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Bump/thump while driving at low speed [message #359113]

Wed, 30 September 2020 17:35

Scott Nutter

Messages: 782
Registered: January 2015
Location: Houston/San Diego

Karma: 4

Senior Member

The coach has started to make a bump/thump feel and sound while driving. Most noticeable between 10-25 MPH. It bumps at each rotation of the tire. So I’m leaning towards a bubble in the tire, a rock or obstacle stuck in the tire groove, a bad CV shaft, or even a loose rim. I really can’t be sure, but I think it’s coming from the front.. Any more ideas before I start removing tires?
Thanks, Scott

Scott Nutter 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI Houston, Texas

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Re: [GMCnet] Bump/thump while driving at low speed [message #359116 is a reply to message #359113]

Wed, 30 September 2020 18:45

Russell Mehlenbacher

Messages: 128
Registered: June 2010

Karma: 1

Senior Member

Check your inner axle bolts! Don't want those u-joints out of joint!
Good luck!
Russ

On Wed, Sep 30, 2020, 6:36 PM Scott Nutter via Gmclist <
gmclist@list.gmcnet.org> wrote:

> The coach has started to make a bump/thump feel and sound while driving.
> Most noticeable between 10-25 MPH. It bumps at each rotation of the tire. So
> I’m leaning towards a bubble in the tire, a rock or obstacle stuck in the
> tire groove, a bad CV shaft, or even a loose rim. I really can’t be
> sure, but I think it’s coming from the front.. Any more ideas before I
> start removing tires?
> Thanks, Scott
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Russ & Linda Mehlenbacher
Rochester Hills, Michigan
'76 Eleganza
'74 Sequoia

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Re: [GMCnet] Bump/thump while driving at low speed [message #359119 is a reply to message #359116]

Wed, 30 September 2020 19:46

johnd01

Messages: 354
Registered: July 2017
Location: Sacrameot

Karma: -1

Senior Member

I had something like that on a car, turned out to be the tred partially
separating from a tire body.

On Wed, Sep 30, 2020 at 4:46 PM Russell Mehlenbacher via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Check your inner axle bolts! Don't want those u-joints out of joint!
> Good luck!
> Russ
>
> On Wed, Sep 30, 2020, 6:36 PM Scott Nutter via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> The coach has started to make a bump/thump feel and sound while driving.
>> Most noticeable between 10-25 MPH. It bumps at each rotation of the
> tire. So
>> I’m leaning towards a bubble in the tire, a rock or obstacle stuck in the
>> tire groove, a bad CV shaft, or even a loose rim. I really can’t be
>> sure, but I think it’s coming from the front.. Any more ideas before I
>> start removing tires?
>> Thanks, Scott
>> --
>> Scott Nutter
>> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21
> final
>> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
>> installed MSD Atomic EFI
>> Houston, Texas
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
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>

--

*John Phillips*
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Johnd01 John Phillips Avion A2600 TZE064V101164 Rancho Cordova, CA (Sacramento)

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Re: [GMCnet] Bump/thump while driving at low speed [message #359122 is a reply to message #359119]

Wed, 30 September 2020 20:35

Bruce Hart

Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming

Karma: 5

Senior Member

If you feel it in the steering wheel it is from the front. If you feel it
in the seat it is in the rear !!!

On Wed, Sep 30, 2020 at 6:47 PM John Phillips via Gmclist <
gmclist@list.gmcnet.org> wrote:

> I had something like that on a car, turned out to be the tred partially
> separating from a tire body.
>
> On Wed, Sep 30, 2020 at 4:46 PM Russell Mehlenbacher via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Check your inner axle bolts! Don't want those u-joints out of joint!
>> Good luck!
>> Russ
>>
>> On Wed, Sep 30, 2020, 6:36 PM Scott Nutter via Gmclist > gmclist@list.gmcnet.org> wrote:
>>
>>> The coach has started to make a bump/thump feel and sound while
> driving.
>>> Most noticeable between 10-25 MPH. It bumps at each rotation of the
>> tire. So
>>> I’m leaning towards a bubble in the tire, a rock or obstacle stuck in
> the
>>> tire groove, a bad CV shaft, or even a loose rim. I really can’t be
>>> sure, but I think it’s coming from the front.. Any more ideas before I
>>> start removing tires?
>>> Thanks, Scott
>>> --
>>> Scott Nutter
>>> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21
>> final
>>> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
>>> installed MSD Atomic EFI
>>> Houston, Texas
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
>
> --
>
> *John Phillips*
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--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart 1976 Palm Beach 1977 28' Kingsley La Grange, Wyoming

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Re: Bump/thump while driving at low speed [message #359125 is a reply to message #359113]

Wed, 30 September 2020 22:04

Scott Nutter

Messages: 782
Registered: January 2015
Location: Houston/San Diego

Karma: 4

Senior Member

Thanks Bruce, I do feel it more in the seat. I will check the rears first.
Scott.

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Re: [GMCnet] Bump/thump while driving at low speed [message #359136 is a reply to message #359125]

Thu, 01 October 2020 10:15

Randy Hecht

Messages: 93
Registered: March 2019
Location: Roswell, GA

Karma: -5

Member

A broken belt in the tire?

Chaplain Randy Hecht
Roswell, GA
Chaplains are ready to Listen when you're ready to talk.

1974 Canyon Lakes GMC the Unicorn Express
80mm Front Disc and a work in progress
Electric Brake Vacuum System

> On Sep 30, 2020, at 23:04, Scott Nutter via Gmclist wrote:
>
> Thanks Bruce, I do feel it more in the seat. I will check the rears first.
> Scott.
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Re: Bump/thump while driving at low speed [message #359333 is a reply to message #359113]

Fri, 09 October 2020 18:40

Scott Nutter

Messages: 782
Registered: January 2015
Location: Houston/San Diego

Karma: 4

Senior Member

***UPDATE***. I’m pretty sure I found the problem.. a good size flat spot on the tire tread of the most aft rear tire......I have read that the aft rear tire has a tendency to lock up. Before I eat up more tires I think I need to back off the brake shoes. I am surprised how much tread on the flat spot was ground down, and I don’t even remember a panic stop...

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Re: Bump/thump while driving at low speed [message #359360 is a reply to message #359333]

Sat, 10 October 2020 12:54

Hal StClair

Messages: 971
Registered: March 2013
Location: Rio Rancho NM

Karma: -12

Senior Member

When the brakes are adjusted correctly it doesn't take a 'panic stop' to drag that rear tire. The reaction arm system will eliminate that issue but thats an expense you'd have to justify. For me it is a no-brainer.
Hal

"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane." 1977 Royale 101348, 1977 Royale 101586, Diesel powered, 1974 Eagle Bus 45',w/slideout, Rio Rancho, NM

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Re: Bump/thump while driving at low speed [message #359364 is a reply to message #359360]

Sat, 10 October 2020 14:49

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

Hal StClair wrote on Sat, 10 October 2020 13:54

When the brakes are adjusted correctly it doesn't take a 'panic stop' to drag that rear tire. The reaction arm system will eliminate that issue but thats an expense you'd have to justify. For me it is a no-brainer.
Hal

I'm right here with Hal on this. I had done bunch of mathematical modeling of the rear brakes and decided that there was nothing to be done without something sincere. Then I saw what Jim and Tom has to show at Amana. If I could have bought a kit that day, I would have. It fulfills its promise.

(A little aside here.. I should have thought of this before Tom Prior (a payback for colley) because this was almost what I did when I changed my Hodka dirt bike that had an uncontrollable rear brake to a "floating backplate". It made a rear brake that was controllable regardless of the track condition.)

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: [GMCnet] Bump/thump while driving at low speed [message #359369 is a reply to message #359364]

Sat, 10 October 2020 15:13

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Ahhh Yes. HODAKA'S I remember those things. Only thing that handled worse
than a Hodaka, was 2 of them. Their back brakes would lock up if you just
thought about applying them. I remember modifying a bunch of them to full
floating brakes. They worked quite well after that modification. They were
not competitive right out of the box, but, a good hop up kit was available
that made them "pipey as a bit%%". Really narrow powerband. But after all
the modifications, they were almost as fast as a good Penton or Husky was
right out of the crate. 2 stroke "nickle rockets" was how people used to
describe them. But, they were cheaper than anything else in their class.
Jim Hupy
Salem, Oregon

On Sat, Oct 10, 2020, 12:49 PM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Hal StClair wrote on Sat, 10 October 2020 13:54
>> When the brakes are adjusted correctly it doesn't take a 'panic stop' to
> drag that rear tire. The reaction arm system will eliminate that issue
>> but thats an expense you'd have to justify. For me it is a no-brainer.
>> Hal
>
> I'm right here with Hal on this. I had done bunch of mathematical
> modeling of the rear brakes and decided that there was nothing to be done
> without
> something sincere. Then I saw what Jim and Tom has to show at Amana. If
> I could have bought a kit that day, I would have. It fulfills its promise.
>
>
> (A little aside here.. I should have thought of this before Tom Prior (a
> payback for colley) because this was almost what I did when I changed my
> Hodka dirt bike that had an uncontrollable rear brake to a "floating
> backplate". It made a rear brake that was controllable regardless of the
> track
> condition.)
>
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Bump/thump while driving at low speed [message #359374 is a reply to message #359369]

Sat, 10 October 2020 16:00

Len Novak

Messages: 676
Registered: February 2004
Location: Las Vegas, NV

Karma: -3

Senior Member

Had that problem right before the aft rear tire blew last year.

On Sat, Oct 10, 2020 at 13:14 James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Ahhh Yes. HODAKA'S I remember those things. Only thing that handled worse
> than a Hodaka, was 2 of them. Their back brakes would lock up if you just
> thought about applying them. I remember modifying a bunch of them to full
> floating brakes. They worked quite well after that modification. They were
> not competitive right out of the box, but, a good hop up kit was available
> that made them "pipey as a bit%%". Really narrow powerband. But after all
> the modifications, they were almost as fast as a good Penton or Husky was
> right out of the crate. 2 stroke "nickle rockets" was how people used to
> describe them. But, they were cheaper than anything else in their class.
> Jim Hupy
> Salem, Oregon
>
> On Sat, Oct 10, 2020, 12:49 PM Matt Colie via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Hal StClair wrote on Sat, 10 October 2020 13:54
>>> When the brakes are adjusted correctly it doesn't take a 'panic stop'
> to
>> drag that rear tire. The reaction arm system will eliminate that issue
>>> but thats an expense you'd have to justify. For me it is a no-brainer.
>>> Hal
>>
>> I'm right here with Hal on this. I had done bunch of mathematical
>> modeling of the rear brakes and decided that there was nothing to be done
>> without
>> something sincere. Then I saw what Jim and Tom has to show at Amana. If
>> I could have bought a kit that day, I would have. It fulfills its
> promise.
>>
>>
>> (A little aside here.. I should have thought of this before Tom Prior (a
>> payback for colley) because this was almost what I did when I changed my
>> Hodka dirt bike that had an uncontrollable rear brake to a "floating
>> backplate". It made a rear brake that was controllable regardless of the
>> track
>> condition.)
>>
>> Matt
>> --
>> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
>> GMCES
>> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
>> Brakes with Applied Control Arms
>> SE Michigan - Near DTW - Twixt A2 and Detroit
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--

*Len and Pat Novak*

*1978 GMC Kingsley*

*The Beast II with dash lights that work and labels you can see!*

*Las Vegas, NV* new email: B52sRule@Gmail.com

http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375

www.bdub.net/novak/
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Len and Pat Novak 1978 GMC Kingsley The Beast II with dash lights that work and labels you can see! Las Vegas, NV new email: B52sRule@Gmail.com http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375 www.bdub.net/novak/

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Re: [GMCnet] Bump/thump while driving at low speed [message #359380 is a reply to message #359369]

Sat, 10 October 2020 17:35

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

James Hupy wrote on Sat, 10 October 2020 16:13

Ahhh Yes. HODAKA'S I remember those things. Only thing that handled worse than a Hodaka, was 2 of them. Their back brakes would lock up if you just thought about applying them. I remember modifying a bunch of them to full floating brakes. They worked quite well after that modification. They were not competitive right out of the box, but, a good hop up kit was available that made them "pipey as a bit%%". Really narrow powerband. But after all the modifications, they were almost as fast as a good Penton or Husky was right out of the crate. 2 stroke "nickle rockets" was how people used to describe them. But, they were cheaper than anything else in their class.
Jim Hupy
Salem, Oregon

Ah Jim, You are mixing classes.

I ran the Toaster Tank 100cc Super Rat. So there was no Husky in the class.
When set up right, I could turn inside a Penton (KTM) or pass him at the end of a straight because he didn't have a rear brake. Yes, they were peaky things, but you has to learn where your pipe was. If you didn't like, get out the torch and change it. For some track where I couldn't use the peak, I would put an additional 4" on the stinger and that got me some low end, but I gave up peak to do it.
The big problem was that there were two Bultacos in the class. If either finished (a rare event), he could beat me.
I got real good at standing the bike on its bars so I could put a new ring (yes single Dykes ring) because they only lasted about 10 hours at best and that was with moly.

I used to weight less than that bike.

Matt

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Re: [GMCnet] Bump/thump while driving at low speed [message #359383 is a reply to message #359380]

Sat, 10 October 2020 18:04

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

If you ran 100 cc class, and weighed less than that race prepped hodaka,
you must have been slim. They didn't weigh much. You are right about KTM's,
in fact most euro bikes wouldn't turn short, but they were great in the
desert and hare n hound stuff. They were fast. Hodaka's were quick, point
to point for sure. I always rode 250 cc stuff. Bultaco's, Greeves, Jawa and
CZ's, and one Husky. Their parts required a bank loan. You could fix
several Hodaka's for what those Husky parts cost. Dykes rings work well,
they just don't live long. Got to thinking, that was a very long time ago.
Decades, in fact. But we're still here. I still have some Greeves parts
around the shop.
Jim Hupy
Salem, Oregon

On Sat, Oct 10, 2020, 3:36 PM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:

> James Hupy wrote on Sat, 10 October 2020 16:13
>> Ahhh Yes. HODAKA'S I remember those things. Only thing that handled
> worse than a Hodaka, was 2 of them. Their back brakes would lock up if you
>> just thought about applying them. I remember modifying a bunch of them
> to full floating brakes. They worked quite well after that modification.
> They
>> were not competitive right out of the box, but, a good hop up kit was
> available that made them "pipey as a bit%%". Really narrow powerband. But
>> after all the modifications, they were almost as fast as a good Penton
> or Husky was right out of the crate. 2 stroke "nickle rockets" was how
> people
>> used to describe them. But, they were cheaper than anything else in
> their class.
>> Jim Hupy
>> Salem, Oregon
>
> Ah Jim, You are mixing classes.
>
> I ran the Toaster Tank 100cc Super Rat. So there was no Husky in the
> class.
> When set up right, I could turn inside a Penton (KTM) or pass him at the
> end of a straight because he didn't have a rear brake. Yes, they were peaky
> things, but you has to learn where your pipe was. If you didn't like, get
> out the torch and change it. For some track where I couldn't use the peak,
> I would put an additional 4" on the stinger and that got me some low end,
> but I gave up peak to do it.
> The big problem was that there were two Bultacos in the class. If either
> finished (a rare event), he could beat me.
> I got real good at standing the bike on its bars so I could put a new ring
> (yes single Dykes ring) because they only lasted about 10 hours at best and
> that was with moly.
>
> I used to weight less than that bike.
>
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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