The past week I've noticed that while in 4th gear at a high speed of say 50 mph or more that my rpms will go up 500 or so without any effect on the speed. I have to carefully keep the gas pushed to the right spot so it doesn't occur. Its when I attempt to accelerate more in a sense.

Am I looking at a bad clutch. My OD on M46 works when cold but not after warming up. (I've got the rebuild kit waiting) Can the OD on a manual trans effect the 4th gear even when its not engaged? When I attempt engage the OD I sometimes sense that its slipping in and out. Meaning I have the light on but my rpms are at 3000 @ 65mph and if I let up on the gas the rpm's drop to 2500 quickly unrelated to speed. I can't be sure if this happens without the light on but I'm pretty certain that its only with the light on unless I'm climbing a hill.

Should I be looking at the clutch or OD or both?

Thanks

Correct the OD first than address the clutch.

I would venture you have more than one issue with the OD.

The increase of 500 RPM along with OK when cold but not when hot points to worn actuating piston O-rings.

Worn O-rings permitting excessive blowby would allow slippage under load due to low pressure failing to hold the slidng member tight against the brake ring. When this happens, the increase in RPM is limited by the OD unidirectional clutch locking up as it does in gears 1 to 4.

The slippage in 2nd may be related to the OD's solenoid holding the OD in ON mode even though there is no voltage applied. Given your symptoms as described, this would be more evident when unit is first driven than when hot.

The more pressing issue is the probability of the solenoid locked on. IF the worn O-rings hold pressure enough to keep the sliding member locked to the brake ring, reverse motion will cause internal OD damage.

Duane

Thanks for the help. Solenoid will be first thing to replace with one on a donor just a mile or two down the road from my house. Just have to get a friend to shave down my wrench.

If in fact I've been damaging the OD while in R then maybe its time I head down the street a couple miles and talk a volvo owner of a 78 wagon with a m46 in it to give up the car after its sat for 14 years. Only 150,000 miles on the transmission and OD. Not sure if the older years would cause me any issues but if I was going to drop it one day to save then maybe its time to just swap out trans and OD and hope the best with a new clutch and every other thing that one can do at the same time.

Tough to know. I've got the OD rebuild kit but I really need my new 90 245 to be running as a back up in case it takes me multiple days. But if I've harmed the OD by now maybe a swap out would be good. Although 14 years of an transmission sitting with fluid sounds like a lot of work and possible problems with the OD. yada yada

Thanks again for all the help. I'll try adjusting the clutch cable some more and think about getting some resolve sooner than later.

I have seen many overdrive units do what you describe - so it may very well not be the clutch on the flywheel.

Make sure the clutch cable is properly adjusted.
Dan

Bad (main) clutch.

I've got a new cable and have messed with the adjustment a bit trying to get it to engage not too far off the floor because if it engages half way then I get slippage in the second.

Is there more than one clutch. Main clutch as with pedal and secondary as in OD?

Thanks for the help.

only one clutch, and that one is slipping. Check for oil leaks when you do the clutch. That's the time to change the rear main and front tranny seal.
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