Transverse leaf spring question

[USAZR1]

VB&P told me they manufacture at least five springs at a time and that every one will have a different rate.

If removing both front shims only drops the front ride height 1/2" and will also lower the spring rate of an already soft spring,I probably should look at other lowering options for our 94.

[mike100]

Originally Posted by USAZR1

VB&P told me they manufacture at least five springs at a time and that every one will have a different rate.

If removing both front shims only drops the front ride height 1/2" and will also lower the spring rate of an already soft spring,I probably should look at other lowering options for our 94.

I consider 1/2" a decent drop. You could try flipping the shims to the outside and try it out without altering the bushing permanently (allowing you to go back). Technically you aren't changing the spring rate...just effectively changing the rate by unspringing it some with the initial tension being softer.

I think you get the idea from the way you replied, but I would offer that the shock stiffness on the front end of a c4 seems more critical to me than the spring- even on the ZR-1.

There seems to be only 5 options on transverse springs (for the front):
1) stock
2) stock bushing with shim(s) removed (less drop)
3) lowering wedge with shims
4) lowering wedge with no shims (slammed -->don't do it- cars is dangerously low and close to bumpstops. Also a gap between spring and frame when car is jacked up).
5) VB&P adjustable spring; this is much lower and even the taller setting is probably well into lowered ride height territory. Advantage is high spring rate for heavy LT5 and you don't need the special GM spring tool or have to remove an A-arm to install because it sits flat at rest (quick and easy install).

[Hib Halverson]

Originally Posted by USAZR1

VB&P told me they manufacture at least five springs at a time and that every one will have a different rate.

If removing both front shims only drops the front ride height 1/2" and will also lower the spring rate of an already soft spring,I probably should look at other lowering options for our 94.

While I lack the equipment to measure spring rates, I suspect that the difference in rates is not great enough to have an appreciable effect on handing but it is enough to have make a differenct in trim height. Also, it's possible that the degree to which the spring is arched may also play into this.

All I know if my 95 came with blue dot springs on both ends so I took all the shims out of the front and, and in the rear, moved all the shims to the bottom and got the car lower but not so low that I lack ride travel.

[USAZR1]

Thanks for the input,Mike & Hib. For starters,I'll probably remove the front shims and install longer bolts in the rear. The new 19" tires are about 3/4" or so taller so that will close up the fender to tire distance a little bit too,when I finally get them installed.

If that doesn't get the ride height where I want it,guess I'll go with the VB&P spring.

[Hib Halverson]

Originally Posted by USAZR1

Thanks for the input,Mike & Hib. For starters,I'll probably remove the front shims and install longer bolts in the rear. The new 19" tires are about 3/4" or so taller so that will close up the fender to tire distance a little bit too,when I finally get them installed.
.

No shims, front, two shims on the bottom for the rear and longer rear spring bolts is the set-up I use, but...

Be careful about lowering the car more than that because you'll run out of ride travel. Once the car's on the bump stops, ride sucks and handling goes away.

Also, be careful about using "fender to tire" distance as a measure of ride height. C4s had terrible build quality as far as body mounting and panel tolerances. That is the car to car variance was large. If you're going to accurately measure trim height, do it the way the Service Manual specifies. That's a lot more accurate.

[USAZR1]

Originally Posted by mike100

Here's what the shims look like when not installed above the spring bushing. my car was slammed and the two aluminum shims are shown here going along for the ride (at least they didn't toss them).

How hard is it to remove the two shims? Does it require removing the spring,first?

[mike100]

Originally Posted by USAZR1

How hard is it to remove the two shims? Does it require removing the spring,first?

While you do not have to remove the spring or control arm, you still have to remove the lower shock mounts and separate the ball joints to get enough slack on the spring arch to be able to get it to come off of the rubber bushings. This will allow you to unscrew the center mounts and push up the bolts enough to slide shims off the top of the stack.

This of course also requires the removal of the brake caliper since it needs to be hung out of the way because the brake line won't drop far enough when the front end is coming apart.

[batchman]

I believe any of the VB&P springs can be built with C5 style screw-type adjusters, you don't have to go to the "adjustable" spring to vary the height - that's for adjusting the rate. In my case I had to wait a while as they were held up on the parts for this style end but guess they'd be set now.

I'm looking forward to changing mine soon. To that end, anyone have good tip on separating the lower ball joints? I don't want to use a pickle fork on these nice aluminum parts, and that's all I've got handy. A friend uses a pitman arm puller but I don't think the one he has will fit. It seems with 2 C4s I'll need to do this more than once so I don't mind buying a rational tool for the job.

Thanks,
- Jeff

[mike100]

Originally Posted by batchman

I'm looking forward to changing mine soon. To that end, anyone have good tip on separating the lower ball joints?

This one fits our A-arms pretty well and I have used it several times already without too much drama. Just heed the directions and do NOT use an impact to tighten the jack screw (it will gall).
http://www.summitracing.com/parts/sp...FQeVfgodKb8ApQ

[USAZR1]

Originally Posted by batchman

I believe any of the VB&P springs can be built with C5 style screw-type adjusters, you don't have to go to the "adjustable" spring to vary the height - that's for adjusting the rate. In my case I had to wait a while as they were held up on the parts for this style end but guess they'd be set now.

I'm looking forward to changing mine soon. To that end, anyone have good tip on separating the lower ball joints? I don't want to use a pickle fork on these nice aluminum parts, and that's all I've got handy. A friend uses a pitman arm puller but I don't think the one he has will fit. It seems with 2 C4s I'll need to do this more than once so I don't mind buying a rational tool for the job.

Thanks,
- Jeff

I assumed "adjustable spring" was referring to adjusting the ride height,not the spring rate. How would it adjust the spring rate? I thought the rate was built into the manufacturing process.

All I have access to,is a pickle fork.