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83 242 Turbo Transmission Whine and Slip[240-260/83] posted by Robert Mohr on
Saturday, 2 May 1998, at 11:01 a.m.

I'm trying to clear up a few annoyances on this sweet little Flathood I just purchased. It has a 4 speed (+OD) M46 transmission.

There's a whine coming from the rear end that appears at about 70 mph. It's related to transmission load, i.e. when I push in the clutch, the whine disappears. It shows up at about 3000 rpm in 5th. However, the same rpm in 4th doesn't result in the whine. It doesn't appear to change as the wheels are loaded and unloaded as I take the corners in the road. It really does appear to be coming from the back of the car and not from the transmission. Any guidance greatly appreciated.

I'm a little new to Turbos, and my experience with driving manual transmissions has been my old 82 NA 244, but I've been having a real problem modulating the clutch in first gear. It seems to slip quite a bit, and, unless I rev the engine a bit to match it, the clutch "shudders" a bit until it finally hooks up. Do I need a new clutch? Additional shims on the cones in the overdrive?

I love this car! If I can get these two problems fixed, I'll cherish it!

Bob Mohr
1983 242 B21FTI "Flathood"
1992 245 B230F

Re: 83 242 Turbo Transmission Whine and Slip[240-260/83] posted by philip bradley on
Saturday, 2 May 1998, at 7:23 p.m.

The trans do whine or whir sometimes and you can hear it in the lower gears at slow speeds. Whine at higher speeds means there is a problem. The center driveshaft bearing could be shot, or maybe just the spring has disappeared. This may also be responsible for your problem leaving the line. A worn U-joint is also a likely culprit. The rear wheel bearings will also cause a whine when they begin to fail. They are expensive to replace. A differential that is low on oil can make noise. A burnt or cracked flywheel can chatter. Also check the clutch cable adjustment. Do the easy things first, like putting good synthetic oil in the rear and trans (Redline MTL in the trans and a synthetic in the rear -- use one for an LSD if you have one). Check the U-joints and center bearing.

The ODs are fine for stock tune. With significantly higher boost pressures, adding shims in the OD will increase pressure. I recommend going up by 100 psi. Remember that ODs do not last forever; typically 150,000 miles.

The stock clutch is fine for up to about 13 psi boost. After that it will slip. The flathoods have the early non intercooler clutch, but the flywheel is 7 pounds lighter. I recommend a Centerforce clutch as a replacement. Mine has over 130,000 miles on it with maximum boost set at 16 psi, and held up to a brief affair with nitrous oxide that broke the trans.

Philip Bradley --
Philip Bradley

Re: 83 242 Turbo Transmission Whine and Slip[240-260/83] posted by Steve Seekins on
Monday, 4 May 1998, at 10:45 a.m.

In addition to the drive shaft, do a thorough inspection of the rear suspension bushings. Worn trail arm and torque rod bushings will result in shudder and chatter.

As to the clutch, if you have to replace it, consider installling the flywheel and clutch from a late model 740 turbo as an alternative to the centerforce. These have larger diameter clutches and recessed flywheels - makes them run a bit smoother and the clutch holds up to the added torque of either some minor engine mods or the larger B2230FT engines.

The whine sounds a bit like a differential whine - does it change when you go from accel to deccel? Do you have any leakage from the diff pinion seal? You should also pull the rear brake rotors and check for evidence of gear oil indicating worn axle bearings and seals.
Steve Seekins,


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