10.5" Sintered Iron Long Style Clutch Assembly

I thought I would take a little bit to show everyone what a basic rebuild looks like and what changes can be made to effect the different setups.

To start off with let me explain the uses and pros/cons of the Long Style clutch. There are 2 versions, counter weighted and non counterweighted. Also you can go to dual disc as well.

Basically the Long Style or "Softloc" type of clutch is good for applications that are in need of being able to control the slippage of the clutch througout a given rpm range. To really take advantage of the counterweight and base you need to run some type of data logger, however it isn't 100% necissary. The data logger can show you if you need to add or remove counterweight or base. Understand that a clutch is effected more by rpm and the chassis's ability to hook than by the horsepower.

FOR EXAMPLE - If you are launching a car at 5000 rpm, and you are shifting at 7500, then we will conclude your engine makes it's best power just under 7500 rpm. So the quicker you can get the engine to that rpm range and keep it there... the faster and quicker you should be able to run. When you look at a long style clutch that doesn't have counterweight, you are relying on the springs to hold the SAME amount of pressure on clutch through the entire run. This means you pretty much have to lock it up at the hit and there is no slippage during the run. With a counterweighted version, you would be able to start with less base, allowing the clutch to slip, but as the engine gains rpm the counterweight has more leverage and is able to apply more and more pressure to lock it up. This is why short shifting with this type of clutch can hurt the run, because you didn't give the counterweight enough time to lock up, which causes the clutch to slip accessivly during the shift and it is hard for it to catch back up.

The clutch shown here is a RAM Single Disc 5135 disc sintered iron Long Style clutch with counterweighted fingers. In this build we changed the fingers to a type that allows for more adjustability as well as lightened and rebalanced them. Making the fingers light doesn't mean as much as making the balance correct. If you have the finger weighing more on the inside of the pressure plate, than on the counter side, then it takes more counter to do the same job, which allows for greater adjustability in lower hp and more traction applications.... which are common!

Above you see all of the parts and pieces layed out for this clutch. There are springs, levers, pins, yokes, disc, flywheel, pressure ring, and hat, as well as base adjusters.

To start off we go through and clean everything up as best as possible and inspect all pins and levers that they are not seeing excessive wear. Often times we can chuck them up in the lathe and polish them, so that the customer doesn't have to spend extra money. Then we surface the faces of the flywheel and pressure ring as well as cut the clutch disc with the diamond cutter on the clutch machine. It is highly important to be sure that all surfaces are flat before you begin.

Here is a picture of the flywheel before any surfacing has been done.
You can see that there is a a little bit of heat spots towards the inner circle... This is normal and is not a bad looking start. It is showing that it is wearing across the entire flywheel, however that could also mean (which in this case does) that the disc itself was wearing in a certain pattern that matched the flywheel.

When we took a machinists straight edge and looked at the flywheel, you could tell it was definately high on the outside edeges, and very low in the middle as seen below!

After surfacing the flywheel and getting it flat, we mic'ed it and felt it was good enough for one more go before the heat shield would need replaced.

This meant it was time to look at the disc and upon inspection it was definately wearing more on the outside of the disc than in the middle, and we used a new disc. I was able to cut the previous disc, however it was down so thin that it wouldn't last long and would require a lot of shiming to make it right upon setup. As well as it wouldn't last more than 15-20 runs.

Upon replacing the disc we also replaced the pressure ring on the hat, however most times a simple resurface is just fine. In this case the customer wanted a new one, so that is what we went with.

Now that all of the surfaces are flat we can begin assembly. We cleaned and repainted the pressure hat, as well as polished the pins, lightened, and rebalanced the fingers. To start assembly we take the pressure ring and place the springs (in this case 360 lb / yellow) in the spring cups.

Then we place the base adjusters ( 2 part - Aluminum base piece with steel bolt) into the tops of the springs. As well as re-insert the fingers with the yokes attached along with new codder pins and polished shafts.
Now it is time to add the hat to the pressure ring. The best way to do this is to place the pressure ring on top of the disc and flywheel, then lower the hat down onto the springs and line them up, dropping it down onto them. By slightly starting the nuts to hold the had onto the flywheel you can compress the springs a bit which will help you get the bolts through the cover and into the yokes of the fingers... However, this is where setup begins. How you shim the fingers makes a great difference in how the clutch will work. By placing shim stock under the hat between it and the top of the yoke, you can raise or lower the levers. You measure this distance by placing a flat edge across the inside edge of the hat, and using a mic, measure the distance down to the edge of the finger at the lowest point. In this case we added to the typical setup and made the fingers slightly lower to start with releasing a bit of pressure.

Here is a Die we use for stamping out our shim stock...
Once we have the fingers approximately where we want them we can lock it all down... however we also had to calculate the shims that are placed under the hat. By placing more shims there, you are putting less base pressure on the disc initially. However as the disc wears it will require the user to slowly add more and more base to the clutch in order for it to perform the same way. This is where a Full Billet Adjustable Pro clutch comes in and we can adjust the stands which adjust for the wear of the discs and floaters.

Here we have the clutch before the finger height has been set or the cover bolts put into place.

And the finished product with everything set and ready to roll here.
I hope some of you find help with this, and if there are any questions or interest, please don't hesitate to ask!

We will soon work on a pictorial build with Pro Billet Fully Adjustable setups too.



Cale Aronson