Home » Public Forums » GMCnet » FYI Steering Gearbox
| FYI Steering Gearbox [message #130017] |
Mon, 13 June 2011 09:52  |
biggreen
Messages: 347
Registered: June 2011
Location: Northeast Florida
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Napa has changed the part # on the 277519 gearbox. New Napa # is 88278080. #164.00 $84.00 core.
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| Re: [GMCnet] FYI Steering Gearbox [message #130036 is a reply to message #130017] |
Mon, 13 June 2011 11:57  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Here's the applications list for P/N 277519 from Rockauto.com (A-1
Cardone remanufactured):
CHEVROLET P10 VAN (1976 - 1979)
CHEVROLET P20 VAN (1976 - 1979)
CHEVROLET P30 VAN (1976 - 1979)
GMC P15 VAN (1976 - 1978)
GMC P1500 VAN 1979
GMC P25 VAN (1976 - 1978)
GMC P2500 VAN 1979
GMC P35 1978
GMC P35 VAN (1976 - 1978)
GMC P3500 VAN 1979
$107.79 + $75 core (I can send a 5% discount # to anyone).
I don't doubt for a moment that it will fit. But I'd use it only
subject to the precautions I posted yesterday because of the incorrect
travel stops.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Mon, Jun 13, 2011 at 10:52 AM, R.D. Hart wrote:
> 277519
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Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] FYI Steering Gearbox [message #130071 is a reply to message #130046] |
Mon, 13 June 2011 18:03 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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I'm not qualified to answer that -- I've never torn down a steering
box. The best references I know of are the manual and Don Wirth's
paper at GMCEast.com. Sorry to have to raise an alarm without being
able to offer a solution.
Ken H.
On Mon, Jun 13, 2011 at 2:17 PM, R.D. Hart <regor5556@yahoo.com> wrote:
>
>
> So if I were to change out this spacer, this box would operate as the original. Is this easy to do? I hate having to spend $400+ one from Calif. is this will work.
>
> Thanks, Ken.
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Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: FYI Steering Gearbox [message #144616 is a reply to message #130017] |
Mon, 26 September 2011 13:04 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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I don't think the 88-278080 part number listed above is correct. The specs say the power steering line threads are metric sizes. Also the output shaft is 3/4" instead of 13/16". Maybe it doesn't matter much.
There are two other NAPA parts that might more correct: 88-278070 (NAPA xref for 1973 Olds Toro) or 88-277080 (suggested by another parts place). Both are SAE ps line threads, 13/16" 32-spline output shafts. The only difference I can find between the two is that the 88-278070 is 4-1/4 turns, and the 88-277080 is "3-1/2 - 4-1/4" turns (not sure what it means when they spec a range...).
I'm planning to order an 88-278070 for overnight delivery. Any thing I'm missing? NAPA says $164 + $83 core (Cardone reman).
Part numbers xref for 1973 Olds Toro:
NAPA 88-278070 $164 + $83 (Cardone reman)
CarQuest 27-6529 $156 + $71 (reman)
Advance SG16529 $130 + $33 (Fenco reman)
AutoZone 6529 $124 + $23 (Duralast reman)
The GMCMI parts interchange list just says "GMC Suppliers", and JimK has a $350 + $250 rebuild on his site. I think I understand the difference. My current gear box came from a shop in VA without much research, so I'm sure it's not a rebuildable core for a motorhome.
1973 Sequoia 260 (since 2011)
[Updated on: Mon, 26 September 2011 13:11] Report message to a moderator |
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| Re: FYI Steering Gearbox [message #144619 is a reply to message #144616] |
Mon, 26 September 2011 13:19 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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| Andrew wrote on Mon, 26 September 2011 14:04 |
I don't think the 88-278080 part number listed above is correct.
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I should clarify that 88-278070 is also the new part number that NAPA came up with for their old 27-7519.
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] FYI Steering Gearbox [message #144634 is a reply to message #144616] |
Mon, 26 September 2011 15:35 |
powerjon
Messages: 2446
Registered: January 2004
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Be sure that it is the one that has the stops in it as as the
incorrect box will damage the CV joints and is 3 1/3 turns L to L.
3/4" 24-point shaft. You should read the article at the GMCES site on
steering boxes before you order.
http://www.gmceast.com/technical/Wirth_GMCMH_Steering_Box.pdf
JR Wright
GMC Great Laker MHC
GMC Eastern States
GMCMHI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Sep 26, 2011, at 2:04 PM, Andrew wrote:
>
>
> I don't think the 88-278080 part number listed above is correct. The
> specs say the power steering line threads are metric sizes. Also the
> output shaft is 3/4" instead of 13/16". Maybe it doesn't matter much.
>
> There are two other NAPA parts that might more correct: 88-278070
> (xref for 1973 Olds Toro) or 88-277080 (suggested by another parts
> place). Both are SAE ps line threads, 13/16" 32-spline output
> shafts. The only difference I can find between the two is that the
> 8070 is 4-1/4 turns, and the 7080 is "3-1/2 - 4-1/4" turns (not sure
> what it means when they spec a range...).
>
> I'm planning to order an 8070 for overnight delivery. Any thing I'm
> missing? NAPA says $164 + $83 core (Cardone reman).
>
> Other part numbers xref for 1973 Olds Toro:
>
> CarQuest 27-6529 $156 + $71 (reman)
> Advance SG16529 $130 + $33 (Fenco reman)
> AutoZone 6529 $124 + $23 (Duralast reman)
>
> The GMCMI parts interchange list just says "GMC Suppliers", and JimK
> has a $350 + $250 rebuild on his site. I think I understand the
> difference. My current gear box came from a shop in VA without much
> research, so I'm sure it's not a rebuildable core for a motorhome.
>
> --
> 1973 Sequoia 260 (since 2011)
> In-transit, westward
> _______________________________________________
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J.R. Wright
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GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] FYI Steering Gearbox [message #144663 is a reply to message #144634] |
Mon, 26 September 2011 18:17 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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| powerjon wrote on Mon, 26 September 2011 16:35 |
Be sure that it is the one that has the stops in it as as the
incorrect box will damage the CV joints and is 3 1/3 turns L to L.
3/4" 24-point shaft. You should read the article at the GMCES site on
steering boxes before you order.
http://www.gmceast.com/technical/Wirth_GMCMH_Steering_Box.pdf
|
Yikes. I read that doc among many others and thought I remembered that detail. When I looked for the source of the memory, I couldn't find it so I just went with the best guess.
However, ALL of the NAPA parts listed, including their new replacement for the old 27-7519, say 32 splines on the input shaft. The AutoZone part has 32 splines on the output shaft and 36 splines on the input shaft. CarQuest and Advance don't offer spec sheets that say one way or another. I can't find a data sheet from NAPA or Cardone that details the original 27-7519.
Oh well. It will be here tomorrow, and we will either be on our way, or not. :-/
Edit: fix one instance of original part #, fix input for output in AZ part spec
1973 Sequoia 260 (since 2011)
[Updated on: Wed, 28 September 2011 11:52] Report message to a moderator |
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| Re: FYI Steering Gearbox [message #144890 is a reply to message #130017] |
Wed, 28 September 2011 11:33 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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Updating..
The original 27-7519 also had 32 splines on the input shaft, according to the NAPA national tech guy that the local store called when I picked up the gearbox.
The new part number is 88-278070, and it has a 32 spline, 13/16" input shaft. I counted the splines, and took the diameter from the specs. It fits a 12-point 3/4" socket perfectly. It does not fit a 12-point 13/16" socket, fwiw. This seems to contradict my reading of Don Wirth's paper on gmceast.com. I'm sure he's right, but NAPA can't cross any new part numbers that have a 24 spline input shaft. I don't know what else to do but put it in and see what breaks.
There's a flat spot on the input shaft where there are no splines. So the 32 splines must be spaced as if there would be 36 without the flat spot. That could explain why the 12-point socket fits on a 32-spline shaft.
Anyway, the gearbox goes in shortly. I'll update again with any discoveries.
Edit: fix original part #
1973 Sequoia 260 (since 2011)
[Updated on: Wed, 28 September 2011 11:49] Report message to a moderator |
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| Re: FYI Steering Gearbox [message #145050 is a reply to message #130017] |
Thu, 29 September 2011 21:39 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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Epilogue, and summary:
New NAPA 88-278070 (13/16", 32-spline input shaft) gearbox went in with no trouble. Old gearbox also has 32 splines on the input shaft, and fits the same 3/4" 12-point socket identically, so I'm assuming it is also 13/16".
The first part number mentioned in this thread (88-278080) has a 3/4", 32-spline input shaft. Maybe this will work too. This part will require changing your power steering hoses to metric fittings via adapter or replacement. It has turn limits of 3-3/8 to 4-1/4, adjustable. 3-3/8 is not the stock 3-1/3, but it is close enough (min 1/48 turn, about 1.5 minutes on a clock, in either direction!) that the additional travel should not case damage.
The 88-277080 might be a good answer too. The ps hose fittings are SAE, and the turn limits are adjustable from 3-1/2 to 4-1/4 (min 1/12 turn, 5 minutes on a clock, extra in either direction).
The part that I'm running now (88-278070) gives 4-1/4 turns lock to lock, not adjustable. That's a little less than a half turn, 27.5 minutes on a clock, extra in either direction. I don't know if that's dangerous -- I checked for any obvious things touching where they shouldn't and found none. My CV joints will probably be under additional strain when making slow parking lot turns...within spec or not, I have no idea. Regardless, I'll be careful.
I failed to salvage the original stops from the old gearbox, so I'm probably going to live with this for a while. If I had to do it again, I think I'd go with the 88-277080.
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] FYI Steering Gearbox [message #145056 is a reply to message #145050] |
Thu, 29 September 2011 22:27 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Andrew,
Did you check these critical locations?:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=25814&title=010made-with2499-ol&cat=4982
Ken H.
On Thu, Sep 29, 2011 at 10:39 PM, Andrew <reynhout@quesera.com> wrote:
>
> ...That's a little less than a half turn, 27.5 minutes on a clock, extra in
> either direction. I don't know if that's dangerous -- I checked for any
> obvious things touching where they shouldn't and found none. My CV joints
> will probably be under additional strain when making slow parking lot
> turns...within spec or not, I have no idea. Regardless, I'll be careful.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] FYI Steering Gearbox [message #145057 is a reply to message #145056] |
Thu, 29 September 2011 22:55 |
midlf
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Registered: July 2007
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Looking at the pictures it's not clear to me what was ground off, the bolt head or the knuckle?
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] FYI Steering Gearbox [message #145061 is a reply to message #145057] |
Fri, 30 September 2011 06:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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A little of both, actually. The arms had been additionally reinforced and
thick-headed bolts installed. I ground the heads slightly, but didn't want
to weaken them significantly so most of the clearance was ground into the
knuckles. I did that reluctantly, but the alternatives were even less
attractive.
During a couple of the seminars at Goshen, the topic of this clearance came
up:
1. Bob Drewes pointed out that when he modified the A-arms for installation
of the 1T front end, he was careful to provide stops on the A-arms to
prevent over-rotation of the knuckles. Those stops were positioned to
normally have a little bit of clearance (1/16"?), purely as a precaution
against flaws elsewhere in the steering linkage. The steering box remains
the primary limiting component.
2. During Dave Lenzi's seminar, he and I discussed the importance of
retaining the steering box stops because of the fact that if the knuckle
stops come into play, unreasonable forces can be imposed on all components.
For example, estimate the length of the knuckle's steering arm from the
steering axis as 10" and the distance of the knuckle stop from that same
axis as 2". Then any steering force applied by the steering linkage will be
multiplied by 10/2=5 times on the ball joints, primarily the lower, where
there's already the hazard of cracking. Also, the entire force of any
steering vector supplied by the steering box will be "dead-ended" rather
than merely causing the wheels to turn.
Ken H.
On Thu, Sep 29, 2011 at 11:55 PM, Steve Southworth <midlf@centurytel.net>wrote:
>
>
> Ken Henderson wrote on Thu, 29 September 2011 22:27
> > Andrew,
> >
> > Did you check these critical locations?:
> >
> >
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=25814&title=010made-with2499-ol&cat=4982
> >
> > Ken H.
>
>
> Looking at the pictures it's not clear to me what was ground off, the bolt
> head or the knuckle?
> --
> Steve Southworth
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: FYI Steering Gearbox [message #145125 is a reply to message #145062] |
Fri, 30 September 2011 20:46 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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| biggreen wrote on Fri, 30 September 2011 07:35 |
The part # in question in the first post was obtained from Jim Bounds when I called him looking for a rebuilt unit. When I called Napa, they gave the the superceded #.
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I wonder if they've changed their old-new mappings for this part. The box that my 88-278070 came in also had the old 27-7519 number on it.
Except for the turn count, which might be less important on other vehicles, the 8070 would seem to be a closer match than the 8080...
Still, the 88-277080 seems closer than both of the others, for our case.
I haven't checked the knuckle-bolt clearance remaining after my extra half-turn, but I will when the weather improves. I assume Ken will be proven correct, and I'll need to start thinking about ways to address the problem. I don't know how complex the stops are, or what they're made of. Could replacements be fabbed at a machine shop? The photo in the MM suggests that they might be simple.
1973 Sequoia 260 (since 2011)
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