fjpikul
GT Owner
Ralphie, I'll send you some Viagra, Cialis and Levitra in varying doses to see which stiffness is right for you and then you can report. I'll send you a Viagra necktie to stiffen your neck as well.
Got new Penske shocks. Which springs to order ?
- Thread starter HUBBSTER
- Start date
sahlman
Ford GT Team Alumni
Crap, the spring rates were nagging at me last night. I looked at one of our prototype documents by accident and not final/production rates (I believe, but will verify with others) are 200 lb/in front and 280 lb/in rear. So Gulf GT's spring rates are right there just a hair stiffer...if I finally have my numbers right.
Also, if this is right then then KW springs noted are keeping the stock ride and handling balance based on my new numbers, just noticeablly stiffer.
Bruce likes a race car (450/700 springs) and has added a bit of aero, which requires more platfrom control, plus freed the car up a fair amount balance wise.
Very sorry for the bad info from a guy who should know. Will get back here as soon as I can with verification on these rates, but the 200/280 make more sense.
Scott
Also, if this is right then then KW springs noted are keeping the stock ride and handling balance based on my new numbers, just noticeablly stiffer.
Bruce likes a race car (450/700 springs) and has added a bit of aero, which requires more platfrom control, plus freed the car up a fair amount balance wise.
Very sorry for the bad info from a guy who should know. Will get back here as soon as I can with verification on these rates, but the 200/280 make more sense.
Scott
sahlman
Ford GT Team Alumni
OK, verified stock FGT rates with McGowan...they are 200 lb/in front and 280 lb/in rear as noted just above. Sorry for the bad information prior.
The KW spring rates of 286 lb/in front and 400 lb/in rear are very close to achieving the stock ride and handling balance...just stiffer ride, less roll, more body control. Slightly biased to the rear, but not a lot.
The math for ride and handling balance is not as simple as keeping the absolute split or the spring ratio front to rear themselves but somewhere in between. But I would bias toward the absolute split within ~100 lb/in of stock and not go more than the KW split of 110 lb/in to keep the stock balance if running on the street a fair amount.
Scott
The KW spring rates of 286 lb/in front and 400 lb/in rear are very close to achieving the stock ride and handling balance...just stiffer ride, less roll, more body control. Slightly biased to the rear, but not a lot.
The math for ride and handling balance is not as simple as keeping the absolute split or the spring ratio front to rear themselves but somewhere in between. But I would bias toward the absolute split within ~100 lb/in of stock and not go more than the KW split of 110 lb/in to keep the stock balance if running on the street a fair amount.
Scott
Wwabbit
GT Owner
I was planning an upgrade myself (if that's in fact what it is, maybe I should just say 'a change'). So this has been very helpful and timely. Thanks for the posts here and your help Scott.
STORMCAT
GT
William , most guys here have ordered the Penske shocks from Alex with T & A shocks, site name " MR2Race " He was part of the Ford suspension set up team. He sells complete Shocks with springs and valved just for the Ford GT. The single adjustable are easy to install and easy to adjust for the track and back to the street.
Xcentric
GT Owner
I have 650 lb/in front coilovers (rear leaf packs) on my 5,500 lb fully off-road armored and lifted Nissan Xterra and the ride is stiff. lol.
Gulf GT
GT Owner
Got our spring rates on recommendations from the man who helped design the Penske's and the stock set up, Alex (MR2Race).
http://www.fordgtforum.com/forums/showthread.php?2994-Penske-shocks-for-sale&highlight=spring+rate
Also, a few years ago I had Steve Millen drive my car for about a half hour to check the set up, and he felt it was a good balance between a road car and a track car.
You can get them from Alex here:
http://www.tandashocks.biz/index.html
http://www.fordgtforum.com/forums/showthread.php?2994-Penske-shocks-for-sale&highlight=spring+rate
Also, a few years ago I had Steve Millen drive my car for about a half hour to check the set up, and he felt it was a good balance between a road car and a track car.
You can get them from Alex here:
http://www.tandashocks.biz/index.html
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BlackICE
GT Owner
Penske manual gives advice for adjusting them too.
http://www.penskeshocks.co.uk/downloads/AdjustableTechManual.pdf
If you buy them from Alex he has already done the work for you.
These are race shocks so as Ed said they need more maintanance than OEM.
http://www.penskeshocks.co.uk/downloads/AdjustableTechManual.pdf
If you buy them from Alex he has already done the work for you.
These are race shocks so as Ed said they need more maintanance than OEM.
Attachments
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Blue/white 06'
sahlman
Ford GT Team Alumni
This is partly why am looking at different options for myself and for sale... a setup that is just as high performance and adjustable, but with OEM background and durability. I have some more package checks and details to complete.
BlackICE
GT Owner
What about Bilstein's ASN series. They seem like they would work great. They also have the option to get adjustable compression and rebound shafts. The problem for outsiders is knowing what range of travel is needed and the type of valving required. If you go for a fixed valve shock probably less than $300 a shock plus springs. Less than OEM.
sahlman
Ford GT Team Alumni
The car should feel good because in the end the rates are very close to stock. Tom Reichenbach, the "T" in T&A determined the Penske adjustable valving, upper mount, shock lengths, spring rates, etc. The base springs rates he recommended compensated for the fact that the stiff rubber upper shock mount was replaced by a free rotating heim. So the spring rates are stiffer to compensate for the lack of rubber mount resistance, but in the end very close to stock wheel rates and shock curves.
sahlman
Ford GT Team Alumni
The ASN series is a rebuildable shock intended for the roundy round local to national guys. Yes, there are a lot of factors in design for a coilover on the GT including compression travel, rebound travel, valving, friction levels, mount types - isolation or not (the rubber top eye mounts for NVH on stock), upper bar pin mount, jounce bumper engagement point and force-displacement characteristics, durability, reliability and craftsmanship. We did not choose Bilstein on the GT program due to production quality issues at the time and I had not had good experience with them in my days in ChampCar and F1. That does not mean they are not good now, but I cannot say because I have avoided them since.
Cost - it takes time and money to do these right and include criteria I note above...one will end up well above $300 each just in making and installing good mounts for each end...not to mention the rest.
Most, not all, rebuildable shocks will require the significant maintenance shown for the Penske’s (I am fairly certain these Bilsteins are the same on maintenance) with things just as simple as gas pressure leaking down versus the sealed OEM shocks.
Honestly, the best current option for non-adjustable shocks, in my opinion, is the stock OEM coilover with the T&A sleeve for ride height adjustment. (We chose one of the highest quality and performance shock suppliers at the time and paid for them. We had a bit of a battle with management on this topic and the cost.) I specified the FGT shock with the removable lower spring seat (just a circlip in a groove unlike typical OEM, which are permanent seats) to allow owners to change springs and allow a threaded sleeve. Tom Reichenbach and Alex knew this removable seat was a design element on the shocks and were smart enough to take advantage of it after the program.
Will keep you posted on my project in case it is of interest.
sahlman
Ford GT Team Alumni
BlackICE
GT Owner
Wwabbit
GT Owner
Scott, I'm curious why the stock ride height was selected, cause it sure looks and drives nice down 3/4" or so. Was it just for general public consumption and street reasons? Is this regulated?
Gulf GT
GT Owner
The Penske setup I have feels slightly stiffer than stock to me, but not dramatically so. Definitely no where near race car stiff. I also notice the creaking and groaning more because that rubber mount is no longer there. I had the stock OEM coilover with the T&A sleeve for ride height adjustment just before I put on the 3-way Penskes, and there is a definite difference in the rebound.
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sahlman
Ford GT Team Alumni
sahlman
Ford GT Team Alumni
General public use on the street. I had to set the ride heights very early on because it dictates a lot, but I would not do it different for general use. I looked at our lowest cars in FoMoCo vehicles (Aston and Jag). 5" was the lowest. I looked at 360 Modena, Viper, Vette and others. Eveyone was at 5" or greater (except maybe the Viper, I think, at 4.75"). I looked at usage for driveway approach, parking the nose to a curb, the big speed bumps that were around and decided 5" was as low as we should go for the street. Scraping and potentially high siding a GT from the factory on a Speed bump was not option. And I have seen some of the custom ramps people use for driveways (not that steep either) to get their lowered cars into. But yes the car looks even better lowered 3/4" to 1 in...and always bettter for handling.\
I don't think ride height, but I think approach and depature angle is regulated...sorry, its been 10 years since I had to worry about this aspect.
sahlman
Ford GT Team Alumni
Yes, sorry the resultant spring rates are pretty close (a little stiffer but close), but the shock curves have a little more control in them than stock. So they should feel different, but not dramatic as you note. Copy on the creaking and groaning due to loss of isolation...tradeoff for heims versus bushings.