CharlieLed

iTrader: (1)

I have a project car that I have installed a 92 Corvette C4 IFS and it has engine mount pads that are at the same width as the C5 LS1/LS6 engine mounts. It looks like it's a slam dunk to drop the LS engine in using the C5 motor mount stands...has anybody else tried this swap?

CHarris

iTrader: (5)

You don't get around much do you, Charlie?

I've got one up and running. There are a couple others who went before me. At least on more is in progress right now.

Links...


Mine with lots of links to pics:

http://forums.corvetteforum.com/show....php?t=1303477


Another thread:

http://forums.corvetteforum.com/show....php?t=1203191

Look for KPforce in those threads. He's doing a LS1/T56 in his

John McGraw

The C4 suspension under an early frame is one of the most popular swaps out there right now, and the LSX engine leads the pack as the powerplant of choice. I have never used the Corvette mounts, I usually just use the early Chevrolet Mounts and a set of mount adapter plates. The engine you have mocked up in there is a F-body engine, and you will need to modify the accessory drives to be able to get the steering shaft to the C4 rack & pinion unit. You will find that the steering shaft will run right into the alternator in almost every case. A high-mount Corvette alternator or one of the custom setups from somebody like March or Speed and Performance, will take care of this conflict. What is that chassis, is it a tri-five chev?
Here are some pics of a couple of my projects.
http://www.villagephotos.com/pubgallery.asp?id_=339303
The 59 is all C4 suspension with a LS1, and the 65 has C5 front suspension with a LS2.

Regards, John McGraw

70 LS1

iTrader: (1)

What rear suspension is that in the pic?

CharlieLed

iTrader: (1)

Here's what I have found about the C4 crossmembers; there are two styles, one has engine stands that look much like an f-body the other (I am assuming this style to be the later C4) has flat pads and will accept the C5 engine mounts without modification. I apologize for the old photo in my first post, this engine is from a 2002 WS6 and I have all the necessary C5 accessories to update it. These pics show the alternator and pwr steering assemblies installed along with one LS6 ex. manifold. I am in the mock-up stage now so there may be inconsistencies in the pics.
Here are my main concerns:
1. As the C5 LS1 engine sits in the C4 crossmember (this is a 92 C4 frame assembly as well), the center of the engine is offset an inch towards the passenger's side of the frame. I have seen offsets before on various cars that are part of the design to compensate for engine torque but I am unsure as to whether THIS offset is by design or is there a problem with the C5 mounts on the C4 cradle?
2. Engine tilt. How much lower should the trans tailshaft be below the center of the crankshaft at the front of the engine? Some have said that the 4L60E pan should be parallel to the ground and that this will take care of the engine angle. I have yet to find any conclusive data on this topic.
3. Pinion angle. I have a C4 IRS so I am not concerned about spring travel in the differential. Once I have the engine/tran angle set I know that the pinion angle should match just as long as the angle don't exceed 3 degrees each. That said, if the engine is offset by 1 inch at the crank pulley, should the tailshaft be offset by 1 inch as well? This will result in a minor misalignment with the pinion yoke but I am told that this misalignment will have no affect on the driveline performance. True?

Here are some pics that I just took of the installation. This chassis is for a 1950 Merc coupe, I have made extensive modifications to add the C4 ZR1 subframe and to fabricate the rear frame members to mount the C4 IRS. The frame itself sits at 4-1/2 inches clearance and when the Shockwaves are installed it will range in height from 1 inch to just about stock height.

nitrovette

iTrader: (13)

I know the early c3 frames the motor is offset to passenger side about that much .

John McGraw

Jeff,

That rear suspension is C4 Corvette. You can't tell from the pic whether it is a Dana 36 or 44. Those rear shocks look real funky, but I am guessing that they are just laying over against the rearend and not installed like that. They would not work very well at that angle.



Regards, John McGraw

CharlieLed

iTrader: (1)

The IRS is a late C4, D36 with 3:07 gears... I am using Shockwaves on all four corners and I have run into challenges both front and rear getting the Shockwaves mounted. I have included a pic of the adapter plate that I fabricated to pick up the lower shock mounting point and the two link bolts...still need to weld a lower shock mount on the adapter plate.

John McGraw

Charlie,

Setting the engine in level is the way to go in my opinion. You need to keep the 1" offset in the centerline of the engine and trans. If you do not maintain this offset, then the two ends of the driveshaft will have unequal angles, which will make for vibration. You do not want to have 0 degree driveshaft angles either, since this will tend to damage the U joints from the rollers not rotating and keeping them lubricated. 1/2 degree is all that is necessary to prevent U joint failure. All Corvettes had this same offset in the driveline centerline due to the independent rear suspension needing to maintain equal length halfshafts. The pinion can't be centered on the carrier due to the design of Hypoid gears, so the pinion has to be offset slightly to maintain equal axle lengths. On a solid axle rearend, maintaining equal length axles is of no importance, so they just center the pinion and make different axle lengths.

Regards, John McGraw

John McGraw

Charlie,

I wanted to put shockwaves on my 59 as well, but I finally just gave up and put coilovers on. I thought about the same setup that you made on the rear, but could never get the front worked out to my liking.


Regards, John McGraw

CharlieLed

iTrader: (1)

John I am humbled...I have just looked at your photo gallery and I must say that you are a master! I only wish I had as much shop space and time for devote to this passion as you appear to have. Is this a business for you? Thanks for sharing your expertise...

John McGraw

Charlie,

Thanks for the kind words, but I am just an old shade-tree mechanic who has finally gotten to the point in my life where I have the resources to build a little better class of car than I did 30 years ago. I do this just for myself, and I really enjoy every single part of the builds from fabrication to paint and upholstery. Cars are my real passion in life, and I would rather work on my cars then almost anything else. I try and do all my own work, and avoid sending stuff out if at all possible. If I could just do my own Chrome plating, I would be just about self sufficient!

Regards, John McGraw

70 LS1

iTrader: (1)

Cool. From the picture it looked like the shocks were supposed to be at that angle and it looked like some cantilever setup similar to F1 or indy cars.

Street Lethal

Well said...

Hersker Hans

im considering making a Drift machine out of a C4, but i know the steering degrees on the C4 really suck, anyone knows how to make the steering radius better on it? its a tpi/zf 6 speed in it now, but i want to install an LS1/t56 of course.