FAQs about Manual Transmissions.

  • Should the flywheel be mirror like or pebbled like a curling rink?
  • Will a diesel tranny go into a gas car without modification?
  • Do I need to pull the engine to change the clutch?
  • Have not moved my car for a few months and now the clutch isn't working correctly, any help?
  • Why can't I shift from 3rd to 4th gear?
  • Clutch questions.
  • How can I sort of the transmission codes?
  • Do I need to use a special transmission fluid?

  • Should the flywheel be mirror like or pebbled like a curling rink?

    Date: Tue, 19 Nov 1991 14:50:57 PST
    From: Darryl_J._Edwards.Wbst311@xerox.com
    Subject: flywheel
    To: volvo-net@me.rochester.edu

    I want to assess whether my machinist did a good job. Since the silly twit lost the dowels and I had to go find new ones, I have grounds for suspicion.

    Should it be mirror like? Pebbled like a curling rink? (figure that one out, you guys in Hawaii) something else?

    Richard Loken VE6BSV : "In England, Justice is Athabasca University, Athabasca, Alberta Canada : open to all, like the tech@cs.AthabascaU.CA : Ritz Hotel." - Lord {atha|aunro}!cs.athabascau.ca!tech : Justice Sir James Mathew


    I believe the surface should have a finish characteristic of a mild grinding operation (no lathe marks -> grooves). The grinding does not have to be fine as a small amount of roughness is desireable. But it must be flat and parallel to the mounting surfaces. There will be swirl marks in the surface similar to what you might see on a resurfaced disk rotor. When you get it back you might like to (soak) clean it thoroughly with solvent before you install it. This will remove any cutting or lubricating oil that has permeated the surface (which will work its way out onto your disk surface ... aarrgghh!).

    It is worthwhile to do a check of the depth of engagement versus the clutch and disk (thickness) combination before you install it. If the flywheel is cut too deep you may have a problem. Not grabbing enough or improper angle, in the rest position, to the mechanism (whatever type you have) that engages the throw-out bearing --> noise, premature wear, different margin for adjustment, and possible interference to the proper action may result. A flywheel cut sometimes has a spec (maximum cut) like disc rotors do.

    Make sure those pins are the proper fit, length, and hardness --> no tolerance at all or a slight tap (diameter wise) to get them in or they wilst make a mess of the flywheel and crank.


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    Will a diesel tranny go into a gas car without modification?

    From: matula@cblpo.att.com
    Date: Wed, 29 Jan 92 07:57 EST
    To: <volvo-net@me.rochester.edu>
    Subject: Re: Transmission swapping

    A Diesel tranny does not go into a gas car without some modification.

    Reason: Bell housing is different. Starter on diesel (a.k.a VW/Audi "6000") is on passenger side. Starter on B23 is on driver side.

    Now, if you can find a gas bell housing, then they match right up.

    I have taken an automatic from a 1981 diesel (BW55), swapped the bell housing from the 1979 gasoline unit, and placed the result into the 1979 car. The torque converter between the two was different, so I had to swap the converter also.

    For the manual transmission, you might want to check if the clutch plate and pressure plate are the same. I seem to remember reading that the diameters are different by 1/2 inch. I'll look in my manual tonight for details.


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    Do I need to pull the engine to change the clutch?

    From: David Gingold <gingold@think.com>
    To: bever@erim.org
    Cc: volvo-net@me.rochester.edu
    Subject: clutch

    Date: Wed, 5 Feb 92 10:04:09 EST From: bever@erim.org (Dave Beverstock) I am considering replacing the clutch myself, as opposed to mechanic, in the 82 245. [...] Can I sleaze by by blocking up the engine near bell housing and dropping the tranny or do I need an engine lift ??

    You don't need to pull the engine. Manuals reccomend taking the bell housing and transmission off as one unit, but I've always taken them off separately. Disconnect the driveshaft, unbolt the transmission mount cross member, and jack down the engine a bit. You'll need a big allen wrench and some leverage to get the transmission off. You'll probably need a u-joint and a long extender to get the top bolts off of the bell housing. Having a spare input shaft helps you get the clutch lined up before you put back the transmission, but it's not strictly necessary -- you can adequately line it up by eye. You'll need an extra set of arms to remove and put back the transmission.

    Get a copy of the Haynes manual for your car. It's much better than Chilton or Clymer, and it will explain the whole clutch procedure.

    What other parts should I replace other than the engine rear main seal, throwout bearing, clutch disc, pressure plate, (cable is new), and pilot bearing??

    I'd leave the rear main seal unless it's leaking. (Mine leaks like hell, and replacing it didn't help.) The pilot bearing and throw-out bearing are good ideas. Get the throw-out bearing from Volvo -- it's all metal, and I presume less likely to disintegrate than the metal and plastic ones.

    I broke a motor mount once doing this. It may have been because I left the engine half-lowered for a week or so. With two of three motor mounts gone, I had to get an engine hoist to get things back together. But I bet that I could have replaced the mounts one at a time with only a jack. And since your motor mounts are ten years old, it might be time.


    Date: 29 Nov 92 23:36:05 EST
    From: Shel Hall <76701.103@compuserve.com>
    Subject: Jim Barnett's clutch

    Jim Barnett sez ...

    >>> I pulled the transmission on my 240 without much trouble (I figure I get a Red-Neck Engineering Merit Badge for getting my pregnant wife under the car to help me do it.)<<<

    Only if she's missing at least one front tooth.

    My wife helped me roof my shop when she was 7 months along, but she also rode her bicycle to the hospital to have the baby ... She's no redneck, though, being a city girl from Copenhagen; she's just tough.

    BTW, "Redneck" is one word, no hyphen.

    >>> 1. The fly-wheel looks smooth but is covered with dust from the clutch disk - is this ok? <<<

    Probably. If the disk has plenty of lining, no cracks, and the springs in the middle look OK (no play or cracks) then the disk is probably OK. If the pressure plate isn't blued, cracked, or scored, and its springs and release parts are not visibly worn or asymmetrical, it's probably OK, too.

    >>> 2. The input shaft to the transmission has 1-2 mm. play in it - is this good, bad, or irrelevant? <<<

    Is this play fore-and-aft or axial? If it's axial is probably irrelevant as long as the seal doesn't leak and the pilot bearing is good. The front cover bearing can't be expected to keep the shaft completely centered, given the weight and the lever arm the clutch disk has to work with; that's why there's a pilot bearing.

    >>> 3. How do I replace the pilot bearing? <<<

    If there's any physical restraint, like a circlip, remove that, then pack the hole in the center of the pilot bearing with grease and drive a dowel or straight drift into the p.b. hole; the hydraulic pressure generated by the punch and transmitted by the grease will lift the bearing right out. I've never fooled with the clutch on a Volvo gasser, but the pilot bearing is generally in the crankshaft itself. You shouldn't have to remove the flywheel to get it out with the dowel and grease method.

    Keep in mind, though, that the pilot bearing only wears when the clutch is disengaged (i.e. the pedal is down) so it's pretty rare to wear one out unless the car has mondo city miles on it. You could drive 1,000,000 miles on the highway and never wear the pilot bearing at all.

    In any case, if the pilot bearing is worn enough to let the tranny's input shaft get off center enough for you to feel a vibration, I'd expect the clutch to "butterfly" and drag like crazy, making bad shifting more of a problem than vibration.

    Any clutch/flywheel induced vibration will be at motor speed, of course, not road speed.

    I must have missed the original posting on the vibration; could you "review the bidding" and tell us (i.e., me) the problem and the measures you've taken so far?

    Good luck.


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    Have not moved my car for a few months and now the clutch isn't working correctly, any help?

    Date: Tue, 2 Feb 93 11:54:52 EST
    From: Dave Teichholtz <davet@ksr.com>
    To: swedishbricks@me.rochester.edu
    Subject: Re: sticking Clutch Woes

    (Bob, I tried to send this to you, but it bounced back with host unknown)

    <stuff about car not moved for a few months and clutch not working correctly deleted>

    I think your clutch disk is just stuck to the flywheel. I have had this happen on two different cars. What I did was to put the car in first gear, start it, let it move a bit, and then step hard on the brake. In both cases the clutch became unstuck, and worked fine afterwards.


    ------- End of forwarded message -------

    Date: 02 Feb 93 17:30:41 EST
    From: Shel Hall <76701.103@compuserve.com>
    To: "Volvo.net" <swedishbricks@me.rochester.edu>
    Subject: Frozen Clutch


    Bob LaGesse's (bobml@msd.measurex.com) clutch is stuck. It happens to cars that sit up.

    Assuming the linkage (cable, whatever) is OK and is actually moving the release mechanism, here's the cure:

    With the transmission in neutral, start the car and warm up the engine.

    Turn the engine off again.

    Put the car in first or reverse, depending on which is the clear path. If both ways are clear, select the path the goes downhill.

    Push the clutch pedal down.

    Start the car. It may just pop the clutch loose, or it may drive off. Continue to drive, holding the clutch pedal down, until it frees up.

    Once the clutch disk unsticks itself from the freewheel or pressure plate, it should work normally again.

    I've used this method numerous times, and it's never failed.

    Of course, while the clutch is stuck, you have to switch the engine off to stop smoothly. Just leave it in gear and crank it again to go again.

    You can even use this opportunity to learn how to shift without the clutch, matching revs carefully so the stick slips from one gear to the next without clashing.


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    Why can't I shift from 3rd to 4th gear?

    Date: Fri, 30 Apr 93 17:28:12 CDT
    From: barnett@mcc.com (Jim Barnett)
    To: moran@uxh.cso.uiuc.edu
    Cc: swedishbricks@me.rochester.edu
    Subject: Cannot Shift to 3rd & 4th Gear -- 1975 Volvo

    That sounds expensive - my guess is that the shift dog for 3rd/4th gear broke off. You'll have to pull and disassemble the transmission to get at it.

    You can look in a Haynes manual for more details (it's better than the Volvo factory manual for working on the transmission), but basically the transmission works as follows: all 4 gears are engaged with the corresponding gear on the input shaft, but not with the output shaft. To shift into a gear, you engage it to the output shaft by moving a locking ring. You move the locking ring by means of a "dog" (in technical terms: "a little hook-like gizmo") along a shaft. There is one dog/shaft combo for first and second gear, and one for third and forth (and something similar for reverse.)

    So if first, second and reverse all work fine, but 3rd and 4th don't, it's likely that there's something wrong with the rod/dog combo for those gears (it would take a very bizarre problem to make 1st and 4th work, but not 2nd and 3rd.) The parts won't be too expensive, but expect to spend a lot of either time or money getting them installed...

    - Jim

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    Clutch questions.

    From: southern@neit.cgd.ucar.edu (Lawrence Buja)
    Subject: Clutch questions
    To: swedishbricks@me.rochester.edu (Volvo mailing list)
    Date: Mon, 17 May 93 8:34:51 MDT

    {Can anyone give me an idea of what it costs to rebuild an overdrive and
    {what a clutch costs? (I know someone recently paid about $700 or so but
    {I believe that there were extraordinary circumstances with that job).

    Last fall I did the clutch in my '74 142. While it was kinda messy working in 18 years of accumulated grunge on the tranny, the job wasn't too bad (the last clutch I had done was 12 years before, on the little jeep that the P's bought us kids to beat^H^H^H^Huse in high school). Parts were in the $200 range. The most useful tool was a little floor jack to move/lower/raise the bell-housing/trans/OD unit. Runners up were the big heavy cardboard box that I used as a floormat, some long extension and bending connectors for the rachet for getting at the bolts between the bell-housing and the engine and a 1/2 gal of Old Elk Brown Ale fresh out of the wall from the Walnut Brewery.

    >From memory, the basic order of operations was:

    Read the Haynes & factory manuals carefully to see what crucial step

    Lawrence forgot to mention.
    Get the car up on 4 car ramps so you've got room to work.
    (the neighbors really love this).
    Drop the driveshaft, remove the stickshift.
    Drain tranny, support with floor jack, then remove rear tranny supports.
    Pull the starter, pull all engine/bell-housing bolts and separate the two.
    Lower tranny, replace clutch disk/pressure plate/bearing.
    Assembly is the reverse of the previous steps.

    I wasted alot of time trying to loosen the bolts on the driveshaft. I ended up cutting them off and buying new ones. I wasted a lot of time trying to separate the OD from the tranny. For some reason I wanted to see how it went together, but it just wouldn't come all the way apart and I was worried about grunging it up with swarf off the bottom of the car. The manual sez to operate the OD while moving, before parking and trying to remove it; I hadn't done that. I ended up sealing it all up and pulling the bell-housing/tranny/OD as a unit without any problems.

    { My friend does not have a lot of money, and is expecting a third child
    {within 6 weeks. I have done several clutches (american cars and a BMW)
    {and it the estimate is quite high I might do the job for him.

    Basically it took me a weekend to do it, working by myself. Though it wasn't too bad, it's definitely not a job I'd volunteer to do for someone else without some very ample compensation. Do your friend a favor and offer to help him, but give him the primary responsibility for doing the work. It's a doable job and with a job like this under his belt, he won't be shy about doing other car work that will save him money in the future. And if he's too cheap to spring for a floor jack, don't do the job. Remember, that's your face under there.

    /\ Lawrence Buja Climate and Global Dynamics Division
    \_][ southern@ncar.ucar.edu National Center for Atmospheric Research

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    How can I sort of the transmission codes?

    From: w2iy@hoqas2.att.com
    To: swedishbricks@me.rochester.edu
    Date: Thu, 27 May 93 09:20:20 EDT
    Subject: Transmission type codes

    Fellow netters,

    A few weeks ago I posted a note about how to sort out the M40/41/400/410 transmission codes. It turns out that what I learned years ago is mistaken and I wanted to correct my earlier misleading posting.

    This information comes courtesy of fellow netter Ray Parsons.

    M40: 4-speed box, used in lots of early models including 71-73 1800 (maybe up to 69 as well?

    Can someone fill in?)

    M41: M40 with overdrive stuck on the end, overdrive

    was Laycock-deNormanville J-type in 71-73 1800

    M400: Beefier 4-speed box used in 164 and 70 1800.

    M410: M400 with overdrive stuck on end, J-type in 70 1800.

    So apparently to indicate overdrive, you add 1 to the

    second place after the M.

    Ratios: M40 M400

    1st 3.41 3.14

    2nd 1.99 1.97

    3rd 1.36 1.34

    4th 1.0 1.0

    Reverse 3.25 3.54

    One way to tell which box you have is that the M40 has its fill hole on the right side (passenger side) and the M400 has fill hole on the left.

    Keep 'em rolling,


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    Do I need to use a special transmission fluid?

    Date: Fri, 3 Sep 93 13:28:21 EDT
    From: wiegman@orion (Herman L. N. Wiegman)
    To: moran@uxh.cso.uiuc.edu
    Subject: Re: Manual Transmission Oil
    Cc: swedishbricks@me.rochester.edu

    netters, [I've been getting a bunch of O/D mail ... here is a summary]

    I know of several new car makes which require special transmision fluid. If the incorrect type is used, the transmision will fail. This tragic failure is usually on Automatic transmision. The Jensen type Overdrives on our Volvo M41/M46 Manual transmsions is, thankfully, more robust.

    >I have a 1976 242 with 4-speed with overdrive. ...
    >The reason I ask you this is because the local mechanic told me the other
    >day to put 10W30 as the ATF was not allowing a smother trasnsition from
    >4th gear to the overdrive. What do you think?

    Well, the question is: Was your '76 M-46 designed with ATF or MTL in mind?

    The Jensen O/D is designed with certain tolerances in the pump/regulator/selenoid valve. (the electric selenoid activates the hydraulic selenoid.) I recommend that you look at the side of your transmision case. If there is a faint white dot or "ATF" symbol, use Type F ATF, or synthetic ATF. If the O/D is older than 1979, it probably requires 30W oil. I recommend MTL, or straight 30W oil. 10W30 works in a pinch.

    Because the tranny is a "clean" environment, the lubricant does not need many detergents, or moisture absorbing additives, as do motor oils. Manual trannies also do not operate over as wide a temperature range as do motors, hence it does not require as many viscosity boosters.

    Basically, MTL is simple stuff, with only a few special considersations.

    ATF is a different beast. It has more requirements on it, hence there are several types and qualities. I believe synthetic ATF is compatible with all three major ATF types.

    More comments or additional notes? I think fluid should be changed every 50kmiles in the Manual O/D trannies to prevent problems. Volvo recomends NO fluid changes in the older units (once at 15kmiles).


    Herman L.N. Wiegman -> wiegman@orion.crd.ge.com
    General Electric - Corporate R&D, Schenectady NY
    - the Flying Dutchman in the DSP Swedish Brick -

    Date: Sat, 4 Sep 1993 20:55:35 -0400 (EDT)
    From: STEVE (516) 282-3018 <GINELL@bnlvs2.nsls>
    To: SWEDISHBRICKS@me.rochester.edu
    Subject: M45/M46 FLUIDS

    Hi to all:

    In regards to a posting of Herm's:

    Volvo switched the M45/M46 transmission fluid to ATF during the 1976 production year. For M45/M46 produced prior to the change over they reccommend switching over when you change the fluid. Thus all m45/m46 can and should use ATF fluid.

    The M46 may have visable or not the ATF printed on the casing near the fill plug. My 1976 242 M46 came with ATF and I have replaced the fluid every 30k as suggested in the manual and have yet to have any problems in 350K. I am also replacing the fluid in my 86 245 158K M46 every 30K.


    Date: Mon, 27 Sep 93 18:22 EDT
    From: pjf@mrst.com (Peter J. Faill)
    To: swedishbricks@me.rochester.edu
    Subject: Re: Redline products

    >> I also just recieved the information package from Redline Products.
    >> My questions have to do as to how really "wonderful" are their products.
    >> Their brochures give a lot of data and there are several testimonials from
    >> racedrivers. I am really tempted to buy their stuff but I must confess my
    >> technical ignorance here. For example, their manual tranmission fluid looks
    >> like it is a far superior product than the automatic transmission which
    >> we are supposed to use with 4-speed with Overdrive.
    > Anybody out there have any good reports from actual use of MTL or synthetic
    > ATF?

    I put Redline's MTL in my '70 1800E this past spring. It transformed the shifting from being sluggish and slow to being crisp and fast. I especially noticed the difference when the transmission was cold. With the straight 30W, I had extreme difficulty getting 2nd gear until the oil warmed up some. With the MTL, it shifts perfectly regardless of the temperature.

    I don't know if I've done any damage to the transmission. Several people warned me to use only 30W or I'd risk damaging my OD. The viscosity charts Redline provided show that MTL and 30W are very similar. After 3000 miles, I haven't had any problems yet.


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