I finally did the clutch in my bug the other day (after only procrastinating for 6 mos) So on the way from work the day i got it back together and than to and from work again I noticed like a belt squeal when letting the clutch out on the 4-3 downshift at speed (like shifting down to pass or panic stop for a red light) it will occasionally do it from 3rd-2nd as well but not very often, it doesn't do it if i slow down first before downshifting though.
I've done clutches on my previous bug and none of them have done this.
Any ideas what might be causing it?
Squealing on downshift
- SCOTTRODS
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Re: Squealing on downshift
Did you change the throw out Bearing as well? That'd be my suspicion unless you can duplicate it by revving and watching the engine and can identify it as a belt... But Hey... Belts are cheap, so why not just replace yours and see if that fixes it? Other items could be a Bad pilot bearing
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- 72vbub
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Re: Squealing on downshift
i replaced both the release bearing and alt belt, I didn't change the pilot bearing, i checked it and it ran free and smooth (i rarely change them when i do clutch jobs and not just vw's, unless they obviously need it). it only makes the noise downshifting, not at any other time like just reving the engine etc...
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Re: Squealing on downshift
It has been a long time since I have heard of this happening and it could be many things. Since you replaced the belt that kind of rules out that... maybe but just in case check to make sure that you didn't accidentally get some grease on the belt. Also check the pulleys to make sure they don't have polished surfaces where the belts ride as this can cause this problem but... being that it is only on down shifting that is confusing.
You didn't say if it did it before the clutch swap but a couple of things you might look into:
Check the condition of your mounts for condition and tightness would be my first, cheapest and easiest suggestion. The pilot bearing is usually not considered when doing a clutch job so this could be a problem. Also you said clutch and throw-out bearing but not the clutch cover/pressure plate; I am going to assume you did that also.
Take your car back out for a ride after you let it sit for awhile (sometimes just sitting and letting things relax/settle back to where they were; fall back into position helps: "did it yesterday but not today").
What kind of speeds are you down shifting are; e.g., RPMs. Do you double clutch during the down shift or just bang through the gears? Double clutching; e.g "finessing" is something us old guys did when we had sliding gears w/synchronizers and/or straight cut gears (kind of like going into first in a VW while the car is still moving). You get the engine to match trans speeds and puts less load/stress on things when you re-engage the clutch.
If you just do a straight down shift but know how to double clutch try going through the same area at the same speeds where you got the "squeal" from both down shifting normally then double clutching and see if you get the same "squeal" noise both times. If you do get the noise when double clutching, especially when raising the RPMs in neutral then I would suspect the belt is the problem but again, it could be other things too. If not then you might want to pull the trans and check it's condition (input shaft bearing as well as some of the other innard bearing and components) as well as the pilot bearing.
I am not a "tranny guy" and not saying that it is internal but I have had a bit of diagnostic experience a long time ago... some of it the hard way. I am not sure about a lot of things inside of the tranny but I seem to remember that the internal working has different loading (acceleration) vs. unloading (deceleration) on it.
For what it is worth.
Lee
My opinion is worth slightly less than you paid for it.
You didn't say if it did it before the clutch swap but a couple of things you might look into:
Check the condition of your mounts for condition and tightness would be my first, cheapest and easiest suggestion. The pilot bearing is usually not considered when doing a clutch job so this could be a problem. Also you said clutch and throw-out bearing but not the clutch cover/pressure plate; I am going to assume you did that also.
Take your car back out for a ride after you let it sit for awhile (sometimes just sitting and letting things relax/settle back to where they were; fall back into position helps: "did it yesterday but not today").
What kind of speeds are you down shifting are; e.g., RPMs. Do you double clutch during the down shift or just bang through the gears? Double clutching; e.g "finessing" is something us old guys did when we had sliding gears w/synchronizers and/or straight cut gears (kind of like going into first in a VW while the car is still moving). You get the engine to match trans speeds and puts less load/stress on things when you re-engage the clutch.
If you just do a straight down shift but know how to double clutch try going through the same area at the same speeds where you got the "squeal" from both down shifting normally then double clutching and see if you get the same "squeal" noise both times. If you do get the noise when double clutching, especially when raising the RPMs in neutral then I would suspect the belt is the problem but again, it could be other things too. If not then you might want to pull the trans and check it's condition (input shaft bearing as well as some of the other innard bearing and components) as well as the pilot bearing.
I am not a "tranny guy" and not saying that it is internal but I have had a bit of diagnostic experience a long time ago... some of it the hard way. I am not sure about a lot of things inside of the tranny but I seem to remember that the internal working has different loading (acceleration) vs. unloading (deceleration) on it.
For what it is worth.
Lee
My opinion is worth slightly less than you paid for it.
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- Joined: Mon Nov 13, 2006 10:17 pm
Re: Squealing on downshift
I forgot to mention: check the bearing(s) on your charging system. I have seen weirder things happen!
- 72vbub
- Posts: 13
- Joined: Mon May 24, 2010 9:53 am
Re: Squealing on downshift
It never made any noise before, I just finally changed the clutch cause the only time I could actually use 4th was cruising on a flat road or going down hill. I guess I should mention as well the engine is a 1600dp in a 63bug that unbeknownst to me was still running the stock 63 flywheel, clutch and starter. So when I pulled it apart I put new trans mounts, release bearing, good used and resurfaced 200mm flywheel with 6V ring gear, 1700 lb pressure plate, rigid disc and alt belt, which the PO had changed before I got the car and I found out from crossing the part # that the belt he put on was actually for a rototiller! Some People! now it makes sense why my charge light would never fully go off before. lol
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- Joined: Mon Nov 13, 2006 10:17 pm
Re: Squealing on downshift
Glad it was an easy fix. A lot cheaper than the direction was heading. As I said, weirder things have happened!
Lee
Lee
- Marc
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Re: Squealing on downshift
Haven't been to STF in a few days...when I saw your original post my first thought was belt squeal. The 9.5x905La belt is adequate for a 30A generator, borderline for a 38A Bus/Thing generator, and totally inadequate for an alternator (except as an emergency spare). There's a reason why the belt was upsized to 11.3x912La for alternator applications; at high RPM the skinny belt can slip enough to actually cause overheating under load.72vbub wrote:...the belt he put on was actually for a rototiller! Some People! now it makes sense why my charge light would never fully go off before. lol