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Dan Wheeler's Rear 4-Link Thread

302BRONC

Jr. Member
Joined
Jan 23, 2007
Messages
85
Eye to eye. The lowers are 36" eye to eye - they match my front 3 link lowers so i only carry one spare. uppers are about 32" eye to eye (this may be generous, i'll go measure to confirm). The upper frame mounts are just behind the body mounts on the frame. Rear axle is pushed back about 7.5" from stock - similar to yours. I'm right at 100" wb on 42s.
 
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DanWheeler

DanWheeler

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thanks for the numbers, guys. Man, those body mounts are really in my way. I can either get 27" uppers or 38" uppers - Body mounts are hogging 10" of prime real estate. Best practice is uppers 75% length of lowers. A 38" upper would be OK if make my lowers 44" which I have room to do but at those lengths, I start losing a lot of triangulation.

My ideal is 40" lower and 30" upper but the dang body mount is in the way.

I've been running a bunch of different numbers through the 4-link calculator and I'm not seeing anything detrimental as far as antisquat, roll over/under-steer and pinion angle at droop if I went with 40" lowers and 27" uppers. 27 seems a little short and out of proportion with 40" lowers but the numbers don't lie. (if you trust the calculator and I'm not missing something)
 

JSmall

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Feb 18, 2004
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When I was researching for my 4 link, I read that the 70% upper was a suggestion to keep the AS consistent through the full suspension travel. 70% uppers will also allow the pinion angle to change through the travel more than some might want on a short WB Bronco. My uppers are about 90% of my lowers. I did that for my AS and pinion angle...it sounded like a good compromise. Not sure how it will work yet, but all the numbers look good in the calc.

I cut apart my Artec brackets, added a gusset where the upper use to me and then mounted adjustable uppers down the frame a little. With the Artec brackets the upper was a little longer than the lower and from all the research I did, that was great for the pinion angle, but compromised AS through the travel.

I will add...this is what I did and may not be the best for everyone. That is my disclaimer ;D

CF0A9366-F7DE-464F-997A-992581CAC0A1_zpsjwoyjyle.jpg
 

302BRONC

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Jan 23, 2007
Messages
85
I remeasured my uppers, they are just shy of 30", around 29 3/4". I didn't want to get too long on the lower links as a flat belly that wasn't too short and create a pinch point was important. Also, the longer the link the easier to bend.

All about compromise on a full bodied rig!
 
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DanWheeler

DanWheeler

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Thanks again for the numbers, guys. I'm leaning towards the 27" uppers. Not ideal but should work.

I've contracted a serious case of while-I'm-at-it-itus.... I think I'm going to re-do the rear floor and get rid of the indented cutout I did for the fuel cell. Thinking about going to a taller but more narrow aluminum fuel cell that doesn't take up the entire area behind the seat - need more room for tools and spares. The hole for the fuel cell was just collecting rust and sand and I never liked how the fuel cell took up the whole cargo area with the filler neck.

Pulled all the fuel lines, brake lines and electrical along the framerail so I can weld on brackets. Will probably re-do those lines while they are out. Seats are all out, stereo amp, exhaust is out from the Y-pipe back (will need to re-do)
 

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JSmall

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You're making quick progress. Do you plan to come down to the NWBR this year?
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
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Jul 31, 2001
Messages
8,604
Watch out Dan, you are quickly venturing into "while I'm at it ", BRONCO syndrome".

it'll be down to the frame rails soon if you aren't careful :)
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
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Jul 31, 2001
Messages
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I'm in the same boat -- started off as a 4 link, now I'm following Jeromy's path but not nearly as complex but-- the front end is coming out and stuffing a 60 in , the doubler and the transfer case were out and swapped, front floors are cut out.... careful Dan!! :)

Why are you shortening your links?

I am 43 inches center to center on the lower and 34 on the uppers so I'm at 79% upper to lower... I had help and confirmation getting these numbers also
 
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DanWheeler

DanWheeler

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Why are you shortening your links?

I am 43 inches center to center on the lower and 34 on the uppers so I'm at 79% upper to lower... I had help and confirmation getting these numbers also

Hey Brian, I could probably get those same numbers it just doesn't seem like a lot of triangulation at that length. Biggest problem is the body mount. I'm either in front of it or behind it. Either really short uppers or really long uppers. I'm considering cutting into the body mount and tying it into my brackets so I can get 30" on the upper.
 
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DanWheeler

DanWheeler

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some pics from tonight - got the upper frame brackets welded together and mocked up on the frame. More frame cleanup and lots more research on antisquat and all that kinda stuff :)
 

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dclack

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Feb 16, 2012
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...I'm considering cutting into the body mount and tying it into my brackets so I can get 30" on the upper.

That's what I was thinking you should do too. You might as well just do it now and get the links exactly where you want them. Better to spend a little extra work now and not be forever regretting it.
 

JSmall

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Feb 18, 2004
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Does mounting the upper on the other side of the body mount (longer upper) mess with your AS or Roll Axis Angle? I have mine mounted there and it didn't have any negative effect on my calculations.
 

302BRONC

Jr. Member
Joined
Jan 23, 2007
Messages
85
Looking great! the shorter uppers will work great. Pay more attention to your anti-squat. I had to play with mine a bit to dial it in (with the adjustable mounts). it's right around 70% and has just enough force to the ground without making the suspension do weird things.

Mounting the uppers that far back also preserves some precious space under the belly.

Mind posting your calcs?
 
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DanWheeler

DanWheeler

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I had been using the V4 version of the 4-link calculator that was modified by someone other than Dan Barcroft (creator) and noticed the anti-squat plot lines looked weird. I downloaded an older version (v3) and my antisquat is way higher and more what I would expect.

So here are short and long options shown in the calc. I'm not seeing a huge difference in AS or roll between the two. From my perspective, the short option requires less hacking, gets more triangulation and rotates the pinion down less than the long option.

Can you tell I'm trying to talk myself into the shorter, 27/37'ish links? :)

Short Option:
y3mbRwRjQQ5is0Dwc537GSenVsV1ZInIq4gJX558HoaG0Xt6xBMAVdqbA2VS0kl0BpIPfmn53NZCKp4qOubV9yEraySqvKqeCCgNvBiFzpsaQolE9BEbGvNNg7ErnEXrsQ49FyQRmu7br5fSYmEQCayYJQPAX7EUhNauHPqUWv6J2A


Long Option:
y3mm0tU73Frti9FyCOC40QHn4DOPCGIIKslI6sy-58hAuzV03qoGCJFn_FmFd3ngjh86JKaoYr9ol1EPBE6uo0nDiwGqrEQBNqDbtV9wF0cHpR9YKfr5RG-aKny7ojMy5Ze0cHaRhRVm9MoEo_eXtdUPkAWdOTZIe1YdCNgzg3VlTo
 

302BRONC

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Jan 23, 2007
Messages
85
Ran into the same connundrum. The short uppers should accomplish all your goals and work great. The calcs look good for a full body rig. What's your ride height, maybe at the frame belly? My uppers are lower at the front by about 1 1/2". A higher ride would be the difference.

I have 80" top of the cage, 22" bottom of the frame, 20" bottom of the flat skid/lower links.
 

Yeller

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If you have the space under the floor raise the upper and lower mounts at the axle. You'll get a noticeable difference. If the lowers get above centerline dont worry it's all good. It will improve either design and either you will be happy with.
 
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DanWheeler

DanWheeler

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Ran into the same connundrum. The short uppers should accomplish all your goals and work great. The calcs look good for a full body rig. What's your ride height, maybe at the frame belly? My uppers are lower at the front by about 1 1/2". A higher ride would be the difference.

I have 80" top of the cage, 22" bottom of the frame, 20" bottom of the flat skid/lower links.

26" bottom of the frame. I'll be trying to get lower once I can control ride height with the coilovers front and rear.

I just got a reply to a thread I had going on Pirate regarding the newer version of the 4-link calculator. It was from the guy who made the changes to the calculator in version 4 and he said the calculator was modified because the antisquat line has been incorrect for 4wd vehicles and that true antisquat on a 4wd vehicle is about half that of a 2wd vehicle.

If that's true, that explains the AS difference between V3 and V4 versions of the calculator. It also means that everyone who used the V3 calc to build their rigs have half as much AS as they thought they did.

I tacked my upper frame mounts in last night in front of the body mounts. At a certain point you gotta just trust the numbers and put it where it fits :)
 

JSmall

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Feb 18, 2004
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I could be wrong, but I believe v3 is correct. The calculation is based on 2wd where all of the drive bias is going to the rear wheels. If you take v4 and make front drive bias = 0 it will give you the same AS.

Like I said though, I could be mistaken.
 
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