a different rate from the suspension. When the engine moves up and down or shifts, it gives uneven weight distribution between the wheels and the transmission with the engine can actually articulate at unusual angles (usually only a few degrees) and make unusual changes in torque and weight on each wheel.
Solid Motor Mounts reduce this problem. I cannot say that they eliminate it completely because if you have blown shocks and sagging springs, than you will do terrible jumpy burnouts and ruin your balljoints, tie rod ends, cv joints and your transmission. Wheel hop is bad in an automatic transmission because the torque converter is designed to handle all of the strain. The torque converter can handle usually up to a 3000 rpm difference in engine speed from transmission input shaft speed. When the wheels hop, they are stopping/increasing the transmission input speed and increasing strain on each gear too quickly for the engine to respond to and ends up wearing out synchromesh plates and can actually ruin the turbines in the torque converter.
Solid motor mounts reduce the amount of free-play in engine/transmission movement. Upgrading from fluid-filled mounts to solid rubber mounts will be a good improvement for a 25% increase in power and generally will be good enough for the everyday driver that just wants a little more power and better handling out of his car. PolyUrethane mounts are a step up. These dont decompose/crack and they are a little stiffer but still give freeplay for vibrations. Under extreme stress, they will still give in and reshape to allow transmission articulation. Wheel hop causes traction loss, reduces wheel torque and can cause serious engine damage in direct drive (stick shift) applications. The difference between fluid-filled economy motor mounts and solid ones is that when the driver stabs the throttle from a cruising start, the motor doesnt need to torque down onto the mounts in order to make the wheels move. IF a man jumps from a building with a bungee-cord on, he doesnt feel the full force of slowing down because there is free-play because of the elasticity. IF a man jumps from a building with a rope tied to his leg, he will stop suddenly and feel the full force. A solid motor mount will give the full force, torque and power that the engine is putting out at the very moment that the clutch is released.
The mounts in my car are Solid Billet Aluminum. These are the last step that you can go to for performance motor mounts. They have no free play and they have no flexibility or rebounding characteristics to them. My particular motor has 3 motor mounts like most do. Alot of front-wheel-drive cars have 3 mounts. They have a front mount which goes on the front side of the transmission and attaches to the front subframe, they have a "tranny mount" which attaches to the backside of the transmission and bolts to the rear subframe, and they have a rear mount that bolts on the backside of the engine black and bolts to the other side of the rear subframe.
Those were transmission mounts that hold the transmission sturdy against the subframe/chassis.
Those were polyurethane-filled VF engineering mounts for 1985-1996 volkswagen jettas, GTIs and Corrados. They are the transmission mounts that are more of a sport rating rather than street or race.
I know this next picture is small, but it is the front motor mount in my car. This is a race mount that has no freeplay.
The other advantages to having solid motor mounts is that the shift linkage will not bind up while you are accelerating extremely hard. Manytimes with FWD cars, if you accelerate quickly in 1st gear uphill, when you shift into 2nd gear, you will grind the gear or jam the shift linkage. What happens is the nose of the car rises so high that the engine and tranny lift up and shift linkage is no longer aligned so it stretches out and cannot make the right reach to shift into the gear correctly and fully engage the gear. With solid motor mounts, your shift linkage bushings will not only last alot longer and your shift pattern wont become sloppy over time but your transmission will last longer in Manual shift cars and youll be able to shift alot faster and dump the clutch without risk of ruining a motor mount or bracket.
An Aftermarket Front mount are needed for 25% increases in power.
A Race front mount along with a rubber/Poly tranny mount are needed for drag racing so that no freeplay is allowed so you snap an axle or ruin your tranny.
A Race Front mount along with a solid Poly tranny mount and a poly/HD rear mount are needed for anything expanded such as drifting, AutoX and Rally. This will reduce the total rocking of the entire engine and keep the weight from shifting around and fucking with the distribution of weight, power and traction on each wheel.
The difference IS felt. When you go for a ride in a really fast car that just seems to pull hard the second that the driver lets out the clutch, it probably has solid motor mounts. Solid mounts will cause the dashboard to rattle like a motherfucker and shake everything inside the car. So it feels like a little gokart but it gives just that little edge during racing and makes your drivetrain more reliable overall. Each mount only costs $40-$50 and manytimes people can convert their original mounts over to PolyUrethane mounts by gutting out the rubber and filling it with their own Home Depot Chemicals.
VOLKSWAGEN TIP OF THE DAY!
And As for that First Corrado Shift linkage picture i posted up top... There are 2 screws that VW left out. this is true for most VWs with stick shifts. They arent necessary but if you want to have cleaner shifts and be able to shift faster, you can get two 8mm screws and install them. What they do is VW left the 2 screws out because it is a universal part for Passats, Jettas and GTIs and they thought they were going to use it in another model so they wanted to make a few different shift linkage bracket holes for different cars. But they didnt end up having tons of different cars that the shift base was used in. So if you install those 2 screws, than it makes the base bolt into the floor of the car alot stiffer and it makes it so it wont shake or anything. You wont have any shift linkage alignment change under wheel load and you can shift alot faster. The 2 holes are seen on the picture underneath the shift rod. They are on the black bracket and have no screw going through them. The hardware costs $.06.
Nov 19, 2007 4:58 pm - if you want to feel the engine moving within the engine bay, put the car in 1st gear and drive it down the street. Hold your hand on the stick shift but dont shift it out of gear. Ride the clutch out and keep the clutch engaged. Hit the brakes with the clutch engaged while keeping your hand on the stick shift. The shifter will move around forward and back because the engine/transmission are moving forward and back which makes the shift linkage change its alignment and makes the whole shift pattern go out of whack. My car has no shifter wobble in any gear with any strain on the tranny because the engine and tranny are held in place with 3 solid hunks of billet aluminum. My dashboard shakes like a whore in church.
Nov 19, 2007 5:01 pm - when i said that rubber mounts are good for a 25% increase in power, what is meant is that this modification should be done once you have increased the power of your engine by 25%. Modern cars are designed to be modded and increased in power by 10% but once you do more than that, you end up breaking drivetrain and suspension components. If you double the power of your motor, you should use solid aluminum mounts. The actual power increase as a result of this mod is only instantaneous and just decreases the time it takes for your car to do a drag launch and makes your 0-60 time 1/2 second quicker.
Nov 19, 2007 6:18 pm - i just wanted to make a car egg for once that is easy to understand, has great results, improves vehicle performance and drivability, is inexpensive and easy to install. The installation for a motor mount is generally about 10-15 minutes long so long as youre not retarded. You just lift the motor up a little with a floorjack, unbolt the motor mount and slide it out, slide the new one in, realign the bolt holes and bolt it down, then lower the motor back down. I had to rip all of my shift linkage out in one of my jettas because i couldnt get my rear motor mount loose to get to the tranny mount. that was a pain in the ass. I had to realign everything. I took a really hard corner while downshifting 3rd to 2nd, i hit a huge bump and floored it and the rocking and strain on my chassis ended up blowing out my motor mount and it gushed grease all over my shift linkage like a fruit gusher (like said before!!).
Nov 19, 2007 6:21 pm - when i blew out that tranny mount, my engine dropped down and sagged and it shook around and used the front motor mount like a hinge. It actually put a huge dent on the inside of my hood point outwards. My intake manifold smashed into my hood and warped it. I actually bent one of my tranny mount brackets at a 30 degree angle when i did that. Welders are always good.
Nov 19, 2007 6:26 pm - thats what happens when you run 340 hp through the stock drivetrain and suspension. Import Drag racers constantly break motor mounts and CV joints because their drivetrain is stock and their engine is all Nitroed up. I always install solid motor mounts BEFORE i even THINK about doing serious engine modifications. AAA refuses to cover me since i had them tow my car 3 times in 2 months after i broke a control arm and snapped the subframe in half once, ruined both CV joints simultanously and i blew out my tranny mount, dented my hood and scraped my oilpan on the pavement at 55 mph around a hairpin turn. I only spilled 4 quarts of oil but the EPA still made a huge stink about it and charged me $1600 for an environment contamination cleanup. $45 on good motor mounts will save you from the $70 it costs to get towed every time you rip your drivetrain to pieces from getting throttle happy.
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