tire and suspension tuning for 86 hilux on "costa rica" roads

[Throbulator]

I live in Costa Rica zona sur with some of the worst roads in the world..... Vehicles are put to the test and only the most reliable cars survive. suspension is the limiting factor in how fast a car can go and stiff cars are irritating and back breaking and you have to go very slowly so you dont beat the car to death.

There are 2 factors that affect drive ability, holes and rocks. in the rainy season water flows over the road and forms potholes. in the deep deep rain time the road will become completely littered with holes. in the deep dry season, as cars drive over the dry dusty road HUGE dust clouds are fomed, as the more fine particles are sent flying from the road and rocks become exposed.

I have an 86 toyota hilux 2800 diesel (motor 3l) with independant front suspension. I use it for hauling african palm fruit (im a palm farmer) and for daily commuting.

I haven't read any good articles that talk about what makes a truck ride more comfortable and with less rocking, so I want to start a topic about that. There doesn't appear to be any obvious factor that really make a car drive well on this sort of road that I can see.

There are a few trucks that I have had experience with that I hold in legendary status for their driveability on these roads.

1991 Isuzu Rodeo: THE ultimate hole eater. when you hit a hole the wheel falls down but somehow the body of the car tends to barely move. you can really haul ass in this car. the rocks dont affect comfort that much, but it gets noisy and makes alot of bangs and the hole car tends to rattle. its been beat to hell it really is a piece of crap now. its not legal either and i dont like the v6 gas guzzler with weak auto trans. such a shame. its sittin at my moms place no one uses it cause its not legal and will cost like 1300 dollars or more to register (costa rica taxes are rediculous)
Its got torsion bars in the front and leafs in the back

1995 Land Rover Discovery: most comfortable car i've driven here. the car feels very solid, you can barely feel the very rocky parts and has basicly no rattle except for the spare tire on the door which is a given. it tends to sway a fair bit more than the rodeo in holes but it tends to do so very softly and the slam from the holes feels dampened. I think part of the reason it does so well is because it has extra big tires it has. its my dads and im looking after it for him while hes out of the country but right now it has a blown head gasket caused by overheating on a blocked radiator.
Its got quad springs

The old Hilux I have I got because of the reliability, its one of the toughest cars ever built. its also got a tough suspension system built for work and hauling loads. It is very stiff and I have to go very slow compared to the land rover. Its not the worst case but its got nothing on the land rover, the rover feels like a tank can just drive over crazy bumps and stuff and dont feel a thing.

So what sorf measures could i take to improve driveability in the hilux on these roads? bigger tires? softer shocks? softer torsion bars? and what do you guys think makes the land rover suspension so awesome?

 

[Devilmans Hand]

good questions, i'd like to hear what others have to say on available choices.

i have limited experience and available information to say anything that may be called knowledge.



I've only ever rode in and drove in 90s RangeRovers from the LandRover lines. To my understanding, LandRover claims that their coil sprung suspension systems have a faster/shorter rebound time. This would put the tire in and out of the hole or washboard low point faster where the suspension should contour to the landscape more quickly than a leafspring. I've drove 90s RangeRovers w/ and w/o the airbag suspension, with the airbag suspension being way softer on bumpy fast moving terrain, but prone to damage. The plain coil sprung RR was a bit rougher, but no where near as jarring as my Fj40 with stock leaf springs front and rear at the same speeds.
Comparing the ride of a long wheel base to a short wheel base though, so take that into account. short wheel base will almost always ride rougher than a longer wheel base. At certain speeds, the fj40 would seem to plow through bumps rather than have the suspension contour around the bumps/holes in the roads.

I'm not familiar with the Hilux, but if it has torsion bars up front then you could set them to the stock ride height so it can function properly. Replacing worn suspension components will prob help a lot. Bigger tires with a greater aspect ratio and at lower pressures should help to soak up the bumps. Higher quality shocks should help you big time. I'm sure someone else will chime in which particular type you should look for to use.

I wonder if a Zuk mod, or a rear coil helper spring, would help on these kinds of roads. It would give you a coil spring feel in the rear, and could be swapped out for differently rated springs depending on your load carrying needs. The combo of the coil spring and the leaf spring might soak up hard bumps a bit better. I'm on the fence about doing this with my 4runner. This should help on paved/dirt roads, but will hurt your rear suspension's overall articulation length if you do any rockcrawling. As one side goes down in the hole, the spring on the opposite side will be fighting to keep the axle centered and the body will twist/roll instead.

Please comment on or correct any craziness that i've said above.

 

[Throbulator]

that zuk mod things looks pretty cool..... I was just checking out 1st Gen 4Runner ZUK Mod DIY/How to (Lots 'o' photos!) - YotaTech Forums, its interesting because it wouldnt sacrifice work load, it would help it!

mmmm and those springs he uses are cheap as, and they come in all sizes!!!! very interesting.........

although Ive heard that the suspension in the front end is what accounts for 80% of the ride comfort. is this bogus or accurate? either way.... if it can help the car hold itself together it would be totally worth it......

 

[GRM]

One trick I did was to install microcellular bumpstops on the front of my truck to help in bottom out situations. Almost all new cars get these so they are smoother at the end of travel.

I would say the truck is 300% better when bottoming out (such as hitting a pot hole at 40mph) compared to how it was before with solid rubber bumpstops.

 

[GRM]

that zuk mod things looks pretty cool..... I was just checking out 1st Gen 4Runner ZUK Mod DIY/How to (Lots 'o' photos!) - YotaTech Forums, its interesting because it wouldnt sacrifice work load, it would help it!

mmmm and those springs he uses are cheap as, and they come in all sizes!!!! very interesting.........

although Ive heard that the suspension in the front end is what accounts for 80% of the ride comfort. is this bogus or accurate? either way.... if it can help the car hold itself together it would be totally worth it......

Thats a ghetto hack job. Don't do that.

 

[Throbulator]

Thats a ghetto hack job. Don't do that.

yea looks like a bit of a rushed job, but the overall idea of sticking the spring in with the leaf looks like it would work.

the bottom out bumper looks pretty sweet for here, lot of random potholes in paved areas that are really dangerous very common to hit some of those once and a while depending on the time of year/area/laziness of the government at the time, especially on long trips back from san jose at night when your tired.

but it looks really tall.... does it squish in like a rubber ducky?

 

[Devilmans Hand]

it is more like a high density foam. It has a solid feel with a center cut out to slip on a shaft.
you see similar ones on shock/strut assemblies.

GRM, did you buy or build those assemblies?
I like the potential function of them better than the standard old school rubber bumpstops.
Is that a picture of a dumptruck? Lots of leaves.

 

[Throbulator]

Well I just made a discovery...... I was checking my bump stops in the front, the right side bump stop is actively touching the lower scissor (whats the real name?). This is because when i changed the upper bushings my mechanic had to readjust the torsion bars, and he did it by measuring the distance from the fender to the wheel, however the fender on one side is sagging so one side was higher than the other.

after reading http://toyota.off-road.com/trucks-4x4/tech/torsion-bar-adjustment-19258.html thuroughly, noting the part about the stock ride height being 13.5- 14 inches from rim to fender, I went and measured my rim to fender and measured 10.5 inches.... there in the picture it shows the distance the suspension has to travel to hit the bump stop, it looks like it has about an inch and a half, one side on mine is allways touching, and the other side has like 1 centimeter...

the funny thing is that it allways has been at about the height it is now. its gotten that way because the torsion bar is sagging like the article sais.... It even sais off road conditions will accelerate sagging!!! im sure that if it was put back to stock torsion height the suspension would work way better.

everyone with an old toyota with these bars if they dont know what the torsion bar is set at should check the rim to fender height, this is probably why my top suspension bushings, front shocks, and rotullas (its that rotating thing that connects the wheel to the suspension) were destroyed.

gona go to mechanic and get him to adjust it properly, and when i can gona replace those bumpstops, they look old and dried up.... probably dont work at all, hopefully they have those microcellular ones for my car, think they would... their just tiny things

 

[GRM]

yea looks like a bit of a rushed job, but the overall idea of sticking the spring in with the leaf looks like it would work.

By the time you put forth all the effort to build correct spring buckets, why not run an airbag overload spring? Or how about running the correct leaf springs for the application? With this setup your loosing the advantages of a coil spring (better fine tuning of the suspension setup due to the links) and still having to spend the extra effort mounting the spring. IMHO, a stupid idea. Instead of running a leaf and coil, how about just running the correct leaf spring? Or a leaf spring plus an airbag overload?

but it looks really tall.... does it squish in like a rubber ducky?

It squishes down from about 6" to around 2".

it is more like a high density foam. It has a solid feel with a center cut out to slip on a shaft.
you see similar ones on shock/strut assemblies.

Its very similar to what you see on a shock shaft. Except its microcellular polyurethane, not foam. But then most shock shaft bottom out bumpers are polyurethane, not foam.

GRM, did you buy or build those assemblies? I like the potential function of them better than the standard old school rubber bumpstops.

I built the assemblies on my '86 Mini. No one on the market currently sells a microcellular stand-alone bumpstop. All the ones on the market are designed to be fitted to a coilover shock shaft.

Is that a picture of a dumptruck? Lots of leaves.

Yes, its a dumptruck

 

[Eleanor62]

i'd like to hear what others have to say on available choices.

 

[Throbulator]

By the time you put forth all the effort to build correct spring buckets, why not run an airbag overload spring?attachmentid=580277&stc=1&d=1323666535[/img]

the airbag system looks attractive but how do they hold up to continual pounding? I think one time someone said they tend to go pop here....

but if those airbags are cheap and reliable for these conditions then it could potentially save alot of damage.

 

[GRM]

If your worried about durability of airbags, then run Timbrens. Vehicle Suspension Kits - Timbren Suspension Enhancement Systems

 

[Devilmans Hand]

If your worried about durability of airbags, then run Timbrens. Vehicle Suspension Kits - Timbren Suspension Enhancement Systems

Thanks for sharing. I had no idea a this kind of option was easily available for our toyotas.

 

[Throbulator]

well i geuss the hilux suspension isnt as tough as i thought.... its just that the suspension in my car is totally shot. torsion bars and leafs are so loose that their just bottoming out all the time on the smallest bump.

ive got my torsion bars jacked up all the way, but it looks like they have to be taken out and turned over a couple teeth to get the car jacked up. as for the leafs, just gona put another one in that should solve it.

after all that im gona try some of those special bumpstops. I think those will really do the trick here.

 

[Throbulator]

I built the assemblies on my '86 Mini. No one on the market currently sells a microcellular stand-alone bumpstop. All the ones on the market are designed to be fitted to a coilover shock shaft.

I don't understand what you mean by you built it yourself, does that mean you bought the material and carved out the shape?

 

[GRM]

I don't understand what you mean by you built it yourself, does that mean you bought the material and carved out the shape?

I work at an automotive design firm by day. I have access to all kinds of parts that most people have a hard time finding. In this case, I bought the bump-stops from a supplier, and then CAD designed and water jet the mounting plates to bolt onto my spring plates.

 

[Tapage]

did you ever consider doing SAS in your hilux .. ? you would be able to source locally ( in CR ) LC II ( light duty ) front axle .. to perform the SAS ..