| Author | Message | ||
| Henry D. Chin (Hanknum)
Junior Member Username: Hanknum Post Number: 203 Registered: 2-2002 |
OK, I'm going to jump in here. I've gone through all the options with perches, springs, additional groove in the shock body, and new shocks and springs. I originally had a set of lowering perches from the first group buy, but sold them. I checked into lower springs, but none of the aftermarket companys had the correct size and the one place that said they could get euro springs never called me back. Some say that the shock body can be machined to accept another groove while others say it can't. I decided on replacing the shocks and springs with an aluminum bodied shock that has an adjustable perch. The shocks are also adjustable for compression and rebound. This is the same setup as sold by other Ferrari "performance" parts places that have been mentioned on this chat. I played with different length shocks, springs, and spring rates (I have not been working for the last few months, so I've had a lot of time to do this). I am getting the final adjustments worked out. The front should be lowered about 1.5" and the rear 1". I still need to see if I can corner weight the car and get a quality alignment. I did drive to Monterey and back (600 mi) via highway 1 (w/o alignment first) to check it out and I was very impressed. There is more negative camber but it does not seem to be extreme. I will post pix and details within the next couple weeks. Henry | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 22 Registered: 5-2003 |
Carl, you are absolutely right in terms of what I am trying to achieve. My main desire was purely cosmetic but, after all the great infos I got from everybody, I may have to re-think the project more carefully. I do not believe I will ever go at 220 km/hr (I just would not have the skill, I guess). Maybe 100-110 mph for a short time max. Mostly around 65-85 mph. Than again, if I will ever go back to Italy, who knows! Gianluca | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 12 Registered: 7-2003 |
Of course, the question really should be, what do you hope to achieve by lowering the car? In my case, the front used to get very light above 220 km/h. A little lower in the front fixed the problem completely. You can chop more out of it for looks, but you will need to adjust the damper internal bump stops otherwise you will ground the car very easily. Also, you need to consider damper compression/re-bound adjustment as well as bump steer implications and suspension geometry changes. Carl. | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 503 Registered: 5-2001 |
Both TruChoice and Koni NA can add adjustable spring perches to the Koni OEM shocks. I'm not sure if they will accomodate the full length OEM springs though. | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 20 Registered: 5-2003 |
Definately lots of interesting alternatives to think about! Jerry, your car is outstanding! The shorter springs (at this price) are a very attractive way to lower the car. Still I like the best the variable perches like Carl's. I will look into how hard would be to make some. I will give, however, a try to Steve's solution (lower perches)because it should be an easy machining job and I enjoy doing that. If some undesiderable handling should result, easy to revert! Also Tazio seems to be happy with them. Steve, thanks for posting the drawings and allow people to use them. Also for the "heads up" about lowering the rear. By the way, I am NOT a professional machinist but rather an amateur machinist. I love to make, repair and restore things. For the members interested in the lower perches, I will post pictures and we shall see... I was sure I was going to get my turning stock today but... no joy. Thank you all, Gianluca | ||
| Jerry W. (Tork1966)
Member Username: Tork1966 Post Number: 912 Registered: 7-2001 |
The 4 was supposed to be a dollar sign! $300.00 Silly me. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 2048 Registered: 1-2001 |
Jerry W. -- Did you add an extra "0" (the price was 4300.00 what?) | ||
| Jerry W. (Tork1966)
Member Username: Tork1966 Post Number: 911 Registered: 7-2001 |
Here is a pic of my 308 after I put on the new lower springs (that I got from England), my newly plated brake parts, ES bushings and urethane painted A-arms. The springs were only about 4300.00 if memory serves me correct. Pic of the car (with lower stance) is in my profile.  | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 991 Registered: 4-2002 |
From the point of view of long life in the spring, I would not recommend http://www.jcwhitney.com/productnoitem.jhtml?CATID=14834&BQ=jcw2 This kind of contraption focuses stress at the point of contact in the spring body. leading to collapsed springs 3+ years down the road. If you want to do it right, get some adjustable spring perches, lower the car, quick align the car, then cornerweight the car (with driver plus optional passenger plus 1/2 tank of fuel, tires at correct pressure), then final align the car. Just lowering the car without cornerweighting can leave you with a car that oversteers to the lef and understeers to the right (or vice versa). | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 2047 Registered: 1-2001 |
Gianluca -- You asked about if the deeper lower spring perches can be used on the 308 rear too, and the short answer is "yes", but there are some points to consider: 1. The rear shock is more upright than the front shock so the ratio between the change in the L1 dimension of the perch and the change in the coachwork height is different so you'll have to do your own L1 calculations for a rear 308 lower perch. See my post in this thread for the explanation of the different front/rear ratios: http://www.ferrarichat.com/discus/messages/112/180756.html 2. Rob (aka Tazio Nuvolari), who has the most (only?) experience on the rears, reported that at full rear suspension droop a deep perch would interfere with some other components (A-arm?) so you need to make your own decision about how much deeper you can go. IMO, a small amount of interference at full droop might be OKish (if things contact/load in a resonable way) as long as there's still reasonable clearance around the operating position. Carl's got the best set-up (short of changing over completely to a modern 2.5" spring/shock set-up), but it's more $ and takes some downtime if modifying your old shocks (which means rebuilding since the shock must completely disassembled to weld the threaded sleeve to the case). When I did the perch design, I couldn't find any alternative 77.5mm ID springs; however, Jerry W. recently posted that he got (properly) shorter/stiffer 308 springs from QV London for <$100 each that gave a 1" front drop -- if available at that price might be worth a look: http://www.ferrarichat.com/discus/messages/21/276763.html | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 10 Registered: 7-2003 |
Hi Phil, My buiness is actually a specialist tyre and wheel alignment shop in Melbourne, we specialise in Ferrari and Porsche. No machining I'm afraid! The job was done about 4 years back by the Koni agent here in Melbourne. The dampers are stock, but they were re-built with different settings (Another thread in itself, maybe later along, with my two years of stuffing around with alignments and tyres ;) The adjustable spring perches were very cheap. They were about $80 AUD each installed per corner and that was done at the same time the dampers were rebuilt which added about $120 AUD per corner) I was very happy with the job and its provided many years of endless mucking around! carl. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 384 Registered: 7-2002 |
Carl Did you do this with the stock Konis? If so, where did you get the parts? Would your machine shop be up for making a couple more sets? | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 9 Registered: 7-2003 |
The nicest way to do it is to add a variable spring perch. Apart from being able to choose your ride height, you can then corner weight the car. I took 6mm out of the rear and 20mm from the front, but note Euro spec ride height to begin with. Here are some pics, and the car but I am sorry about the one of the car as it sits, it's not a good example but it's the only digitial shot I have. Carl.     | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 382 Registered: 7-2002 |
I may be up for a set if Gianluca is up to make several pairs. Philip | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 500 Registered: 5-2001 |
Gianluca, Lowering the front and rear by the use of special spring purches will lower the body. The body is attached to the frame, therefore the chassis will be lowered. The inboard A-arm pickups are attached to the chassis so they will be lowered also. The overall effect of the lower inboard pickups on a 308 will be a lowering of the front and rear roll centers and also the center of mass or center of gravity (CG). While cornering, the CG will want to rotate around the roll center. Aside from the esthetics, you will have to decide if this is a handling improvement. It would be a good idea to have your alignment checked after the modification. Toe-in/out and caster may be affected. Camber will become more negative. What will you use for alignment specs? I recommend you monitor your tire wear patterns to ensure it is acceptable. I am not suggesting that you don't do it, only that you become aware of the consequenses. | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 19 Registered: 5-2003 |
Mike, let me see how they turn out and I will post some pictures. If all is well, I would be glad to make a few. Gianluca | ||
| Mike Charness (Mcharness)
Member Username: Mcharness Post Number: 927 Registered: 8-2002 |
Hey, would you consider making an extra set or two once you've got the machining set up...? | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 18 Registered: 5-2003 |
For the front, the full 25 mm (it is my understanding that the actual drop would be a bit more). For the back, if at all possible, maybe 20 mm. Since I can make my own, I can experiment a bit. While I am aware that some change in geometry may occur, wouldn't lowering front and back using the lower perches mosty just drop the body of the car? By the way, street use only, as spirited as the Virginia Troopers would allow... Gianluca | ||
| mike 308 (Concorde)
Member Username: Concorde Post Number: 281 Registered: 8-2002 |
Gianluca - how much of a drop do you plan to use? | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 17 Registered: 5-2003 |
Thank you all. George, I was going to try the specially lowered perches ( I will machine them this week-end, hopefully). I was just trying to be lazy... http://www.happyisgood.com/perch/index.htm Can the lower perches also be used in the rear? Gianluca | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 499 Registered: 5-2001 |
Gentlemen, Please be aware that lowering the car by any means will affect the suspension geometry. This is because the inboard to outboard pivot points are being changed in relation to each other. The results may be totally acceptable, but there will be a change in the geometry. Even changing wheel or tire sizes will affect the geometry. A change in the geometry changes,among other things, the front and rear roll centers (connected together by a straight line this is the roll axis). | ||
| Tazio Nuvolari (Nuvolari)
Member Username: Nuvolari Post Number: 275 Registered: 9-2002 |
I lowered my 308 using the previously described lowering perches. This is a very useful upgrade and there is tons of information in the archives. Here is the link to the engineering drawings: http://www.happyisgood.com/perch/index.htm | ||
| Verell Boaen (Verell)
Intermediate Member Username: Verell Post Number: 1085 Registered: 5-2001 |
Search the archives for 'lowering' 'springs' 'bilstein' There's a long thread from early this year on lowering. Lots of great technical details & why you DON'T want cut-down springs. Also good info on a streetable & a track only shock/spring systems that will lower the car's center of gravity & greatly improve handling. | ||
| George LaFleur (308geo)
New member Username: 308geo Post Number: 43 Registered: 12-2002 |
Gianluca, A year or two back (on the Ferrari List) one of the guys engineered and created "lowering perches" for the stock front springs to sit on. The idea was that the geometry and function of the original design would not be affected, yet the front wheel gap would reduce that "wheelie" look that the 308 sports. The other way to get this was special "cut" springs that were designed for racing, but some people said these had a drawback of some sort. I got a set ($250) pulled the towers out myself and had the local shop use their spring compressor to do the switch. It did reduce the gap by 25mm (the max that was possible to achieve) thus removing about an inch of the gap. I saved my stock perches incase I sell the car and want to put them on another 308. I think I may still have some saved e-mail correspondence regarding who I got them from. I'll look tonight and forward it to you. I do remember that we had to get 5 or 8 takers to make it cost effective for the group. You may be able to search the archives of www.ferrailist.com and find out more about these. | ||
| Al Johnson (Bigal)
Junior Member Username: Bigal Post Number: 139 Registered: 3-2002 |
Mitch Alsup did a very interesting analysis on car height, tires, traction, and handling at Moorespeed a while back. Maybe he'll see this post and reply. | ||
| Bill Sebestyen (Bill308)
Member Username: Bill308 Post Number: 498 Registered: 5-2001 |
Gianluca, I wouldn't do that to my car. At the very least it would add unwanted unsprung weight and potentially ruin an otherwise good handling car. There are some options however: 1. install adjustable spring purches 2. install fixed but specially designed spring purches 3. have the springs shorted All of these will affect suspension geometry. | ||
| Gianluca Chegai (Gianluca)
New member Username: Gianluca Post Number: 16 Registered: 5-2003 |
Has anyone tried something like this? http://www.jcwhitney.com/productnoitem.jhtml?CATID=14834&BQ=jcw2 Strictly from the point of view of making the car a little lower, would there be any problems? Thanks, Gianluca |