Suspension to Control Rear on Road Course

[DoogieT]

I Time Trial this Mk4 and to be competitive I need to increase corner speed. I have the FFR stock suspension coil over Koni (Red). Solid rear axle limited slip diff. Could you help me to understand an incremental (upgrade over time) path for suspension upgrades to tame the rear turns?

I'm SCCA HPDE 3 with TT License, 4000 miles driven on 14 tracks in 9 States. I max turns with no lift, stearing back online. I sometimes spin but I know the drill having learned to drive a stick in MI snow in the 60s when snow was plentiful and snow days off school are memorable.

Here's we have for the track: 331 Stroker 400BHP/324WHP. MSD/distrib, elect pwr steer, Edelbrock intake and Holly 750, dual brake fluid, Willwood 6 pist front/4 rear, offset rims, Yokohama 10.5" front, 12.5" rear, extended lugs and spacers all around, fuel cell, driver race seat and Tremec TKO600. 2nd Roll bar, not willing to install cage. Suspension is stiffened, toe in 2-3".

[phileas_fogg]

I've got nothing that'll help you, but I'm looking forward to getting a little bit more edjoomacated from the responses. :p

So thanks for asking the question!


John

[Gordon Levy]

I guess the first questions to ask is, when you say stuck suspension is it a 3 link rear or 4 link? What are your spring rates. From there we can start to think about a plan to make the car quicker.

[J R Jones]

Anti-roll bars? Panhard bar? Gear ratio? Alignment specs? Weight balanced?

[NAZ]

Doug, once you've provided the boys some basic car configuration and set-up specs, you should provide some handling details that you're experiencing. Pretty hard to troubleshoot a condition simply described as I spin it once in a while. You got the attention of the the right crew chiefs, now try to explain how the car handles in the corners like a professional driver would. It's not uncommon for a car to handle differently in different parts of the corner, i.e. push in entry, and be loose in exit. Try to give as much detail as you can so Gordon and JR can better assist you.

And you might want to rethink that toe adjustment of 2" to 3" -- just sayin'...

[OVCobra]

It would also be helpful to know what control arms you're using...stock Mustang control arms with rubber bushings were/are notorious for binding up and then unloading

[Rdone585]

These cars tend to be fairly well balanced wet, with no driver. But when the driver gets in the car, they (at least mine) is overweight on the left and rear. I've noticed better performance on left turns when compared to right turns, so this all makes sense to me now. A couple of years ago with an engine swap, the balance of the car changed because the battery was moved from front right to rear left. Not the best location but options were limited in my build. I'm looking to make some improvements with balancing the corner weights and considering upping the spring rates front and rear over the winter. Perhaps you could share your corner weights and spring rates so others could help with their knowledge on this topic. You might also share what brake system you have. I swap brake pads between street and track.

[TriPower]

Listen to Gordon.

I track mine and have Gordons, 5 link, Torsen diff, sway bar front only, mild spring rate to make it better on roads. Engine is 347- 490 Hp 425 ft-lbs. I run for fun, not time, but have spun only three time. Once I increased tire pressure to 25, I now run 18 psi on Nitto NT05 and traction is very good. Once was after lunch on summer perf. tires in cold weather, it was about 55 F. The third time was on me, my turn in was late. I mainly run on RA, Blackhawk Farms, but want to try Autobahn next year. Also several tracks in AZ, but just a few times.

Lee