[Ride Height of 1985 Avanti]

I have decided to install an 84 Corvette independent rear suspension in my 1985 Avanti. Unfortunately before I took the car apart I had not made this decision and I only measured the ride height distance from the ground to the point on each fender well just above the centerline of each wheel. However, I did not measure the distance from the ground to any part of the frame in the rear and I am now trying to place the frame at the original ride height before I place the Corvette suspension for attachment. I was wondering if anyone out there might know approximately what the measurements might be to a specific point on the frame in the rear such as the center mounting bracket attached to the rear cross bar, or other points.

David

[independent rear suspension modification]

Thanks for the clarification, that really helps. From some of the information I have it seems the later model Corvette rear ends like the C5 present issues with smaller wheel sizes like the 15 inch rims I currently have along with new tires. Thus the 80s C4 rear ends I have been looking at. This fits with what you are saying about the possible smaller brakes as I think the calipers in the later models cause interference with the smaller wheels.

Actually I am trying to get the weight down as much as possible and with the modifications I am making I plan on trying to balance the car more like 50/50 which is what the tag on the car shows. When I first had the car weighed I was a little shocked that the distribution was about 60/40. I guess when you put three passengers and some stuff in the trunk you might get back to the 50/50. But to me the Avanti seems too heavy in the front, thus the need for power steering? (something else I would like to get rid of)

I just got my back issue of the Avanti Magazine #118, those guys are fast. The article I was looking for was written by Gene Ester. It appears that the C4 Corvette front and rear suspension was used to update the Avanti suspension. If I keep trying to keep up I'll have to install the front suspension and updated steering. Since this is a 2002 article I doubt that the email is the same for Gene and I could not find him in the 2007 roster. Would have liked to see more photos and maybe talk to him because it doesn't look like the rear portion of the frame was modified at all from what I can see.

I would love to add all this new stuff but I have a lot of other expenses to getting this Avanti back on the road so for now it looks like I will stick with the C4 rear end.

David

[independent rear suspension modification]

Tom, yes I did look at the newer Mustang Cobra rear ends and was thinking about buying one. The width is in the 61-62 inch range, mounting surface to mounting surface and from what I could determine from wrecking yards and Ebay they were at least as expensive as the Corvette 80's rear end. Like the mid 90s T bird and Lincoln Mark VIII the Mustang is sort of in a sub frame and is going to be heavier than the Corvette as well as most people I talked to indicated you probably could not narrow them to the 58 inches of the Avanti. With the Cobra and others you not only have to modify the half shafts but the sub frame and probably the control arms which is not really practical according to those people I have talked to.

Are you saying the Corvette bolt pattern is the same as I now have? Where did you get the discs in the pictures? Will they fit on the Corvette?

David, in Fairfield.

[independent rear suspension modification]

Sorry to all, I have not been back on to comment and thank others for their comments. In the last few days I have been doing more research and ordered a back issue of the Avanti Magazine which is supposed to have some information on installing a Corvette rear independent suspension. I found a place within 15 miles of where I live which deals only with Corvettes and who actually has two mid 80 units. So far it appears that I may well be able to adapt the current 15 inch Lincoln Towncar Ford rims to the Corvette unit. These rims came with the car and cleaned up nicely. They have the newer Ford pattern of 5 lug on 4.5 inches. I picked up a number of the parts for the Corvette rear end and they do seem very light weight in that may are aluminum. If necessary the half shafts can be shorten.

I have also been talking to Flat Out Engineering about their kits which may allow you to almost bolt in a Corvette rear end but so far I don't have a final answer. I have some frame repair to do anyway and a bolt kit would save considerable time as some of the work will be done by someone I trust to do the job right. I have read the step by step procedure which can be found with a link on their web site and it really seems straight forward. I plan on eliminating the leaf spring for the original Corvette rear end and installing coil overs which are also available from Flat Out Engineering. Pictures are on their web site.

I did send an email to Electro-Dynamics and received a very nice email back along with a price list for the Viper adaptor and a lot of other components. I am looking this over to see what I might be able to use and the note indicated that I might want to just purchase the Viper adapter and make the remainder of the parts myself. They have beautiful stuff including a stainless steel Avanti frame but for $13,000 I'll have to wait for a while. It sure would be tempting to purchase some of their products as the end result would be very nice.

Tom, I don't know where you live but I think that I will have a Dana 44 which will not be needed sometime in the future. The Corvette, as I understand it has either a Dana 36 or a Dana 44 rear end but some of it is also aluminum so again it helps me with a weight reductioin. I had looked at the composite leaf springs which are about $200 each but since I need the rear end fixed to the frame that idea went out the window. As things progress I will come back and note what I find out.

David

[independent rear suspension modification]

"You can still have a Dana 44, and independent suspension as well, in your Avanti. Here is a Viper differential, which is a Super Dana 44."

I saw this Viper differential in another post and the first thing I thought was this was really nice. The next thing I thought was this must cost a lot of money. Where would you get the Viper components and the adaptor plate? Any idea on how much modification of the floor pan is needed?

I'm more interested in ride and reducing weight than in going fast. I did that when I was a lot younger. Some very interesting information here.

Thanks to all so far. David

[independent rear suspension modification]

Tom, thanks for the reply, I am a member of AOAI and actually thinking of getting the five year membership on renewal. I checked the back issues like you mentioned, I had forgotten about this, and see that 118 is still available.

I sort of have a special need for having the rear end fixed with relationship to the frame but I understand the ride may be better with the independent suspension and I would also like to add disc brakes to the rear since I am starting with a bare frame. I had looked at changing the leaf springs to the composite type but that alone would cost about $400. I'm wondering what others ran into by making the modification. Any idea on the negatives?

Thanks again, David

[independent rear suspension modification]

I am new to the forum so I hope I am doing this correctly. I have a 1985 Avanti and I am looking for information on modifying the rear suspension to an independent rear suspension. I understand that a number of articles have been written in the Avanti Magazine but do not yet have access to these. Is there anyone out there who has information on doing this modification or has the back issues 89, 118, or 122?

David