4 link or 3 link because 2link stinks
- Thread starter FJ40Dude75
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question is, where is the caster? You might be able to compromise with pinion angle but try and maintain +3-4 in caster. Most like, cut and turn required.....
- Thread starter
- #83
right now its at 8*s so that will be to much? even with a cv driveshaftwhat is it at stock
caster is +8? too much....stock is +1 (top trunion is angled back 1* behind the lower trunion)....set it around 4 and that's correct for a Crusier housing....
IMO....
you may be able to adjust that out with the upper link...
IMO....
you may be able to adjust that out with the upper link...
what kind of wall thickness should be used for the links? I remember (I think) seeing links for 4-link that were 15/16 walll thickness.
lowers should be absolute minimum .250 wall....mine are just shy of .500 wal (.375+.120 sleeve), and as much as they get landed on, it's a good idea.
Uppers can be .250, mine are .375.
IMO, material is just as critical....my uppers are mild steel, lowers are mild steel with a DOM outersleeve.
Uppers can be .250, mine are .375.
IMO, material is just as critical....my uppers are mild steel, lowers are mild steel with a DOM outersleeve.
is there a certain lengh that the links have to be?? Progress pics?
OK, for the bottom links...dont they have to twist as the axle moves up? I see how the link would move up easy enough but would it also need to tilt in? Do the joints that are being used do that?
OK, for the bottom links...dont they have to twist as the axle moves up? I see how the link would move up easy enough but would it also need to tilt in? Do the joints that are being used do that?
heims and other joints all allow for rotational twist on various planes, they account for any inward movement of the axle.
Link length is largely determined by what fits...lol....mine are 35" rods plus heims, totalling ~38" eye to eye....my uppers and lowers are all the same length. Advantage: one spare to carry, pinion remains in relatively the same plane throughout travel (best for a non-CV rear driveshaft). Disadvantage: pinion doesn't tip up during downstroke to assist with clearance, "should" run pinion tipped more down for non-CV shaft.
IIRC, the "rule of thumb" from a magazine was 80%....38" lowers x .8 = 30.5" uppers....for a CV-rear shaft, this keeps the pinion pointing at the t-case output during the entire travel range.
however, there is also a "rule of thumb" that your links should be the same length as your rear driveshaft.
There are piles of other rules too, all of which are made to be broken.
Regardless....lower links should be relatively long and end up relatively flat to minimize rear steer characteristics. I was at a buddy's shop the other day, he was flexing up a rear 4-link he just did....holy crap....30" lowers and uppers, damn near tied them into the inner frame at the same spot...LOTS and LOTS of rear steer....said he was experimenting. Glad I wasn't that customer.
Link length is largely determined by what fits...lol....mine are 35" rods plus heims, totalling ~38" eye to eye....my uppers and lowers are all the same length. Advantage: one spare to carry, pinion remains in relatively the same plane throughout travel (best for a non-CV rear driveshaft). Disadvantage: pinion doesn't tip up during downstroke to assist with clearance, "should" run pinion tipped more down for non-CV shaft.
IIRC, the "rule of thumb" from a magazine was 80%....38" lowers x .8 = 30.5" uppers....for a CV-rear shaft, this keeps the pinion pointing at the t-case output during the entire travel range.
however, there is also a "rule of thumb" that your links should be the same length as your rear driveshaft.
There are piles of other rules too, all of which are made to be broken.
Regardless....lower links should be relatively long and end up relatively flat to minimize rear steer characteristics. I was at a buddy's shop the other day, he was flexing up a rear 4-link he just did....holy crap....30" lowers and uppers, damn near tied them into the inner frame at the same spot...LOTS and LOTS of rear steer....said he was experimenting. Glad I wasn't that customer.
lol
I still have not figured out how the 80% rule keeps the pinion pointed at the tcase. It seems to me that it would do the opposite.
an 20% smaller arc on the top link "should" force the pinion downward instead of upward..
My rear suspension is a doubly triangulated 4 link.
Both the uppers and the lowers are angled.
Uppers and lowers are the same length.
let me go find a pic..
I still have not figured out how the 80% rule keeps the pinion pointed at the tcase. It seems to me that it would do the opposite.
an 20% smaller arc on the top link "should" force the pinion downward instead of upward..
My rear suspension is a doubly triangulated 4 link.
Both the uppers and the lowers are angled.
Uppers and lowers are the same length.
let me go find a pic..
- Thread starter
- #91
well I just got my coilovers in the mail today yeeehaaaw. what kind of angle should they be on when installed was going to angle them in some but wasn't sure how much is to much.
Here are some that I have done.
Nolen's rear 4 link:
My rear 4 link
My front radius arm setup
Ed
Nolen's rear 4 link:
My rear 4 link
My front radius arm setup
Ed
wow thanks for the responses...
Just when I thought I had a lil bit of a handle on it....
So, if the rear links are as long as my rear drive shaft...(some where close to 3 miles) this sounds like a big area to hit on rocks??
I dont really understand the 80% thing....I thought the lower links were stationary (non-adjustable) and the upper ones controled the caster??? is this correct line of thinking? And would this keep the pinion at the same angle all the time?
Just when I thought I had a lil bit of a handle on it....
So, if the rear links are as long as my rear drive shaft...(some where close to 3 miles) this sounds like a big area to hit on rocks??
I dont really understand the 80% thing....I thought the lower links were stationary (non-adjustable) and the upper ones controled the caster??? is this correct line of thinking? And would this keep the pinion at the same angle all the time?
Make both sets of links adjustable. It is much easier to get the axle centered under the truck (no crabwalking)
To keep the pinion at the same angle all the time you need to have parallel links that are the same length...
Anything else and you are going to have pinion angle differences through the travel of the axle.
The easiest way to keep the pinion pointing at the tcase is to do a radius arm suspension..
the reasons to make the links the same length as the rear DS is to almost remove the need for a slip shaft.
I have 36" rear links and a 23" DS. I use maybe 3-4" of slip.
To keep the pinion at the same angle all the time you need to have parallel links that are the same length...
Anything else and you are going to have pinion angle differences through the travel of the axle.
The easiest way to keep the pinion pointing at the tcase is to do a radius arm suspension..
the reasons to make the links the same length as the rear DS is to almost remove the need for a slip shaft.
I have 36" rear links and a 23" DS. I use maybe 3-4" of slip.
what is a radius arm suspension if ya dont mind me asking?
radius arm = front early bronco type suspension...actually, the 80-series front can be considered a radius arm as well.
ahhh like the old setup on space ghosts.......right?
yep...same basic idea....single arm on each side of the axle, with a panhard to control side to side movement.
woody said:
Would this same idea work for the rear...or would it be better to 4-link it? Would the 4-link also require a panhard?
rear can run a true 4-link, no panhard required.....
Front "requires" the panhard due to steering, much improved unless you can REALLY triangulate the uppers.
Front "requires" the panhard due to steering, much improved unless you can REALLY triangulate the uppers.
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