harvs ek 327 wagon

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Blacky
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Re: harvs ek 327 wagon

Post by Blacky »

does your diff have the factory bump stop plates on it ? Can you post a pic Harv ???
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Harv
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Re: harvs ek 327 wagon

Post by Harv »

Blacky wrote: Wed Oct 25, 2017 11:25 am does your diff have the factory bump stop plates on it ? Can you post a pic Harv ???
To be honest, I'm not sure what bump stop plates are on the diff :oops: . The only bit I am confident on is that the factory bump stops are bolted up to the subframe (can remember repainting the rectangular plates and bolting them in). I'll try and take a picture (and have a play with the piece of string) when I am home this weekend.

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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Errol62
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Re: harvs ek 327 wagon

Post by Errol62 »

Harv
Not claiming to be an expert but I think it would be reasonable to assume that the front portion of the spring won’t deform significantly with changes in load. Therefore the contact points can be assumed to be in the same radial arc. In other words the distance from the front bush centre pin to the centre of plate and top of bump rubber should be the same. That’s my theory.
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Clay


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Re: harvs ek 327 wagon

Post by Harv »

Errol62 wrote: Wed Oct 25, 2017 12:27 pmHarv
Not claiming to be an expert but I think it would be reasonable to assume that the front portion of the spring won’t deform significantly with changes in load. Therefore the contact points can be assumed to be in the same radial arc. In other words the distance from the front bush centre pin to the centre of plate and top of bump rubber should be the same. That’s my theory.
Cheers
Clay
This is what I think happens (I could be wrong though).

The spring has an eye one end (on the left in the diagrams below), and a shackle on the other (on the right). As you compress the spring (like the 2nd image), the spring straightens out. The distance along the top of the spring doesn't change. As the spring goes over a bump, it tries to flatten. To allow the curve to flatten, the shackle moves backwards, like in the 2nd image. This makes the diff move slightly backwards as the suspension goes over a bump.
bumpstops.png
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To simulate this without mooshing the suspension, you run a length of string from the eye, along the top of the spring (like the red line in the 3rd image). This distance never changes. You then pull the spring tight, and arc it up (like in the 4th image, though wihout moving the suspension like the 4th image). The end of the string show you where the bottom of the diff will move to.

Cheers,
Harv
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Craig Allardyce
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Re: harvs ek 327 wagon

Post by Craig Allardyce »

Harv I think I would question him again on this. If he means that the bump stop wont meet with the diff i.e. directly on top of the new pad on the diff housing then ok. But if he is talking about not making contact because of distance to the stop then he's wrong.
You are using the standard springs mounted at the factory points and using the same centre bolt location so nothing should change travel wise unless you have fitted shorter stops.
I am assuming that you have refitted the old brackets to the leading edge of the diff?
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Harv
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Re: harvs ek 327 wagon

Post by Harv »

Craig Allardyce wrote: Wed Oct 25, 2017 2:37 pm Harv I think I would question him again on this. If he means that the bump stop wont meet with the diff i.e. directly on top of the new pad on the diff housing then ok. But if he is talking about not making contact because of distance to the stop then he's wrong.
You are using the standard springs mounted at the factory points and using the same centre bolt location so nothing should change travel wise unless you have fitted shorter stops.
I am assuming that you have refitted the old brackets to the leading edge of the diff?
As far as I understood it, the engineer was concerned that when the spring compressed the factory bump stops would not hit the diff (i.e. that the diff would bottom out on the floorpan/subframe instead of on the bump stop.

To be honest, I have not done anything to the diff other than bolt it in. I sent a VP Commodore diff off to V6 Conversions with directions to “narrow it to suit an EK”. V6 Conversions narrowed it, and welded on the appropriate mounting pads (made out of RHS) for the U-bolts. They also managed to loose the diff for a few months, but that is another story. I didn’t even think to look for bolt-on bump stop pads… I’ve got some homework to do when I get home again.

The engineer also mentioned limiting suspension travel (from memory to 110mm). This didn’t make sense to me either, as I thought NCOP etc all encourage retaining as much of the original suspension travel as possible.

The engineer owes me an email summarizing what he wants done, which I am hoping will clear up a few things. In the meantime, I’m trying to understand the issues better myself. Been a bit of a learning experience.

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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Re: harvs ek 327 wagon

Post by EK283 »

Hi Harv,

I'm with Craig on this one, and also the drawing you have you have to remember the spring is longer on the rear so will flatten first before the front (which wont really move the diff forward and back that much)

Have you got the original bump stop brackets welded to the front side of the diff housing tubes ?

If not the bump stops will be in the wrong location and miss the housing tubes at full compression.

Your new diff may also be larger in and around the crown wheel area and that could be the issue.

Measure the distance between that and the floor and the bump stop distance to the diff and you may get some answers.

Regards
Greg
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Craig Allardyce
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Re: harvs ek 327 wagon

Post by Craig Allardyce »

Maybe if the diff centre part of the new housing is substantially bigger then the old banjo unit you might come close but you'd have to carrying a heap of weight in the back to get remotely close to flatening out the springs. Probably towing something like a tandem trailer with another early Holden on it!! I think I have seen a picture of that somewhere Harv. :D

It's a long way to the floor from the diff centre.
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Errol62
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Re: harvs ek 327 wagon

Post by Errol62 »

I still think the straightened out spring length won’t be significantly longer.
Why not load up the back of the car until the travel is taken up? I’m sure you’ve got a bit of heavy iron lying around.


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Re: harvs ek 327 wagon

Post by Blacky »

Have a look at this post Harv, does your diff have the bump stop brackets on the diff or have they forgotten to put them back on ?

http://www.fbekholden.com/forum/viewtop ... 26&t=12209

Shows clearly the difference between FB/EK and HR diffs.
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Harv
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Re: harvs ek 327 wagon

Post by Harv »

Craig Allardyce wrote: Wed Oct 25, 2017 5:14 pmProbably towing something like a tandem trailer with another early Holden on it!! I think I have seen a picture of that somewhere Harv. :D
I reckon I could get a job as the Hayman Reese test pilot :mrgreen:
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Thanks for the input guys - appreciated. I'll do some thinking and measuring once I'm home this weekend, and post the results.

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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Re: harvs ek 327 wagon

Post by Harv »

I now understand why the brake booster doesn't want to play. Pedal ratio was OK (5:1 as per factory). The Chev only has 13"Hg of vacuum at idle though... the 87º of valve overlap probably doesn't help :mrgreen:. Needs at least 16"Hg to run the booster. Looks like a vacuum tank and pump are on the cards. I've got room on the drivers side inner guard (where a NASCO brake booster would go), so should fit OK.

A couple of weeks of driveway stop starts after the oil change, and the oil is still honey coloured. Looks like it probably was the green run-in oil that was making the oil green, not glycol. Fingers still crossed though.

Time to go play bump stops.

Cheers,
Harv
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Re: harvs ek 327 wagon

Post by Errol62 »




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Re: harvs ek 327 wagon

Post by Harv »

Put the back end of the wagon up in the air, and sorted a few things yesterday. Put some spring washers under the diff u-bolts, rebent the brake lines off the diff and made two p-clamps to hold them to the diff tubes, and made a heat shield for the fuel pump. Painted them all up and refit (good painting weather yesterday).

That lot went well. Then I looked at the bump stops :( .

The diff has no bump stop brackets at all... just the factory axle tubes. I ran the string out along the spring, then pulled it taut and arced it up. The centre of the diff tube almost hits the bump stop. If you picture where the rubber meets the steel bump stop retaining plate (on the aft side), that's where the diff tube hits. It would tend to smoosh the bump stop forward, and tear it out of the retaining plate. I can see now why the FB/EKs had the little bracket on the front side of the diff tubes.

More of a worry though is that Greg is right - the diff pumpkin wants to hit the floor before the diff tubes hit the subframe. The BW pumpkin is pretty hefty. There is only 140mm between the pumpkin and the floor, but 200mm between the tubes and the subframe. With the factory bump stops, there is bugger all compression on the rubber before the pumpkin would want to tear its way into the cargo space :shock: . Now I know why the engineer wanted me to limit suspension travel.

So all up I need some bump stops that are slightly more rearward, and a bit taller than the factory ones. I'm trying to avoid welding brackets onto the diff (I can't weld), and also trying to avoid making new holes in the subframe for the bump stop plates (I don't own a nutsert gun). What I'm figuring is that polyurethane is recognised as an acceptable bump stop material for many cars, and is firmer than rubber. I'm figuring buying a block of it, and cutting it to fit the subframe curve. Make it overlap both subframe bolt holes. Drill, and bolt it on (use a couple of washers recessed into the polyurethane block). Should be rigid enough to accept the bolts, unlike a rubber block. Make them tall enough to limit diff travel (80-90mm tall). Any alternative views?

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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Errol62
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Re: harvs ek 327 wagon

Post by Errol62 »

Another alternative would be to remove the body mounted bump stops altogether and fit some nice long EJ - WB style ones to the axle. They just slip under the u bolt tops. No welding. No fabricating assuming g you can get the right size to fit the axle etc.
your idea sounds good though.
Cheers
Clay


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