Coilover Clearance issues

[hokejka]

I want to run a 245 on a 8.5 inch rim in the front. Seems that ST XTA coil overs' perches make you run a et30 offset to clear the rim. Thats a ridiculous offset for an 8.5 in the front. I see a lot of people running et40 18x8.5 in front and clearing a 245 no problem. Is this problem specific to the XTAs? Do different coil overs have different clearance issues?

[drewster99]

All i know is that I'm running a 225 in the front on a et45 8.5" rim and there is very, VERY little clearance between the spring perch and the wheel. I'm probably going to need 3-5mm spacers up front. I have the XTA's as well.

[hokejka]

Originally Posted by drewster99

All i know is that I'm running a 225 in the front on a et45 8.5" rim and there is very, VERY little clearance between the spring perch and the wheel. I'm probably going to need 3-5mm spacers up front. I have the XTA's as well.

that makes perfect sense. 5mm spacer will work perfect if you want more tire. I am assuming that the guy I heard this from didn't raise his perches to max.

sounds like yours are raised?

[drewster99]

I think I set the front perches 18 threads up from the bottom. I still want it about 1/2" lower but will probably need spacers to do so.

[hokejka]

i don't plan on lowering the car by much so I think I will be in the clear. I would be happy with a 3/4" -1" drop

[RyanDavies]

Buy springs that allow you to run the perch above the tire. I'm running 255/40/17 tires with an effective ET33 on my car.

[hokejka]

Originally Posted by RyanDavies

Buy springs that allow you to run the perch above the tire. I'm running 255/40/17 tires with an effective ET33 on my car.

how much camber to clear that

I assume in in 18 rim the 255 would ba little bit tougher to fit right an extra 1/2 inch in diameter

[E82MSport]

Originally Posted by hokejka

how much camber to clear that

I assume in in 18 rim the 255 would ba little bit tougher to fit right an extra 1/2 inch in diameter

A 255/40/17 is 25" OD, a 245/35/18 is 24.8" OD. These numbers might vary by a couple tenths depending on what tire you're running but in this case they are roughly the same diameter.

The issue is spring perch clearance like mentioned above. I don't have the same coilovers but I do run a 245/35/18 in front with an 18x8.5" ET45 offset. I have shorter springs from Swift and custom spacers that raise the entire damper giving an additional 10mm clearance along with -2.5 degrees of camber.

Does this kit use linear springs or like stock?

I suggest contacting the manufacturer and getting the spring rates that came with the kit. I would also ask how much higher of a rate you can effectively run that will still work with the damper.

[hokejka]

Originally Posted by E82MSport

A 255/40/17 is 25" OD, a 245/35/18 is 24.8" OD. These numbers might vary by a couple tenths depending on what tire you're running but in this case they are roughly the same diameter.

The issue is spring perch clearance like mentioned above. I don't have the same coilovers but I do run a 245/35/18 in front with an 18x8.5" ET45 offset. I have shorter springs from Swift and custom spacers that raise the entire damper giving an additional 10mm clearance along with -2.5 degrees of camber.

Does this kit use linear springs or like stock?

I suggest contacting the manufacturer and getting the spring rates that came with the kit. I would also ask how much higher of a rate you can effectively run that will still work with the damper.

Thanks for the details. I remember comparing sizes before. didn't realize it was 1/4" and backwards haha.

KW makes the st kits and they won't give out spring rates although supposedly its a clubsport front with a kw v2 rear non linear springs. As much as I'de like swift liners I think its smart to keep the stock kit springs because the car is a DD. They are supposed to work very well from what I have read

[hokejka]

Fidiman Can you add to this? You have convinced me to go st xta from our previous conversation

[Fidiman]

I will add some pics and mesurement asap Without any value, I can say I don't have any clearance issue : I'm running ET40 and 8.5" front with the VMR VB3 for DD. With a more agressive wheel, like my OZ for the track, I'm running ET34 (I have to verify) and 8" wide. I have -1°28' front.

For the rear, don't have problems either with the OZ in the same size nor the VMR in 9.5" ET45.

That's my 2 cents Will try to do som pics and mesurement this weekend !



Edit : In addition, you definitvely cannot go wrong with these coilovers. With some other bits, you will be able to have a real track ready machine ! If I were you, I wuoldn't run 245 front ... Too much IMO. I would try 225 max and camber like -2° ...

[hokejka]

Originally Posted by Fidiman

I will add some pics and mesurement asap Without any value, I can say I don't have any clearance issue : I'm running ET40 and 8.5" front with the VMR VB3 for DD. With a more agressive wheel, like my OZ for the track, I'm running ET34 (I have to verify) and 8" wide. I have -1°28' front.

For the rear, don't have problems either with the OZ in the same size nor the VMR in 9.5" ET45.

That's my 2 cents Will try to do som pics and mesurement this weekend !



Edit : In addition, you definitvely cannot go wrong with these coilovers. With some other bits, you will be able to have a real track ready machine ! If I were you, I wuoldn't run 245 front ... Too much IMO. I would try 225 max and camber like -2° ...

\

Thanks for verifying. Are your spring perches maxed out?

I have never heard anyone say "too much tire" unless the ratio of sizes was off. I think a 245/265 is a great combo. I also have a 135i so I want the extra rubber in rear, to hold/grip then need the front to balance that/break.

[ShocknAwe]

Originally Posted by hokejka

\

Thanks for verifying. Are your spring perches maxed out?

I have never heard anyone say "too much tire" unless the ratio of sizes was off. I think a 245/265 is a great combo. I also have a 135i so I want the extra rubber in rear, to hold/grip then need the front to balance that/break.

Probably referencing too much for the space available with that coilover installed. I would LOVE to run a 245 up front with 265 out back.

[hokejka]

Originally Posted by ShocknAwe

Probably referencing too much for the space available with that coilover installed. I would LOVE to run a 245 up front with 265 out back.

why are you not able to? 245 should be fine in front at et40 about 2 deg of camber and a rolled fender

[E82MSport]

Originally Posted by hokejka

why are you not able to? 245 should be fine in front at et40 about 2 deg of camber and a rolled fender

The lower spring perch will most likely rub the tire even with an ET40 without installing shorter springs. In reality the only way to know is if someone has the exact same coilover and wheel/tire setup OP is wanting to run. The alternative is to measure and calculate what's needed in order to make this work.

IMHO a 215 or 225 is far from adequate for these cars if you plan on auto crossing or HPDE's. Even weekend canyon runs are borderline with these sizes.

If all you want is a fun daily I'd say an 18x7 ET40 running a 225/40 with -2.0 camber and a decent brand of tire. I'm guessing you would be close and maybe need a fender roll but it most likely wouldn't require shorter springs. - yes I realized (hokejka) basically mentioned this.

[ShocknAwe]

Originally Posted by hokejka

why are you not able to? 245 should be fine in front at et40 about 2 deg of camber and a rolled fender

19x8 et 45 up front with 235-35-19, any larger and I would rub the fender badly. At least that's my read on the situation.

[hokejka]

Well looks like I will be the test dummy. Unless Fidiman could give some more insight/picture of his inner wheel/tire to strut/perch clearance... please

[Kgolf31]

Your shock/perch clearance relative to your wheel will never change with more/less camber. This dimension is fixed.

So, IMO find out what you need to clear the shock and perch (throw your wheel up now and start doing calculations) and you'll see where you need to end up.

I use to have 17x8.5 ET40 APEX wheels and I wanted to go to a 17x9 ET45 wheel. Figured out I needed a 12mm spacer and now I am fine with no issues.

You'll need camber to solve your fender clearance issues.

[hokejka]

Originally Posted by Kgolf31

Your shock/perch clearance relative to your wheel will never change with more/less camber. This dimension is fixed.

So, IMO find out what you need to clear the shock and perch (throw your wheel up now and start doing calculations) and you'll see where you need to end up.

I use to have 17x8.5 ET40 APEX wheels and I wanted to go to a 17x9 ET45 wheel. Figured out I needed a 12mm spacer and now I am fine with no issues.

You'll need camber to solve your fender clearance issues.

Seems to be not enough information to know what I need to clear shock and perch but if people running et40 225/40 are clearing it et40 245/35 will be closer but should be fine.

I understand that camber moves the entire system but it seems some responses were concerned with my overall fitment desire, thats why I mentioned the camber to clarify that.

There are a ton of people running 245/35/18 and 255/35/18 in front so I don't see why it would be an issue as long as these coil overs are the same as the rest it will be a matter identical to everyone else...

1/ make sure they don't rub strut - usually need et40 for a 245-255 tire
2/ dont rub fender - usually a roll with about - 2 deg for a 245 tire works

If I am doing the above and the tire hits from inside than these coil overs must have extremely low perches or have altered design from most other coil overs systems .. which i doubt

[E82MSport]

Originally Posted by hokejka

Seems to be not enough information to know what I need to clear shock and perch but if people running et40 225/40 are clearing it et40 245/35 will be closer but should be fine.

There are a ton of people running 245/35/18 and 255/35/18 in front so I don't see why it would be an issue as long as these coil overs are the same as the rest it will be a matter identical to everyone else...

1/ make sure they don't rub strut - usually need et40 for a 245-255 tire
2/ dont rub fender - usually a roll with about - 2 deg for a 245 tire works

If I am doing the above and the tire hits from inside than these coil overs must have extremely low perches or have altered design from most other coil overs systems .. which i doubt

The first problem is that the majority of the coilovers out there have lower spring perches than a factor strut, thus the clearance issues. People that run a 245 or 255 are either running factory struts or coilovers with shorter springs.

I bought Ohlins thinking it was the end-all and it was far from it. The Ohlins kit was barely able to fit a 215 with an ET42 with the supplied springs. The only kit out I'm aware of that addresses this issue is possibly TCK because they run shorter springs with the intention of raising the perch as far as possible for tire clearance.

These coilover manufacturers design with factory tire/suspension in mind and not up-sizing for the most part. On most vehicles this wouldn't be a big deal because you could just run a lower offset but not on the 1-series. The Ohlins kit was built for the 3-series and repackaged for the 1er without taking into consideration of the clearance. I think this is probably the case with 90% of the coilover kits out there. Intended for the 3-series and adapted for the 1.

[hokejka]

Originally Posted by E82MSport

The first problem is that the majority of the coilovers out there have lower spring perches than a factor strut, thus the clearance issues. People that run a 245 or 255 are either running factory struts or coilovers with shorter springs.

I bought Ohlins thinking it was the end-all and it was far from it. The Ohlins kit was barely able to fit a 215 with an ET42 with the supplied springs. The only kit out I'm aware of that addresses this issue is possibly TCK because they run shorter springs with the intention of raising the perch as far as possible for tire clearance.

These coilover manufacturers design with factory tire/suspension in mind and not up-sizing for the most part. On most vehicles this wouldn't be a big deal because you could just run a lower offset but not on the 1-series. The Ohlins kit was built for the 3-series and repackaged for the 1er without taking into consideration of the clearance. I think this is probably the case with 90% of the coilover kits out there. Intended for the 3-series and adapted for the 1.

thank you for the excellent explanation. this makes sense now. I remember reading about a people often swapping for swift springs.

i did also look up tck and in all the pictures significantly shorter springs are shown when compared to most other coilover systems.

are there downsides to shorter springs? I assume less travel?

can you swap just front springs or would it make sense to swap all springs at the same time? Any recommendations?

[hokejka]

@ginger_extract I belive you run tck. can you give some insight on tire clearance and streetability of those coilovers with linear springs?