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Summit Wagon AWD suspension
http://www.4g61t.org/forum/viewtopic.php?f=100&t=25411		 Page 1 of 2
Author:  grndsm [ Sun Jun 08, 2008 11:03 am ]
Post subject:  Summit Wagon AWD suspension
My Summit has been making "banging" noises ever since I got it. Sure enough, it was ever so familiar sway bar end link failure. And I was actually able to unbolt those end links! Got to love Southern cars! :)

While I was there, I noticed that front struts were virtually identical to 1G DSM, which means that it should accept EVO 8-9 suspension in a similar manner to a 1G DSM.

One difference was the top mount. It appeared that Summit shared the same upper strut mount with the EVO, but I was wrong... It was close, not close enough. The pattern itself was the same, but the base circle on it was position was slightly larger on the EVO top mount.

I could have swapped in Summit top mount onto EVO strut assembly, but EVO parts were like new and I liked the idea of converting EVO parts, so I elongated the Summit mounting holes ~ .12" outward and it did the trick.

To say that EVO8 a LOT stiffer would be and understatement! It feels SOLID when compared to a worn out Summit suspension! Though I haven't driven with it yet.

Installing stock EVO springs resulted in .25" height reduction. I would have preferred a bit lower ride, so I might have to upgrade to shorter springs later on.

So far, it looks like a promising upgrade! In the front...

Rear upgrade will be much more challenging. The suspension geometry is completely different from DSMs (1G or 2G) or EVOs. It uses separate shocks and springs (as apposed to spring over the shock arrangement that were are used to).

I am not yet sure what I am going to do to match front end's stiff suspension. First step would be to find the spring rates for the original suspension and go from there.

Leon
Author:  89Mirageman [ Sun Jun 08, 2008 11:52 am ]
Post subject: 
The 2wd Summits sit a tad bit lower than the awd's do so a pair of fwd rear springs will bring it down a bit in the rear. I doubt they'll be any stiffer though. I really want to slap a 2g mani, some 450's, a 14b and a super afc on mine. I think that would liven up the sluggish sohc 2.4 quite nicely for a fun daily driver. The downside would be my stock clutch with 149k on it and 93 octane.
Author:  grndsm [ Sun Jun 08, 2008 12:39 pm ]
Post subject: 
Did some more research in FSM:

.....................Front................Rear
Spring rate:....137lbs/in.........375lbs/in
Spring height:...13.5".............10.12"AWD/9.55"FWD
Damper Exp......254lbs..............176lbs
Damper Cont.....128lbs..............66lbs

Some other points:

Dampers have the same spec for FWD/FWDAUTO/AWD/AWDAUTO

Springs have ALL THE SAME rate! But different heights! The way to achieve that, is by having different spring wire diameter. There is that break down (I do not really care about the front but there are rears):

Spring...............FWD............AWD
Wire Dia----------.56"----------.57"
ID.....................4.496".........4.508"
Free height........9.547".........10.118"
Rate.................375lbs/in.....375lbs/in

Some people might find rear spring rate extremely high, but that is normal, Summit suspension geometry places the spring closer to the pivot point, so there a lot more leverage compressing them.

Converting to FWD springs is a way of lowering the van while maintaining stock spring rate, however, I want higher spring spring. So unless I can find a stiffer spring meeting my specs, I might have to cut it to achieve that higher spring rate.
Author:  grndsm [ Sun Jun 08, 2008 8:54 pm ]
Post subject: 
Looking strictly at the spring rates, I am going from:

137lbs/in to 180lbs/in (stock EVO springs), that is 31% increase in spring rate.

Rear coil springs rely on compression of 4 coils. If I cut out one coil, I am looking at the increase of approximately 25% in spring rate.

So I should be able to bring the spring rates into the right neighborhood. But leveling the ride height and finding stiffer dampers might prove to be a bit more challenging...
Author:  supersayianjim [ Mon Jun 09, 2008 9:12 am ]
Post subject: 
i have seen kyb agx's for the fwd summit if you can use the front springs for the rear that would stiffen up the ride. and as for springs is there an alternative?? can you use another models springs(like the vr4)??
Author:  grndsm [ Mon Jun 09, 2008 9:49 am ]
Post subject: 
Quote:
i have seen kyb agx's for the fwd summit if you can use the front springs for the rear that would stiffen up the ride. and as for springs is there an alternative?? can you use another models springs(like the vr4)??
KYB makes GR2 shocks for the FWD, but not AGX. And nothing for the AWD. I have to check the manual to see if I can mount FWD rear shocks on the AWD.

VR4s (I am assuming that you mean Galant), DSMs and EVOs all us spring over the shock design, so they will not work on Summit.

I wonder if I can use Mitsu RVR parts (JDM version of Expo LRV that came with a turbo!). Do have any members from down under on this forum?

Leon
Author:  grndsm [ Wed Jun 11, 2008 9:09 am ]
Post subject: 
Well, last night I figured out how to adapt EVO rear shocks (which are used as dampers inside of the spring), as just the shocks in Summit rear end.

The problem is that they might a bit TOO STIFF!!! The original shocks did not appear to be blown, but they are very soft and easy to compress (though, not as easy to expand). EVO shocks seem to be 4-5 times stiffer!

I think that I will perform a compression test using my shipping scale.

I also cut the rear springs by 1" (free height), which was a full coil + about 1/4" worth actual spring. So I will now put it back together to see just how much it lowered the car.

Leon
Author:  Goat_Boy [ Fri Jun 13, 2008 12:13 am ]
Post subject: 
Quote:
KYB makes GR2 shocks for the FWD, but not AGX. And nothing for the AWD. I have to check the manual to see if I can mount FWD rear shocks on the AWD.
You can. I directly bolted GR2s for the FWD on my 95 summit AWD.
Author:  supersayianjim [ Sat Jun 14, 2008 5:12 pm ]
Post subject: 
well heres proff positive they do make agx's for expo's and summits
http://cgi.ebay.com/ebaymotors/95-Mitsu ... .m20.l1116
Author:  grndsm [ Sat Jun 14, 2008 7:06 pm ]
Post subject: 
Quote:
well heres proff positive they do make agx's for expo's and summits
http://cgi.ebay.com/ebaymotors/95-Mitsu ... .m20.l1116
The fact that you can use front 1G AGXs on AWD summits/LRVs is hardly news... Neither is the fact that AGXs SUCK!!! They blow all the time! I was looking for something reliable. And EVO struts offer just that!

FWD GR2s rear shocks do work, but they are basically the same stiffness as stock :(.

BTW, I was able to adapt EVO shocks in the rear of my wagon. More on that later :twisted:
Author:  fjo_newport [ Sun Jun 15, 2008 1:44 pm ]
Post subject: 
We need some pics!
Author:  grndsm [ Sun Jun 15, 2008 5:52 pm ]
Post subject: 
Joe, I am working on it ;). I will finish welding the rears and will then post the photos.
Author:  supersayianjim [ Wed Jul 09, 2008 7:03 pm ]
Post subject: 
hey whats the deal on the picks and walkthrough on this swap?? really dying to know how you pulled it off??
Author:  grndsm [ Thu Jul 10, 2008 12:11 pm ]
Post subject: 
I used the same technique as 1G/Galant VR4 use. But I slightly adjusted it for the Summit :).

I am waiting to drive the car before I comment farther and post the photos. That can happen tomorrow :twisted:
Author:  grndsm [ Mon Jul 14, 2008 12:07 pm ]
Post subject: 
EVO 9 suspension upgrade is very similar to 1G/GVR4 upgrade.

Front:

Knuckle connection ? EVO uses 14mm bolts where as DSMs/LRVs/Summit use 12mm. Some people just use oversized washers and fix everything in the ?most negative camber? position. That works OK, but because holes are oversized, things can come apart. So I welded some washers in the ?most negative camber? position.

The knuckle on the EVO is 27mm, DSM/LRV/Summit knuckle is 22mm. Therefore you need two 2.5mm spacers to take up the space.

Here is a photo of welded-on washers and spacers.

Image

Installed photo:

Image

The EVO strut top mount is very similar to the LRV/Summit top mount. They have 3 mounting studs, spaced at 120 degrees of each other. The difference is that the studs on EVO top mount are located on a larger base circle. So you just have to elongate the holes a bit.

Image

On the other side, I elongated those holes to give me a maximum camper. So I will end with slightly more camber on the passenger side, which could come in handy during left turns?

Image

Next, I had to mount the brake line bracket. I simply used a ~3? extension to pick up the mounting point on EVO strut.

Image

Rear:

Springs, stock riding height was ~1? higher in the rear than in the front. Therefore, I have decided to cut out 1? worth of spring (one coil) to increase the spring rate.

For the dampers I used EVO 9 rear shocks which have received a ?DSM/GRV4 style? modification in the rear (welded in stock bottom mount).

Image

On top, I simply installed Summit/LRV upper mount, while leaving out the spring.

You will also need to cut down the rear spring perch or you could kit the body and/or inside of the wheel. My original trimming was not enough and I scraped my balancing weights on the rear wheel.

Image

I was afraid that this upgrade will result in a very harsh ride. I was wrong! The ride is very reasonable and handling is great! I still haven?t aligned the car, so I am not sure about the specs that I ended up with. And I haven?t pushed it to the limit yet. But from a few miles (and on-ramps) I am very happy with this upgrade!

Final ride height:

Image

Image


Passenger side camber:

Image

I whish I would have done this on both sides.

Future plans:

- Front and rear struts bars - I am usually not a big fan of those bars. In most cases they are done purely for looks. But in this case, I have more than doubled the stiffness of my suspension on what isn?t known as particularly stiff chassis. So I think that using bars is a very good idea.
- Upgrade the rear springs - I wan?t to get stiffer rear springs. Mitsubishi EXPO (7 passenger wagon) come with stiffer version of these springs. I will get it a shot next.

Leon
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