Front Spring Lowering Shackle

[Washout]

Using the drawing that Bob L. produced for this problem I decided to lower the front ride height of my GT. Since a neck injury is keeping me away from Carlisle I had to do something or go nuts so I decided to fab up a set of these shackles because the front of my GT just sat way too high. I finally got the energy to install them today and they did a great job of lowering the car, it looks just like I want it to. There is one little problem though. When I turn the front wheels too far left or right they the spring shackle is hitting the tire rim. I've included some pictures here in the hopes that someone can tell me what I did wrong.

[GTJIM]

It's worse than you think! The shakle now allows the spring eye to move in and out as the spring flexes so the contact area will move further outwards as the suspension compresses. Looks like you need larger diameter wheels to give a bigger openning for the bits to move out into while going over bumps.
Another option, which has been discussed before - but not done by me - is to narrow the spring eye and us parallel side plates for the shakle (or is it shakel??) which are a bit shorter.
On the bright side - there won't be any squeeks from that poly bush (lots of teflon grease there!).

This is the only pic I can find of the same area - looks like aftermarket wheels and offset further outwards gives more clearance.

You may have to consider suitable wheel spacers to use stock rims.

[Washout]

Thanks GTJIM, You basicly confirmed what I already suspected. I'll get some wheel spacers for the short run and when I decide on what new tire and rim combination I want, I will allow for the extra travel. It really did a nice job of lowering the front end......... even if I can't really drive it yet. :o

BTW, what rim and tire size are you running?

[civin]

Washout is that a stock front spring, did you have to fab the shackles? Your before picture looks exactly like my GT's ride height.
-JD

[Washout]

That is the factory stock spring and I fab'd the shackles. I really like the new stance, it's just a matter of making the wheels work now. But in the end it will be worth it. It always bugged me that it sat so high in the front.

[garrymc]

How close are you to the bump stop now ?

[Washout]

Without going to the shop and crawling under the car, I'd say I have about an inch to an inch and a half clearance. I may cut the bump stops down some just to allow more room before bottoming out.

[GTJIM]

Originally Posted by Washout BTW, what rim and tire size are you running?

BBS 15" X 5 1/2" rims with 195 x 50 x 15 Pirrelli tyres - rims from scrap bin at local car dismantlers $1.70 a kilo! - new tyres though.

Want to keep the tyre height the same as stock for speedo accuracy (it is a law requirement that you do not change tyre height here) and also kept the width down to ease the steering.

[Washout]

Thanks GTJIM, I'll start looking around the scrap yards here and see what I can come up with.

Gregg

[Washout]

Garrymc, I crawled under the car and measure 1 and 1/4 inch between the tips of the rubber bump stops and the frame. I think you could probably cut off another 1/2 inch from the rubber stops before getting into the bolt that they are molded to. Given the current rim clerance problem I haven't had a chance to drive the car to see how much the front end will travel now. I have to believe that without the biding that was built in from the factory that the front end will probably want to travel quite a bit vertically. Tommorrow I will try to drag the local junk yards for some 15 inch rims,

[GTJIM]

The rims I found were off an Nissan Skyline some of which had them as standard fitment - yes German BBS wheels on Japanese Cars as standard!
I got the caps from a mag wheel dealer in New York and they were German parts in Nissan boxes with Nissan part numbers! Good luck with your search!
There is a pic of one of my wheels in my gallery.

[nobody]

More of a question, what does the shackle do to the front end geometry? I did the lowering spring and I was told to reverse the upper ball joints. Is this needed when you do the shackle? Seems to me that it would be. I would hate to see you wear a new set of tires funny or have other problems associated with doing this.

[garrymc]

Originally Posted by Washout Garrymc, I crawled under the car and measure 1 and 1/4 inch between the tips of the rubber bump stops and the frame. I think you could probably cut off another 1/2 inch from the rubber stops before getting into the bolt that they are molded to. Given the current rim clerance problem I haven't had a chance to drive the car to see how much the front end will travel now. I have to believe that without the biding that was built in from the factory that the front end will probably want to travel quite a bit vertically. Tommorrow I will try to drag the local junk yards for some 15 inch rims,

Thanks for the info. Let us know how you feel the shackles effect the ride quality.

I fear you will not find any 15 inch rims with a 4X100 mm bc that will have a low enough ET. Most will be FWD type offsets. I sometimes see a BMW 14 inch rims that would fit good on a GT. Take a look at the RWD Impulse alloys, they are mostly 14X6 ET 24, I think they would fit good if you can get used to the style.

Garry

[GTJIM]

Quite right garymc! The offset on the Nissan rims is ET42 but with 20mm spacers this brings it back to 22mm and the scrub radius about the right place again for the GT. Fortunately they will fit real well with the Impulse diff I am going to use and also the front discs/spindles from the Impulse too.
I figure if the whole brake package is used from the same car then it should be more balanced. The Isuzu front discs are 256mm diameter, 16mm thick ventilated rotors that are far lighter than the original GT ones - which, with the BBS rims, will lower the unsprung weight significantly. Just recieved a phone call to say the rims are polished and ready to pick up so will be able to weigh them and compare with standard ones today!

PS: My other passion IS Isuzu Piazzas' (as Impulses are known here). I have become used to the "tic-tac-toe" mags on the Impulse but it does not do much for the GT - even though they fit! One of the spare Piazzas has a real nice set of Enkil mags but they are only 13 X 6 size

[73Manta72gt]

I made a set of shackles but never installed them....Can they be used with stock wheels without spacers or do they rub?

Thanks guys

[Washout]

73Manta72gt, I installed the shackles with a stock set of rims and they rub as you can see in the first picture. Tomorrow I will try to get a set of spacers and see how much they help.

[jordan]

Has it been confirmed that it is impossible to use spring shackles with stock rims with out them hitting?

[Bill Hoffmann]

Originally Posted by jordan Has it been confirmed that it is impossible to use spring shackles with stock rims with out them hitting?

I have a set of the shackles on my shelf to prove it. They definitely hit the stock rims unless you limit yourself to 50 foot radius turns

[jordan]

Darn, Still a great idea if you have aftermarket rims.

[Bill Hoffmann]

Originally Posted by jordan Darn, Still a great idea if you have aftermarket rims.

Since this is fresh in your mind, and you may have made some measurements, what do you think is the minimum wheel diameter for the shackes to clear? 15" assuming same backspace? Remember, going from 13" to 15" is a clearance change of only one inch. I've been meaning to get back to the project of finding wheels so I can use my shackles.

[jordan]

I was under the impression that 14" bbs rim would work, but you are right, that would only be an extra 1/2' of clearance and I personally would like to have at least that as safety clearance. Probably 15" rims would be the smallest that could be safely used.

[Washout]

I went to 15 inch rims and they still hit. It may have been my set of shackles but I finally gave up and bought a lowering front spring which did improve handling but the ride quality did suffer. I used new springs front and back as well as adding anti sway bars front and rear. I really handles now! ........... well it did until I dropped the rear cylinder! New engine in the process now.

[bendele]

Originally Posted by GTJIM Another option, which has been discussed before - but not done by me - is to narrow the spring eye and us parallel side plates for the shakle (or is it shakel??) which are a bit shorter.

Has anyone tried this method? I was thinking about making some shackles for my car using this method. I was a little concerned about cutting down the spring eye but I think the amount of material being removed shouldn't cause any issues.

Advantages:
1) Can have less than a 1.5-2.0 inch drop in the front.
2) The spring eye should stay a little more "tucked up" to avoid rubbing the inside of the wheel (at least for the 15"s I'll be using).

Disadvantages:
1) Slightly weakening the spring eye.
2) Cutting the spring could add stress to the metal that causes it to crack later????

If I do this, I'll take some pictures.

Chris

[jordan]

I don't fully understand what you intend to do but if it actually involves cutting and welding the opel gt's front suspension transverse leaf spring I highly advise against it.

[GTJIM]

I now have a spare front spring and have discussed this with a local Blacksmith/Spring Maker and we have come to the conclusion that if the narrowing is done with the change in width fared back along the spring with a quite long taper that this is a doable modification. All the stress raisers need to be carefully polished out and any grinding done along the spring edge - not across it.

My spare spring is on the workshop floor right now and careful measuring shows that very little metal will need to be removed as if the rubber in the spring eye is replaced with a thinner flanged Delrin bush a 3/8" or 10mm plate will fit with minimum of modification.

We cannot weld suspension parts here (LTSA Rules - Land Transport Something Authority) so there is the real added advantage of being able to use a straight bar of steel here - instead of a welded 'dog leg'.