suspension tech for 75x

[rockcrawler31]

Hi all.

I know it might be boring for most but i thought i'd try and help anyone with a 75 series truck.

After spending ages trying to get my rear suspension working properly i've made some advancements and some discoveries that i thought i'd share with you all.

Firstly it's a 91 troopcarrier that recently went on a diet and no longer has a rear tank, rear bar or draws.

I took out a few leaves and now it only has four leaves (main and wrap and two others), it finally flexes well in the rear but i have worked out that perhaps 4 isn't quite enough to carry anything other than just the weight of the car.

With three inches of lift it happily fits 35"claws with only a little scrubbing on the rear inner guards.

I reckon i'm going to go to two 100mm extended leaves and a set of coil overriders and a track bar so that i can quickly and easily change the coils to suit the trip requirements. I also found that the gas shocks are no longer up to the task and allow the springs to bottom out on bumps. My thoughts are that the leaves no longer have the self dampening capabilities of a full pack and i will need to go to shocks that are more suited to a coil sprung truck.

I've also found that the front end was chewing bushes and bending shackles (2" extended) due to the high twist in the springs at full flex. Everyone said i should have rubber bushes because they flex more, but i found that they flog out too soon (like one trip ) leaving too much room around the spring eyes and allowing shackle twist.

I've gone back to poly bushes which although they are more expensive, seem to hold up a lot better and don't limit flex at all. I now have 15 inches of travel at each end with the combination of springs and shackles i have now.

I know that a lot of you don't really need this info but i thought i'd post up my findings for anyone else with a 75 cruiser who's trying to get it to work better.

MILO

[baddboy]

Thanks for sharing the info. I think it's time we got a 7X series cruiser bible!!

[balzackracing]

Hey milo, got any new pics of the rig to post. how did the chop go.

[rockcrawler31]

here ya go.

for the first time in it's life it has more flex in the rear than in the front. actually this is the first time in it's life it has ANY flex in the rear. it still had about 5 inches of travel left in it but i ran out of stump

this is the truck



and the two loves of my life.



me and my mo'



and the rear end

[rockcrawler31]

the chop is coming in about a month or so. it's all about having the time and being home long enough to get it done.

can't wait though. I gave the truck a bit of a pizzling this weekend and she loved it. the donk revved freely all the way to 4 and a bit grand and never got warm so i/c turbo is in the plan.

as an additional little bit of tech. while trying to sort out the heating probs (turned out to be a reblocked rad - which had already been given an all clear ) i made a hi flow thermostat by putting 4 quarter inch holes in the body. It was never meant to be a permanant thing, but i have found that the coolant temps now sit on 65 degrees on the highway and 70 - 75 when i'm giving it shit or pulling the ranges. the downside is that it takes ages to warm up. Might be good to someone running a 1hz and turbo and planning to give it a constant bootful.

[mac1cruz]

Thanks for sharing the info. I think it's time we got a 7X series cruiser bible!!

X2 Awesome troopy mate keep us up to date on the chop and rebuild those pics look like LCMP...

[hulsty]

Here are some pictures of my 70series flex, the first one has some more in it, rear left is still 2'' from bump stops but tyre was hard on inner guards. Second one rear bump stops lengthened by 3'' and that stopped rubbing, tyre was just spinning lightly in the mud so thats about all it had. The setup is 2'' springs of unknown origin and cross country shocks. At the moment the brake lines are nearly tight so i've got to fix that and i think the rear shocks are to short. I've got 6 leaves in the back and 7 in the front, waiting till i fit steel bull bar and dual batteries before i take one out of the front. Thinking of extended shackles too


cheers

[smithie]

Its good to see the old leaf sprung 7x series cruiser's flexing it up! Just goes to show that they can be made to work quite well.

Heres my 70 series suspension setup:
1" lifted springs with 2 leaves removed from each spring pack. I think there are 5 remaining. (Spring packs probably dont provide any extra height)
2" greasable extended shackles with polyurethane bushes.
Removed Swaybar.
Stock shockers at the moment, but they are pretty well knackered so will hopefully change them soon. I'd probably gain another 2" of travel with longer shockers.

Also, the front axle has been relocated 30mm forwards and a 2" bodylift installed so that the 35" rubber fits under the gaurds. In all honesty, they fit by miles, I could reduce the bodylift to 1" and they'd still fit.
The only place that they scrub is in the rear inner gaurd, and its not by very much.




Cheers,
Dan

My Buildup
http://carl.outerlimits4x4.com/viewtopic.php?t=105544

[hulsty]

smithie how do you find he extended shackles? they help with flex? i'm thinking of fitting them to mine for a little bit extra height when i weigh it down with heaps of steel. Hows do you find the front sway bar removed? mine is still fitted. Also is it hard to move the axel forward? do you just removed the springs and redrill the whole 30mm forward and leave the old hole
?


cheers

[baddboy]

And the new guards 100mm wider without the rubber flare

[rockcrawler31]

I found that the longer shackles helped a bit, but longer springs will probably get even more flex out of it and make best use of the shackles. At full compression the shackles still have more room to move upwards.

I have no body lift and the 35's fit with rubbing on the rear inner guards only. i put rear bumps up front though so that it won't compress up to the top of the guard.

Good to see 70x series leaf trucks

I'm pretty sure that i can get another 4 inches flex each end at least. that will take it to at least 18inches each end.

[baddboy]

Back side

[mac1cruz]

Nice job on those guards baddboy it looks awesome ive got a brand new set of black rims in the shed just waiting on funds to put some mtz under my oldgirl...I know you've seen my ute but this is the flex that i have 2" efs springs superior extended shackles ranch rs5000 shockies works quite well took out last week at the back of dayboro in the forest and was surprised at what the old girl can do but i must say i cheated twice and used the front airlocker She's only got 31's...



Cheers Azza

[smithie]

hulsty,
The extended shackles definantly help the springs to flex, but I've also found that they make the steering a bit more 'floaty' than standard. Its not too bad, just something to be aware of.
I'd ditch the swaybar, you probably wont even notice the difference.

Just remember that to move the axle forward 30mm, you drill the new hole to the rear of the existing one. The hole is drilled in the spring mount on the axle and the plate that goes under the springs. so by drilling the hole rearward, when the pin on the spring packl is located in that hole the axle is effectively moved forward. clear as mud? it'll make sense when you look at it.
Measure twice, cut once. Pre-drill the hole with a smaller size and work up to the final hole. use cutting fluid if you need to. Those mount plates are pretty thick. Other wise you can buy axle relocation plates from the likes of snakeracing/superioreng etc etc.

Baddboy - very nice workmanship on the gaurds.. did you do that yourself? Are they fibreglass? They look pretty good.. did you do anything on the rears gaurds/tray?

[baddboy]

Hey Smithie, thanks. Luckily my brother in law works at a local Toy dealership as a spray painter. Made that job fairly simple.
Going to be putting a new tray on it soon, although have modified it to get the tyres inside.
Next step is to change to 80 series diffs and do a spring over conversion. Fairly soon for that one.

[smithie]

I thought you may have been planning to swap some wider diffs under your cruiser! I'm planning to do the same conversion. I have a full 1996 model 80 series chassis at home... so in the not-too-distant future I'll hopefully gain some track as well! Any reason that your sticking with the leaf springs and not going full coils??
I'd love to be kept posted on any progress you make with the 80's diff conversion.
Cheers
Dan

[hulsty]

hulsty,
The extended shackles definantly help the springs to flex, but I've also found that they make the steering a bit more 'floaty' than standard. Its not too bad, just something to be aware of.
I'd ditch the swaybar, you probably wont even notice the difference.

Just remember that to move the axle forward 30mm, you drill the new hole to the rear of the existing one. The hole is drilled in the spring mount on the axle and the plate that goes under the springs. so by drilling the hole rearward, when the pin on the spring packl is located in that hole the axle is effectively moved forward. clear as mud? it'll make sense when you look at it.
Measure twice, cut once. Pre-drill the hole with a smaller size and work up to the final hole. use cutting fluid if you need to. Those mount plates are pretty thick. Other wise you can buy axle relocation plates from the likes of snakeracing/superioreng etc etc.

Baddboy - very nice workmanship on the gaurds.. did you do that yourself? Are they fibreglass? They look pretty good.. did you do anything on the rears gaurds/tray?

Thanks mate, did you have to take the diff out ofteh car or can it be done in car? whats the benifit of moving the diff forward anyway? going to look into longer shackles and shocks, anyone remend longer shocks for more than 2'' of lift ? cause at the moment my shocks go aslong as they can (cross country brand)

cheers

[smithie]

you'll have to remove the springs, but once they are out there is just enough room to drill the plate on the bottom of the axle housing. Just remember safety first.. wear glasses to stop swarf dropping in your eyes and make sure the vehicle is properly supported if your gonna be lying underneath it.

The main reason to move the front diff forward is so that 35" tyres dont rub on the rear of the inner gaurds.

cheers.
dan

[Pauwolf]

If anyone is iterested, I have converted an 80 series front diff for leaf spring setup with reverse shackle in my 60 series which is now for sale, will fit either a 60 or 75 with reverse shackle springs. I can even show you how I did the reverse shackle conversion. pretty easy if you can weld. I have gone coil in the front of my 60 now.

paul

[baddboy]

Bring it on and let us see what you did!!!

[Pauwolf]

here is the link to the build of my truck in the members, if you have any questioins dont hesitate to ask.

http://www.outerlimits4x4.com/viewtopic ... highlight=

paul

[baddboy]

Is that link right?

[Pauwolf]

No

[Pauwolf]

Fixed the link above. If you want to see the rest of the buildup

http://www.outerlimits4x4.com/viewtopic ... highlight=

Nice truck badboy, like the guards

Paul

[hulsty]

what are people running regarding their front shock absorbers? I'm think mine are limiting my down travel at the front, with the front swaybar disconnected it still doesnt drop that much, the shackle barely moves back past 90 degrees, while the other side which is fully compressed is not that much forward of 90 degrees. Also think of putting my middt rear springs into the front, should move the diff forward 15mmm and the springs are 70 mm longer overall hopefully with stock shackles it will work better. Are there any issues or other things to modify when moving the front diff forward ?

cheers

[bad_religion_au]

hulsty,
The extended shackles definantly help the springs to flex, but I've also found that they make the steering a bit more 'floaty' than standard. Its not too bad, just something to be aware of.
I'd ditch the swaybar, you probably wont even notice the difference.

that floaty feeling is probably due to changing the castor angle of the front diff. get some diff wedges and it should handle nicely again.

[bad_religion_au]

If anyone is iterested, I have converted an 80 series front diff for leaf spring setup with reverse shackle in my 60 series which is now for sale, will fit either a 60 or 75 with reverse shackle springs. I can even show you how I did the reverse shackle conversion. pretty easy if you can weld. I have gone coil in the front of my 60 now.

paul

you sure it'll fit a 75, considering that the spring pads on the diffs would need to sit narrower for them to line up with the spring mounts on a 75 series chassis?

[Tapage]

I can post 60 series ?



OME suspencion ( old one about 7 years now ) SR kit + SO + extreme 6" shackles rear.

[shorty_f0rty]

hulsty,
The extended shackles definantly help the springs to flex, but I've also found that they make the steering a bit more 'floaty' than standard. Its not too bad, just something to be aware of.
I'd ditch the swaybar, you probably wont even notice the difference.

that floaty feeling is probably due to changing the castor angle of the front diff. get some diff wedges and it should handle nicely again.

X2... more lift = bigger degree wedge.. i had 2" lifted springs plus longer shackles and 3deg wedges brought the steering back to normal..

well worth the investment.. also.. if you can find them get center bolts with longer heads, i found with the wedges that there wasn't enough meat making it through the spring perch on the diff, i have gone through a few busted center bolts before the upgrade made everything sweet..

[shorty_f0rty]

also, anyone know the length difference of 75# vs 79# rear springs? I have heard that the 79's have a longer spring inthe rear, would this help you guys with longer shackles get more out of your suspension without getting new leaves made up?

just a thought..