Frequently Asked Questions is the place to find answers to the most common questions we are asked – if you don't find what you need, contact our technical services at (714) 630-3668.
• MCLEOD'S PRODUCT TRAINING GUIDE (pdf format)
• TOP QUESTIONS
• BELLHOUSINGS
• PRESSURE PLATES
• FLYWHEELS
• CLUTCHES
• CLUTCH DIAGNOSTICS
• ENGINE TRANSMISSION CONVERSION
• DISCS
• HYDRAULIC THROWOUT BEARING
• STREET TWINS
TOP QUESTIONS
Q. What clutch do I need?
A. There are many different vehicle combinations out there. Depending on horsepower, gear ratio, tire size and driving styles, McLeod has a clutch for you.
Q. At what horsepower do I need a Street Twin clutch for my car?
A. About 500 to 600 HP and above or when slicks are used.
Q. Can I use my flywheel with the McLeod Street Twin?
A. No. The McLeod Street Twin is designed around a special flywheel to allow it to fit inside a stock bellhousing.
Q. Does McLeod make a SFI approved Bellhousing for my car?
A. McLeod makes SFI approved Bellhousings for, Chevy, Pontiac, Oldsmobile, and Ford. Chrysler and AMC coming soon.
Q. What series Hydraulic T/O bearing do I need for my car?
A. McLeod makes two different styles of hydraulic T/O bearings. The Slip On version (1400 series) requires 3.0” of clearance between the face of the transmission and the tip of the pressure plate fingers. If there is not enough clearance, then you can use McLeods Bolt On Hydraulic T/O (1300 series).
Q. I have an early Chevy and I want to install a T-56 transmission to it. Does McLeod make an adapter for this installation?
A. McLeod makes an adapter plate to mate a T-56 transmission to your stock bellhousing. McLeod also makes Modular Bellhousings for Chevy, Pontiac, Oldsmobile and Ford small and big block engines, to fit a variety of transmissions to these engines, including the T-56.
Q. I want to install a Richmond Transmission into an early Camaro. Does McLeod make a clutch for this conversion?
A. Yes. McLeod makes a clutch conversion for most any engine/transmission combinations.
Q. Which Flywheel should I use on the street, steel or aluminum?
A. Most of the time, we recommend a steel flywheel rather then aluminum, because the weight of the steel flywheel helps move the car from a stop light and it also dampens the impulse of the engine, making a smoother idle. The aluminum flywheel is good for racing, when engine braking and hard acceleration out of a turn is desirable.
Q. How much T/O bearing travel is required to release a McLeod Street Twin?
A. All of McLeod Street Twins are checked with .500” bearing travel to check for proper clearance between the pressure plate and disc.
Q. Do I need to resurface my flywheel, when changing my clutch?
A. Yes. McLeod recommends that you resurface the flywheel when installing a new clutch, so that disc can seat into the flywheel. Just as you would resurface the rotors on your car when doing a brake job.
Q. What size Master Cylinder do I need in order to work with the McLeod Hydraulic T/O bearing?
A. McLeods Hydraulic T/O bearing is designed to use a 3/4” bore master cylinder. You can also use a 7/8” bore master cylinder to get a little more travel, but this will increase the pedal pressure slightly
Q. What type of hydraulic fluid do I need to use in my McLeod Hydraulic T/O bearing?
A. McLeod requires DOT 3 brake fluid ONLY.
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BELLHOUSINGS
Q. Does McLeod offer SFI Certified Bellhousings?
A. McLeod makes SFI Certified Bellhousings for Chevrolet, Buick, Oldsmobile, Pontiac, and small block & big block Ford engines. Chrysler to come soon.
Q. Does McLeod offer a Bellhousing to swap a Tremec TKO 5 speed or a Tremec T-56 into an earlier car?
A. McLeod has a modular Bellhousing to fit most transmissions to any GM V8 and some V6 engines or Ford engines. These Bellhousings come with all the hardware needed to bolt up the transmission and meet SFI specifications.
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PRESSURE PLATES
Q. What is static pressure?
A. Static pressure refers to the amount of base pressure, in pounds, exerted to the pressure ring by the internal springs when engaged.
Q. What is centrifugal or roller assist?
A. Certain McLeod pressure plates feature centrifugal assist for increasing pressure plate load to prevent slipping and high RPM plate/disc separation. The Borg & Beck design utilizes rollers inside the cover that are forced to the outside under centrifugal force to increase plate load as RPM increases. Certain Long-Style pressure plates use levers that have extra weights on the levers to provide centrifugal assist.
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FLYWHEELS
Q. Should I use an aluminum or steel flywheel?
A. Aluminum flywheels with their lighter weight, are typically used in oval track and road race applications and are also popular in high horsepower, light-weight drag cars. These vehicles rely on engine horsepower to drive the wheels. Steel flywheels are used when additional engine torque is required for performance. A heavier flywheel can help acceleration from a standing start and add power up through shifting. These are characteristics needed in street, most drag race and other high-torque applications.
Q. What is the difference between Neutral (internal) Balance and Detroit (external) Balance Flywheels?
A. Neutral (internal) Balance engines and flywheels are each balanced as an individual unit. In other words, the engine and flywheel balance with or without the flywheel mounted to the crankshaft. A counter balanced engine uses the flywheel to balance the engine. With the flywheel off of the engine, both the engine and flywheel are out of balance. Mcleod offers a complete line of flywheels enginereed to allow the out-of-balance weight to be bolted on or unbolted, depending on what the application calls for.
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CLUTCHES
Q. How should I adjust my clutch?
A. First of all, be sure all mounting fasteners are torqued correctly, this is very important. The actual adjustment will vary depending on the type of pressure plate being used. With the clutch pedal completely depressed, a diaphragm should have .030-.040 air gap between the disc and the flywheel. For a Borg & Beck the air gap should be .040-.050 and for a Long-Style pressure plate it should be .050-.060. On linkage, with the pedal released, an air gap of .250" should exist between the throwout bearing face and Pressure Plate fingers. On cable and hydraulic applications, the throwout bearing face should rest lightly on the pressure plate fingers.
Q. Should my McLeod Clutch be balanced before installation?
A. No, all McLeod pressure plates and flywheels are dynamically balanced to extremely close tolerances. However, if you are having the engine assembly re-balanced, it would be a good idea to include the clutch components to insure tolerances be as tight as possible.
Q. Can my McLeod clutch be rebuilt?
A. McLeod can rebuild our Borg & Beck and Long style pressure plates, clutch discs and flywheels.
Q. I have an engine that makes 700 hp and I drive it on the street. What clutch should I use?
A. The McLeod Street Twin was designed for the high horse power cars on the street and vehicles that are pulling a lot of weight.
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CLUTCH DIAGNOSTICS
Q. How important is proper bellhousing alignment?
A. Bellhousing alignment is crucial for proper clutch function and reliability of the related components. Due to manufacturing tolerances of engine blocks and bell housings, it is possible for the transmission centerline and crankshaft centerline to be misaligned. The result of this misalignment may result in hard shifting; pilot bearing/bushing wear; transmission main shaft bearing wear; and/or failure of the clutch disc hub (pleas refer to the vehicle's factory service manual).
Q. What parts in the clutch release system/linkage should I inspect before installing a new clutch?
A. All related clutch parts should be checked for wear or possible problems. The clutch linkage starting from the clutch pedal crank (Z-bar) to the clutch fork and pivot ball or point should be inspected for wear or damage. Any questionable parts should be repaired or replaced. If your vehicle uses a hydraulic release system, check for any hydraulic leaks as well as wear on the push and pull rods operating the hydraulics and all hoses. Hydraulic systems, especially systems with high mileage, may have internal leakage beyond als. Keep in mind these leakages are difficult to diagnose because there may be no external leakage. It should be checked for damage, stretch, excessive resistance or binding. If any of these conditions are found, replace the clutch cable. Refer to the vehicle's service manual for factory specifications, regardless of the vehicle's linkage type. Always inspect the throwout bearing collar for signs of wear and galling.
Q. What could be the causes for clutch judder (chatter or shudder)?
A. Judder can be the result of any number of problems. Possible causes may be as follows:
- Improper break-in procedure.
- Flywheel was not properly resurfaced before the new clutch was installed.
- Flywheel is not parallel, or the friction surface is out of parallel with the crank flange surface.
- Flywheel has severe hard spots or hot spots.
- Flywheel has an improper step or cup dimension.
- Damaged or excessively worn CV joints.
- Bad u-joints in driveshaft or u-joints misaligned.
- Excessive backlash in differential.
- Excessive driveline angle.
- Bad leaf springs, bushings or mounts.
- Improper gear ratio versus tire diameter.
- Defective pressure plate and/or disc.
- Disc has inadequate or no marcel--not enough cushion between friction facings.
- Oil or grease contamination on clutch facings.
- Worn or damaged clutch linkage.
- Bent cover assembly and/or disc.
- Improprely tuned engine.
- Worn or damaged engine mounts or transmission mounts.
Q. What could be the cause for improper clutch release?
A. Improper clutch engagement or disengagement (release) can be the result of any number of problems. Possible causes may include:
- Release linkage not properly adjusted or reset.
- Flywheel not surfaced before a new clutch installed.
- Flywheel surfaced improperly--incorrect flywheel step or cup dimension.
- Flywheel machined too thin or not manufactured to stock (OEM) specifications.
- Release linkage worn or damaged.
- Hydraulics defective, leaking or air is trapped in hydraulic system.
- Release linkage cable stretched or damaged.
- Improper clutch fork geometry due to flywheel being too thin or bellhousing deeper than stock.
- Improperly adjusted pivot ball.
- Clutch disc installed improperly (backwards).
- Clutch disc hitting flywheel bolts.
- Clutch disc binding on transmission input shaft.
- Input shaft bent, causing clutch disc runout.
- Pressure plate assembly and/or clutch disc bent or damaged.
- Clutch disc is too thick or has excessive marcel.
- Pressure plate has defective or damaged drive straps.
- Damaged, worn or improperly installed pivot bearing/bushing.
- Damaged or worn throw out bearing collar.
Q. What are the possible causes for clutch slippage?
A. Clutch slippage may be the result of any number of problems. Possible causes may be as follows:
- Improper clutch adjustment.
- Improper release linkage adjustment–reset factory release linkage, where applicable.
- Incorrect throw out bearing–too long or too short.
- Clutch assembly contaminated with grease or oil.
- Clutch assembly not fully seated in–improper break in procedure.
- Flywheel not properly resurfaced and clutch disc is glazed.
- Clutch assembly not designed for the vehicle.
- Clutch assembly not designed for the specific type of use (racing, competition, etc.).
- Clutch assembly not adequate for the vehicle's power.
- Incorrect gear ratio to tire diameter.
- Clutch disc has broken or missing friction material.
- Clutch assembly has failed or is defective.
- Flywheel improperly resurfaced.
- Damaged or worn throw out bearing collar.
- Damaged or bent clutch assembly.
Q. What are the causes of poor shifting quality or notchy shifting?
A. Poor shifting may be the result of any number of problems. Possible causes are as follows:
- Improper clutch release caused by faulty linkage and/or improper release linkage adjustment.
- Improperly installed shifter.
- Improperly adjusted shifter or shift linkage.
- Damaged transmission parts–bent shift fork.
- Worn transmission synchronizer rings.
- Improper transmission lubricant–check factory service manual for proper fluid type and viscosity.
- Pilot bearing/bushing binding on transmission input shaft.
- Clutch disc hub spring pack hitting flywheel or flywheel bolts.
- Damaged or defective pressure plate drive straps.
- Bellhousing misalignment.
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ENGINE TRANSMISSION CONVERSION
Q. I have a T56 6 speed out of a 1993 - 97 Camaro. I want to install it behind an early Chevrolet engine, but the input shaft is too short to reach the pilot bearing. What should I do?
A. This transmission has a pull to disengage clutch in the orignal Camaro. If you are using the pull clutch then you will have to mount a master cylinder on the firewall to the pedal to activate the slave on the bellhousing. If you are converting to a push to disengage clutch, then you will have to use a hydraulic throwout bearing and may have to change the flywheel at the same time. For any adaption, it is better to talk to our tech department for more complete details on making these adaptions.
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DISCS
Q. Why are there button type facings and full type facings and what do they do for my car?
A. The different type facings are used to accomplish different functions in the vehiecle. The principle of a button facing, works on psi or pounds per square inch. This gives you a harsher engagement when the pressure in the pressure plate is constant. The full facing would be less harsh or smoother engaging when using the same pressure. The full facing works on the principle of square inches and gives you greater holding power for torque. The best combination is to have a button type facing on the flywheel side for positive lock up and a full facing on the pressure plate side for a smooth engagement.
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HYDRAULIC THROWOUT BEARING
Q. Which hydraulic throwout bearing should I use, the slip on or the bolt on?
A. While both are equal in quality and workings, there is a difference in how they fit into the bellhousing. The slip on is adjusted before you install and the bolt on is sent with the correct piston length for installation. Slip on bearings will not fit into the bellhousings and have the proper clearance unless you have approximately 3" from the outside surface of the bellhousing down to the crown of the fingers of the pressure plate. Bellhousings that are 6.5" or less, usually will not have this clearance. Always measure before ordering. Bolt on models will replace your current front input collar and will have an oil seal installed from the factory.
Q. What do I need in order to install a hydraulic throwout bearing?
A. You will need a master cylinder if the vehicle does not have one already. The master cylinder will connect to the hydraulic throwout bearing with a line. Steel braided teflon inner lines are preferred. Before you are connected, be sure your master cylinder has a bleeder on it. Bleeding should be done first at the master cylinder and then the bearing, then the master and then the bearing again.
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STREET TWINS
Q. How much horsepower will McLeod’s Street Twin hold?
A. McLeod’s Street Twin will hold up to 1000 hp with street tires. If you are going to use slicks, we can change the disc to handle over 1500 hp and still be street-able.
Q. Will the Street Twin fit inside a stock bellhousing or will I have to get a steel aftermarket bellhousing?
A. Yes our Street Twin is designed to fit inside a stock bellhousing.
Q. Can I use my stock clutch linkage with McLeod’s Street Twin?
A. On most cars you can use stock linkage. On cars with cable linkage the fork may need modifying. We make a modified fork for Ford vehicles.
Q. At what RPM’s can I shift, with the Street Twin?
A. We have customers shifting over 8000 RPM’s.
Q. How stiff is the pedal with the Street Twin?
A. Because we use a performance Pressure Plate, some customers may experience a little more pedal pressure, but not much.
Q. What vehicles do you offer the Street Twins for?
A. We offer the Street Twins for Chevy, Ford, Pontiac, Oldsmobile and Chrysler vehicles
Q. I sent my Street Twin out for balancing, and when I got it back, it was all apart and I lost my instructions. How do I reset up my Street Twin to factory specs?
A. Unit is shipped to you ready to install; if unit has been disassembled for balance or is being re-installed again, see instruction.
SPECIAL INSTRUCTIONS
Allow 500 miles break-in before hard driving.
When performance driving, all traction control devices must be turned off or clutch slippage can occur.
- Look unit over before disassembly.
- Unbolt pressure plate, remove nuts (Note, Blue stripe on p/p, floater and flywheel. This is how unit should be re-assembled).
- Remove top disc. Note: hub points toward the trans. Re-assemble this way. 4. Unbolt (3) three bolts that hold floater (Note: strap-on floaters are on the flywheel side. Floater must be re-installed this way.
Special note: Three (3) floater straps, stands and assorted shims. Keep the same amount of shims and the same thickness shims with each stand. Set aside each stand and shims with its own bolt. This prevents mixing or loss.
- Remove bottom disc. (Note: Hub points toward transmission. Also re-assemble this way.)
- Hand thread (6) 3/8 –24 twelve point nuts back on the (6) studs so you won’t lose or drop pressure plate stands and shims.
- Install flywheel on crank. Torque to factory specification.
- Once flywheel is installed on engine, you can now remove (6) 3/8” rod nuts from the p/p studs.
- Re-assemble unit, check disc hubs and floater strap direction. Blue alignment stripe on all parts must line-up.
- After installing bottom disc and floater plate, use a feeler gauge to check the clearance between them. .020-.025 should just slip in between. The bottom disc should just turn by hand with little front to back movement. This is checked with the flywheel turned up on its edge not lying flat, if too much gap is present (over .025) the floater will push the top disc into the pressure plate, eliminating release. If there is not enough release (less than .020) the bottom disc will drag on the flywheel and floater, and it will not release.
- Torque three (3) floater strap bolts to 25 lbs max. – red lock-tite is advised.
- Torque six (6) pressure plate nuts 35 lbs. Max. No lock-tite.
- Finish installation of bellhousing & transmission
Also, the shims used may be different thickness, keep them in sets.
Note: On Chrysler cars with helper spring under dash, remove spring completely. Allow more free play at t.o. bearing than normal, checking that car goes in reverse, from neutral, without grinding.
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