Front/Rear Track Discussion

Suspension and other discussion

Front/Rear Track Discussion

Postby b00staholic » Sat Oct 22, 2005 2:02 pm

First of all, I haven't been able to find much discussion on the internet on how changing front and rear track (relative to each other) can affect handling that is specific to AWD cars.

The general consensus for FWD/RWD cars (or maybe all cars?) is that increasing rear track relative to front track will lead to more understeer.

What exactly are the front and rear track dimensions for the ST185? I'm finding a lot of conflicting info.

From http://www.alltrac.net/specs/st185USAspecs.html,

F/R: 1480mm = 58.3 in. (I don't think front and rear are the same)

From my 1990 Car and Driver review of the ST185,

F: 58.3 in.
R: 56.9 in.

From http://www.rallycars.com/Cars/Toyota_GT ... ST185.html,

F: 1475mm = 58.1 in.
R: 1445mm = 56.9 in.

From my owner's manual, it says that widebody liftback's (not sure if the All-Trac would be different than normal Celica's) have

F: 1475mm = 58.1 in.
R: 1440mm = 56.7 in.

What's with all the discrepancies? Which numbers are correct?

I know it may seem like small differences but I would like to get at the truth here.
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Postby b00staholic » Sat Oct 22, 2005 2:09 pm

Straight from the Mitsubishi and Subaru websites:

2005 Lancer Evolution (all variations):

F: 59.6 in.
R: 59.6 in.

2005 Subaru WRX sedan:

F: 58.5 in.
R: 58.3 in.

2005 Subaru WRX STi:

F: 58.7 in.
R: 58.9 in.


The Evo has an even track, the WRX has a slightly shorter track in the rear (difference between front and rear track is smaller than ours), and the STi actually has a slightly longer rear track. All of them have wider tracks than our cars.
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Postby b00staholic » Sat Oct 22, 2005 2:18 pm

What are the F/R tracks of the actual rally Celicas?

From http://www.tte.de/st185.html,

F: 1510mm = 59.45 in.
R: 1510mm = 59.45 in.

This site http://gamma.nic.fi/~globe/rally/paradi ... cat4wd.htm says the same thing.

They may have been on to something with going with an even track?

If we can determine what the ACTUAL track is on our production model cars, we can better decide which spacers to use on our cars to get closer to an even track.

For example, if the 25mm H&R rear spacers that everyone has makes the rear track longer than the front, maybe some 7mm-10mm spacers could be used up front for even more improved handling.
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Postby CMS-GT4 » Sat Oct 22, 2005 2:36 pm

I would say the track listed in the manual to be most accurate.

When putting the 1" spacer on the rear is still slightly shorter than the front. So that range seems close.

I think toyota followed the rwd formula for a shorter rear track for the sake of the consumer using aftermarket dished wheels in the rear.

But toyota trying to keep costs down barrowed hubs and wheels from the gts. I guess toyota figured if you can blow near 30 grand for a celica a couple grang fir wheels won't kill you.
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Postby b00staholic » Sat Oct 22, 2005 2:43 pm

You have to add 2" to the rear track because its 1" on each side, making the rear track significantly longer.

I have no idea what Toyota was thinking, but I honestly don't think they were thinking about aftermarket dished wheels. How common were aftermarket dish wheels in the early '90s?

If Toyota really was looking out for the enthusiast, they would've just made the car handle better to begin with, not borrowed parts from the regular Celica models. Regardless, no one can know for sure why Toyota did what it did.

CMS-GT4,

I was looking through some old posts and remembered that you had tried the 25mm rear spacers with 8mm spacers up front. An 8-10mm spacer up front combined with the 25mm rear spacer seems to get the F/R tracks pretty close to even.

How did you like the handling then? I interpret your results to say the car handled more "neutral."
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Postby CMS-GT4 » Sat Oct 22, 2005 2:55 pm

Actually the front stuck out a bit further than the rear w/ the 8mm up front, but the car also changed. I am not sure if it is related to track width or scrub radius. By adding the front spacer the car lost its rwd characteristics. But the car went whereever you pointed it. The car was more direct and relied on the steering more than it had before.

You do bring up a good point about adding 1" to both sides. That makes me think the data was wrong since the rears were still slightly shorter even after the spacer. We need someone to get out there and take some close measurements on a flat lot.
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Postby b00staholic » Sat Oct 22, 2005 3:08 pm

How are you basing these statements:

"the front stuck out a bit further than the rear w/ the 8mm up front"
"the rears were still slightly shorter even after the spacer"

No offense, but if you're quantifying these visually, I don't think that has any basis. That is why I want to get the actual F/R track numbers sorted out.

Our rear fenders are huge, even compared to the front, so it's going to be easier to make the front wheel look like its sticking out more past the fender than it will be to achieve the same look with the rear wheel/fender. This has no bearing on the actual track though.
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Postby CMS-GT4 » Sat Oct 22, 2005 6:19 pm

THats why I suggested someone get out there and measure it. Mine is up in the air right now so, I can't do it right now.
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Postby furpo » Sun Oct 23, 2005 3:46 am

ok i have just been out and measured by narrow body st185. these measurements are to the outside of the rim however, they do give an idea of how much shorter the rear track is to the front with no spacers.

front = 1705mm
rear = 1665mm

so the rear is 40mm total, 20mm each side shorter than the front. the 25mm spacers would make the back 10mm wider than the front.

i think a better way of getting rid of the track difference is to reduce the front scrub raduis by making aftermarket hubs and use a combination of spacers on the rear.

as for how that evo went well it won. probably more of a result of it being a complete 600hp car than just the wider rear track. food for thought.

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Postby b00staholic » Sun Mar 18, 2007 7:21 pm

Interesting thread from the Evo forums:

http://forums.evolutionm.net/showthread.php?t=201444

They seem to confirm that adding spacers to the rear = more understeer and worse handling, and adding spacers to the front = less understeer (more front grip) and better handling.

Something to think about for all those adding rear spacers.
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Postby gearhead313 » Mon Mar 19, 2007 1:47 am

Wow, I love this. I've been wondering about his for a long time now. I even took pictures b/c i noticed how different the track widths were on at least my 165. Sorry, i'm not a good picture taker:


Image


Image


Image


Image



I have no backing to my opinions, but I do agree that having a smaller rear width will help with turn-in and rotating the car. I haven't driven too many cars that have the handling charactoristics of my alltrac (which is still all stock suspension). I can try to measure mine and see what it actually is. I'll try looking for some more info too.
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Postby coyoteboy » Wed Jun 27, 2007 7:10 pm

I lobbed 25mm rears on mine when i first got the car, and 5mm on the front. Thining back I cant really think objectively because Ive changed so many things, but im fairly sure it understeers more than when i first got it. I had to take the 5mm of the front - they were causing it to tramline like a fecker and totally screwed up the handling.
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Postby CMS-GT4 » Thu Aug 14, 2008 7:52 pm

Just to add to the notes here is the st205 specs.

Front track: 1510mm

Rear track: 1490mm

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Re: Front/Rear Track Discussion

Postby athousandleaves » Mon Mar 04, 2013 7:14 am

Specs for front and rear track widths from the 1992 Owners Manual

F:1480mm / 58.3in
R:1455mm / 57.3in

Specs taken from the FIA ST185 Homologation Paperwork

F: 1491mm / 58.7in
R: 1456mm / 57.3in

Specs from Turbocelica.nl
Narrowbody
F: 1465mm
R: 1430mm
Widebody
F: 1475mm
R: 1445mm


First post on this thread appears to quote the owners manual with the track widths for a narrowbody, not Alltrac.
My 92 manual has the Narrowbody Liftback, Coupe and Convertable track width at F:1470mm R:1440mm and Widebody at F:1480mm R:1455mm with an asterisk saying the larger widths apply to All-Trac/4WD models.
So either they changed the track width in the 92-93 facelift or my manual is printed incorrectly... time to pull out the tapemeasure!
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