|
Platinum Member
Join Date: Aug 2010
Location: Minnesota
Posts: 12,382
|
Erb spring for lifts "warning"
This is a premature for me to put up at this point, as it is not totally resolved for us at this point, but I think with all the talk of lifts and springs for Chevies lately I need to do this part now.
The Bill Erb springs have been making there way to the top of the heap of available springs, to a large extent because Tufftruck has kind of bailed on the market because of complaints of rough ride.
The results we have heard about the Erb springs have been very positive, but inconsistent in the results people have gotten, and based on spring descriptions and claims, not really understandable to me.
An embarrassing thing came up for us while I was relooking at all the information we have seen, and even our Tufftruck springs, which were likely the first ones installed in a Roadtrek, didn't seem to match very well with what others had seen with the same spring part number for height and ride quality. I never had the springs in my hands when the were put in at a truck shop, as they ordered them, received them, and put them in. The specs said they were 1.060 wire, 17.7" tall, 2024#/in. The tech set them next to the stock springs, and they were very close the same height, but that is all I saw. I crawled under with a micrometer and found them to be 1.031 wire, but with exactly the same wind and coil number as the pix we have seen of the the 1.06 wire springs. This would explain why we saw about 3/8" less lift, and better ride than others reported. Big OOOps on our part for not checking them sooner, but others did as receiving them and theirs were all 1.06 wire. Tufftruck now seems to have made that spring longer at 18" and rerated it to 1880#/in, and those numbers compare well to what we would expect based on our 1.031 wire springs.
When I changed our rear airbags to the type with the built in bump stops, the rear ride hit the sweet spot a bit higher by 1/2 to 3/4 inch for driving and that made for adjustments to get level on flat campsites. I figured it would be a good time to call Erb and see what he had to say about what I should expect from a set of his springs for the Roadtreks. We have 1.75" of lift over stock right now, and he said his springs would give 2-2.5" over stock, so that sounded good for us as we would get .25-.75" higher, and early users of his springs reported that amount of lift and fairly smooth ride. I also asked him about the Roadtreks he did for Mycopsycho and Halibutman, who both got much more lift than that, and came out 1.25" and 1.5" higher than us, respectively, and he said that is because both of them started out very low and that is why the got more change. If they were that low, that would be correct. I also asked about if he measured the heights of the vans before and after to see where they were compared to the Chevy trim height spec, and he said he didn't, and I don't think he was even aware of the spec or how to measure it. He thought we would get what we wanted at about .5-.75" above where we were.
I measured the springs carefully when we got them at 18.2" tall and 1.00 wire, ground flat on one end, mostly closed on the other, high wind angles and a full coil less total coils and about 2 active coils less than the Tufftruck springs. I ran the calculator and got really weird numbers for springrate that looked to be higher than the 1.060 wire Tufftruck spring.
I had the springs put in and the results were, understatedly put, not very good.
2.125" of lift ABOVE the 1.75" we already had, so 4" of lift over stock
To get that high, working the number backwards to our old springs and height, the Erb springs have to be at least 15% higher springrate than the ones we had, as the extra length would only account for a bit over 1" of extra lift if they were the same springrate as ours.
This puts the van at 1.625" above the high limit of the Chevy spec for trim height is at a point where the upper control arm is about 3/8" from contacting the frame. This is the hardstop for wheel travel and never should be contacted, so that is way too close, as you actually stop the travel with the shocks and they have some give in the bushings. The actual wheel drop max was in the 1.5" range, and I had to tweak the shock to start stopping the drop at about .75" to try to prevent frame contact with the upper A arm. I did the shock mod so I could at least get a driving impression without wrecking parts.
It drove better than expected, but not nearly as well as before. It developed some bump steer that was noticeable on low speed bumps as a shimmy I could feel in the steering wheel. It was lighter steering effort, and less directionally stable, which is likely due to loss of caster from raising the front that much. 2" more lift would take away about .75 degree of caster, and we are already maxed out on one side. The ride was also noticeably harsher, likely due to the higher spring rate and horrible suspension angles.
My guess it that once you get to much above 2.5-3" of spring lift, you are going to start seeing some handling degradation. 2.5" would put our van right at the high limit for trim height, so that makes sense. By the time you get to 4" of lift, you are way out of spec and we saw the handling degrade. You also have the chance of part damage, and likely accelerated wear from the bad angles.
I appears that the Erb springs are giving more lift over time. The early ones gave the 2" that he claims, the last 3 we have heard of are at 3.5", 3.8" and 4.0". They have also gone from being called smooth ride to know being referred more often as harsher but OK ride, which makes sense.
I now have the Erb springs out and on the bench, along with lower A arms. I bought a compressor and took them out myself this time. The shop managed to get them in, difficultly, without a compressor, but they mangled both lower ball joint boots so I will be putting in new balljoints also. I compressed the Erb springs to 14.5" which is what is needed to get them out of the van with either method of removing (disconnecting balljoint or a arm pivots). The normal compressed height with a 2" lift is about 15.2", so not a lot of compression beyond normal ride height and should be no issue, IMO. The springs came out about 1" shorter than the were, and are bowed. I have never seen a spring yield that early, so very strange. It is interesting that the height the spring is now would give a less lift than we had, so they would have been low if compressed that far going in. I don't know if these springs were just weak, or if Erb manages to get them in with very little compression, which I think may be possible if you remove both the balljoint and the pivots when putting them in. I am going to test that when I put our old springs back in.
At this point, I am not saying folks shouldn't go to Erb for a lift, but I think they need to be very careful in setting some exact specifications for the final results, to stay away from the going to high issues. If someone chooses to accept the shortcomings of going to maybe 3.5", but based on trim height, that would be their choice, but they would need to be very careful with shock lengths.
If you go to Erb, I would recommend:
Before you go, get an accurate read of your actual trim height. It is not a convenient thing to measure, and best on a drive on hoist or pit, but driving onto blocks also makes it possible. Coming off a jack onto blocks will mess up the measurement.
Based on the trim height you get, figure out what the amount of actual lift change you want. Trim height is 4.3" +/- .5". At 4.3", it appears that most Roadtreks will have about 2" of lift over stock (210s will get a bit more somethimes as they may be lighter in the front like Hondo is).
Once you figure out how much lift you need/want, measure the front wheelwell heights so you can check how much lift you have gotten easily once the springs are in. Being about 1/4" high at this point is probably OK or desirable as it will settle some.
Tell Erb exactly how much lift over what you have that you want, and hold him to it. Be sure to roll van back and forth a ways before measuring to get a good measurement.
I don't know how Erb got to be making springs that go that high unless he is counting on them getting shorter from the compressors, although some have been installed by other than him and came out high also, but not as high as ours. The fact that ours got so short from compressing is very odd, and may indicate that the heat treating was bad, making them too stiff and not with enough ductility.
So we are back to not very good options for getting a front spring lift. If I had a choice right now, I would wish for a spring that is the same as our Tufftruck with the 1.031 wire, but about .3" longer. I think that would put is right about at the upper limit of the trim height and be a good place to be. I have been messing around with spacers to see if I can shim ours, but it is not as easy as it first looks.
|
Linear Mode
