When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
That's a lot of work. That gasket now answers my question on who would use a desktop laser cutter. If you move the subframe rearward, you need to investigate/consider your shock angle since that mount would remain static at the body- unless you move it with an offset hole in the hat?
Moving rear axle centerline back reduces load on rear wheels and reduces traction and weight transfer, too. If anything, you want it forward, the front axle forward, and the engine rearward for drag racing advantages. But I wouldn't do it.
Since you don't have a ppf, maybe moving the engine and transmission back slightly would be feasible but not necessary for traction at this point. Always something you can do later.
The True Trac LSD arrived. Decided to put it in a few days ago. Opened up the diff I bought (used, good condition LOL) and it ate a bearing and was full of bearing material and whatever oil ford poured into it when it was manufactured. So I'm tearing it completely down and doing a full rebuild. New bearings/seals throughout. The ring gear appears to be in great condition, but I'm going to clean it again and reinspect. Gears are cheap so if it's damaged at all I'm replacing it. Still waiting on all the parts to arrive to now rebuild the diff. Also ordered a crush sleeve eliminator kit to install since I gotta tear everything down anyways. The stock crush sleeve is the weak link after installing a true-trac. Apparently 1000+whp launches on slicks can sometimes crush the factory crush sleeve resulting in gear damage. Solid spacer kit will fix that weakness. I got the ring gear removed from the open diff, but haven't pulled the pinion yet as I gotta buy a socket to remove the pinion nut and a puller to press the pinion flange off.
I have looked into getting a custom driveshaft made, there's actually a couple different folks selling them for reasonable prices on ebay. So far not one of them will email or call me back! Might try again, dunno. Worst case I'll buy parts and make my own.
For now the plan is to wait till the parts to rebuild the 8.8 arrive, then build that and have it ready to go. Once the axles arrive, I'll test fit them to the diff to confirm they fit, then figure out if I'm gonna drop the subframe or not and then pull the car apart and start working on the mounting system to hold the 8.8. Driveshaft will be last once the diff is in. If I don't have a custom driveshaft lined up by the time I start swapping in the 8.8, I'll buy parts to make my own.
sixshooter, good point on moving the subframe back actually reducing traction. Hmm. I kind of doubt I'm going to move it back now.
Got an email today, AXLES should arrive on Thursday!!!! Going to try to find some time to get the diff built before the axles arrive if possible. I got all the parts I think. I had to buy some more tools since apparently building a 8.8 takes a few different tools but I think I got everything now. I'll take some pics once that gets rolling and post them. Definitely will post pics of axles once they arrive. Hope they fit right, they have different inner stubs to fit the explorer 8.8 vs the normal cobra/thunderbird 8.8 most folks run.
This 8.8 is putting up a big fight. Spent a few hours trying to figure out why one of the bearings I bought didn't fit. Turns out my diff has a bigger pinion bearing than the regular 8.8. In fact, the 2013-2015 GT500 has a 8.8 with a bigger pinion bearing, and turns out the explorer diff has the same size rear pinion bearing. It was 103 bucks from the local Ford dealer, and had to be ordered, and no there is literally no company that makes an alternative bearing, go figure.
So I got all the bearings now, and shims and parts and blah blah. Made up the shims for the solid pinion spacer. Put it together with old mock-up bearings and the pinion was loose. So.... Crap. If I assemble it with good bearings and the pattern is off requiring new shims behind big bearing on pinion, that sucks. Cause I destroyed the old shims removing that bearing last time. Also, removing that bearing is awful. I'm using mock up bearings now, the old ones with the center ground out a big so they are no longer a press fit.
Ok, boring talk. Time for pics! Axles arrived. For reference I have a stock miata top, then a MSM axle, then the driveshaft shop level 5 axle.
The 8.8 Case is a lot wider/taller/etc. It looks like it goes in a dump truck. I'll take a pic of it next to my MSM diff when I remove it. I don't think the axle shaft length will matter for compression, the axle doesn't compress the CV's do and they should have plenty or range of motion, or at least I hope so!
Update!
So I got the 8.8 diff built finally. New diff specs are
Explorer 8.8 aluminum Housing
Detroit TrueTrac LSD
3.55 Ford gears
All new bearings/races, all Timken or Ford/Koyo, all new seals
Solid pinion spacer installed/no crush sleeve for extra strength.
Ended up having to buy several tools, and it took me like 3 days to get that diff built correctly. This diff fought me the whole way. Wrong bearings, broken bearings, missing spacers in spacer kit, trying to get all the parameters right and the pattern right too, and my inexperience and caution trying to not mess it up! The pinion spacer thing is a huge pain. Getting the preload just right was a nightmare. I swear I took the diff apart/assembled the pinion like 70 times it seems. The carrier about 30 times. The new diff was not the same as old diff, so old shims didn't work on it. Given I probably will never make enough power to fail a stock crush sleeve, I probably should have just used one of those.... But at least it's done now, so that "weak link" is no longer in the diff. Pretty sure this 8.8 could handle 1k hp reliably now.
New diff is setup for 10 though backlash, pattern looks great, and I put 5-6 thousands preload on both sides of carrier bearings. Pinion preload was 20 in-lbs. Diff is basically ready to go now, just need to RTV the cover on and pop in the axle seals. I took a few pics, will post those soon. Didn't take any pics till I was putting the carrier together though.
I got my Subaru apart currently to do some repairs that popped up on it (some leaky hoses causing a bad idle) once it's fixed I'll probably procrastinate for another 2 weeks and then pull the MSM diff and start working on putting the 8.8 in the car.
the hub end of those axles looks considerably different. Have you test fitted them yet?
The axles come with custom hubs that have been machined to accept the larger spline of the new axles. The axles do fit the hubs. I haven't installed the hubs into the car yet though.
Got my subaru fixed so now time to procrastinate until I decide it's time to put the 8.8 in!
I found a shop that sells RX7 8.8 swap kits. I'm going to buy some parts from them. They have what I think will bolt right to my 8.8, and then bolt to the stock miata subframe where the stock diff bolts. Their part looks really nice, it's this:
It will bolt to my diff, but I don't know if it will locate the diff in a way that it fits the stock subframe. If it does hit the front of the subframe, if it's not bad I'm modding the subframe. Hopefully it just bolts in and works. I can fab front diff mounts a lot easier.
I like that. I've seen some similar kits that hold it by the case holes. Seems weird to me but I guess it's the accepted mounting solution. It's cool how it uses stock subframe mounts.
Yeah I'm not a huge fan of the miata 8.8 kits, none of them look as strong or rigid as this one. The explorer diff has a unique case cover so I was hoping to use it to do the mounting system, but given the time/money that would take I'm just going to buy their cradle and hope it fits with the miata. Will speed up the 8.8 swap a lot if it works. If it's not usable then I'll build my own setup or mod theirs to make it work. I do like it using the stock mounting points, that's a fairly big selling point to me. Their parts are still in production, haven't taken my money yet so probably be 2.5-3 weeks before I receive it.
I think the "hold it by the case bolts" thing is pretty common with diffs that were originally designed for live axle applications where you don't bolt the diff to anything.
I wouldnt worry about it, the case seems thick and the clamping load of that many big bolts is a ton. If you really were worried you could add some triangulation to actual mounts on the diff.
Small update. The diff part I ordered was delayed, so although it should be here by now, it has not shipped yet. Supposedly should ship out on Monday though, so HOPEFULLY gets here by the end of next week.
I did some looking around, and for 350 bucks I found a company on SummitRacing that will make a custom driveshaft that includes the slip yoke and tube, but not the rear flange yoke. It's pretty much a drag racing spec driveshaft (chromoly 3" DOM tubing, 1350 spicer U-joints, TIG welded, steel slip yoke), something that I will never be able to break. It's kind of funny, the stock driveshaft is probably the only thing I've never broken. Anyways The plan is to order a rear flange yoke, install diff, fab new rear transmission hanger, then measure and order a new driveshaft.
A buddy of mine is setting up to sell nitrous, and he's offered to fill bottles for a pretty reasonable price. It's tempting to put some nitrous back on the car. The problem is the car doesn't have the safety requirements to go as fast as it could with nitrous, so while it would be faster I would just get kicked off the track. If I go cheap, I'm thinking single fogger 75 shot, and spray it out of the hole to get the turbos spooled fast, and to get a good launch. Would like to do direct port but it's much more expensive to buy.
04-13-2017, 08:26 AM
1
