Leaf Spring vs Mono
Thread Starter
Instructor
Joined: Aug 2007
Posts: 131
Likes: 0
From: Madison NJ
Leaf Spring vs Mono
I was sold a mono leaf to replace my wore out old leaf. The mono leaf jacked the car up so much that the rear of the car looks noticeable higher then stock. I'm being told that it's the right spring.
How do I check that the car is at stock height?
How do I check that the car is at stock height?
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
If you provided some info on your car, someone might be able to help you.....
The AIM ( Assembly Instruction Manual ) for your particular year will have the details.
If you've got a 68, I can help out.
The AIM ( Assembly Instruction Manual ) for your particular year will have the details.
If you've got a 68, I can help out.
Instructor
Joined: Jan 2007
Posts: 195
Likes: 2
From: Wilmington MA
I have an 81 and replaced my 9 leaf w a composite mono leaf. I love it. You should be able to adjust the ride height by adjusting the rear spring mounting bolts. By running the the nuts down on the bolts, you can lower the rear of the car. If there is not enough thread, get longer bolts. I believe they come in three lenghths. Original are 6.5 " VBP sells them in 8,10 and 12 lenghths. You have reached the correct ride height when your rear half shafts are horizontal (parallel to the ground).
Hope that helps, at least thats what I've been through w mine.
Hope that helps, at least thats what I've been through w mine.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
I have an 81 and replaced my 9 leaf w a composite mono leaf. I love it. You should be able to adjust the ride height by adjusting the rear spring mounting bolts. By running the the nuts down on the bolts, you can lower the rear of the car. If there is not enough thread, get longer bolts. I believe they come in three lenghths. Original are 6.5 " VBP sells them in 8,10 and 12 lenghths. You have reached the correct ride height when your rear half shafts are horizontal (parallel to the ground).
Hope that helps, at least thats what I've been through w mine.
Hope that helps, at least thats what I've been through w mine.
Drifting
Joined: Oct 2007
Posts: 1,317
Likes: 22
From: Marina CA
Long bolts will work but keep in mind that a 10" and longer bolt will be below the edge of the rim and if you have a tire go flat, the bolt end will hit the road and quite possibly do some damage.
Also you run the risk of the end of the mono leaf being too close for comfort with the tire sidewall.
I'm having just this issue with the rear of my 68 being too high. It has a TRW mono leaf which will be coming out and a VB&P mono leaf will be replacing it.
Also you run the risk of the end of the mono leaf being too close for comfort with the tire sidewall.
I'm having just this issue with the rear of my 68 being too high. It has a TRW mono leaf which will be coming out and a VB&P mono leaf will be replacing it.
Team Owner
Joined: Jul 2004
Posts: 40,338
Likes: 786
From: Redondo Beach, California
Adjusting the ride height by changing the trailing arm to spring bolt length is the principal technique. The fiberglass spring kits come with thick rubber cushions (~ 1 1/2 Inch) for joining the bolt to the trailing arm. You can get thinner cushions (~ 3/8 inch). Using the thinner cushions provides another technique to adjust heights. Guldstrand used the thinner cushions to help adjust the ride heigth of my 68.
Thread Starter
Instructor
Joined: Aug 2007
Posts: 131
Likes: 0
From: Madison NJ
I looked up the ride height but the only dimentions I can find are from the ground to the top of the fender opening. This dose me no good as that has been modified.
How about the stock bumper height?
Ground to center of front and rear bumper. I know it my not be exact because of the differences in tire height but I can at least reference the difference in the two dimensions.
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Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
This is the typical AIM data for a 68.....
If you're not after NCRS certification, why don't you adjust it to your preference..... From aesthetics, having a smaller gap between top of tyre and guard is appealing.... just my opinion.
If you're not after NCRS certification, why don't you adjust it to your preference..... From aesthetics, having a smaller gap between top of tyre and guard is appealing.... just my opinion.
Racer
Joined: Jan 2006
Posts: 382
Likes: 24
From: Uxbridge Ontario
The numbers from the AIM for a 71 are close to the above. I installed the TRW and had to use the 10 inch bolts to get the ride height close to the numbers in the AIM. I cut the bolts down a bit so they don't hang out as far. Would I do it again, YES the ride is such much better then the steel spring.
Drifting
Joined: Jul 2005
Posts: 1,562
Likes: 2
From: Spring Texas
If your old leaf spring was worn out, then the car was probably sitting lower than specs before you changed out the spring. The mono leaf is less likely to sag over time, so switching from the stock 6" bolts to 8" bolts should put you very close to the AIM specs, and allow for a little more adjustment up or down to achieve correct ride height, or one that is at least aesthetically pleasing to you.
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
Long bolts will work but keep in mind that a 10" and longer bolt will be below the edge of the rim and if you have a tire go flat, the bolt end will hit the road and quite possibly do some damage.
Also you run the risk of the end of the mono leaf being too close for comfort with the tire sidewall.
I'm having just this issue with the rear of my 68 being too high. It has a TRW mono leaf which will be coming out and a VB&P mono leaf will be replacing it.
Also you run the risk of the end of the mono leaf being too close for comfort with the tire sidewall.
I'm having just this issue with the rear of my 68 being too high. It has a TRW mono leaf which will be coming out and a VB&P mono leaf will be replacing it.
Anything over a 8" bolt (9" if you are running 17" wheels) is asking for trouble. If it is a TRW spring you are better off junking it and getting a VBP spring like Fordman. The TRW spring is known to jack up the rear 2"-3".
