Is it normal to be very jumpy over rough pavement?

[bradford]

Originally Posted by ianc

I've talked to people who've said it's more of a thing that is best for the track, but not that critical for the street. Dunno because my suspension is all stock at the mo...

ianc

It's certainly not critical for the street to the average driver. However, the average 1-series driver thinks the car is FWD, remember...

[MastaMind]

I thought there was a noticeable improvement in street driving. In fact, the change was immediately apparent the first time I backed down the curb at the end of my driveway. My favorite mod by far.

[bradford]

Originally Posted by MastaMind

I thought there was a noticeable improvement in street driving. In fact, the change was immediately apparent the first time I backed down the curb at the end of my driveway. My favorite mod by far.

I agree. There is a stretch of my commute where the tollway passes over a bridge, and there's a "hump" in the road that runs across at about a 45 degree angle. Every time I went over this hump before upgrading to the M3 bushings, it would require a large steering correction, but afterwards, I'm able to simply track straight over it with no effect.

[bradford]

Additionally, when I'm on the throttle hard, the squirminess in the rear end has been eliminated. No more wiggling effect.

[ianc]

Interesting. I'll have to think hard about that after I see the effects of springs\shocks and M3 sway and tensions\wishbones.

The thing I don't like about it is that I have to pay someone else to do it...

ianc

[MastaMind]

Originally Posted by bradford

Additionally, when I'm on the throttle hard, the squirminess in the rear end has been eliminated. No more wiggling effect.

Yes, that was completely eliminated. Good thing because it drove me absolutely nuts!

I really don't understand why people say that it's not needed or noticeable in a non track environment. The only negative side is a slight increase in harshness/decrease in comfort, but the benefits far outweigh the detriments. I'm still on stock RFTs, however, so I hope to regain a bit of smoothness after I switch out the tires.

[arrutled]

I think I got it. Basically saying the centerline of the car and the rear axle do not remain perpindicular or remain to be perfect right angles to each other?

Originally Posted by bradford

How much do they flex? Based on the fact that you can move them around pretty easily with your bare hands, I would guess they deflect a $hitload, to use the technical term. The M3 ones are solid rubber, not webbed.

Let me clarify the effects of the bushings...Toe is the angle of the wheels in relation to each other. Since the wheels are mounted to the rigid single piece subframe, toe is not affected by the bushings. You could toe the wheels in 5 degrees and rotate the subframe side to side and the toe would remain constant. Replacement of the suspension *LINKS* with the M3 ones will affect dynamic toe, as the bushings in the links are stiffer. However, what *IS* affected by the subframe bushings is thrust angle, which is the angle of the virtual rear axle in relation to the centerline of the car. When the subframe bushings deflect, the rear axle can rotate slightly, effectively giving you unwanted 4 wheel steering. Hitting a bump midturn can cause the subframe to twist in relation to the chassis, which is why the 135i has such excessive bumpsteer, IMHO.

Hope this helps.

[ianc]

Basically saying the centerline of the car and the rear axle do not remain perpindicular or remain to be perfect right angles to each other?

That's it exactly,

ianc

[bradford]

Originally Posted by ianc

That's it exactly,

yup.

[arrutled]

Originally Posted by bradford

yup.

word

[thez99]

OK!

So where in the shit do I get these wonderful bushings from heaven??

N please dun tell me to search, just worked 10 hours, my everything hurts n my brains been farting like crazy.

[arrutled]

Here:
http://hpashop.com/product.sc?produc...categoryId=120

I think you can find them cheaper at dan@united site but his site was down when I checked.

[ianc]

Gawd, aren't they lubberly? And it'll only cost you ~1k$ to get the little bastards put in!

ianc

[thez99]

Wow..$300 for 4 bushings eh? Are these polyurethane? The description hardly says a thing, id sure like to know a lot more bout em before dumpin 300 bucks. And is the install that difficult? Would it make sense to just go ahead and install springs while im at it?

Im still hesitant on springs, I really dont have any huge complaints about the cars ride because I know that once I switch out of these RFT's itll be a huge difference, Im just worried about the whole suspension getting messed up going lower n all..Kinda paranoid about that I guess

[bradford]

Originally Posted by thez99

Wow..$300 for 4 bushings eh? Are these polyurethane? The description hardly says a thing, id sure like to know a lot more bout em before dumpin 300 bucks. And is the install that difficult? Would it make sense to just go ahead and install springs while im at it?

Im still hesitant on springs, I really dont have any huge complaints about the cars ride because I know that once I switch out of these RFT's itll be a huge difference, Im just worried about the whole suspension getting messed up going lower n all..Kinda paranoid about that I guess

They're metal and rubber. Yes, the install is that difficult, do a search.

The rear springs would be cake while you're in there. Front would be additional labor. I personally would not do springs without also doing a matched set of shocks.

[arrutled]

Originally Posted by thez99

Wow..$300 for 4 bushings eh? Are these polyurethane? The description hardly says a thing, id sure like to know a lot more bout em before dumpin 300 bucks. And is the install that difficult? Would it make sense to just go ahead and install springs while im at it?

Im still hesitant on springs, I really dont have any huge complaints about the cars ride because I know that once I switch out of these RFT's itll be a huge difference, Im just worried about the whole suspension getting messed up going lower n all..Kinda paranoid about that I guess

Will attempt to install next saturday and report back. Got two daring car hacks and the will to complete the task. wish us luck.

[thez99]

Originally Posted by bradford

They're metal and rubber. Yes, the install is that difficult, do a search.

The rear springs would be cake while you're in there. Front would be additional labor. I personally would not do springs without also doing a matched set of shocks.

Interesting cuz I thought the UPGRADEs were the polys and the stock shits were rubber n metal, hence the soft smooshness of em. The stock ones on my previous gti were metal n rubber, the upgrades were these sexy stiffer poly's...hmm

I just cant justify $300 for 4 little rubber/metal bushings? Specially when the install is gonna cost that much more.

[arrutled]

nobody is twisting your arm. you gotta drop the subframe to do replace them. I am guessing a 750$ install. You might not even be able to notice these issues on the stock setup anyways.

[thez99]

Yea i def say screw that..

[ianc]

Will attempt to install next saturday and report back. Got two daring car hacks and the will to complete the task. wish us luck

Hey, please please please document this with a DIY, will you?

I keep hearing everyone saying how great this mod is, but without a proper service manual, I don't really know what's involved, so would be very interested to see what the install's actually like. I know it will be a big PITA because of the magnitude of the project, but to my knowledge, no one else here has documented it. I'm sure everyone will be



ianc

P.S. IIRC, you're going to need a special tool to press those bushings in, which is also kind of pricey, unless you can borrow one. You probably know that, but I wouldn't want you to get the whole thing apart and have that for a showstopper...

P.P.S. Good luck!

[bradford]

Originally Posted by ianc

I keep hearing everyone saying how great this mod is, but without a proper service manual, I don't really know what's involved, so would be very interested to see what the install's actually like. I know it will be a big PITA because of the magnitude of the project

Remove exhaust. Disconnect and drop driveline. Remove heat shields. Drop subframe. R&R bushings and everything else.

This makes it sound easy, right?

Here are a few pics from my install...

[arrutled]

Originally Posted by ianc

Hey, please please please document this with a DIY, will you?

I keep hearing everyone saying how great this mod is, but without a proper service manual, I don't really know what's involved, so would be very interested to see what the install's actually like. I know it will be a big PITA because of the magnitude of the project, but to my knowledge, no one else here has documented it. I'm sure everyone will be



ianc

P.S. IIRC, you're going to need a special tool to press those bushings in, which is also kind of pricey, unless you can borrow one. You probably know that, but I wouldn't want you to get the whole thing apart and have that for a showstopper...

P.P.S. Good luck!

Ill do what a I can. There is just so much detail in the project it will be hard to capture it all. We are just going to use a threaded rod/nut/and some cups. We are installing on my buddies 135 first because he has a second car. So, if we have a showstopper we can get what we need and he can drive car number 2 until we have the right tools. After autocross today I noticed a really awesome set of tires goes a long way to masking this issue. going from RFT's to star specs was amazing.