50mm Passenger Side Belt Setup|
W/Custom water pump assembly
and Custom Idler assembly
(click on images to enlarge them - any image on the page)
I have gone through more belt drive assemblies than any person really should ever have to do. The nice part is after all the changes I have learned a ton and found a combination that really works. The problems all started when I converted to a cog drive setup. I started with a set of 30mm wide pulleys made by ASP that worked well but didn't really hold up that long at the track. I found that on the dyno I would destroy a belt every 4 or 5 pulls and on the track a belt would not even make a single pass. My Vortech YSi Trim supercharger making 22lbs of boost was just too much supercharger for a 30mm belt.
I searched for a better system and found that the Vortech cog system was 35mm wide. Another 5mm may not sound like a lot but with the Vortech setup my dyno life was double but the track results were still rough as I would waste a belt about every pass. It was determined at this time that my bracket was flexing and causing the belt to slip off the front of the pulley. I spent a long time deciding how to fix this problem and eventually ended up with a SCH Renegade Bracket setup. This bracket and tensioner system once again doubled my belt life and now I was able to make it through the traps at least a couple times before I lost a belt. This was the configuration I ran with at the Hot Rod Magazine Pump-Gas Drags.
I was still not happy with the system as belts get very expensive. An average day at the track would result in 3 or 4 destroyed belts and at $100/belt that gets pretty expensive! After talking with some racers and a distributor of industrial belt drive systems we decided that part of the problem was the tensioner on the drive (torque) side of the belt. Because of the passenger side setup and size constraints it was impossible to completely remove the upper idler but I found I was able to modify the SCH bracket to accept a lower fixed idler (dual idlers). This system worked extremely well but I was still going through a belt or two every day at the track.
Eventually I decided to try a 50mm cog setup that was completely custom. Nobody makes a 50mm passenger side system for a Vortech supercharger so I had to have one custom made. After working with both Vortech and ASP I combined the Vortech upper pulley and idler with a custom ASP drive pulley.
Getting a 50mm drive setup to fit on a Mustang is not easy. To make the system fit a lot had to be changed. Luckily for me most of the changes I had already done in previous work to allow other parts to work properly. The changes to make the 50mm setup fit included.
When the 50mm cog setup first installed I loved the "cool' factor. A 2" wide belt is pretty damned big and it looks really aggressive sitting on the front of the engine. I was surprised however that I was losing belts even more frequently than with either of the other setups. After some intense diagnosing it was determined that centrifugal force from the larger 50mm belt at high RPM's would bow the belt out and it would hit the water pump pulley. After analyzing this situation I am sure that was also causing problems with the 35mm belt but was made much worse with the larger belt and the 75 -vs- 73 tooth crank pulley.
After more research I found a manufacture that could make me a custom water pump that was 1.5" shorter than a factory pump. This pump was made by taking a new housing and milling down the end of the pump-snout and modifying it to accept a larger front bearing. The inner bearing was also replaced with a heavier duty unit and the internal seal was an improved design. The impeller design is unique to this manufacture and offers 40% more low RPM flow than a stock pump. At high RPM the flow is still greater than a factory pump but not so much that it stresses the gaskets or pump seal. To give you an idea this is the same pump that Ford Racing offers as a standard rotation pump for street rod use. The difference is the pump I had made has the reverse rotation impeller design and a slightly different snout (for my application).
The next step was to make a new pulley to fit the new water pump. The shorter shaft design provided plenty of clearance for the belt but a stock pulley would not fit. I searched many wrecking yards trying to find an appropriate pulley but finally had to have one custom made at D&G Motors. The pulley started as a piece of 4" raw aluminum stock and was turned to size on a metal lathe then had the holes precision cut on a bridgeport milling machine. The final product is amazing looking and works very well. you will notice that the pulley is way wider than it needs to be. For now I plan on leaving it this size so I can make any other changes without having to cut a new pulley. Eventually I will cut the pulley down to a size just larger than the width of the serpentine belt.
*** Sales Plug ***. After having this pump an pulley designed I don't know why anyone building an 87-93 Mustang wouldn't use this setup. The water pump is an awesome design, the pulley looks really trick and works very well, and the room you gain on the front of your engine will make working on everything very easy. Even if you are not running a supercharger I would run this setup. I am working with D&G Motors to make the pump/pulley combo available to anyone who wants one. We are estimating a final price of $275 which is a great deal. The pump alone is worth $160 through Ford Motorsports (without the modifications for reverse rotation) and an aluminum pump pulley typically retails for around $100. When you factor in that these parts are custom you are getting a trick setup for the normal price of general parts - that doesn't happen very often. Note: This system would be perfect for those trying to run an 8" crank pulley (serpentine) or a 74 tooth or larger cog pulley. You will not have any problems with the supercharger belt hitting the water pump anymore!
The next problem to overcome is the fact that every Mustang passenger side supercharger mount puts the idler on the drive side of the belt and that the idler is on the back side of the cog belt. If you look at any race application cog setup you will see the idler is always on the cog-side of the belt. The reason is cog belts are molded in a process that bonds the cogs to a normal belt with a nylon-type mesh. This design is not setup to be bent backwards as is caused by running the idler on the back of the belt. This separates the cogs from the belts and will eventually cause all the cogs to rip off (I have a big collection of cog belts with no cogs - LOL). The problem is you had to have the idler on the back of the belt with a passenger side setup due to the water pump interfering with the belt. With the new pump/pulley combination this is not a problem.
The second problem is the idler is on the power side of the belt. What this means is the crankshaft turns clockwise (while looking at the front of the engine) and the idler is between the crank pulley and the supercharger pulley. This means the whole force of the rotation is applied to the pulley. Look at any race car and you will see the idler is NEVER on the drive/power side of the belt. The problem is how do you move the idler to the bottom?
The first problem you run into is the idler (where the smog pump was) is now directly in the way of where this idler must move (with the tensioner hitting the pulley). The answer to solve this problem is machining the rear plate to counter-sink one of the bolt holes and then tapping and helicoiling a 1/2 20 insert close to the water pump to re-locate the idler. The nice part about this setup is it provides more belt wrap for the alternator. The downside is the belt is much shorter now so you have to go buy a new one - damn those things are expensive!
Now that the idler is out of the way a replacement front plate for the SCH Renegade bracket had to be made. A trip to Discount Steel netted a 1/2" thick 12" x 9" plate that was the starting point. Next we had to replicate the existing mounting system in the new plate and cut a modified tensioner mount that located the pulley on the bottom side of the belt. A cardboard template was made of the new shape and transposed onto the aluminum plate to help in locating the new location for the tensioner. Next the part had to be cut to final shape using a band saw and polished.
So, there you have it. The only proper passenger side cog setup I have ever seen. The process was not easy but I really enjoy fabricating new parts and solving the problems that most people would just ignore.
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