peter_werkes

If anybody was wondering to get the car lower in the rear and used the 10in bolts from the corvette vendors but we're still looking for more low, well might of found how to.
The suspension springs on my car are the 92 base ones, so keep in mind zo7 z51 owners, it's easier for you to get lower. This is to match the lowered front end on my car; 2.125 on the front spoiler in the middle directly to the ground for reference.

Excuse the dirtyness, it was raining the day before.
Honestly the 10in bolts were only good to level the rear to the front stock height and looks like *** when you lower the front.
I also used 11 and 11.5 bolts for the rear and the 11.5 is good if you like the stock style rake.
Now, if you want to have everything nearly even with a small rake, then I suggest foot longs.
Yes they clear just fine and I haven't seen any rubbing from my 285 35 19 set up with 53 offset. I see no real adverse effects from doing this other then the ride being a little rougher but it corners so much flatter it's unbelievable. I'll report back with pics and a lil more on the effects.
I used grade 8 .5in 13 thread, btw.

WVZR-1

Your choice of hardware was a poor one. 14mm is OE, 9/16 is generally accepted and your 13 USS thread also a poor one. SAE (fine) or METRIC fine if using M14 hardware. I'd consider getting either correct spec hardware (M14 X 2.0) or at least 9/16 - 18.

GKK

I want to use a Grade 8 12" long bolt but, can't find any?

Some members here have used threaded rod from Lowe's or Home Depot but, I'm not going to do that.

Where did you buy the bolt?...

peter_werkes

the only threaded rod home depot sold was only grade 2, so I wouldn't use it.
You can pick up the bolts from fastenal, it's a bit pricy though.

peter_werkes

My mistake, they are 20 thread, they don't make a 13 thread anyway.
The difference in shear strength of the new bolt in its proof load capabilities is negligible because it's nearly the same (new bolt is marginally stronger) as it's stock counterpart; the reason for choosing .5in was cost effectiveness.

WVZR-1

Fastenal does have an M14X2.0X300 spec bolt in 8.8 and I believe that in this particular suspension related area I might prefer the correct diameter hardware and maybe sacrifice the grade which actually could be to an advantage, the higher the grade of the bolt the more susceptible to "shear" I believe it is where as a lower might bend it's less likely to "break". Your hardware is something just over 10% less in dimensional specs. I have never checked an OE bolt for class but I'd think it's maybe 9.9 so the 8.8 I doubt is a stretch. You should have your OE bolts. What class are yours?

The actual OE advantage is the finish of the bolts. It's done for "under-car" specifications, there's way more to OE hardware than just the class of the product!

WVZR-1

If you wanted to check an 8.8 metric class 300mm long bolt this might take you to it. There are other options but they do get more expensive. This bolt is the correct diameter and has just over maybe 2 1/2" of thread. It's 5mm short of 12" for an "under-head" measurement.

http://www.fastenal.com/web/products...Punchout=false

peter_werkes

OE bolts are actually pretty terrible as they are just grade 5 bolts that are untreated as are most aftermarket lowering kits. My OE ones had some surface rust where the finish was chipping on the bolt

WVZR-1

I don't believe they're grade five, that is an SAE spec and the "real" hardware is/was metric. Maybe someone had already been there before you. Regardless I just thought I'd point you towards maybe a more desirable product.

Z51JEFF

Got mine from VB&P.

GKK

Thanks, WVZR-1!...

peter_werkes

Anyways, here's what it looks like

3JsVette

Looks great!
Thanks for the write up.

USAZR1

Vette Brakes wants $106.99 for a pair of their 12" rear bolts. That seems kinda ridiculous. The Fastenal 14mm bolts are $21.86/each.

WVZR-1

VBP mentions Grade 8 so I would expect the product is 9/16" likely SAE so there's certainly difference in the product. Choices! It's all about choices.

The bolt I mentioned is 8.8 metric and the finish is mentioned in the Fastenal description, it's very possible that the VBP has a different finish.

I only mentioned the availability of a different product that I felt maybe more suited than the under dimensioned product the OP mentioned using. I've never used the Fastenal product and am not suggesting the use of their product, it's just another possible option.

It's certainly I'd think a better option than some of the "choices" that through the years have been mentioned as using. Threaded rod comes to mind.

THEKING_10

I have an 88 I believe it has the z52 suspension what is the easiest way to lower the rear cause I have no clue what any
Of dis bolt stuff means sorry if I seem confused but my dream car sounds like it comes wit a special language as well lol

USAZR1

I took your advice,Dave,and ordered two of the 14mm bolts from Fastenal,today. Getting the 300mm long bolts would have been very difficult but they were able to order 280mm bolts which equate to a little more than 11" long. Price was $12/ea with a two-day delivery time.

dayle97se

how does lowering the rear suspension of a C4 (via the longer bolt method) affect the front height of the car? will the front be any lower or higher (relative to the ground)?

vetteLT193

It lifts the nose slightly. It's ideal to do the two in unison or they look funny. The OP has big wheels which is why going extra low doesn't look too low, the wheels effectively jacked the car up a bit and now he's cranking it back down.