How about H&R Sport front and BMW OEM Rear?

[Johno]

Would it hurt anything to run H&R sport springsin the front and BMW OEM springs in the rear?

H&R of course says that bad, but the front and rear springs are already different, wiht different rates. How could it hurt to have them a little more different?


The H&R Red springs fall out if I jack up the car, and I have a dim view of the next 4 years of repairs in which the dealer will need to be trusted to guide the H&R sports back in position by hand as they slowly lower the car.

H&R sport falling out of the rear suspension is absolute B.S.

JO

[Gene V]

don't think you want to do this...

[96technoM3]

I dont know how different the spring rates between H&R sports and stock are, but I asked H&R about this and they advised against it. Take that for what its worth. Have you considered H&R OE sports in the rear if you dont like the drop of your current rear springs?
Christian

[Johno]

H&E said OE and Sports would be a bad mix.

However, I question the technical accuracy of a company that designs springs that fall out of the car when you jack it up. Did they intentionally design the spring so it would do that? If yes, it's a shitty design. If the answer is no, that design characteristic was not intended, then how do we trust the rest of the design. Would not "stays in the mounts" be one of the basic design criteria? If they got the basics this bad, how much attention is really paid to the spring rates?

For instance, OEM front and OEM rear springs clearly have different rates. Front and rear H&R Sport springs also have different rates. True? So at what objective point do the differing rates between H&R sport front and BMW OEM rear become a problem? Or is there in fact a problem? By what quantity is there a "dangerous" mismatch? And for that matter, what is the effect of the mismatch, and why is ithe difference in the springs significant in the case of Sport vs. OEM but not in the case of OEM vs. OEM?

I definitely don't know the answers, but the more I get into this the more I have questions.

John

P.S. I found some information on spring rates in another thread:
------------------------------------

"I saved this from a post somewhere so i don't know how accurate it is...

Spring -> Front Rate -> Rear Rate
Stock E36 M3 ->105 ->335
LTW E36 M3 ->138 ->402
Eibach Pro Kit M3 ->148 ->428
Sachs M3 coilovers ->215 ->395
H&R 29910 (Sport) ->200 -> 380
H&R 29910 DTM(Race) -> 345 ->515
H&R Coilover ->340 -> 380
Dinan ->150 ->400
------------------------------------------
So in other words, the setup I am considering would be:

200 front and 335 rear.

In other words, the difference between the two will be 135 instead of 180. 180 what I'm not sure. Given that the difference between the H&R coilovers is only 40, I can't see how they claim having a 135 difference can be harmful.

I'm wide open to any other input....

john

[jvit27]

dont mix and match.

the spring shouldnt be falling out when you jack up the car. the shock holds tension on the swingarm. the wheel should just hang less with lowered suspension. with my coilovers unloaded, the wheels hang at what is about stock height lol

[Johno]

the spring shouldnt be falling out when you jack up the car. the shock holds tension on the swingarm

In my car, the weight of the wheel decompresses the shock enough for the suspension to drop and the red spring falls right over.

If that hapens on both sides at once, the average tech at a dealership will be hard pressed to get the car back down on the ground, I'm afraid.

[Gene V]

Originally posted by Johno
If that hapens on both sides at once, the average tech at a dealership will be hard pressed to get the car back down on the ground, I'm afraid.

If that happens then the average tech at the dealership can get another average tech at the dealership to give him a hand...

You sound as if the car will be spending most of it's time at the dealership...don't worry about it until you have to take it in, then tell the service writer about the short springs and let them take it from there...if they're working at the dealership, then they should be able to handle a simple task like this...

You don't mix stock and aftermarket springs because they are both match sets...mixing them could make for an evil handling car...

[12:03]

You know I have always wanted to do this. I think the OEM rear height is good but the front could stand to be lowered a bit.

Everyone has always said dont do that but no one ever says why...

[96technoM3]

I'm just trying to help Johno because I had the EXACT same problem as you. I had to deal with the same company and same problems. The only differnce I can find is that your car did not drop as much as mine did in the rear. If you look under my name you will find many posts about this. My rear was so low that with my stock 8.5 inch wheels in the back my car would rub on almost any bump or turn. Just for the hell of it, I had TireRack send me the other rear springs that have been known to raise most cars (gray 29910's) and tried these. These springs are actually taller than stock springs, but once I got them into their keepers and let the car settle for a day the ride height was back to stock.
I'm not sure why some cars drop more than others given identical suspension setups (I also have koni's and H&R sports) but if you are looking to keep the sports and have run out of other options you might want to try this. Might work, might not, but it does make me question H&R's R&R and their quality control.
And yes it is crazy how the red springs dont stay in the keepers. Its almost impossible for them to. If you measure them they are about 7 inches tall, which if i remember correctly is almost 2 inches shorter than stock springs. Under fool droop you can almost pull them out without unbolting the shock...

[Johno]

Everyone has always said dont do that but no one ever says why...

Bingo.

Lets assume that that spring rate list is accurate. I don't know whether it is. That list shows many variations of spring rates front to rear.

Why is one more variation somhow un-desireable?

Is there some factor other than those numbers that governs whether a setup is good or bad?

Furthermore, I'm now curious what the effect is on handling from one set of springs to another.

For example, what's dinan like vs. stock? Of Eiback pro vs. Dinan, where the spring rates are close. Could a difference be percieved in those cases?

Anyway, that's beside the point.

The point above about just teling the service writer is valid. However, my experience has been that repair shops generally give you shit about anything other than stock. That said, I'm not so concerned about the repair experience as I am curious about whether the ride would be somehow dangerous or sub-optial from a handling perspective.

After all, some of those spring combinations are VERY close front to rear, and others are quite far apart. To me this erodes the argument that there is some great sensitivity that needs to be considered.

My main problem is the freaking springs fall out. I don't care whether its the dealer working on the car or me swapping my winter wheels or whatever. Springs should stay in the car when you jack it up. No matter what springs you have.

JO

[incubus]

Johno, I would imagine that if the Dinan set-up is safe, yours would be as well. I too think it can be done (and I plan on doing it).

The only thing that I can see that would make one brand different from another is their progressiveness. The numbers you'd posted aren't static rates, but rather their average spring rates.

I don't know if this would make a difference or make the car less safe to drive though.