Lex_GTX

I currently have the M030 package on my 86 951 including the front coilovers, sway bars and new rear Konis.

This car was a non M030 so I still have to install the rear t-bars out of the M030 kit. This is not something I've looking for especially since I don't think they are too terribly stiff and a pain to do.

So are there any good alternatives? A mild coilover in the rear to add to the current stock 86 torsion bars? This is a street car and not tracked but I feel the rear is too soft even for the street. There is way too much squat under acceleration.

Lex_GTX

I should add, I have seen the Koni and GC setups for rear coilovers. Do the rear torsion bars have to be re-indexed when adding a rear kit such as this or will the ride height remain unchanged?

http://www.ground-control-store.com/.../II=749/CA=221

Dougs951S

You generally will need to reindex anytime you add a coilover. You can lower it with the eccentric bolt, but no lower than the limit of its adjustment unless you reindex or remove the TBs. Personally I would just remove them and be done with it, and go with a nice stiff rear spring. It honestly isnt that bad removing them, reindexing them and getting the ride height correct and level is way more of a pain than just pulling them. For what its worth, I'm running 28mm TBs right now with 300 lb/in front coilovers. They are nice, but still not stiff enough for me. I will be pulling my TB's completely shortly and going to a rear coilover setup with 600 lb/in springs. Also planning on moving to 375 lb front springs, car is a mix of track/aggressive street use.

chrenan

Ground control provides a custom eccentric bolt with their rear coilovers that allows you to lower the rear beyond what the stock adjustment allows. This is to keep the rear at a reasonable level when using coilovers as helpers to the torsion bar. Although I do agree with you Doug that pulling the bars is a more elegant solution.

dmcampbell

Doug: I am running the 30mm solid TB's with 425# up front and find the ride just right. I started with the 375#, but felt they were to soft for track use. Also, I could not find the GC eccentrics on their site. Mike

Dougs951S

dmcampbell, does your car see street use? 600 lb/in rear springs are equal in wheel rate to the 30mm TBs and I already know my car is going to have some serious oversteer if I dont stiffen the front up. I'm having trouble deciding between 375 and 400 lb springs. Your set up basically mimics factory wheel rate ratios except obviously stiffer, so I'm guessing your car has a slight bit of understeer? How is your squat under full power? I would like to dial that out and have the car set up neutral or even with the slightest hint of oversteer. My car is also basically my daily driver. What would you recommend?

mikey_audiogeek

600lb rear springs are not equal to 30mm tb's. 850 are a closer match.

Dougs951S

I dont think this is correct. 30mm TBs have a wheel rate of 335 lbs, 600 lb/in springs have a wheel rate of 337 lbs.

Van

That's a pretty small difference... But I suggest the 400s - only because the turbo is a little heavier in front.

Dougs951S

Sounds good, one question though. Is the m030 rear sway the same as the 951 rear sway? I have the 24mm hollow m030 front sway, and 18mm solid rear sway. This is the same as an m030 optioned car, correct? Also Van can you weigh in on the above statement, that 30mm solid TBs are not the same wheel rate as 600's and that 850's in the rear are a closer match? It is my understanding that 850 rear springs would be just slightly less stiff than 33mm solid TBs.

Van

On this page, there are both the stock torsion bar sizes (and M030 is larger than 951) and a chart of torsion bar effective rates: https://www.paragon-products.com/kb_results.asp?ID=58

dmcampbell

Doug, yes I do drive it on street about 5k miles/year, but do run 6-10 DE weekends a year - driving to and from track. Also, it is still very heavy at 3250lbs with full fuel and me in it. It did slightly understeer with the 425# at first, but I have compensated by adding a bit of front toe out and have moved to 255/40-17 Nt-01's on front, (275/40-17 rear), and now it is very neutral. However, with the 375#'s, I had some oversteer even with the rear bar in softest, 3rd hole - I am using the 968 030 bars front and rear. As far as squat, my signature photo is turn 11 at Sebring, which is a 3rd gear WOT left hand corner. I think the car looks very flat, with very little squat. Van, I originally wanted the 400#, but at the time I could not find them so I went with the 425#, and actually, I am happy with this setup. Mike

PS - more pix from May 2013 DE at Sebring - http://www.awolphoto.smugmug.com/key...3117&k=TF5Q7jH

jmj951

The GC eccentric bolts come with a rear coilover setup, so they might not be listed separately. I didn't even know about them until GC said those would be included so that I could lower the rear enough to compensate. I did not need to reindex my TB's.

I have an ER Polybronze set ready for installation and am probably going to swap to stiffer rear coilovers and delete the TB's, since I'll have all of that apart for the Polybronze installation anyway. I have 440lb springs up front. Since we're on the subject here - and I hope you don't mind hijacking the thread because I think this adds to the OP's area of interest - what do you guys recommend for the rear coilover rate to match 440lb springs in the front?

dmcampbell

625#/350 effective? Mike

chrenan

Same for me. Give them a call Mike, they are very helpful and knowledgeable.