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Discussion Topic:
transmission grinds
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ole_Bill |
08-01-2011 @ 7:20 AM
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New Member
Posts: 165
Joined: Dec 2009
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Just got my '36 on the road and have found the transmission grinds with every shift. Goes into gear, but complains about it (grinds). Clutch works well and has about 1" of play before starting to engage. Suggestions?
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TomO |
08-01-2011 @ 7:43 AM
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Senior
Posts: 7271
Joined: Oct 2009
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The clutch pedal free play is measured when the clutch is fully engaged, that is no pressure on the pedal. It should be about 1" until the throwout bearing touches the pressure plate. I would reduce the pedal free play by backing off about 1/2 turn on the turnbuckle. Tom
This message was edited by TomO on 8-1-11 @ 7:44 AM
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supereal |
08-01-2011 @ 9:28 AM
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Posts: 6819
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Also, be sure that the engine idle speed is not too high so it will allow the rpms to drop between shifts. It also helps the old boxes to shift a bit easier if you use 140W oil.
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37RAGTOPMAN |
08-02-2011 @ 4:29 AM
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Senior
Posts: 1969
Joined: Oct 2009
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Was wondering if it grinds in all gears? like 1st and reverse ? or also in 2nd and 3rd ? and WHAT YEAR TRANS,??? is it rebuilt ? and who rebuilt it and what parts were used,and are they USA made ??? more info would help ? 37RAGTOPMAN
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40 Coupe |
08-02-2011 @ 4:44 AM
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Posts: 1688
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look for some type of loose linkage or pins that waist some of the clutch pedal travel, if none, it is possible B-7108 the syncro hub is in bad shape. The 36 trans uses brass rings inserted into the hub to match gear speed for a synchronized shift. The hub is very hard to find new and the brass rings can not be replaced. When shifting, pause, just before entering the new gear this will give the hub some time to match gear speeds.
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ole_Bill |
08-02-2011 @ 4:46 PM
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New Member
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The transmission was in the car when I got it, don't know if it is original or has been rebuilt. It grinds in all gears and it doesn't seem to help to try to match RPMs. The only way to shift it is to muscle it into gear and ignore the grinding.
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37RAGTOPMAN |
08-02-2011 @ 5:53 PM
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Senior
Posts: 1969
Joined: Oct 2009
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ole-bill when you had the old 36 engine did the trans grind then? if might be that you have a modified engine with more power,is causing the problem, a lot of times hot rodders went to the 39 gear boxes that seemed to shift better then the older transmission. my 3 cents 37RAGTOPMAN
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Henryat1140 |
08-04-2011 @ 3:00 PM
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Could it be related to loose motor mounts? Or missing/loose steadyrods? How about rear spring ubolts, if they were loose would that be a contributing factor? For a test, you could adjust the clutch linkage so there is barely any free play - IOW the clutch is getting max actuation and throw. Do this just to test it and don't leave it that way.
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40 Coupe |
08-05-2011 @ 6:26 AM
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Posts: 1688
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ole_Bill: I am not sure you understand my remarks about matching RPM. To achieve gear changes without gear clashing (grinding) the clutch has to disengage the engine from the transmission input shaft. Once this is done the input shaft to the transmission is rotating but it is no longer driven by the engine. Then it is the job of the syncro rings, in the transmission, to match the RPM of rotating gears. Once the gears are at the same speed the outer part of the syncro hub (Syncro sleeve, 7106) can lock the gears together. Matching the RPM as previously mentioned is outside the control of the driver or the engine. The syncro hub #7108 does this job when slowly moving the shift lever from one one gear to another. So #1 is to make sure the clutch is disengaging, this will NOT happen with loose or worn parts, look for lost movement of the pedal travel. with every small movement of the clutch pedal does the throwout bearing react. If the pedal moves and the throw out bearing doesn't your not going to disengage the clutch properly.
This message was edited by 40 Coupe on 8-5-11 @ 6:27 AM
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ole_Bill |
08-05-2011 @ 6:42 AM
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40 - You're right, I did misunderstand. I thought you were talking about the situation where you match speed and RPM to shift without using the clutch - and no, I don't do that. The clutch has about 1" of free play at full engagement, but there is a noise going on that I take to be the throwout bearing turning. When the clutch is depressed, the noise stops. All parts were new when installed.
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