Distributor shaft wobble. Is this okay? - Ford Mustang Forums : Corral.net Mustang Forum

Old 06-19-2009, 05:10 PM Thread Starter
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Location: Montgomery (north of Houston), TX
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Distributor shaft wobble. Is this okay?

I just picked up a rebuilt 1991 5.0 distributor from NAPA. Normally I try to stay away from rebuilt things but I usually trust NAPA a little more.

Anyway, the distributor shaft seems to wobble side to side quite a bit. If I grab the cam gear, the shaft moves from side to side. I took it back to NAPA and the parts guy called his Ford tech buddy and he said that Ford distributor shafts will move (side to side) and are "locked" into place when you install it into the engine. Another pro mechanic was standing there at the parts counter and he said the same thing. My original distributor shaft has little to no play in it.

What do you guys say? I brought it back home but I'll take it back and buy something new if you guys suggest. I don't want to take any chances. My Mustang has been unreliable recently and its no fun being stuck on the side of the interstate.

See my thread here if you're curious and you've got extra time on your hands. Yeah, right !

Should my fuel line be pressurized??

'91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster

'02 WS-6 Trans Am

'80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks

Last edited by dannyUAL91GT; 06-19-2009 at 05:13 PM. Reason: added info
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Old 06-19-2009, 05:19 PM
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I don't care what the parts guy said, I'd ask for a replacement.
From my experience, a bit of up/down movement is normal, but a side to side wobble is trouble.

frankstang is offline
Old 06-19-2009, 05:38 PM
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Well – now that I’ve torn-down both my stock 5.0 (300,000-mile) distributor, and “new” (3,500-mile) eBay find - (a ’89 stock 5.0 distributor that sat in a box for 15-years after a early MSD replacement.) IMHO, I don’t know how any stock 5.0 distributor could NOT have some “wobble” in it. There is no bushing at the bottom of the housing – more like a 3-fingered, “flared” end which doesn’t make contact with the shaft . The actual bushing is up high in the housing more towards the rotor.

'86 GT : Original Owner, Speed-Density 331
'86 GT Convertible : Mostly Stock 5-speed
'67 Convertible : 289 Resto-mod
'74 F100 : 240 I6
Mark Harrell is offline
Old 06-19-2009, 09:19 PM Thread Starter
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Quote:
Originally Posted by Mark Harrell View Post
Well – now that I’ve torn-down both my stock 5.0 (300,000-mile) distributor, and “new” (3,500-mile) eBay find - (a ’89 stock 5.0 distributor that sat in a box for 15-years after a early MSD replacement.) IMHO, I don’t know how any stock 5.0 distributor could NOT have some “wobble” in it. There is no bushing at the bottom of the housing – more like a 3-fingered, “flared” end which doesn’t make contact with the shaft . The actual bushing is up high in the housing more towards the rotor.
This is exactly what the pro mechanic standing there said!

'91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster

'02 WS-6 Trans Am

'80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks
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Old 06-20-2009, 05:54 AM
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Location: Devore Hts, Calif...FIRE COUNTRY
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and THAT IS WHY THE STOCK unit ,

or a rebuilt unit

...when it wobbles...

.....IS WORN OUT.....

go and buy a new one...

what was bad in the original distributor that you had since you have said that it "wobbles" less than the rebuilt one.....???

just replace the electronicKs inside the less worn housing.....

I have gone down the road that you are only now about to travel.
tires are the great equalizer
a degree wheel, EIGHT INCH dial caliper & adjustable pushrods should be just as normal as a 1/2" wrench in your toolbox
there aint no shortcuts to doing it RIGHT....
Kato Engineering is offline
Old 06-20-2009, 08:33 AM Thread Starter
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Quote:
Originally Posted by Kato Engineering View Post
and THAT IS WHY THE STOCK unit ,

or a rebuilt unit

...when it wobbles...

.....IS WORN OUT.....

go and buy a new one...

what was bad in the original distributor that you had since you have said that it "wobbles" less than the rebuilt one.....???

just replace the electronicKs inside the less worn housing....
.
On Thursday, I pressed off the steel cam gear but there was another "collar" that I couldn't use the hydraulic press to get off to remove the distributor shaft. Here is a pic of a screwdriver pointing to what I'm talking about:

I just went out and messed with the collar. I used that screwdriver to lightly pry on it (downward toward where the cam gear was) and it moved! I still need a small gear puller to remove it but I can use one from Advance Auto Parts for free. Then I can remove the stator and replace it .

I have another issue, though. Take a look at this pic of my reluctor wheel. Look at those marks.

Doesn't it look like the reluctor wheel has contacted the stator pickup? That can't be good. There aren't a lot of marks and it is only on a few of the reluctor wheel "windows." The top distributor bearing still feels nice and snug with no play.

Please let me know what you think.

Danny

'91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster

'02 WS-6 Trans Am

'80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks
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Old 06-20-2009, 10:24 AM
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Wow - that collar is certainly different compared to both my stock units. Mine are much smaller - more like the size of a nut... and they were not pressed - just "snug" - I got them to slide off by hand. Maybe some WD-40 on the shaft will get it off.

I'd say those marks on the wheel are certainly not good. Neither of my units show that. Also - I'm going to take a closer look at the bottom "bushing" before I agree or disagree it Kato...
=================================================
Edit:

OK – here’s what I found. The dist. shaft is held firmly in place at the top by the dist. housing bushing/sleeve (which measures ~ 1.8”) and the block bushing/sleeve at the bottom of the shaft (where it meets the oil pump driveshaft – block sleeve measured ~1.15”.) The bottom of the dist. housing and shaft have huge clearance – which means the bottom of the housing is not a “wear point” - and plays no part in holding the shaft in place (or keeping it from wobbling.)

Here you can see the shaft/housing clearance at the bottom of the (brighter aluminum) distributor housing.

I “tested” how snug the bottom block bushing/sleeve was by seeing how much wobble or slop was at the top of the free-standing dist. shaft(s.) I got ~.050 with my old, and .042 with the new.

I then added the housing. This proved my old unit had some wear compared to the new. The old housing and shaft measured .002 (two thousandths.) New housing and shaft may have measured .0005 (half a thousandth) but I'm not sure as I was yanking/pushing/pulling pretty hard.

It appears to me that Ford designed the stock 5.0 distributor to have enough clearance between the shaft and dist. housing bushing to allow for some oil lubrication/splash to reach at least the bottom of the shaft/bushing. (My old unit had lots of oil-buildup inside the bottom of the housing.) The shaft also has a spiral groove cut in it where it rides inside the bushing – this groove spirals in a downward direction which appears it would keep oil from reaching the top of the shaft and filling the inside of the distributor.

It’s my guess Ford distributors came off the assembly line with a wide range of “wobble” tolerances - from almost none to “significant.”

IMHO – a little “wobble” at the base of the housing while holding it in–hand is irrelevant – because once you stab the dist. in the block and “plug” the bottom of the shaft into the block bushing – all wobble is virtually eliminated.

I think a better distributor bushing “wear test” would be to check if you can feel any free-play (wobble) at the top / rotor-side with it in the block. As I described in the 3rd photo - my old unit has very slight movement - I could feel it. The new unit may have .0005, but I can't feel any play. (Again, while holding the new unit in-hand it does have slight wobble/play at the bottom.)

'86 GT : Original Owner, Speed-Density 331
'86 GT Convertible : Mostly Stock 5-speed
'67 Convertible : 289 Resto-mod
'74 F100 : 240 I6

Last edited by Mark Harrell; 06-20-2009 at 04:45 PM. Reason: Add info after shop-time...
Mark Harrell is offline
Old 06-21-2009, 09:38 AM Thread Starter
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Location: Montgomery (north of Houston), TX
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Mark, those are some great pictures that are worth more than a million words! Now I can see why there is no bearing/bushing at the bottom of the distributor housing. Its "held" in place by the block itself. This tends to confirm what the pro mechanic at NAPA and the NAPA counter guy's buddy said.

Yes, my original, from the factory distributor has a collar that is different. My rebuilt, NAPA unit has a much smaller collar; probably like yours.

Those marks on my reluctor wheel have me concerned. Its possible that something is wrong with my stator to have caused contact, but I don't really know what is wrong. There aren't all that many contact marks. Upon close inspection of the marks, it almost looks like the reluctor touched the stator pickup during assembly of the distributor. Like things weren't tightened down and someone spun the shaft and the reluctor kissed the stator pickup. But what do I know? Heck, I don't even know if these things were built by hand at the factory .

I'm back to an indecision point. Do I rebuild my stocker or do I keep the $114, rebuilt NAPA unit ? '91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster '02 WS-6 Trans Am '80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks dannyUAL91GT is offline Old 06-21-2009, 03:50 PM Thread Starter Registered User Trader Feedback: (0) Join Date: Mar 2002 Location: Montgomery (north of Houston), TX Posts: 1,193 I just got my distributor apart and I cleaned the shaft. I put some oil on it and stuck the shaft back in. Spins like its brand new. Even though there is only one bushing at the top of the distributor, my factory unit has very little wobble. I looked at those marks on the reluctor again. There is no way that I can believe that those few marks were made due to contact with the stator pickup while the engine was running. I'm going to return the NAPA rebuilt and get a new stator and put my original back together. '91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster '02 WS-6 Trans Am '80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks dannyUAL91GT is offline Old 06-22-2009, 02:10 AM Registered User Trader Feedback: (0) Join Date: Oct 2003 Location: Devore Hts, Calif...FIRE COUNTRY Posts: 17,637 even though the lower end of distributor shaft is supported in a small ledge inside the engine block, ... more support as possible is still better... when the block ir shaft diameter tollertance is loose, it can wear the hex inside the shaft or oil pump.. when the shaft is loose at the bottom, it allows the spark to be irratticK... \it can also allow the top of ruluctor to wobble and hit the outer pickup as seen in the detailed photo. when oil pump hex drive is forced to run out of concentric, then the parts wear even faster. a good unit from msd will not be loose as seen. some makers will sell / offer onl;y a unit that is "billett" aluminum , which thus has a bearing or bushing on the bottom I have gone down the road that you are only now about to travel. tires are the great equalizer a degree wheel, EIGHT INCH dial caliper & adjustable pushrods should be just as normal as a 1/2" wrench in your toolbox there aint no shortcuts to doing it RIGHT.... Kato Engineering is offline Old 06-22-2009, 10:05 AM Registered User Trader Feedback: (8) Join Date: Dec 1999 Location: San Antonio, TX Posts: 2,448 Danny – similar to yours, my factory stock (300,000-mile) unit’s shaft was hard to turn due to 20+years of baked-on oil residue on both the shaft and bearing. I cleaned it up and it does spin freely – but now there is some slight side-to-side “slop” in it once installed. (I’ll take a guess that the oil buildup actually kept the shaft tight – and now that it’s clean there’s added “clearance” – which may cause issues as Kato described.) Again – with the “new” unit bolted in-place with a clean and free-spinning shaft – I can detect no “slop”. Test yours – stab and bolt it down – push/pull (side-to-side) on the top of the shaft to verify there’s no side-to-side movement (plus I'd certainly verify the reluctor can’t make contact with the stator.) Kato – I posted a thread a few weeks ago asking advice on a new distributor, and the consensus was stick with a stock unit. On one hand you’d certainly think an after-market unit like an MSD would be superior to stock – then you read lots of other posts saying they are a waste of$\$ as the electronics fail “often”?? It’s confusing…

'86 GT : Original Owner, Speed-Density 331
'86 GT Convertible : Mostly Stock 5-speed
'67 Convertible : 289 Resto-mod
'74 F100 : 240 I6
Mark Harrell is offline
Old 06-22-2009, 12:24 PM
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.......AS the world turns...and changes..

...so far, the best distributor HOUSING and shaft is a MSD unit.. but , ..yes, I have returned a few "loose" units over the years....msd just probably sells them to someone else.

but then I allways install a FORD produced internal electronicKs...
but reciently, many more than what was commonly accepted previously have had issues with the ford produced electronicKs.....

so, we all take our chances.

the main other issue with a "so called rebuilt unit" is that when the MASS rebuilder takes apart wagon loads of old units, ...and then mixes the pieces all up in a barrell...and they fall out on the worktable...ya never know what piece was in what housing..

most rebuilt stuff is just a cosmetic minimum cleanup and replacement of electronicK component......if shaft or bushing is loose,..who cares!!!!..they dont.

you will get the best out of a junk yard CORE,..... IF YOU PULL IT YOURSELF out of an actual engine that you can get your hands on....and that DOES NOT MEAN, to "ASK" the guy at the front counter to get you one....

dont forget or loose perspective that a distributor housing is made for pennies...and sold for many dollars....

I have gone down the road that you are only now about to travel.
tires are the great equalizer
a degree wheel, EIGHT INCH dial caliper & adjustable pushrods should be just as normal as a 1/2" wrench in your toolbox
there aint no shortcuts to doing it RIGHT....
Kato Engineering is offline
Old 06-22-2009, 07:23 PM Thread Starter
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Join Date: Mar 2002
Location: Montgomery (north of Houston), TX
Posts: 1,193
I returned the NAPA "loose" distributor and got a USA made NAPA stator. I installed it, pressed the cam gear back on and drove in new roll pins. The installation back into the engine went fine and I timed it back to what it was before; the factory setting of 10° BTDC. The car is running fine and hopefully it'll be reliable now.

'91 GT, Hedman X-pipe, Dynomax Ultra Flo Welded, Flowmaster tailpipes, FMS clutch, UPR quadrant & firewall adjuster

'02 WS-6 Trans Am

'80 Z28, 406SBC, World Sportsman heads, Comp Cam, Speed Pro forged pistons, Weiand Team G, MSD Digital 6, Hedman headers, Richmond Gear 6-sp, 3" exhaust, PST polygraphite front suspension, Moog coils, Edelbrock IAS shocks
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