James G. Posted December 30, 2010 Share Posted December 30, 2010 Hey guys. I have a '72 Monte that I believe was originally an automatic (TH400) but now is a 4-speed manual. It is an original 454 car, and I just picked it up at the end of the summer. Well, it's winter here now, so it is safely tucked away in storage, but, I want to get going on the one big issue with the car which seems to be a clutch problem. When you are on the gas hammering through the gears it seems to run fine, but when you are off the gas and coasting down in speed, the car seems to "buck" back and make kind of a growling noise from under the front end. It seems to be some sort of clutch issue, but it does seem to shift into gear fine when I do clutch it to shift, so I am confused. It is worse at lower speeds in 2nd gear, or even 1st gear when you are coming down toward a stop. It is not a hydraulic clutch, it is a manual one, and I believe it is an M20 4-speed tranny in the car. I was hoping maybe somebody else had this problem and it is possibly a simple linkage adjustment, or if it something worse like a flywheel or pressure plate, please let me know if you have had the same problem in the past, and what you did to fix it. I am not used to working on manual trannies, but am willing to tear into it to get it running smooth. I love the car, and this is really the only issue I have with it. Thanks guys, any help would be greatly appreciated. - James Quote Link to comment Share on other sites More sharing options...
mrj52 Posted December 30, 2010 Share Posted December 30, 2010 Question? Is the motor modified? {Big cam} If the engine is running lean and your off the gas the motor has a tendecy to buck. The engine is surging do to the drying up of the intake system. There could be also be a light wieght flywheel installed which make any engine tune issues stand out. If you on the gas and it does not slip or it shifts fine under load i would look at the flywheel wieght. The growling noise COULD be that you have a M22, Those trannies make a lot of noise under load slowing down. Keep us posted, Manuals are fun. TIM Quote Link to comment Share on other sites More sharing options...
James G. Posted December 30, 2010 Author Share Posted December 30, 2010 Yeah, it has a big cam in it, and it pushes 425hp, so maybe that has something to do with it also. I assume there is a a more heavy duty flywheel that could help? I was thinking about the lean issue that you mentioned also, as I have had to try and do some fine tuning on the Edelbrock carb to get it somewhat right already, and am still not convinced that I am running rich enough. What is the easiest way to find out if it is either an M20, M21, or M22? Thanks for the info, I appreciate it! - James Quote Link to comment Share on other sites More sharing options...
wallaby Posted December 30, 2010 Share Posted December 30, 2010 I'm not convinced that it has anything to do with the clutch. From your description, it makes noise & vibration when you decelerate?...and it's worse at low speeds? Bad motor mounts maybe? U-joints? Quote Link to comment Share on other sites More sharing options...
Mikstudie Posted December 31, 2010 Share Posted December 31, 2010 Sounds like possibly throw out bearing, when the noise happens SLIGHTY depress the clutch and see if the noise changes,if it does you have a clutch problem,if not look some place else. I have NEVER seen a cluth problem,pressure plate or throw out bearing not change in some way if you SLIGHTLY depress the clutch. I had a problem that was like what you discribe and it was the bearing . You should be running a 11" clutch,corse spline with that kind of motor and HP. Trans info is on pass side of trans. Quote Link to comment Share on other sites More sharing options...
overdrive Posted December 31, 2010 Share Posted December 31, 2010 HI James. Here is a great site to help ID the trans. There are others. Just Google Muncie identification. Does the car make the noise and buck when you are slowing down with the clutch pedal down or up? Dan Quote Link to comment Share on other sites More sharing options...
James G. Posted December 31, 2010 Author Share Posted December 31, 2010 With the clutch pedal up Dan. When I depress the clutch it goes away, which is why I was thinking some kind of clutch issue rather than something else. Basically, if I want the noise to stop, I can just pop the car in neutral when I get to a lower speed and let it coast to a stop and the noise is gone as soon as I take it out of gear. That is the best way to describe what is going on. I really appreciate the feedback, and I will investigate further ASAP. Dan, thank you for the link, it will be very helpful, and as soon as I crawl under the car to ID, I will post up which type of tranny it is. Thanks, you guys are the best. - James Quote Link to comment Share on other sites More sharing options...
Mikstudie Posted December 31, 2010 Share Posted December 31, 2010 With the clutch up the bearing is riding free and can make some odd noise's. With the clutch depressed your putting pressure on the bearing and most of the time the noise will stop. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted January 1, 2011 Share Posted January 1, 2011 sounds like the trans to me, not the clutch you say when you push the clutch, noise goes away, you also say if you pop it into neutral (clutch up) it also goes away, eliminating the clutch is it more noticeable in a certain gear or go away in any of the gears? Quote Link to comment Share on other sites More sharing options...
James G. Posted January 2, 2011 Author Share Posted January 2, 2011 Sam, it is really more noticeable at lower speeds slowing down, I would say mostly in 1st and 2nd gears since those are the main ones used at lower speeds. I would really like to get rid of that feeling like the car is "bucking" at the same time I hear the noise, too. Like I said before, shifting up through (and running in) the gears seems to be fine, but when the car slows down when I am getting ready to stop you hear the noise and the car bucks back and forth a bit unless you keep your foot in on the lcuth or pop it into neutral. I guess that is the best way I can describe what is going on. Thanks! - James Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted January 5, 2011 Share Posted January 5, 2011 a manual trans will do that some, even more if someone installed a clutch disc with a solid hub and the noise you hear is just a by-product of it do you ever watch NASCAR? if you watch during caution laps from the in-car cameras, you can see the cars "buck" and the noise associated with it, the bucking also gets worse with taller gears the bucking is all the back-lash threw the gears in the trans and rear axle added up and bouncing back & forth worn suspension pieces can/will add to the bucking Quote Link to comment Share on other sites More sharing options...
overdrive Posted January 9, 2011 Share Posted January 9, 2011 Where did you go, James? Did you figure out the problem? Dan Quote Link to comment Share on other sites More sharing options...
James G. Posted January 13, 2011 Author Share Posted January 13, 2011 Sorry Dan, it's been crazy around here lately. I actually got a good deal on a new clutch assembly (just in case I need it), now I just have to finish shoveling out a path to the barn where I store the Monte in the winter so I can work on it. You guys are the best, thank you so much for the advice. Hopefully I don't have to replace the clutch, but if I do, at least I have a spare one on hand ready to go. I will re-post when I get under the 'ole girl and see what's going on. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted January 16, 2011 Share Posted January 16, 2011 Hey James I had a thought, I'll pull my th350 and all related parts out and you pull your 4 speed and all related parts and well just swap even. You dont want all that trouble of all that shifting and clutching and adjusting all the time. Just a thought I'll make that sacrifice for a friend. BTW I have relitaves in the Brunswick Topsham area thats where my dad was born. Good luck with it. Quote Link to comment Share on other sites More sharing options...
James G. Posted May 26, 2011 Author Share Posted May 26, 2011 Alright, so check this out guys, here is an update and resolution on this issue of the car bucking and jerking on me when I slow down. I picked up my 72 Monte in the fall of last year, and didn't have too much time to mess with it before storage season up here, but I did put in new plugs and a bunch of new high end electrical upgrades to the ignition system. So, I had not gotten to re-checking the timing until this past weekend (due to some crappy weather up here for the past few weeks), and that brings me to what I thought was a clutch issue with the car from my previous posts. It turns out it was actually a timing issue. When I checked the timing it was way off from factory spec's, and nowhere near where I wanted to run the car at, so after re-doing the timing I took it for a ride and presto, when I slow down with the car no more jerking or bucking or anything, it's very smooth. Also, who ever installed the bracket that holds down on the distributor got the wrong part, as this one barely contacted it, and I could actually turn the distributor without ever loosening the bolt up! Yikes! So, I got the new bracket and buttoned up the car and she is running like a champ, so this is just an FYI for anyone else having a similar problem to the one I had, don't just assume as to what you think the problem is, because cars love to throw you curveballs from time to time. Thanks guys for the help, and if my story with this issue helps someone else out, then I will be thrilled. At least I have a new clutch assembly if and when mine does decide to die! Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted May 26, 2011 Share Posted May 26, 2011 So I guess you didnt like my idea eh James? Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 26, 2011 Share Posted May 26, 2011 wow! who would of thought we're talking clutches and tranny's and end up with timing! Quote Link to comment Share on other sites More sharing options...
James G. Posted May 26, 2011 Author Share Posted May 26, 2011 Steve, I am still "mulling it over", lol. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted May 26, 2011 Share Posted May 26, 2011 Steve, I am still "mulling it over", lol. Yea im sure you are Quote Link to comment Share on other sites More sharing options...
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