| Author |
Message |
John Rigby (24.174.235.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 7:41 pm: | |
I am going to make a bracket to go under the front crank shaft bolt to come out each side and stop the fan hub ( should it break away from the rubber vulcanized materiel again )from going forward and aeroplaining the fan into the radiator like two weeks ago on my 671/4104.
The question is if the bracket is side ways across the end of the crank held on by the crank bolt. will this cause any undue out of balance condition??
I intend to have a machine shop make the bracket out of a maybe 1.1/2"wide flat.
I would appriciate your input and or questions.
Thank You
John |
DonTX/KS (66.82.9.20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 7:57 pm: | |
My first thought would be to put a couple of such straps across the radiator from side to side, would keep the fan out of the radiator and would appear to be easier? |
TWO DOGS (66.90.218.183)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 8:35 pm: | |
I would think it would cause a balance problem and premature failure |
John Rigby (24.174.235.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 8:43 pm: | |
What happend the last time the rubber let go, the fan and outer part of the hub still kept turning , but slowly moving out toward the radiator. the first thing the fan blades hit was the side of the radiator this bent the blades at an extreem angle so they finally started hitting the radiiator core and digging deeper.
My fear would be that if the rubber lets go and it moves towards the radiator I would probably have a simular problem as last time.
But if I can hold the fan hub in the same possision with a small bracket, I can save fan/radiator and probably the engine. I was lucky I did not blow the head gasket or crack the head.Two weeks ago.
It would not be so bad if there were any new fan hubs out there but there are none.
But in puting a bracket on I do not want to put the crank out of ballance.
Thanks
John |
TWO DOGS (66.90.218.183)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 9:04 pm: | |
I guess a machine shop could balance your contraption...you could take the whole assembly to them...I think..........unbalanced,would last 1/2 as long,....maybe less |
BrianMCI96A3 (65.40.154.50)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 9:13 pm: | |
John, I think you could do it if you drill the hole in the strap dead on center, and the same diameter as the crank bolt... then if you could get it to balance across the center of the bolt hole, it ought to work.
I'm not saying you need it, but the idea has been done before.
Brian |
John Rigby (24.174.235.149)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 9:18 pm: | |
Two Dogs,
The 671/04 fan hub is a very bad design, only rubber holding the fan and the hub on the end of the crank shaft.
I may take the hub to a drive shaft shop and have it balanced with the bracket on.
Thanks
John |
Jayjay (152.163.252.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 9:27 pm: | |
Unbalanced ...it could last only a few hours. Engine manufacturers go to great pains to balance their products to within a few grams, to keep everything smooth. Not only is it a matter of balance, but where weight is placed can affect the dynamic harmonics of the total reciprocating mass, causing undue stress on the crankshaft, bearings and seals. I'll have to agree with Don and suggest shrouding the radiator. Be very careful with add-ons. ...JJ |
Mike McC (64.252.213.103)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 10:34 pm: | |
If you are going to a machine shop, any chance of having a replacement for the rubber made out of aluminum that you could bolt the fan/hub to?
Maybe a stupid suggestion...I can't picture your set-up. |
BrianMCI96A3 (65.40.154.50)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 10:39 pm: | |
Actually, I have seen something exactly like what John is talking about...
As for engine manufacturers that take great pains to balance their products...
Well they do try I suppose, but when you have seen some of the things that engine manufacturers do, you tend to be a little sceptical... These things ARE mass produced...
GM had a little trick a few years ago that it was using on NEW crankshafts that didn't meet spec.
They'd turn each journal down until it was correct for an oversized rod bearing...
Bad enough...
BUT to save money on TOP of using out of spec. cranks, each journal was only cut to the minimum for the bearing that would fit.
So, you might have three journals that would be 10 thousandths undersized, another two might be 30 thousandsth under and the rest standard!
Lovely...
They take pains alright.
John, taking the assembly to a machine shop is an excellent idea
Brian |
Gary McFarland (Gearheadgary) (64.134.135.117)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 11:26 pm: | |
Actually, many manufacturers (All?) sent cranks out undersized--but all rods, and/or mains uniformly, AFAIK.
I was reading up on engine decoding recently and I ran across this. Previously I thought all cranks keft the factory.......Stock. |
BrianMCI96A3 (65.40.154.50)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 11:39 pm: | |
You might think that they would be standard or stock in a new vehicle, huh?
By the way, I was floored when the word came back from the machine shop about the first incident with mismatched journal sizes.
Brian |
Guy Bouchard (161.184.194.13)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 09, 2003 - 11:59 pm: | |
Hi John;
This is only a suggestion,but why don't you try changing up to a viscous damper? They make them in many configurations and a lot of Detroits used them over the years; no chance of it coming apart at the rubber,since they are one piece. Just make sure you don't hammer on it.
Guy4905 |
Tom Connolly (Tomconnolly) (64.58.196.218)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 6:26 am: | |
John,
Over the years several of my friends have solved the problem much easier! They simply drilled and tapped the crankshaft, installed a bolt and large washer with blue locktite, this insures the fan can't move into the radiator.
Tom C |
don (Bottomacher) (216.130.152.51)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 8:54 am: | |
I knew about the GM mismatched journals, but I thought they were sold only as "Targetmaster" engines. I had one of them with one cylinder bored .020. I've never rebuilt a factory engine that had a mismatched crank. Is it still going on? |
BrianMCI96A3 (198.81.26.38)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 11:30 am: | |
I hope not, I haven't run into one in a long time... You'd hope they cleaned up their act a little, but like I said, I'm always a bit sceptical.
Brian |
John Rigby (65.112.227.94)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 2:38 pm: | |
Tom
The washer would be 3.3/4" dia but I could not drill the centre off the crank shaft as the blot that holds the hub on goes there.if I drilled it off centre then I would really have a out of balance situation unless I dont undestand what you mean?
John |
Rick (12.250.174.20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 8:45 pm: | |
Can you use a stud in the crank with the first nut holding the dampner on and a second lock nut washer as a safety?
Rick |
Jayjay (64.12.96.105)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 10:00 pm: | |
Mis-matched journals? Yes, but still it was done to achieve a good balance. That's why we rebuilt brand new engines before we raced them. GM, and the UAW wonder why the Pacific Rim folks kicked their ass in the marketpalce for so many years! I never got more than 80K miles on any GM product before it needed major repairs, but my first Toyota went 283K miles with only $200.00 in repairs. (excluding rotables such as tires, filters etc.) If GM had built cars like they did my 4905, Honda/Toyota/Nissan would still be sitting on the docks in LA! Hey John, thanks for the coffee at the Flying J in Orange,TX, on my way thru. Cheers...JJ |
BrianMCI96A3 (65.40.154.50)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 10, 2003 - 10:46 pm: | |
Mis-matched journals? Yes, but still it was done to achieve a good balance.
Say WHAT?
Jayjay, no... it was not done to balance the engine.
GM found a way to save a buck by using reject castings, cranks whose journals wouldn't clean up when turned down to standard, or stock diameters.
AND THEN... just to save a little more, they only turned each journal enough so that they WOULD clean up, then stuck in what ever oversized bearing that fit.
That my friend, has nothing to do with balance...
Well, that is, unless you meant to say:
..still it was done to achieve a good balance in GM's bottom line.
If so, I agree!
Brian |