C4 Lowering Kits
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 1,040
Likes: 2
From: BowlingGreen KY
C4 Lowering Kits
Has anybody used these? How difficult are they to install? Got any before and after pictures. Can you just buy some longer spring bolts instead of spending $40 on the kit? Thanks.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: C4 Lowering Kits (KYVette90)
The rear is rediculously easy to install. If you want to just buy longer bolts, make sure they are strong grade 8 bolts. The ones in the kit are 1" longer than the stock ones.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: C4 Lowering Kits (KYVette90)
I believe MAD and Eclker's sell just the longer bolts and nuts to lower the rear; the price is pretty low too.
The thinner poly blocks in the kit go under the front spring to drop the chassis a little. I used two floor jacks, removed each wheel separately and it took like 1/2 to 1 hr to lower the rear.
I bought the entire kit from MAD but after I lowered the rear 1 1/8" even the front fender wells fit the front wheels better so I didn't bother lowering the front. Measure the distance from the top of each tire to the fender well before you start to have some idea of where to set the new bolts.
You'll be amazed at how different the car looks and feels after lowering just the rear. When I first sat in it I actually "felt" that it was lower.
[Modified by 65Z01, 4:41 PM 1/12/2002]
The thinner poly blocks in the kit go under the front spring to drop the chassis a little. I used two floor jacks, removed each wheel separately and it took like 1/2 to 1 hr to lower the rear.
I bought the entire kit from MAD but after I lowered the rear 1 1/8" even the front fender wells fit the front wheels better so I didn't bother lowering the front. Measure the distance from the top of each tire to the fender well before you start to have some idea of where to set the new bolts.
You'll be amazed at how different the car looks and feels after lowering just the rear. When I first sat in it I actually "felt" that it was lower.
[Modified by 65Z01, 4:41 PM 1/12/2002]
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: C4 Lowering Kits (65Z01)
Another word of advice. BEFORE you mess with the rear bolts, measure how many inches are showing from the bottom of the castle nut to the end of the bolt. This will allow you to return the car to stock height easily if you need to. For example my car had 1 1/16" showing, so on the new bolts I had to have 2 1/16" showing to put it back to stock. :)
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Race Director
Joined: May 2001
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Re: C4 Lowering Kits (KYVette90)
You know Kale Co, sells an easier lowering kit. You might want to check it out http://www.kalecoauto.com
They are a little slow, I've been waiting for my custom O-Pipe for 6 months.
They are a little slow, I've been waiting for my custom O-Pipe for 6 months.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: C4 Lowering Kits (ANTI VENOM)
I just ordered the muffler bearings from Kaleco.
Mine at the original ones and must need to be replace by now.
Can anyone tell me where they are located on a 91' Vette?
I've looked all over trying to find them.
Thanks
Mine at the original ones and must need to be replace by now.
Can anyone tell me where they are located on a 91' Vette?
I've looked all over trying to find them.
Thanks
Drifting
Joined: Aug 2001
Posts: 1,606
Likes: 14
From: Vacaville, CA
Re: C4 Lowering Kits (KYVette90)
The rear bolts are slightly different than Grade-8 bolts in the lowering kits. They have a very heavy and deep thread which will prevent shearing. Grade-8 bolts are strong when tension is constant, but with jouncing as in the rear susp. I'm not sure the threads are large enough. The lowering of the back only is unsafe at high speeds. The car was designed to have a slight rake to the front. With the back lowered only, the car will get loose at high-speed. As far as the front is concerned, the aluminum plates holding the stock spring can be removed to lower the front about 1/2". This should be enough to prevent scraping over every driveway in town. There is also a technique of trimming down the stock poly wedges. Probably better than trying to glue-in some aftermarket stuff. Vette Brakes & Products sells an aftermarket sport spring for the front which is much better than the stock spring. There spring will lower the front somewhat since it has much less camber than the stock one. There spring will add a little stiffness, but will also handle better than a stock spring.
Team Owner
Joined: Aug 2000
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From: Sydney, Australia
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Re: C4 Lowering Kits (KYVette90)
I used the MAD kit front and rear. Seems most people I've spoken to glued their wedges onto the spring - I glued mine to the frame with gasket adhesive and they stayed in place until about a little over a month ago (after being on the car for about two years) when I pulled the front spring out again at which point one fell off and I had to pull the other one off.
The method I used to determine how much to trim the front aluminium spring retainers after removing the OEM spring wedge and installing the new wedge is:
Stock leaf spring bushing height (measured from top of spring surface) - replacement lowering wedge height = Amount to trim retainer.
These are the before and after measurements I took:
Height measured from the lowest edge of the wheelarch to the top of the wheel rim (with a full tank of fuel) -
Before lowering:
Front: 13.3cm
Rear: 14.9cm
After lowering:
Front: 11.5cm
Rear: 12.4cm
Sorry about the metric measurements, I suck with imperial measurements :rolleyes:.
If you plan on doing any high speed driving I would also recommend against only lowering the rear IMO.
The method I used to determine how much to trim the front aluminium spring retainers after removing the OEM spring wedge and installing the new wedge is:
Stock leaf spring bushing height (measured from top of spring surface) - replacement lowering wedge height = Amount to trim retainer.
These are the before and after measurements I took:
Height measured from the lowest edge of the wheelarch to the top of the wheel rim (with a full tank of fuel) -
Before lowering:
Front: 13.3cm
Rear: 14.9cm
After lowering:
Front: 11.5cm
Rear: 12.4cm
Sorry about the metric measurements, I suck with imperial measurements :rolleyes:.
If you plan on doing any high speed driving I would also recommend against only lowering the rear IMO.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
Re: C4 Lowering Kits (Red 90 L98 Coupe)
I'll agree with the others on the rear only lowering. Without the rake your vette will get squirrely above 120mph. I did the lowering job and it takes few hours and that hard, just time consuming. Good time to really look at the suspension parts and see what else needs replacing or adjusting. I glued the wedges to the frame with contact cement a year ago and all is well thus far.
Measure the car at all four corners before you begin. Reason, because you don't want to end up with a 1/4in difference between sides or corners when you are done. Although unlikely, I'm sure it can happen. GM used shims (aka spacers) on the transverse springs to counteract any differences in the suspension. You can just trim the rubber bushing down a bit and remove the aluminum spacers to lower the car a bit instead of doing the full on lowering job. You will still have to trim down the retainer brackets a bit. You'll know what I'm talking about when you get there. I did a write up on this on my webpage. :seeya
Measure the car at all four corners before you begin. Reason, because you don't want to end up with a 1/4in difference between sides or corners when you are done. Although unlikely, I'm sure it can happen. GM used shims (aka spacers) on the transverse springs to counteract any differences in the suspension. You can just trim the rubber bushing down a bit and remove the aluminum spacers to lower the car a bit instead of doing the full on lowering job. You will still have to trim down the retainer brackets a bit. You'll know what I'm talking about when you get there. I did a write up on this on my webpage. :seeya
