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Rear Height, Springs & Tires

H

Hijinx

Guest
Hello All. Just purchased my first Vette ('73), and just signed up here and need some info. My '73 sits high in the rear. Its probably stock ride hight, but sits higher than I would like. Too much open wheel well between top of tire (225x70R15) and the fender well. I plan to go to 255x60R15's in the near future. I have the 7 leaf spring. What do I do to lower the back end? Is there a way to crank it down about an inch, that's really all I need. Also, what is the general feeling on the carbon-fiber leaf's? Worth the money? Lastly, is the 255 tire size the max I can run on the stock rims without rubbing? I want to go as big as I can, but not too low profile. I like some meat on the sidewall. Thanks for any info you can provide, or direct me to.
 

Tom Bryant

Well-known member
Administrator
Joined
Nov 9, 2000
Messages
7,294
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
The easiest way to drop the rear an inch is to replace the spring bolts on the outer ends with ones that are an inch longer. be sure to drill the new bolt for the cotter pin.

Not sure on the tire size other than 255 is probably a big as you would want to go on the 8" rims. I have seen wider rims and tires though.

Do a search on the topic of rear springs or fiberglass springs. You will find several lengthy threads on the subject.

Tom
 
H

Hijinx

Guest
Took a look out at BFG's web site. Here is some sizing info. It looks like I could run a 265/50r15, if its not too wide. It comes closest to approximating the hight of the existing tire. I'v run a 31/10.50R15 on an 8 inch rim, so all of these should fit. Anybody with experience on the 265/50 rubbing? I went through the post and found one where someone was running a 295/50 on the rear. I'm not much worried about the rear, its the frount that might have some trouble. Here is some general sizing info if anyone is interested;

225/60R15 - W-9.0 - H-25.6 (Current Tire)
255/60R15 - W-10.2 - H-27.1
275/60R15 - W-11.0 - H-28
265/50R15 - W-10.9 - H-25.5 (best fit/size?)
295/50R15 - W-12.2 - H26.7
 
B

Bullitt

Guest
Welcome to the CACC, Hijinx. It's a nice place to hang out. I have a '71 which the previous owner was running a 275/60 15 on the rear. The problem was that it rubbed on the parking brake cable bracket. I went to offset arms for other reasons, but you can have your bracket relocated by a welder. The big tires give the car a hunkered down look in the front, though. On the front right now are 245/60 15 BFG tires. I read somewhere that this size is getting harder to find. Good luck finding some skins. --Bullitt
 
H

Hijinx

Guest
As usual I boned up on the tires (didnt remember to measure twice and cut once). I am running a 225/70R15 that has a width of 9.0 and a hight of 27.4. Therefore, the 255/60R15 would be my closest approximation. It looks like anything else will require modification on the front to run the width. Unless someone has different experience. :crazy I've seen the 255's on plenty of C3's, so they must not rub. They are also almost $20 per tire less than the 265/50's and much more available. I hope to pick up the longer bolts to drop the rear end down level with the front. These two things will make the whole car look better, in my opinion. However, one of the sharpest Vettes I can remember had so much meat under the rear fender that it had to rub when it ran over a stick. :eyerole OK, so from what I could find on the postings;
A) Scratch the composit leaf, they tend to break. Go with a 9 leaf over my 7 leaf for better ride
B)Lower back end with longer bolts (very cool as it wont cost much)
c) Stick to the 255's unless I want to do mods
Thanks all (of course any additional or new info would be appreciated).
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Hijinx,

Please post some pictures of it as soon as you get the new shoes on.

The tires size and ride stance go hand in hand. You are planning on doing two things at once. That is, lower the rear and change tire size. When you lower the rear one inch, it will actually make the front look different as that one inch plays out over the length of the car.

At one time I had 275 60 15 BFG on my 74. I put a spacer on each bolt in the rear to raise it up a tad to keep it from rubbing, and went with 255 60 15 in the front.

The truth is, that is old school now. Nothing wrong with it, but you will see more and more sharks moving to 16,17,18" rims with complete different tire profiles.

In the end, I would always suggest wider and taller on the rear than the front to keep that wedge thing going. I agree, when the front is higher than the rear the car looks very strange.

Can't wait to see some pics.
 
Joined
Nov 4, 2000
Messages
946
Location
Scottsville, Kentucky
Corvette
08 Jetstream Blue Z51 coupe
Hijinx,

The standard tire size on most sharks from 68-82 was 225-70-15 with the optional tire size 255-60-15. Some year sharks will be a tight fit between the tire and the back edge of the front fender due to the extra tire width. The front fender fit was actually customized at the factory for the optional tire on 80-82 sharks due to this problem.
 
6

69vettester

Guest
Thanks for the post Hijinx, Ive been deliberating these exact issues for the past 6mos. Eventually I will pounce, for now Im still reading the posts about it with interest.
TomC
 
H

Hijinx

Guest
My ride hight issue in the rear is pretty dramatic. I counted the leaf's again last night and come up wiht 8. So, I'm not sure what's happening there, as I understand that it came with either 7 or 9 leaf springs. I ordered new bushings last night from Ecklers, but could not stomach $29.95 for two 8 inch bolts with lock nuts. I should be able to get them at a local bolt place for around $6. A little rake is good, but I'm a good 2 inches higher in the rear. Tonight I am going to move a set of 275/60R15's I have on my '72 Cheyenne over to see about clearance. By tape measure, they are the same hight as the 225's (go figure, probably because the 225's are Goodyear and the 275's are BFG) I know they will be fine on the back, the question is whether or not I can stuff them under the front end. I wouldnt mind doing a small (non-visible) amount of triming to make them work or a little repositioning. I'll let you know if it works. If someone has already done this, let me know. I suspect the 275's are too wide for the front end. We will see.
 
6

69vettester

Guest
Hijinx,

7 and or 9 leaf are the options. You would have the 7 leaf , thats counting only the leafs, and not counting the main spring.Someone correct me if Im wrong..

In my research Ive heard the only trouble mounting 275 60 15's on the rear is the wheel hits the parking brake cable mounting bracket on some C3's?
Ill be mounting 255's four corners, thats plenty of tire for me and, they have no clearance problems on the rear, and probably none in the front either.

Yep, Your right about the savings on the bolt too. Incredible huh. Just dont cut corners on setting the bolts up though. A cotter pin and slotted nut setup would definitly not allow your new ride height to change as you put miles on. Lots of exceptable ways of doing that procedure though I would think.

Congratulations on your new C3 by the way , looking forward to the pics..
TomC
 
B

Bullitt

Guest
I think it was Hot Rod or Car Craft that had an article on bolts and different tensile strenths, bolt stretch and more stuff that hurt my brain. I'd go with a grade 8, since I think this is what Vette Brakes uses, themselves. You can always get some aircraft grade bolts, but I have no idea how much they cost. With the suspension, I wouldn't try to cut any corners. Though, I do believe that the factory used grade 5. --Bullitt
 
H

Hijinx

Guest
Grade 8 is the toughest. However, I too have heard that they can be brittle. There is a good bolt place close by my office and they carry everything. I will probably go to them and tell them what I am using it for. I'll post what they give me. I hope to do that tomorrow. As for the tires, I want the max allowable rubber under the fender. I like the ridge runner look, and that's what I am going for. I'll post the 275 fitment tomorrow. I'll also take a few pic's tonight to give everyone a quick view before and after. Thanks
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
If you think $29 for a couple of bolts, nuts, pins, and washers is bad, you don't want to know what I spent on headlight trim pieces today.

The little things KILL. As most of you know, my car is a miricale to even be in sort of one piece right now. Most of the parts came from other places.

I THOUGHT I had all the hardware to put the bulbs back in the housings. Well, yes and no. Some of it was there but frozen or broken, and the other was missing. The trim bezel screws have welded themselves into the cup that holds the bulb. They are available new for $15 per plus $15 per on the bezel. That is $15 x 8. I had a good time talking to the sales girl, because I was also buying nice chrome screws to hold light cover section in. She told me, "that will be a Buck a Screw":J

I wonder who is getting scr**ed?:mad

Oh well, you wanna play, you gotta pay. My paying is up for now. It will take me through the holidays to pay this debt down and be ready for the next round.
 
H

Hijinx

Guest
If you are near a major metro area you can normally find a nut & bolt place. Here around Dallas, Couch sales has every conceivable type. I buy stainless steel allen head bolts for most of my projects by the bag for under $20 (depending on size). They are not polished, but they are stainless and they are allen and look great. I keep a supply on hand for everything. I am starting to see that anything with "Corvette" on it, from a part standpoint, cost 2,3 or 4 times what standard Chevy stuff cost. Not that I didnt expect it, but it is a drain on the pocketbook.
 
R

redmist

Guest
I went with 16x9 rims and 255-50's. If I had to do it over I would have gone with 18x9 with 50 series tires in the rear. The extra rim diameter clears the parking brake mount. The tires fill the wheel wells and the "rake" is maintained.
The 16x9s look fine in the front after lowering in fact they look "slammed".
 

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