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Discussion Starter #1
hi. i am currently looking to build a mk2 celica supra for use as an off-road (rally type) vehicle. I was wondering if anyone can suggest a good set of struts that can handle bumps without losing too much traction (and that don't cost an arm and a leg). as far as springs are concerned, i was considering contacting Ground Control to see if i can custom order a set of springs that leave the car at just about stock height (perhaps slightly higher), but have a stiffer rate. Can anyone suggest a good spring rate to get for off road use? i am not too familiar with the weight balance of the mk2, so i was wondering how the f/r spring rates should compare to each other. also, can anyone suggest a good tire for off-road use? i am currently doing my own research on tires, but any suggestions you can give will certainly help. i am considering most likely using a 15x8" wheel all around. does anyone know of any strong cheap wheels that will fit the celica supra? i was looking at Summit Racing at those black steel wheels, but most of them use a 5 lug bolt pattern. they are a great price however. is there any 5-lug swaps available for the mk2? well...sorry for the long first post, but hopefully you guys can be able to help me out, or perhaps point me in the direction of someone who will be able to help. thanks in advance.
 

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I heard that someone makes linear rate springs (would be nice for offroad). As for struts, for the rear I would think you should go custom and find some struts from a truck or jeep that would fit. Be sure to weld a cage around the driveshaft and some sort skid plate around your differential.
 

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IIRC, Suspension Techniques makes a stock height and a 1.3" drop spring, both linear rate. Dont know how they stack up compared to Tokico's, etc, but the tokicos are not linear.
 

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You mean Eibachs?

will
 

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Discussion Starter #5
speaking of springs...does anyone know the stock spring rate? i was reading another website on rally cars and they said as a general rule to use a spring that is twice as stiff as stock, and same w/ the damper. also, i just ordered a book from Amazon about how to make a rally car, so hopefully that will help. i think the mk2 should be a decent platform for an offroad car, seeing as how they used the Celica from the same era to compete in WRC at the time, and by looking at this picture, hehehe...

 

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Discussion Starter #6
ok, now i know that GC coilovers are available for the front, so perhaps i can use those. does anyone know if GC can wind a custom rate spring that will fit in the rear that sits at (or slightly higher than) stock height? are the Tokico HP's discontinued? i think i might be leaning more toward using Tokico HP if they will work well at stock height...does anyone know the leghth of the HP's at full compression and full extension (front and rear)? does anyone know the length of the stock shocks at full comp and extension? i will eventually get around to this research on my own once the car is in my possesion and able to be torn to pieces, but i'm just trying to get a head start here, just wondering if anyone already knows of this stuff, or can point me to where this info is available. thanks to anyone who can help out.
 

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What is your budget? Look at Proflex as an option - once you rally on a similar setup you will not go back to anything else. You also get adjustable bump (slow and fast) as well as rebound. Make sure you have adjustable height as well - if rules allow you may want to rose joint fron and rear to get camber adjustment (I am doing this now on my road car for the rear).

The spring rate will depend on the surface you are rallying on - if it is a hard and smooth surface, stiffer is better. However if it is a rough surface you will want the suspension to work - too hard and the wheels wil not be on the ground and you will lose traction and cornering speed.

We have two sets of springs for my current rally car (not a Supra) which are for smooth or rougher surfaces. We make final adjustments using the dampers to improve traction out of corners, traction at high speed and also low speed. Final settings come with testing time.

I think the Supra would be a reasonable package for rallying - especially good on fast and flowing stages. The tighter and twistier stuff you will have to work hard but a nice all round package.

I assume you are looking a the SCCA Pro rally series in the US? What are the rules for engines etc? Make sure when you build the car you strengthen the entire chassis by stich welding and tying the cage from front suspension to rear - helps if it is as stiff as possible - any changes in suspension are then much more noticeable and gives a lot more flexibility for you as a driver to set the thing up so it is easy to drive :)

Remember, look at the picture as a whole. My last car was run in a RWD category for bigger cars - we chose a smaller V6 engine where all others are running V8s - makes the car much better balanced, we can run it lighter and hence it is more competitive! Look at the entire car as a whole before you build it to get the maximum performance from it.
 

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Discussion Starter #8
my budget is not very large...

do you know if there would be an "easy" way to mount the Proflex-type shocks to the supra? i doubt they would make a bolt-on kit for the mk2. are there any other cheaper shocks/springs you can suggest? im not necessarily looking to compete with the car just yet. the roads i will be driving on are pretty solid, not very bumpy at all. thanks for your help! i'm glad i got a response from somone experienced in rally car tuning.
 

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DirtRoadMk2 said:
my budget is not very large...

do you know if there would be an "easy" way to mount the Proflex-type shocks to the supra? i doubt they would make a bolt-on kit for the mk2. are there any other cheaper shocks/springs you can suggest? im not necessarily looking to compete with the car just yet. the roads i will be driving on are pretty solid, not very bumpy at all. thanks for your help! i'm glad i got a response from somone experienced in rally car tuning.
Proflex are generally custom made to suit - so if you have a limited budget it may not be for you. We had custom made stuff for our car (a ute of all things) as no-one had ever requested a setup for this type of vehicle before :) For a WRX like I just raced in China it is off the shelf but the price is not that much cheaper anyway.

For a limited budget you could always run something like Bilsteins or Konis. Konis are rebound adjustable but in my experience overheat a bit quicker than Bilsteins. They are also more easily rebuildable and can be re-valved. This *can* be done with bilstein but not as easily. I have not used Tokico before so cannot comment on those. It is also not that difficult to modify your current struts to have adjustable height - you can by the threaded tube and weld to your strut - also need to make the platforms. We generally use a smaller diametre spring when doing this so it is just larger than the tube diameter. Tops need to be modified accordingly. The rear you will need to have a few sets of springs or play with spacers for height adjustment.

If you are going to be airborne at all on hilly sections make sure you have enough travel to absorb the impact on landing as well. Nothing worse than a car which runs out of travel and on compression hits the bump stops (usually on the rear) and kicks the back up causing a nasty nose dive on landing = $$ to repair :)

Hope this helps a little more. There was one fellow in Aus who rallied a Supra a couple of years ago - his car was quite low and he had a lot of underbody damage. But on the fast flowing stuff it was quite competitive from memory.
 

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I run prerunners (not the tacoma's... real prerunners), there is a lot more to the suspension setup than just springs and shoks in an offroad app... but if you need to do it on the cheap it can be done. You want to run 50-100% stiffer spring rates and if it is available adjustable dampening shocks (if you need to go really cheap go you can get rancho's) If you can score a coil over setup for the AE86's that would work really well, you can manually set the preload for those, that would cover front end. Dont forget bump stops, gas stops are nice but the rubber ones will do fine on a budget, just remember that you will be smacking those things a lot so stock ones arent going to cut it. Last but not least make sure you strap your suspension to keep things from over-extening when you get off the ground. Good luck!
 

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im putting 1.3 inch lowering springs which are much stiffer than stock then using hard rubber spacers to bring bach an inch or so, you could do the same thing with more spacer, get 1.3 inch drop springs then add 1.5-2 inches of spacers deppending on how much clearence you want. you could also adjust it this way for different coursess if you get really energetic about it.
 

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TOYMAN321 said:
I run prerunners (not the tacoma's... real prerunners), there is a lot more to the suspension setup than just springs and shoks in an offroad app... but if you need to do it on the cheap it can be done. You want to run 50-100% stiffer spring rates and if it is available adjustable dampening shocks (if you need to go really cheap go you can get rancho's) If you can score a coil over setup for the AE86's that would work really well, you can manually set the preload for those, that would cover front end. Dont forget bump stops, gas stops are nice but the rubber ones will do fine on a budget, just remember that you will be smacking those things a lot so stock ones arent going to cut it. Last but not least make sure you strap your suspension to keep things from over-extening when you get off the ground. Good luck!
What type of roads are these? Smooth and fast? Bitumen? I am guessing this because you mention "strapping" of your suspension for jumps - I assume this is to stop springs from displacing? I would not run a set of springs that would not remain placed even on full extension! I would have considered a progressive rate spring is a much better option.

Funny that this should have come up again - I was just watchig some footage from the UK rally series from the mid eighties last night and Per Ekland had an MA61 Supra in rally trim which was a TTE prepared car - looked great on the tarmac. I will see if I can get some of the footage uploaded for you viewing pleasure :)
 

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Strapping is not to keep the springs from comeing un-seating, it is to prevent "topping out" when you suspension is at full droop, on a truck when this happens your shocks and springs are now having to support the full weight of your axel and drive shaft which can damage your shocks and springs, really nasty on a solid axel rear end. Keep in mind many of these trucks are running 1 1/2 - 2 feet of travel, not exactly what you are working with for a rally car.

THis pic a good example, coil over with bypass, air/oil bumpstops and if you look on to the right of the bump stop you will notice the two black straps to limit droop
 

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Ah, ok, mis-understood why - yes, I have seen strapping done but more in serious off-road applications like buggies/trucks etc in safari/paris-dakar style events where lots of travel is required and there are many big jumps. I have never seen it used in rallying in Australia or China - even at national level (and in Aus we have one of the hottest Gp N championships world wide).

As you mentioned, it makes sense when you have a serious amount of travel - a typical rally car does not need anywhere near the sort of travel that off-roaders do.

BTW, nice rear-end setup - what is the base vehicle?
 

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Very true you wouldnt need something that big for rally, that pic is of a Ford Ranger (post I-beams) I couldnt find any pics of my front end, which is nearly identical but on a 97 4runner.... it's probably one of the only 4runners of that generation that sees the dirt instead of the shopping mall parking lot on weekends.... atleast here in Cali :D

These setups are built up for racing/prerunning (i.e. baja) lots of speed, lots of air time, lots of fun, lots of broken parts :D
 

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Hehe - I would love to have a go at a serious off road event like that. Closest I got was in 1998 in the Around Australia Rally (18000km in 21 days) but even that was in a Subaru WRX. I remember that on the smooth stuff we blitzed but on the rough stuff the guys with serious travel just flew past us like we were standing still!! Awesome to see. I know what you mean about few 4wds getting off the bitumen - same goes here in Aus!

I will try and capture some of the MKII Supra I have in the UK rally series from the late eighties - great to watch.
 
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