I have read threads on B&B rear springs that mentioned going to stiffer springs to keep from hitting the bump stops. I have also emailed and talked to other members on the phone to get opinions and measurements on their cars. During the last week I had my rear axle out fixing a few things and I decided to take some measurements to determine what the issues are and decide a course of action if needed. My goal would be to have reasonable suspension travel without hitting the bump stops and have a decent ride for the street. I know there are some guys out there building cars that may be interested in this issue.
First off after talking to some members I found that for years B&Bs came with the 8.8 rear axle. Later the 9" was available. This becomes an issue because the 8.8 has 2.8 dia. axle tube and the 9" is just about 3.5". As far as I can tell the 2x2 steel bump stop down tube is 4" on all the cars. So you take the difference between the two, and take half of that, and for the 9" you end up with just about .35 less travel than the 8.8. So with the 9" your are slightly more likely to hit your bump stops than with the 8.8. With this in mind I decided to slid the axle under the car, hook the arms up and do some measuring to determine why the steel bump stop 2x2 tube could not just be shortened by maybe a 1/2". This would restore the travel lost between the 8.8 and the 9" axles.
I removed the bump stops and moved my 9" axle up a 1/2" higher. I then looked for any clearance issues and found two things. A bracket I made to hold an emergency brake cable needed to be lowered, and the left rear brake line tab at the rear left of the frame needed to be moved up. The added travel put just a little to much strain on that rubber brake hose going to the rear axle. I fixed those and then cut the steel 2x2 bump stop tubes and rebuilt them so the stop is a 1/2" shorter, or higher, and the rubber bumper would go back in as designed. I also checked the drive shaft for any U-joint issues.
The end result is the car now has 1 1/2" of compression travel with the ride height at 28" fender lip to the ground. When compressed, hitting the bump stops, there is 1/2" of clearance from the top of 295/50/15 tires to the fender lip. If you have tires that extend out past the fender lip this may not be an option for you. Another car with a 9" axle and the same ride height and a 4" bump stop tube may only have 1" compression travel before hitting the bumps stops. So, with the stock 185 lb springs you add a driver and a tank of gas and sometimes a passenger and no wonder some people go to heavier springs to keep from hitting the bump stops. Of course many just choose to raise the ride height a little. We will see how this goes before going to heavier springs.
Picture with the car level and setting on the ground with a ride height of 28". Yes, it was hard to get this picture.
