Vibration - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 09-19-2008, 01:06 PM
Registered User
 
Last photo:
Join Date: Sep 2008
Location: Temecula, CA.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Vibration

Hi to all, and I hope I'm doing this first post correctly.
I've read many posts on here about vibrations, and even though close to my nightmare, they're not quite the same. I just bought a 32 roadster in July, and have noticed a vibration that starts at 45 mph and disappears at 75 mph. It is a pulsing spaced at 1 seconds intervals, and it starts at the firewall, and heads to the back under the seat. I have run the car up to 55 mph and put it in neutral, and the vibration is gone. I have also left the car in second gear and taken it up to 55, and no vibration. The cars sports a Jag rear end, and at 75 mph it only turns 2700 rpm, and at 55 it is 2000 even. The tires have been rebalanced, and the motor and tranny mounts are fine. It has been brought to my attention that the stall converter might not be right ( I know nothing about stall converters), and if the stall is to high, it could be a problem because the car generates little rpm. The car is like new, and only had 5200 miles on it. It just bugs me that this is the only problem it has, and unless you drive at 40, you experience it every day.
I've read some posts on here, and a lot of guys have done a ton of things to find the vibrations. This one, after the above tests, seems to definately be an rpm (engine) related issue. Any, and I mean ANY help you can give will be appreciated. Thanks in advance, GW

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-19-2008, 01:18 PM
F&J F&J is offline
Registered User
 

Last journal entry: 32 Ford cabriolet conversion/windshield
Last photo:
Join Date: Mar 2007
Location: Connecticut
Age: 62
Posts: 1,571
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
How about sitting still in neutral; then gradually changing rpms up and down? There should be no vibrations in your mirrors, or place a fluffed up rag on the cowl or hood to watch.

2nd thing, you may be misdiagnosing by using the 2nd gear @55; that changes the load on the driveline compared to normal driving at 55.


To me, the pulsing sounds like driveshaft, ujoint, or maybe enen halfshaft. But you need to prove that the engine, flexplate and convertor are Ok as you sit in neutral. Try that rag deal and really go all over the rpms slowly, trying to get a vibration to show....before chasing elsewhere
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-19-2008, 01:59 PM
Registered User
 
Last photo:
Join Date: Sep 2008
Location: Temecula, CA.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the ideas F&J. I have gone out and did the rpm test as you mentioned, 0 to 3000 rpm, and it gets a clean bill of health. No vibration. The drive shaft sports a sticker on it that reads, Drive Line Service of San Diego / Dyna Balanced, and it looks like it has zero miles on it, let alone 5200.
One thing I forgot to bring up, and it was brought to my attention was, I'm running Billet Specialties wheels and the back tires are BF Goodrich Drag Radials. A mechanic said that the tires don't hold a balance good, but I had them checked and they were fine. Have any other ideas for things to look at?
Thanks, GW
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-20-2008, 08:48 AM
F&J F&J is offline
Registered User
 

Last journal entry: 32 Ford cabriolet conversion/windshield
Last photo:
Join Date: Mar 2007
Location: Connecticut
Age: 62
Posts: 1,571
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
This is hard to diagnose without being there.

Not likely, but worth a look: Get under the car and grab both ends of the driveshaft to feel for up & down play, especially at the front where the trans output bushing is. On very rare occasions, the wrong yoke O.D. size could cause a lot of movement there.....or a bad/loose pinion bearing at the differential.

Failing that, maybe borrow a set of rear wheels & tires?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-20-2008, 09:06 AM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
The only reason the BFG Drag Radials may not stay balanced is when running low pressure at the track they can slip on the rim when they hook and become out of balance.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-20-2008, 12:24 PM
Registered User
 
Last photo:
Join Date: Sep 2008
Location: Temecula, CA.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks F&J and SSedan64
Checked the drive shaft and maybe at the trans there is a thousandth or two play. Very minimal, and nothing at the back end. SSedan64, your comment is correct about the tires, but with this Jag rear it is impossible to break the tires loose due to the gearing. Maybe in some water, but I even doubt that. The two rear axles show no sign of being balanced, IE., drill marks, weight added, etc., if indeed they would be balanced that way.
I mentioned the stall converter in the first posting, but haven't heard yea or nay about it. Any comment on that, just to get it out of my head. I have a 383 stroker roller motor that I was going to put in this car, but I was told not to waste my time and money as long as the Jag rear was in there. With a 4000 lb. stall, it would eat itself up, and never perform the way it did in the other car I have. Now, like I said before, I know nothing about stall converters, but it kind of makes sense that if the car at 75 mph turns 2700 rpm, maybe the converter in this car is higher and never engages. Yes, NO???
Any other ideas before I TRY to find tires and wheels for this thing? Thanks in advance, GW
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-20-2008, 01:55 PM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
1Sick32 what trans are you using in this car?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-20-2008, 02:45 PM
Docc's Avatar
Dry Heat
 

Last journal entry: along the weird tale..
Last photo:
Join Date: Jul 2007
Location: Southern Arizona
Posts: 136
Wiki Edits: 0

Thanks: 5
Thanked 5 Times in 4 Posts
Quote:
Originally Posted by 1Sick 32
I have a 383 stroker roller motor that I was going to put in this car, but I was told not to waste my time and money as long as the Jag rear was in there. With a 4000 lb. stall, it would eat itself up, and never perform the way it did in the other car I have.
I wouldn't be concerned about a 383 with the Jag rear. The Jag diff is a Salisbury (Dana in the US). I know of a LOT of 454BB converted Jags running these as they are extremely strong.
One guy races in Australia with a twin turbo 454 in an XJ6..
[IMG][/IMG]
I retro kit is availbale to use Dana 44 gears set..if it you use a turbo..or
blower..
My Jag has the older Salibury with a built 350..very strong. These were used at LeMans and the 6 had about 350+hp. Diff problems are quite rare..

However..
If the IRS is not exactly trued in the install you might get vibration from shaft angles

Last edited by Docc; 09-20-2008 at 04:30 PM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-20-2008, 04:46 PM
Registered User
 
Last photo:
Join Date: Sep 2008
Location: Temecula, CA.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
SSedan64
I have a 350, mild cam, and running a TH350 trans.
Docc
Thanks for the input. The car, visually, is perfect. It looks as good on the bottom as the top, and was the one reason I bought it. But, as we now know, it has a problem. Would it pay, since I am going to get the rear axles rechromed, to have them checked for balance, and would a drive shaft balancer do them? I have read that the Jags came in all different widths. Would it be possible that someone cut to fit, and maybe didn't re-balance? Thanks again for all the help, GW
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-20-2008, 05:43 PM
F&J F&J is offline
Registered User
 

Last journal entry: 32 Ford cabriolet conversion/windshield
Last photo:
Join Date: Mar 2007
Location: Connecticut
Age: 62
Posts: 1,571
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Rule of thumb, as I was taught, "The longer the shaft-the more balanced it needs to be". Seems like very short halfshafts would have to be WAY off??

What rear gear? a 4.00 is more fussy than a 3.00 as far as critical balance.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 09-20-2008, 07:06 PM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
Quote:
Originally Posted by 1Sick 32
SSedan64
I have a 350, mild cam, and running a TH350 trans.
Docc
Thanks for the input. The car, visually, is perfect. It looks as good on the bottom as the top, and was the one reason I bought it. But, as we now know, it has a problem. Would it pay, since I am going to get the rear axles rechromed, to have them checked for balance, and would a drive shaft balancer do them? I have read that the Jags came in all different widths. Would it be possible that someone cut to fit, and maybe didn't re-balance? Thanks again for all the help, GW
It's possible they may be out of balance. But like F&J said, they would have to be very unbalanced being so short. Worth a check anyway.
The reason I asked about the trans is when using a Overdrive such as 2004R or 700R4 with a lockup torque converter clutch and numerically low ratio gears. When the engine is turning very low rpms it can transmit the engine firing pulses through the drive train and cause vibrations that can be almost impossible to correct without changing the rear gears.
It really doesn't sound like your torque converter has a high stall speed since it's not turning but 2700rpm @75mph. Do you know what the rear ratio is?
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 09-20-2008, 09:18 PM
Registered User
 
Last photo:
Join Date: Sep 2008
Location: Temecula, CA.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks again for the replies. I have no idea what the ratio is. I was hoping with the speed and rpm's I noted, maybe you guys could figure out that one...haha! It's possible I could call the guy I bought it from in hopes he would know. I know there's a logical answer that if it was in the rear, why the vibration starts from the front of the car and works it's way to the back. Is there a mathmatical way to come up with a ratio, or is it wrench time? GW
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 09-20-2008, 11:46 PM
Docc's Avatar
Dry Heat
 

Last journal entry: along the weird tale..
Last photo:
Join Date: Jul 2007
Location: Southern Arizona
Posts: 136
Wiki Edits: 0

Thanks: 5
Thanked 5 Times in 4 Posts
Quote:
Originally Posted by 1Sick 32
SSedan64
I have a 350, mild cam, and running a TH350 trans.
Docc
Thanks for the input. The car, visually, is perfect. It looks as good on the bottom as the top, and was the one reason I bought it. But, as we now know, it has a problem. Would it pay, since I am going to get the rear axles rechromed, to have them checked for balance, and would a drive shaft balancer do them? I have read that the Jags came in all different widths. Would it be possible that someone cut to fit, and maybe didn't re-balance? Thanks again for all the help, GW
The axles are chromed..the differential was installed by someone who may or may not have aligned the unit true to the rest of the drivetrain. The axles may have been cut to size..so it is difficult to know without some measurements what maybe going on.

Sometimes rods are built as show more than cruisers..a little misadjustment doesn't reveal itself around town..but open road may not have been concidered.
I have always thought that this mod was for the look as certainly no hotrod is going to need or be able to handle like an XK-E..nor be driven like one. The complexity of the IRS is not needed.
The cage obivously holds the unit together..but shims..and the relation of the fulcrum shafts through the horseshoe shims..even worn bushings could cause a vibration at speed. The diff is held by 4 bolts top..14 on bottom plate..if anything is loose..it will be noticable.

If you think it's the IRS..I'll point you to places that can answer more of this. First, get codes off diff so to identify the exact year/model Jag donor. Most likely a XJ sedan..as these are cheapest at plentiful in yards. I would guess yours has the earlier center mounted disk/calipers (next to diff housing). The 94 XJS on..moved the brakes outboard.


I at one time long ago..wanted to put the E Type IRS under my XK120 (V8)..but having thought about the complexity..and benefits..decided to just keep the live axle. I much easier..simpler..system. So long as I'm not racing at Laguana..I'll only know cause I don't have to deal with the inboard calipers heating up by differtial and exhaust..

Last edited by Docc; 09-21-2008 at 12:08 AM.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 09-21-2008, 12:17 AM
Docc's Avatar
Dry Heat
 

Last journal entry: along the weird tale..
Last photo:
Join Date: Jul 2007
Location: Southern Arizona
Posts: 136
Wiki Edits: 0

Thanks: 5
Thanked 5 Times in 4 Posts
Here is just one post from the Jag board..similar to your situation..there are many..however these are in cars with factory installed units

I posted some time ago about the ďroad vibrationĒ my 69 2+2 was
experiencing and its finally taken care of.
The symptoms seemed much like tires/wheels, a vibration at 55mph
and above, but smooth running in the city. I replaced the wheels
and got new tires... that did nothing My second thought was
universal joints, but there was no clunking when coming to a stop
and I couldnít feel any appreciable slop in the joints. I could
feel a nibbling in the steering wheel at road speeds, so the rack
mounts were the next item. It didnít make any difference in the
vibration. Next, the right front wheel had some play when yanking
on it top and bottom, so I put new wheel bearings in. Not the
problem. A friend said the lower ball joints were showing some
wear, so we replaced them. Not the problem. Finally, very annoyed
and in a foul moods, we dropped the IRS and drive shaft. With new
universals, the 2+2 runs smooth as can be. This was the first time
Iíve seen bad universals that didnít click or clunk when coming to
a stop. I originally bought this 69 2+2 for my wife to tool around
in until we get her 120 on the road, but it runs so smooth now
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 09-21-2008, 01:18 AM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
Look at this site to calculate the gear ratio. You need your tire diameter also.
http://www.hardcore50.com/members/calculators.htm
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mystery Vibration: long post Dano1972 Engine 6 06-20-2005 02:51 AM
Vibration at speed Doc68 Transmission - Rearend 141 01-22-2005 07:53 PM
Vehicle Vibration Smittyd55 Transmission - Rearend 3 03-01-2004 05:31 AM
drivetrain vibration catscan4free Transmission - Rearend 8 12-27-2003 03:43 PM
Troubleshooting Driveline Vibration PrimaDude Transmission - Rearend 9 07-01-2003 10:57 AM


All times are GMT -6. The time now is 10:29 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.