Front & Rear Coilovers - Is this DIY?
#1
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Front & Rear Coilovers - Is this DIY?
I desperately need a new suspension in my 944T before doing DE this year. I currently have the all original cheapest factory option installed and it's sagging to the point of allowing the front tires to rub due to worn bump stops if it bottoms out during a turn.
I've been doing a lot of research and I'm wondering if this is something a novice mechanic can tackle in the driveway?
It looks like it should be a lot easier than the exhaust or turbo were, it's only half a dozen bolts to remove the shock itself in the front.
I'm leaning towards the Bilstein Escort Cup coil overs front and rear with the street valving, and probably 300 pound 2.25" springs in the front, probably 400 pound springs in the rear with a t-bar delete. This is primarily a street car and I can handle a fair amount of harshness in the ride. Some have recommended that I go 350 in the front but I've heard a lot of people say that's too stiff. My car isn't lightened and I'm a big dude so I'm hoping 300 is a safe number. I'd like to hear from people who've gone lighter though, maybe in the 250 range. Maybe that would be better option?
I've read several people recommending the rear spring bushing upgrade at the same time as the t-bar delete. Is that a must have out of the gate, or can it wait? I'd also like to do the monoball bushing replacements back there. I'd just like to avoid doing it all at once if I can avoid it. I need to have this thing ready for the track by April.
Any other parts need replacing while I'm in there bolt wise? Like those elliptical bolts? They're expensive, but mine are likely original. I don't know if they're something that should get changed out on a strut job.
Thanks guys
I've been doing a lot of research and I'm wondering if this is something a novice mechanic can tackle in the driveway?
It looks like it should be a lot easier than the exhaust or turbo were, it's only half a dozen bolts to remove the shock itself in the front.
I'm leaning towards the Bilstein Escort Cup coil overs front and rear with the street valving, and probably 300 pound 2.25" springs in the front, probably 400 pound springs in the rear with a t-bar delete. This is primarily a street car and I can handle a fair amount of harshness in the ride. Some have recommended that I go 350 in the front but I've heard a lot of people say that's too stiff. My car isn't lightened and I'm a big dude so I'm hoping 300 is a safe number. I'd like to hear from people who've gone lighter though, maybe in the 250 range. Maybe that would be better option?
I've read several people recommending the rear spring bushing upgrade at the same time as the t-bar delete. Is that a must have out of the gate, or can it wait? I'd also like to do the monoball bushing replacements back there. I'd just like to avoid doing it all at once if I can avoid it. I need to have this thing ready for the track by April.
Any other parts need replacing while I'm in there bolt wise? Like those elliptical bolts? They're expensive, but mine are likely original. I don't know if they're something that should get changed out on a strut job.
Thanks guys
#2
Did the front coil-overs in my garage and it was an easy job. If you go 300 in the front, 400 in the rear with a torsion bar delete might be a little soft. What size sway bars are you using?
#4
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Thread Starter
Welding machine? I didn't know welding was involved. I think if welding is involved, this is something I'm going to have a shop handle. I didn't read anything about welding in my research... what needs to be welded? I was hoping for a bolt on operation
Or am I sorely mistaken about what a t-bar delete entails? It's always bothered me as far as a modification goes. I haven't found a good write up for it. I wouldn't be surprised if welding was required to improve the support structure for the upper strut mount in the rear, but I think I've read that people use the stock shock bolt location?
I put a 30mm sway bar in the front and a 19mm sway in the rear this summer. The car had always suffered from severe over steer but the bigger front sway bar and the sway bar stiffeners helped a bit it seems.
Is 300 pounds too soft for the track or the street? The car will see maybe 16 track days this summer if it survives any of them. And probably 160 street days. 350 does seem to be the most common spring rate I see reported on forum posts for non-race setups. I've been compiling a list of everyone's rates.
I'm just thinking of the 7 hour drive to Watkins Glen this summer and I'm just worried if my body can take that abuse if the car is too rigid
Or am I sorely mistaken about what a t-bar delete entails? It's always bothered me as far as a modification goes. I haven't found a good write up for it. I wouldn't be surprised if welding was required to improve the support structure for the upper strut mount in the rear, but I think I've read that people use the stock shock bolt location?
I put a 30mm sway bar in the front and a 19mm sway in the rear this summer. The car had always suffered from severe over steer but the bigger front sway bar and the sway bar stiffeners helped a bit it seems.
Is 300 pounds too soft for the track or the street? The car will see maybe 16 track days this summer if it survives any of them. And probably 160 street days. 350 does seem to be the most common spring rate I see reported on forum posts for non-race setups. I've been compiling a list of everyone's rates.
I'm just thinking of the 7 hour drive to Watkins Glen this summer and I'm just worried if my body can take that abuse if the car is too rigid
#5
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Suspension DIY replacement
Hi PlayerO,
I'm in the identical situation but I was looking at Ground Control (http://www.ground-control-store.com/...ory.php/CA=170)
I was emailing Jay and he thought that with only a 250 front spring, then the rear torsion bars should be left alone.
I haven't made a decision yet but I too was leaning toward a 300 front but a 450 rear without a torsion bar but stock sway bars (to start).
It's the DIY piece that is important to me too so I'll be watching this thread.
Cheers
Andrew
I'm in the identical situation but I was looking at Ground Control (http://www.ground-control-store.com/...ory.php/CA=170)
I was emailing Jay and he thought that with only a 250 front spring, then the rear torsion bars should be left alone.
I haven't made a decision yet but I too was leaning toward a 300 front but a 450 rear without a torsion bar but stock sway bars (to start).
It's the DIY piece that is important to me too so I'll be watching this thread.
Cheers
Andrew
#7
Rennlist Member
Thread Starter
Thank for the good info. The Escort Cup "street" valving is listed at 380/150 front and 565/218 rear. I'm not too familiar with how valve rates correspond to spring rates other than knowing that they have to be matched. Hopefully the dealer/installer will help me out with some of the nitty gritty details though I hope to understand it too.
I just want to make sure I'm asking for the right thing. If 350 is too stiff and uncomfortable, I'll have flushed a lot of money down the drain if 250 is the better option. But I haven't heard anyone say to go lighter yet.
I should also add that I want to set this car up for neutral to slight under steer. It might just be the worn suspension but the handling right now is pretty hairy. There's no hope for me if the *** breaks loose so I'd like to keep that from happening I'm not that good of a driver yet.
An excessive rear spring rate, say 350 to 550 is going to introduce more oversteer compared to 350/450, which is where my little internet survey shows a lot of people go (though 400/550 is maybe the second most popular option).
But looking at the escort cup valving numbers, 350/550 looks like the numbers match up more... so maybe that's the intended rate for that valving? And maybe this is the correct balance point for the car.
I just want to make sure I'm asking for the right thing. If 350 is too stiff and uncomfortable, I'll have flushed a lot of money down the drain if 250 is the better option. But I haven't heard anyone say to go lighter yet.
I should also add that I want to set this car up for neutral to slight under steer. It might just be the worn suspension but the handling right now is pretty hairy. There's no hope for me if the *** breaks loose so I'd like to keep that from happening I'm not that good of a driver yet.
An excessive rear spring rate, say 350 to 550 is going to introduce more oversteer compared to 350/450, which is where my little internet survey shows a lot of people go (though 400/550 is maybe the second most popular option).
But looking at the escort cup valving numbers, 350/550 looks like the numbers match up more... so maybe that's the intended rate for that valving? And maybe this is the correct balance point for the car.
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#8
Nordschleife Master
FYI The valving numbers have no correlation to the spring rates, you don't get a matched spring/damper set-up by getting the numbers close. My advise fwiw if you want your spring/damper combo to work well go with someone's proven set-up...or be prepared to spend some time with different springs on a shock dyno.
#10
Pro
I am going to run a 400# spring with the 380/150 valved Bilstein in the front. Seems this is the hot setup for this application.
#11
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Why do people delete the T-bar? Just harder to do the calculation with it involved (harder to calibrate/adjust it, etc)?
I worry if I remove the T-bar, that I would be stressing mounting points not meant to handle the sheer forces (have seen some bolt-sheer pics/threads).
I worry if I remove the T-bar, that I would be stressing mounting points not meant to handle the sheer forces (have seen some bolt-sheer pics/threads).
#13
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Thread Starter
Yeah, I don't have the experience necessary to hand pick my own components. So I'm basically going off of reference builds and by the expertise of the dealers. These are things I want to learn but it's not something I can learn overnight.
I'm not 100% sold on the t-bar delete. There are clearly differing opinions there, so for someone like me without the experience it comes down to simply making a choice between one expert opinion or another.
It sounds like my dealer is recommending the t-bar delete and claims that most of his customers go that route. Considering that re-indexing the t-bar is something that would probably take me 3-4 attempts in the driveway in jack stands, there's no doubt it's probably the easier option, especially if I adjust ride height or spring rates down the road.
As far as the mounting point failures, based on my reading on this forum and others, it seems that most cases are caused by upper bolt failure caused by it backing out? I guess it'd be a good idea to use a good loctite and get a high grade bolt?
What about 2.25 springs versus 2.5 springs? I've seen some people convert to 2.5 and I suspect it's a more common size but I'm not sure if there are other advantages there.
I'm not 100% sold on the t-bar delete. There are clearly differing opinions there, so for someone like me without the experience it comes down to simply making a choice between one expert opinion or another.
It sounds like my dealer is recommending the t-bar delete and claims that most of his customers go that route. Considering that re-indexing the t-bar is something that would probably take me 3-4 attempts in the driveway in jack stands, there's no doubt it's probably the easier option, especially if I adjust ride height or spring rates down the road.
As far as the mounting point failures, based on my reading on this forum and others, it seems that most cases are caused by upper bolt failure caused by it backing out? I guess it'd be a good idea to use a good loctite and get a high grade bolt?
What about 2.25 springs versus 2.5 springs? I've seen some people convert to 2.5 and I suspect it's a more common size but I'm not sure if there are other advantages there.
#14
for spring selection, theres' basically 3(or 4 depend on how you count) things to consider
1) spring rate
2) length. depends on how much adjustablility your coilover threads have, you want to make sure you have enough height adjustability
3) coil diameter & wire diameter. i think this is the often overlooked. a smaller wire diameter (at same spring rate) allows for more spring travel before binding. spring rate, coil diameter, and wire diameter are interlinked. change one, you change the other two. but when you compare two off the shelf products of the same spring rate, definitely look at the wire diameters
1) spring rate
2) length. depends on how much adjustablility your coilover threads have, you want to make sure you have enough height adjustability
3) coil diameter & wire diameter. i think this is the often overlooked. a smaller wire diameter (at same spring rate) allows for more spring travel before binding. spring rate, coil diameter, and wire diameter are interlinked. change one, you change the other two. but when you compare two off the shelf products of the same spring rate, definitely look at the wire diameters
#15
Pro
I think some people like run 10" springs on them which are only available in 2.5" dia. The 2.25" you can get up to 9", so your ride height will be lower with it.