good NON-adjustable coilovers for road/track?

[ZDan]

Spring rates in the ~5-7 F/~7-9 R range.
Do such coilovers even exist?

Adjustability costs me points and adds weight! ~40 lb. each for ride height adjustability and every dimension of damping adjustability.

Not averse to spending a few $$$ on good quality and revalving for desired spring rates.

[Racecomp Engineering]

Bilstein B14, change the springs and possibly revalve as needed.

- Andrew

[Tristor]

Seconding Bilstein B14s and then running Raceseng CasCam camber plates in the front w/ Shocktop rears. Gets you full travel, minimal effect on roll center due to the camber plates, and gets much more and simpler camber adjustments in the front.

[ZDan]

Should have gone into current setup:
Swift BRZ Sport springs (3.8F/4.5R)
Raceseng camber plates
Stock PP/Sachs dampers, with bumpstops cut down from ~60mm to ~25mm

This setup is semi-OK at the track, but on the street the loss of front bump travel is intolerable. The Swift BRZ Sport springs lowered the car 1.5" front and 1.25" rear, I added in 1/4" spacers to the front upper spring seat to give -1.25" all around. Note that Raceseng camber plates cut significantly into bump travel, ~15mm IIRC from measuring.

At the track the lack of front bump travel helps to minimize roll during cornering but gives mid-corner understeer which is tolerable at most tracks but sucks at Palmer CW Turn 4...

Would like to go stiffer on spring rates all around while increasing front bump travel significantly.

[Drifter X]

Sorry I know I'm not contributing to this, but it's it normal practice to cut the business bumpstops? I have SACHS dampers also.


Sent from my iPhone using Tapatalk

[wparsons]

Originally Posted by Drifter X

Sorry I know I'm not contributing to this, but it's it normal practice to cut the business bumpstops? I have SACHS dampers also.


Sent from my iPhone using Tapatalk

Most lowering springs either include new ones, or include instructions on where to cut the stock ones.

[Tristor]

Originally Posted by ZDan

Should have gone into current setup:
Swift BRZ Sport springs (3.8F/4.5R)
Raceseng camber plates
Stock PP/Sachs dampers, with bumpstops cut down from ~60mm to ~25mm

This setup is semi-OK at the track, but on the street the loss of front bump travel is intolerable. The Swift BRZ Sport springs lowered the car 1.5" front and 1.25" rear, I added in 1/4" spacers to the front upper spring seat to give -1.25" all around. Note that Raceseng camber plates cut significantly into bump travel, ~15mm IIRC from measuring.

At the track the lack of front bump travel helps to minimize roll during cornering but gives mid-corner understeer which is tolerable at most tracks but sucks at Palmer CW Turn 4...

Would like to go stiffer on spring rates all around while increasing front bump travel significantly.

With being down only 1.25" in ride height, if you're on the bump stops that often I think that's indicative you need higher spring rates and a damper valved for those rates. It'd be probably be worth investigating Bilstein B14 and getting it custom valved so you can run 6-7k springs in the front and maybe a little higher in the rear, depending on your tires and aero.


Are you running any aero? It can have significant impact on the necessary spring rates.


I'm not sure who all the tuners for Bilsteins are, but I've heard good things about FCM.

[Lincoln Logs]

Originally Posted by Tristor

Seconding Bilstein B14s and then running Raceseng CasCam camber plates in the front w/ Shocktop rears. Gets you full travel, minimal effect on roll center due to the camber plates, and gets much more and simpler camber adjustments in the front.

Extended shock mounts do not magically give you full suspension travel. You trade droop travel for bump travel.

If you are wanting a non adjustable coilover, I would personally stick with camber bolts and factory top hats to reduce NVH.

[Tokay444]

Penske will build you whatever you want.

[Captain Snooze]

Or have a word to 949Racing. I think they will build you a non-adjustable damper to what ever specs you like.

[ZDan]

Originally Posted by Tristor

With being down only 1.25" in ride height, if you're on the bump stops that often I think that's indicative you need higher spring rates and a damper valved for those rates.

Issue seems to me to be upwards of 2" lost due to lower + camber plates combined with lack of bump travel with the factory Sachs dampers.
I do want more spring stiffness to minimize roll at the track.
But I don't think that will help regarding bottoming the fronts over bumps on the street.

It'd be probably be worth investigating Bilstein B14 and getting it custom valved so you can run 6-7k springs in the front and maybe a little higher in the rear, depending on your tires and aero.

Seems like a solid option, might try them as-delivered damping rates and maybe something like 4.5k front 5.5k rear springs...
The springs they come with are progressive at 2.5/4.5 front, 3.0/7.0 rear.

Come to think of it I'd probably just try them with as-delivered springs first anyway.

But at that point it might make more sense to just run the current 3.8F/4.5R springs and Raceseng plates with B6 or B8, hoping they have significantly more bump travel vs. factory Sachs. Softer springs than desired, but -40 lb. for no height adjustment!

Are you running any aero? It can have significant impact on the necessary spring rates.

No aero.

[ZDan]

Originally Posted by Racecomp Engineering

Bilstein B14, change the springs and possibly revalve as needed.
- Andrew

Ha, just saw this! Yeah, that seems a solid option, or as said above compromise-rate linear springs with "stock" B14 damping. But again at that point might just consider B6/B8 with existing 3.8/4.5 lowering springs...

[strat61caster]

B14 lower perch is for 60mm ID springs, make adapters or replace top hats to use any 60mm spring you want. You might save a few bucks up front on the B6s but as soon as you bore of the 90mm springs you're looking at sleeves or fab work.

[Racecomp Engineering]

B6 are roughly the same bump and droop travel as stock. B8 have less droop. They may have shorter bumpstops but that's it. Good shocks but don't buy them for more travel!

Certainly could try the B14s as is and go from there. I'm sure 5k/6k would be good on standard valving, 6k/7k maybe a little underdamped in front. I do have Bilstein branded 7k springs if you're interested. Edit: and KW branded 5k 200mm springs if you want to create a German Frankenstein's monster. Lol. Obviously there are tons of other choices, we were just doing some shop clean up today

The raceseng plates work much better for coilovers if I recall. With their upper perch the stack height is small and you don't lose bump travel, but you'd have to buy that from them.

I would not recommend 2 inch drop rear mounts.

I would expect the coilovers set up with proper travel to be a large improvement in driveability over your current set up.

- Andrew