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I did one using a kit from autofab. It takes some fabrication work.
1. Biggest issue is modifying the fiberglass storage boxes so that the axle sits in the right position. It will hit if you don’t cut enough out. You also won’t be able to drop the car low enough. Strip everything out of the interior and do it once, not 5-6 times like I did.
2. Crossmember center section needs cut down and welded so the driveshaft doesn’t hit.
3. Cutting out the stock IRS compenents and welding in the 4-link brackets and spring mounts are pretty straight forward.
4. I would also research the best springs. I think mine are 150 lb and are VERY stiff. I haven’t raced it enough yet but may need to go a bit softer. Several guys on this forum have done this and raced so could get you done good info I’m sure.
5. Also get a brake kit that works with the stock ebrake cable. I got the stock cast iron single piston gm setup and it works fine. I think there is an aluminum caliper that also works but I’m not sure what one.
Final version has the cut down/reversed /modified storage door. Note the offset bulge (9” is offset). I test fit the test end MANY times before I finally got it to the point where the axle would go all the way to the frame mounted bump stops.
Last edited by Corvettedave02; Jan 13, 2021 at 11:36 AM.
I also used the autofab 4 link kit. I was very lucky as I did not have to cut any bolts. Everything unbolted easily. Even the front trailing arm bolts. I didn't even have to modify my storage compartments. Rather than use a 9in. Ford, I used a Dodge 8.75in rear. Everything that came with the kit went together perfectly. The only cutting that was needed on mine was as was already pointed out in a previous post, the rear crossmember needs clearanced so the driveshaft doesn't hit while the rear is moving up and down and a piece comes with the kit for that. The springs that came with the kit seemed perfect as the ride and handling seem to be the same as before. I even kept the drum brakes that came with the rear and after driving quite a bit, see no reason to change to discs.
This was a very well thought out kit.
Rick
Big Block 69
Last edited by Big Block 69; Jan 13, 2021 at 11:59 AM.
Good point Rick. The offset 9” center section is what required all of the box mods. I think someone on this forum used a 12-bolt with their kit. Can’t remember if they had to clearance the boxes. In hindsight I probably would have gone 12-bolt depending on ratio options. I needed a 3.25 with the tko. I also wanted a Detroit locker and not sure what options the 12-bolt has.
Last edited by Corvettedave02; Jan 13, 2021 at 03:49 PM.
This could be done for durability or for the Dragstrip. For me, it was done out of being cheap and lazy. 40 years ago the left rear wheel bearing seized. While pulling it apart, I bent the rusted trailing arm. Spindle, trailing arm and misc. parts from the Chevy dealer were about $400. About 5 years ago, it seemed the right side was heading down the same path. Parts total would have been much more than $400 this time. I had some 8 3/4 rears from a Dodge project. I think the autofab kit cost about $1100. This job will never need done again and gear changes are a breeze. For some people, it may be worth the work and maintenance to keep the IRS. For me, the solid axle was the right move.
Rick, you are obviously knowledgeable and kudos for the mopar axle swap idea but I think you are presenting this as a bit easier than it is for most ppl. Even what you did is not easy and arguably harder than my 9” conversion, which was ordered as a complete unit, depending on skill set. This is not a bolt in conversion.
He needs the correct width 8 3/4” or needs to cut one down. In that case new axles. Did you use an A - body? Also the spring perches need cut off and the new spring mounts setup on the axle and 4-link mounts AND done so to assure proper pinion angle. The brakes and ebrake also need worked out. Wheel width and backspacing also will need worked out.
I would also research a 12- bolt gm conversion using the auto fab kit. As Rick pointed out with his 8 3/4” he didn’t have to clearance the storage boxes which is a pita but doesn’t require any critical skills. I suspect the 12-bolt solid axle might work like this. I know there was a forum thread about 10 years ago of someone who did this.
Cost is obviously always a balance too. I chose to spend more to get a complete unit to reduce potential mistakes I might make. I suspect it’s more cost effective to get a solid axle done than an upgraded IRS but the IRS would be more of a bolt in deal. I think Detroit Speed has a very heavy IRS conversion but it’s $10k + as I recall. The complete auto fab axle and bracketry and brakes is closer to 4-6k depending on what you get and like Rick says you could do an 8 3/4” for $1100 + the cost of the 8 3/4” + springs and shocks $1500? But you have some welding and setup to do. You seem set on a solid axle which is what we did because it’s a much stronger setup for overall strength and definitely for drag racing. Lots less potential for things breaking with a solid axle, but the car won’t handle like an IRS car anymore.
anyway. My .02. Looking forward to seeing what u do.
Last edited by Corvettedave02; Jan 14, 2021 at 12:56 PM.
A 95-01 Explorer 8.8 rear end with the long side narrowed to match the short side might work well for one of these swaps. It'd be about 56.5" wide which I think is just a little narrower than a stock C3 rear width but might still work. They have heavy wall axle tubes, 31 spline axles, disc brakes and a decent enough posi to keep using plus you can find them with 3.73 gears.
Last edited by lionelhutz; Jan 14, 2021 at 01:37 PM.
I must have gotten lucky because the parking brake cables worked fine with the Dodge rear, the cable just needed adjustment at the handle. The parking brake actually works now, it never did before. The brakes are the stock drum brakes that were on the rearend. The $1100 price I quoted for the autofab kit also included springs and QA1 shocks. They may have updated their pricing. My rear was a B-body rear. It needed narrowed 4 inches total, 2 inches on each side. A small local shop did this for $80. I had to order axles from Dr. Diff, who specializes in Mopar rearends. These were $400 and they were drilled with a chevy pattern since I already had my wheels. My driveshaft needed shortened. Another $80 including new rear u-joint to mate the Chevy driveshaft to the mopar rear.
Dave is correct that this is not a "bolt in" but I thought if I can do it, anyone who can read english can do it, especially with the amount of talent and skill that I see on this board.
Rick
Big Block 69
A couple of added thoughts.
1. I doubt an A-body 8 3/4” is 4” narrower than a B-body so it appears you would need to narrow any mopar 8 3/4”. Rick probably knows for a fact?
2. Regarding the 8.8 explorer diff. It’s implied but to be clear you would need 2, short side axles after narrowing the long side as noted above. Disk brakes and a posi that comes with it make this look like a great cost effective option.
3. Narrowing the axle tubes is fairly simple from what I have seen my brother do ( he bracket races a valiant) but you need to have a jig ideally and also know how to weld.
Buddy built one for his LS3 powered '57 Chevy. He's got around $600 in it and that was 2 junkyard axles and all new brakes including backing plates. He was looking for a 9" axle, but anything built for the power he needs is $4k to $5k around here so I showed him the 8.8" and he went that way.
Buddy built one for his LS3 powered '57 Chevy. He's got around $600 in it and that was 2 junkyard axles and all new brakes including backing plates. He was looking for a 9" axle, but anything built for the power he needs is $4k to $5k around here so I showed him the 8.8" and he went that way.
I also put an 8.8 in mine. If you're going with the 8.8, be careful with the axle tube size as I don't think the larger diameter tubes will fit into the autofab kit. I shortened both sides to allow for a deeper rear wheel. build link
Well, I saw posts from 3 or 4 guys in Fox bodies who ran 8's and 9's in the quarter mile and that was on 28 spline axle versions. That certainly is not recommended, but they are pretty tough rear ends.
Very important, if going with the 8.8, get rid of the "C" clip axle retention in favor of the press on collar and axle retainer plate. Mine was the bigger tube rear from an F150. Comes with 31 spline posi. While narrowing the tubes, I welded on Big Ford axle ends and went with the 9" axles.
