Short Rear Shock Options


I’m looking into what options there are for the “short shock” replacement on many of the other Daihatsu models, to see what might be applicable for the M1XX Sirions.

It seems the Hyundai Excel X1 / X2 is the go to short shock absorber option when moving to a lowered height. Of these it looks like the most common is:

  • KYB Excel-G (p/n 343183)

However there is also options from Monroe, Webco, Gabriel (two options a “Guardian” and a higher Spec “Ultra”), and no doubt others.

Is anybody able to share experiences with these shocks with respect to track-work?
Are there options from other models that are known, that may have more sports-orientated offerings?
Has anyone installed the shorter shocks on the Sirion model?

A bit of background into why:
The BC Racing Coilovers in my M101 are 3kg/mm springs, and I’m after higher rate ones.
I’ve got a lead on high rate springs with the 95mm ID applicable to the Daihatsu’s (basically 4K upwards in 2kg increments all the way to 20K), however they’re drastically shorter than the factory springs and shorter again than the rear springs the BC’s have. Factory ~300mm, BC 225mm, High Rate 150mm. Additionally I won’t be able to use the height adjustable collar as the BC springs are custom 118 top ID and 95mm bottom ID. So without the height adjustable collar these springs will provide whatever height they provide. My concern is that if you do get a wheel lift while cornering the shock length will have to be such that it won’t allow the spring to become un-captive. Hence the possible option of shorter shocks.

I’ve also approached BC for higher rate, to which they’ve said:
“Unfortunately the only option they make is the 3kg. This is due to the custom design of these springs”
So they’re no further help.

I’ve reached out to King Springs who can do custom springs to order.

Thanks in advance.

I had the excel shocks and lowered German hot bits springs in my l200 was fun at the small track in Goulburn nsw.

@evilhighway had some success I think with super secret shocks for a wagon r

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Using the KYB and Monroe websites - you can search via end types and lengths.
So there are KYB Exel-G, Gas-A-Just and Premium options that would suit
Monroe’s a little more difficult to decipher.
Which would be ‘better’ is obviously hard to discern as in these sizes they do not have their outright ‘best’ options available (ie KYB AGX).

super secret suzuki wagon r shocks or even daewoo matiz can be used both need slight bolt hole mods and spring seats are lower on both. The wagon r struts would be the better choice out of the 2. mira kig springs for the fronts go into sirion struts as well as the other 2 mentioned. That is all for the front.
The rear I am using hyndai x2 shocks there are slight difference in ride comfort between brands but for track it’s not a great deal. I tried the hyundai’s in the copen when we had that and it made the ride much firmer but because it was a street car I opted for comfort but if I was going to go to track I would have changed to the x2’s.
I have tried gabriel guardians x2 and now have them in my swift, all other’s have been what ever is cheapest on ebay at the time. one was a generic brand and another I cant recall the name of but its on the sticker n the move.

the spring rate for mira king springs are as follows:
KDFL-81 = 140lb (fronts which are perfct for me)

KDRL-82 = 260lb (rear These were too soft for me).
I hope some of my dribble may have helped.

I currently have ford gc8 front chopped spring’s in the rear on the move with hyunai x2 shocks and sirion struts with mira king springs in the front and although the car is not low it handles very well, but please remember it is a tissue box that is too tall and has no place on a track and makes passenger’s quite concerned with how I treat corner’s.

That has helped - especially the comments about the Copen.
I was also thinking of Copen front struts and rears - but if the X2 rear shocks are as good/better - then that is an easy option.

Well the Sirion isn’t exactly the most aerodynamic car either!!
Looks like I could be in for some trial and error :slight_smile:

Keep the front as soft as possible. Use the lowest rate that just keeps off the bump stop during our events. Going up in the front normally means going up in the rear rate too. The front of the car needs to move around to keep weight equal on both front tires. If it is stiff one side will become unweighted. This unweighted actually sends weight diagonally. So stiffening the front sends weight to the back. The opposite is where the rear that is so stiff that the back seems not to roll at all will send weight to the front. Keep the shock short so a wheel comes off the ground (the inside wheel will be doing little and the outer rear which does not have to provide drive and is on the lighter end of the car will have enough traction. Keep the front tracking the ground so it won’t wheel spin. Keep sending weight to the front as that is where the drive is needed and corner grip is needed. Rear sway bars can take some of that rear grip away and reduce understeer, however, the smallest sway bar (or omission thereof) keeps each side of the car independent. Why have independent suspension and then add huge couplings? McLaren use no sway bars at all.

Go with a Koni red as a minimum. Monroe and KYB are not competition items and will have little bump damping and more rebound. The Koni Red double tube non-gas in the rear will be 5min a side to adjust the rebound. They can be pulled apart and you can change the oil viscosity to increase bump (or even change the valving). In circuit racing, hill climb or khanacross you will improve times more per dollar spent if you prioritize #1 tires #2 suspension.

Flat section helper springs can solve the captive spring issue. They would raise the car a slight amount and depends on the rate. Once the weight of the car is on them they go flat and have have no rate, as in “solid”.

Or run a perch of some sort. I’d machine up HDPE bases in the requisite thickness if rules said I couldn’t touch the spring seat. Sometimes I have cut (turned off the in the lathe) the spring seat and welded back on. Mainly though I do this with std diameter seats and they come down such that the tire just clears (nom 25-30mm). Other times I turn up my own adjustable threaded section and seats.

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Helper Springs! Yes, that’d solve the issue. I see Eibach has some 95mm ID (3.75") Helper Springs.

Regarding HDPE mounts/perches - I don’t have the tools/equipment to manage that.

The problem with the Koni Website/Info is that none of it lists compressed and extended lengths, you can’t search by Upper Eye and Lower Eye mounts etc. Atleast the Monroe/KYB sites allowed you to search that way. Also Koni don’t have listings for the common ones discussed. There are Koni Yellow for the Hyundai Veloster - no reference to dimensions though…

The Koni item to suit same vehicle is going to be the same compressed as extended length and mounting the same. Try some of the Hyundai Excel race guys (ie, they might help. I had a set but sold them and never wrote down the part number (I’ve gone to something even shorter and changed the mount type. So anything that fist the rear of a Catherham fits mine). You could also try the wholesaler, GSA Automotive. Let them know you want to purchase locally but need a part number.

A good point, although I did see they have short-versions of certain models. Which, would be good to have that data on their website. But can use the info from other sites to ensure the top/bottom mount is accurate. Looks like I need to make a spreadsheet!

Outside of std Koni occasionally have variations. Mostly though there are longer options for 4wds. For example you can get Koni red double tube hyd for all Navarras that give around an extra 50mm of travel taking things to the factory articulation limits. At the last trade show I went to the GSA guys promised me the master Koni list, I am still waiting on it, sigh.