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Jimny caster bushes
http://auszookers.com/forum/viewtopic.php?f=5&t=52726		 Page 1 of 1
Author:  jonno_racing [ Thu Jun 30, 2016 5:44 pm ]
Post subject:  Jimny caster bushes
So i currently have about 2 inches of lift in my Jimny. I recently added 20mm spacers front to level it out.
It has blue castor correction busshes currently.
On the wheel alignment machine it came up exactly 0' of caster. And it definitely feel like that as well. It tracks, is toey etc.
Question is can you get different levels of bushings?
Plenty of people seem to run over 50mm of lift and dont complain of this?
Author:  pete_79 [ Thu Jun 30, 2016 7:42 pm ]
Post subject:  Re: Jimny caster bushes
You can get different degrees of correction bushes.
From memory I found 2, 2.5 & 3 degree bushes.

I've got links saved on my laptop, if I remember tomorrow I'll throw them up here for ya..
Author:  jonno_racing [ Thu Jun 30, 2016 7:46 pm ]
Post subject:  Re: Jimny caster bushes
Cheers.
I'm putting some thought into a new chassis end mount, dropping the bolt height 40mm and going to standard bushings.
Even if it only has 2mm now, 3 wont be enough
Author:  Mike57 [ Thu Jun 30, 2016 10:06 pm ]
Post subject:  Re: Jimny caster bushes
Isn't it normal to do the correction by replacing the arms if you need more than 3 degrees. As Gwagensteve explained to me a long time ago the castor correction bushes inhibit flex.
Author:  got_bar_work [ Fri Jul 01, 2016 7:06 pm ]
Post subject:  Re: Jimny caster bushes
Moving the chassis mount down is the best idea. It will flex more and drive heaps smoother
Author:  watermouse [ Fri Jul 01, 2016 10:23 pm ]
Post subject:  Re: Jimny caster bushes
Might be worth checking that the bushes are in the right way. ie rotating the diff in the correct direction, to roll the top backwards.
0 castor would have the kingpins vertical wouldn't it?
Author:  vet 180 [ Sat Jul 02, 2016 7:57 am ]
Post subject:  Re: Jimny caster bushes
got_bar_work wrote:
Moving the chassis mount down is the best idea. It will flex more and drive heaps smoother

As in lower to the ground? If making new mounts wouldn't it be better to move them more towards the rear of the car and run longer arms also? I guess lowered chassis mounts is relatively simple and cheap though and the pivot point will be much better.
Author:  got_bar_work [ Sat Jul 02, 2016 5:31 pm ]
Post subject:  Re: Jimny caster bushes
It would but making new arms is a lot of hassle with geting engineering passed
Author:  vet 180 [ Sat Jul 02, 2016 9:46 pm ]
Post subject:  Re: Jimny caster bushes
got_bar_work wrote:
It would but making new arms is a lot of hassle with geting engineering passed


Not disagreeing but it seems stupid to me that arms mounts are no issue for engineering but the actual arms cause issues. For me a mount point is far easier to get wrong and the consequences are the same.
Author:  Gwagensteve [ Mon Jul 04, 2016 10:43 am ]
Post subject:  Re: Jimny caster bushes
Who said lowering the chassis mounts is less hassle for engineering? I can see no reason why it's any different - welding and design need to be engineered either way.

Moving the chassis mount down is good for ride and caster, but the result is suspension lift with no increase in ground clearance at the lowest point of the chassis - the front arm mount.

Considering that Jimny's are heavily tyre size limited for all sorts of reasons unrelated to suspension lift, I can't really see the point in lifting the car and ending up with no increase in clearance at the lowest point.
Author:  jonno_racing [ Mon Jul 04, 2016 2:24 pm ]
Post subject:  Re: Jimny caster bushes
2 inch lift give much better ride quality than stock with more bump travel.
making up a new mount and miging it in is looking to be a good option,
i wouldn't think that a 2inch lift would require this amount of work??
Author:  GraphicX [ Mon Jul 04, 2016 2:41 pm ]
Post subject:  Re: Jimny caster bushes
i had no issues with my 2 at +40mm & +50mm & once with +25mm spring spacers to fix front end sag.
Author:  Gwagensteve [ Mon Jul 04, 2016 2:47 pm ]
Post subject:  Re: Jimny caster bushes
Jimny's seem to be VERY caster sensitive. My guess is they run borderline caster stock because they were (are?) still available with manual steering. Adding substantial caster significantly increases steering weight. My Gwagen ran a huge amount of caster compared to Japanese 4WD's. Even with 60mm of lift it had miles more caster than pretty much anything.

My problem with lowering the mount is it's likely to a permanent mod - the stock mount is going to need to be cut and reworked, and it's loosing you ground clearance.

I think corrected arms, whilst also a compromise, are a better solution for most people.
Author:  jonno_racing [ Tue Jul 05, 2016 10:13 am ]
Post subject:  Re: Jimny caster bushes
mine has no shake issue, ok well it has a little shake under brakes coming down past 70kph so thats not an issue with it.
mine is/was actually a manual steering unit, it curently has all the bits to convert it to ps currently! so it get a much better "feel" with P/S, i will hold off any modifications till that point. the fact its manual steering may be why i think it feels crap? my sj80's steering became much nicer with p/s
my jimny does mostly touring stuff and light-mild offroad work, so the downside to the bushes isnt an issue with me, however it has crossed my mind a few times to fab up some tube arms as i have never been a fan of the of the shelf units.

i did find that 4wd1.com sell a 3' bushings that are a one piece unit, my current ones are the 2 piece and from what i can find there a 2' job.
Author:  Gwagensteve [ Tue Jul 05, 2016 11:16 am ]
Post subject:  Re: Jimny caster bushes
He stock arms are supposed to flex. Careful with tube arms- they don't flex and are much harder on the mounts and bushes.
Author:  pete_79 [ Tue Jul 05, 2016 12:10 pm ]
Post subject:  Re: Jimny caster bushes
I didn't bother with the links when you where talking about replacing the whole mounts, but after checking them today it looks like my info was too old anyway.
I'm sure none of this is news to you, but others might find something useful.

Ironman did 2 and 3 degree bushes, but their website has changed, my links didn't work and I couldn't find anything searching on there today.
Dobinsons still do 2.5 to 3 degree bushes
4WD products do standard bushes and 2.5 degrees
And Jimnybits have 2 options.
Author:  sideways [ Tue Jul 05, 2016 4:48 pm ]
Post subject:  Re: Jimny caster bushes
Gwagensteve wrote:
Jimny's seem to be VERY caster sensitive. My guess is they run borderline caster stock because they were (are?) still available with manual steering. Adding substantial caster significantly increases steering weight. My Gwagen ran a huge amount of caster compared to Japanese 4WD's. Even with 60mm of lift it had miles more caster than pretty much anything.

My problem with lowering the mount is it's likely to a permanent mod - the stock mount is going to need to be cut and reworked, and it's loosing you ground clearance.

I think corrected arms, whilst also a compromise, are a better solution for most people.


Jimnys run 1° 55' caster, almost a whole degree less than a Sierra. In addition, they have 13.5° king pin inclination (shitloads) so zero scrub radius. By comparison a Sierra runs 9° KPI and lots of scrub radius.

Looking at the other super wobble prone live axle 4WD, Patrols. It's pretty much the opposite story, more caster than a Sierra, less KPI, more scrub radius.

I guess shitboxes just wobble. :D

I'd agree, I wouldn't lower the mount. If you're going to the effort of of moving mounts you might as well just add 2 and 3 link it.

Everything is a compromise at the end of the day. For most of us who aren't chasing every last mm of flex I think caster bushes are a great option. It's been proven many times that you can get good flex with caster bushes, it's not like they're going to limit you to 4" of travel or anything.
Author:  GraphicX [ Tue Jul 05, 2016 4:52 pm ]
Post subject:  Re: Jimny caster bushes
there's a thread on bigjimny where a french fellow called renard went from stock bushes, to caster corrected bushes to caster corrected arms with stock bushes & i'm pretty sure he posted some comparison photos using the same roadside ditch if you're keen to go googling.
Author:  31zook [ Tue Jul 05, 2016 5:58 pm ]
Post subject:  Re: Jimny caster bushes
Why does nobody 3-link their jimny already?

Also why not flip stock arms upside down? If you want to reverse just buy a new housing. And you can properly set caster in them

I think Steve is right about the caster being pretty sensitive, and to add to the wobble debate, ive seen jimny hubs that the wheel bearing races fall in and out of. The maching tolerances are poor at best.
Author:  Marko_SJ [ Wed Jul 06, 2016 10:44 am ]
Post subject:  Re: Jimny caster bushes
Gwagensteve wrote:
Jimny's seem to be VERY caster sensitive. My guess is they run borderline caster stock because they were (are?) still available with manual steering. Adding substantial caster significantly increases steering weight. My Gwagen ran a huge amount of caster compared to Japanese 4WD's. Even with 60mm of lift it had miles more caster than pretty much anything.

My problem with lowering the mount is it's likely to a permanent mod - the stock mount is going to need to be cut and reworked, and it's loosing you ground clearance.

I think corrected arms, whilst also a compromise, are a better solution for most people.


Would it be a no-no to trial corrected arms and dialing in a bit more caster with bushes? We solved the really bad wobble on my brother's Jim the other day, but there is still a slight shimmy under the right conditions.

Failing that it will get a reduction in lift and tire size.
Author:  Gwagensteve [ Wed Jul 06, 2016 4:09 pm ]
Post subject:  Re: Jimny caster bushes
Sure you could, although the risk is that roll stiffness might go quite high assuming the corrected arms don't flex like stock and knowing corrected bushes don't.
Author:  Marko_SJ [ Wed Jul 06, 2016 8:47 pm ]
Post subject:  Re: Jimny caster bushes
Gwagensteve wrote:
Sure you could, although the risk is that roll stiffness might go quite high assuming the corrected arms don't flex like stock and knowing corrected bushes don't.


I doubt the aftermarket tube arms would flex much at all.

For the intended use I dont reckon that would cause too much of an issue provided no other part lets go.
Author:  31zook [ Thu Jul 07, 2016 4:16 am ]
Post subject:  Re: Jimny caster bushes
^steve is saying that the tube arms don't flex like the factory ones do.

Why doesn't someone make a kit like the 80series superior engineerjng arms for a jimny?

https://www.superiorengineering.com.au/ ... er=222,355
Author:  shep [ Thu Jul 07, 2016 6:46 am ]
Post subject:  Re: Jimny caster bushes
Pretty sure that stock arms won't flex any better then my tube arms.

Image
Author:  shep [ Thu Jul 07, 2016 6:48 am ]
Post subject:  Re: Jimny caster bushes
I would love for someone to explain how a tube arm limits flex?
Author:  Marko_SJ [ Thu Jul 07, 2016 8:43 am ]
Post subject:  Re: Jimny caster bushes
31zook wrote:
^steve is saying that the tube arms don't flex like the factory ones do.



That's what he wrote: "assuming corrected arms don't flex like stock ".
That's why he cautioned about the corrected bushes, saying they have less movement than ordinary standard bushes, hence logic would say those twisting forces *could* be put onto the mounts, and cause adverse offroad handling.

** the car in question gets driven up and down the highway, once the destination is reached it has to deal with some sloppy mud.

That's all it has to do. Reduced flex or an unbalanced car are OK so long as the thing is stable on the highway and deals well with mud once off the tar, hence why bigger tires are preferable.
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