Cheap L300 torsion bar upgrade

Post by **Growlerbearnz** » Thu May 03, 2018 2:41 am

After fitting air shocks to the rear of my van, which slightly stiffen the rear suspension, I've been thinking that the front suspension is way too soft.

The Japanese market L300 4WD wagon (P25/35W) has 20mm diameter torsion bars on the front suspension. Light springs like these make for a comfortable ride and good suspension flex offroad, but on the road they're a bit weak. Add some extra weight, and 20 years of sag, and you end up with a van that corners with the stability of a newborn giraffe, and cataclysmic nosedive under braking.

2WD L300s have 22mm torsion bars, which might be a decent upgrade. Dobinsons.com.au make 24mm bars, which are about perfect, but the AU$500 price is a little painful.

You know what else has 24mm torsion bars? A Hyundai H100 van. Like this 1998 one at the wreckers:

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The H100 is basically an L300 underneath, and the torsion bars are a perfect match... and they only cost $40 from the local wreckers.

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Hyundai part numbers were written on the bars. LH side = 5415043160, RH side = 5416043160.

Hyundai don't fit rubber boots to protect the splines, but it's easy to swap your boots from your old torsion bars to the Hyundai ones. It's about a 45 minute job to swap both bars, and another 15 minutes to set the suspension height.

Results: I think it's just about perfect. It's still a big, floppy 4WD, but it feels a bit more modern to drive. Turn-in is sharper, and the nosedive under braking is less comical. Motorway driving has lost the slight floaty feel and wobble when changing lanes at speed.

Sylquebec · Post by **Sylquebec** » Fri May 04, 2018 3:26 pm

thanks for the info

Envoyé de mon SM-G950W en utilisant Tapatalk

Lapprentis · Post by **Lapprentis** » Sat May 05, 2018 5:55 am

GOOD FIND ! Any idea of the part number, from which model/year ? There seems to be a few options available: 5416043150, 5415043420, 5415043160. Partsouq seems to have some at less than 100CAN each but none in stock... Also on Alibaba, Chinese made, could it be the same ? Minimum 10 sets order, at less than 15USD a set ???????? (https://www.alibaba.com/product-detail/ ... 25390.html) ! Thanks again.

Lapprentis

Post by **Growlerbearnz** » Sat May 05, 2018 2:56 pm

I wouldn't trust a torsion bar from anyone but a reputable manufacturer- they're the sort of highly stressed component that can fail from one tiny flaw.

Hyundai part numbers were actually written on the bars, which was nice:
LH side = 5415043160
RH side = 5416043160

The H100 I got the bars out of was a 1998.

Lapprentis · Post by **Lapprentis** » Sun May 06, 2018 9:11 am

Thanks Growler ! autopartmaster.com seem to be the best option for North American L300 Owners ! Will cost about 1/3 of Dobinson.

Lapprentis

Killbert · Post by **Killbert** » Mon Jun 11, 2018 6:55 pm

Genius. Thanks Growler.

K

sk66 · Post by **sk66** » Thu Jun 14, 2018 11:10 am

Be aware that the H-100/Grace is also equipped with 20mm torsion bars (i.e. 5415043151)... so make sure you get the right part numbers!

don't ask how I know this....

sealica · Post by **sealica** » Wed Jun 20, 2018 3:37 pm

When looking to purchase used torsion bars are there any tests one can conduct to check that they're not worn out already?

Post by **Growlerbearnz** » Sat Jun 23, 2018 7:44 pm

When I pulled them out of the Hyundai I checked the mileage- 120,000km so probably fine. But I also figured they're thicker bars holding up a lighter (2WD) vehicle that only drives on the road, so they're probably not going to sag even at much higher mileage.

sk66 · Post by **sk66** » Thu Jul 12, 2018 1:22 pm

I did this mod today. But when I set the body height the same as before the bump stop measurement went from the 45mm spec'd to a little over the 51mm spec'd for the 2wd... I can't see why, and I'm not sure which I should use.

Post by **Growlerbearnz** » Thu Jul 12, 2018 3:38 pm

sk66 wrote:when I set the body height the same as before the bump stop measurement went from the 45mm spec'd to a little over the 51mm spec'd for the 2wd

Set the body height by measuring the bump stops; unwind the adjuster until the bump stop measurement is 45mm. If you set the adjuster to the length they were with the soft springs, the ride height will be higher because the new springs are stronger and won't flex as much as the old springs.

sk66 · Post by **sk66** » Thu Jul 12, 2018 6:20 pm

I was measuring the body line off of the axle hub... can't fathom why the same body height has a different bump stop spacing. I must have measured something wrong is all I can figure...

Post by **Growlerbearnz** » Thu Jul 12, 2018 7:10 pm

Ah, sorry, I totally misunderstood your post. You're right, the relationship between bump stop height and body height can't change unless you change the bump stops or alter the suspension pivot points. Your measuring must be as reliable as my memory

sk66 · Post by **sk66** » Fri Sep 07, 2018 9:53 am

I was looking at a lift/mods that was posted on another site and it got me to thinking about how these mods actually affect things. The mods included a lot of things I think are questionable for offroading, but probably ok enough for just around town driving (looks over function)... not that I really care.

But it got me to thinking about the torsion bar upgrade and adjustment... The 2WD cargo van uses the 22mm torsion bars and specifies a different static height, 51mm vs 45mm at the upper bump stop, which should equate to a 6mm lower body height and less preload of the torsion bars. By cranking the heavier torsion bars to the same 4WD spacing you are placing the same amount of preload on them.

I'm thinking that this might do three things... the first is that it will definitely reduce the flex/travel under slow/static loads simply because the heavier torsion bars will resist compression more, this will also make the ride harsher/stiffer (both are worse for off roading).
The third I'm less sure about; but it seems to me that the lower preload spec for the heavier bars is probably to allow the suspension to utilize the different spring rate. And by preloading it beyond spec you are somewhat negating that characteristic. I have to suspect the difference is even more significant when going from 20-24mm vs the 20-22mm torsion bars, although I'm not entirely sure as to what that characteristic might actually be (on/off road).

I'm off road (minor to moderate) about 20% of the time and I find the 24mm torsion bars adjusted to the 4WD spec to be harsh... and harsher on the crappy paved roads we have around here (potholes/expansion cracks/etc). I think I'm going to loosen mine up at least to the 2WD spec (maybe more) and see what that does. It will put the front suspension closer to the middle of travel at static ride height rather than near the top. That should allow for a little more articulation under slow/static loads and a smoother ride with fast/hard loading. I'm hoping that the higher spring rate of the heavier bars combined with the new/upgraded front shocks (KYB Gas-A-Just) will still be a notable improvement over the 20mm stock bars (and worn out shocks) while preventing the suspension from bottoming out earlier. Unfortunately it will cost me that little bit of ground clearance, but I'm not going bouldering in MudBuggy so it shouldn't be a big deal... I don't think it will cause my 30" tires to scrub under compression while turning.

Any thoughts on this?

sk66 · Post by **sk66** » Fri Sep 07, 2018 9:56 am

sorry about the double post...forum won't allow me to delete.