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bogus | Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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I have had this bad shudder in the driveline when backing up for some time.
I asked Bill @ ZFDoc about it and he didn't think it was coming from the transmission, so that leaves the rear diff. It's really the only part going "backwards." This problem existed before I did the ujoints last year and it's been getting progressively worse. It almost feels like the clutch is slipping, but again, it's been there since before the clutch was replaced a few years back (but only 20k miles). I can't find anything about this in the Helm manual... Thoughts? |
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Posted on: 2014/2/2 2:31
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Matatk | Re: Bad shudder when backing up | ||
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That is strange. I don't think it would be a differential issue since it doesn't happen going forward. What if you put the rear end on jack stands and remove the load from the differential? That might be a good way to isolate things.
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Posted on: 2014/2/2 3:06
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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that's a good idea...
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Posted on: 2014/2/2 3:38
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Churchkey | Re: Bad shudder when backing up | ||
Guru
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When in reverse the motor wants to torque counter clockwise when viewed from the cockpit. Suggest checking motor mounts for tightness, integrity etc. Hood open & brake torque in reverse should give a visual on motor movement.
Dog bone & bat wing bushings are also suspect. C beam bolt torque OK? |
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Posted on: 2014/2/3 1:29
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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good points.
I can't speak of the bat wing... that's a mystery. The c-beam is tight, and has torque plates. the motor mounts are new. dog bones are not an issue, I have the full on Banski rear suspension kit. Everything is tight. |
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Posted on: 2014/2/3 2:09
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jonszr1 | Re: Bad shudder when backing up | ||
Senior Guru
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andy , you might want to ck the bottom motor mount bolt the vertical one . I found mine had worked loose . the other thought that came to mind was that maybe something is starting to go in the rear end like the pinion bearing .when you are backing up the pinion bearing would be trying to work its way out of the case . just what I thought it might be .could be way off base . only other thought would be the front yoke on the driveshaft might be worn .
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Posted on: 2014/2/3 8:45
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i have a blast playing with my 4 babies 2 zr1s and 2 mustangs 68 coupe with a jon bennit 408 art car fully rollered c4 with a gearvendors over drive .88 mustang built by my kids with a ported lt5 and a bill boudreau blue printed zf 6 spd. with these 4 ... |
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Matatk | Re: Bad shudder when backing up | ||
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Lots of good ideas I never thought about!
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Posted on: 2014/2/3 13:10
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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Well... lots of ideas, but lots of changed parts, too.
1. new ujoints showed no issues with the driveshaft. 2. the motor mounts are new, and the problem existed before that... but I will check for any loose bolts, just to be sure. If anything it's either my technique - meaning I am over slipping the clutch - or the input shaft bearing is going south... |
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Posted on: 2014/2/3 16:49
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Ultraman | Re: Bad shudder when backing up | ||
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There is a guy over on CAC asking the same thing.....he has a ZR1 Super Natural.......what is a Super Natural...?
http://www.corvetteactioncenter.com/f ... dder-when-backing-up.html |
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Posted on: 2014/2/3 17:50
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BrianCunningham | Re: Bad shudder when backing up | ||
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I'd check all the mounts, including the batwing and the C-beam bolts
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Posted on: 2014/2/3 18:05
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jonszr1 | Re: Bad shudder when backing up | ||
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I was the one asking for andy ,just thought to try another site and see if we could find a answer to help out our friend
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Posted on: 2014/2/3 19:23
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i have a blast playing with my 4 babies 2 zr1s and 2 mustangs 68 coupe with a jon bennit 408 art car fully rollered c4 with a gearvendors over drive .88 mustang built by my kids with a ported lt5 and a bill boudreau blue printed zf 6 spd. with these 4 ... |
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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Batwing and input shaft seem to be the most likely culprits.
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Posted on: 2014/2/3 21:04
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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joeld | Re: Bad shudder when backing up | ||
Guru
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Quote:
Very possible! Suspension parts act a lot different when reverse torque is applied. Plus, there is more torque applied in reverse simply from the much lower gear ratio. Think how much wheel hop there was in the movie Bullitt when McQueen had to back up during the chase scene! Joel |
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Posted on: 2014/2/3 21:24
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teebee | Re: Bad shudder when backing up | ||
2014 Memorial Day Car Show Winner!
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OK I posted an idea over on CAC, but what about adding positraction additive to the rear end. It sounds like posi-clutches slipping.
????? Maybe? That's what my 64 did back in the day and that fixed it. Not so sure I didn't have to add it to my 94 too. |
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Posted on: 2014/2/3 23:42
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teebee | Re: Bad shudder when backing up | ||
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I would almost bet money the positration additive will fix it.
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Posted on: 2014/2/3 23:45
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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Nice thought, but the oil in there is about 20k miles old, and has 2 bottles of additive in it already!
that was one of the reasons I moved on the clutch when I did (summer 2009). I pull the engine, did all the oil seals and gaskets, did the clutch and such. Last year, May /June, I did ujoints... and about a year ago, I did an entire engine swap... with new motor mounts. If I am going to tear into the batwing, bet your ass I am going to get the diff rebuilt, too. No wasting all that labor. |
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Posted on: 2014/2/4 3:01
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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jonszr1 | Re: Bad shudder when backing up | ||
Senior Guru
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andy , I emailed bill b and here is what he said , he believes either the bolts that hold the pressure plate aren't tightened down evenly or your motor mounts are loose .do you have a puck type clutch ? if you pm me your email I will email the message he sent me . I am in the hospital now but can still use my computer
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Posted on: 2014/2/4 3:15
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_________________
i have a blast playing with my 4 babies 2 zr1s and 2 mustangs 68 coupe with a jon bennit 408 art car fully rollered c4 with a gearvendors over drive .88 mustang built by my kids with a ported lt5 and a bill boudreau blue printed zf 6 spd. with these 4 ... |
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Ultraman | Re: Bad shudder when backing up | ||
2015 Memorial Day Car Show Winner!
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Geez Brad mojo on getting out of the hospital, hope you are ok.....
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Posted on: 2014/2/4 13:51
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2010 Grand Sport Coupe Gone but not forgotten... Vote DeSantis in 2024.... Make the IRS go away... |
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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Yea, Brad, get well soon!!!
I hope the flywheel is torqued... I used a torque wrench, in the proper sequence, set at the right ft lb... If this was the flywheel, that means the last two flywheels I installed were lose, or, one came loose, but I use red threadlock on the bolts... Also, the motor mounts are newer. I replaced the original 185k mile units with nice 61k mile units when the engine was swapped. And they were hammered home with an impact gun!! You can email me at andy@corvetteguruforum.com That's the public email for the site, so that's fine!! THANKS!!!! |
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Posted on: 2014/2/4 15:01
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_________________
The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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jonszr1 | Re: Bad shudder when backing up | ||
Senior Guru
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andy did you get the email sent to you ????/
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Posted on: 2014/2/5 2:08
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i have a blast playing with my 4 babies 2 zr1s and 2 mustangs 68 coupe with a jon bennit 408 art car fully rollered c4 with a gearvendors over drive .88 mustang built by my kids with a ported lt5 and a bill boudreau blue printed zf 6 spd. with these 4 ... |
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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yes! I just got home to read it.
THANKS! To answer some of his points, the clutch, I don't think, is the problem. I replaced it due to wear/tear and such, plus, the shudder. Figured a new clutch would clear that up... no luck, unless I installed it exactly wrong like I would have had to the first time. The motor mounts are 60k mile units, and are really tight. The more this is developing, the more I think it's in the batwing and the differential. |
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Posted on: 2014/2/5 3:51
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_________________
The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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Churchkey | Re: Bad shudder when backing up | ||
Guru
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The posi suggestion brought to mind a problem I solved on a customers car a long time ago that was posi related. Without going into a detailed explanation the problem turned out to be tires. Both rear tires had identical size markings however when both tire circumferences were measured there was a 1.5 inch size difference left/right.
Suggest measuring tire circumference @ the center of the rear tire thread. Rear tires of identical circumference = a happy posi unit |
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Posted on: 2014/2/5 4:40
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bogus | Re: Bad shudder when backing up | ||
Grand Imperial Pooh-Bah
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Gee... I would hope BFG has better QC than THAT!
Besides... new tires, problem existed before... |
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Posted on: 2014/2/5 18:37
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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