Solid-Axle Conversion?

[Dave-O]

Now now, don't start throwing bricks and stones at me just yet ...

 

I've been considering different IRS options for the rear of my Starion, including Cobra, Nissan S-chassis, Mazda FC RX7, etc. etc. ALL of these will require custom rear subframes to mate the suspension locations of the cars they came from, to the frame of the Starion.

 

Then I got to thinking about solid axles. I've been doing a lot lately with older Corollas, Supras, and Mustangs, and having driven several of them in a relatively hot manner, I can't really complain about the handling. One of the Mustangs I've driven recently is a Solo2-prepped '03 GT, with a number of suspension and brake upgrades. To say the car stuck, is an understatement. Even on BFG KDWs it wouldn't slide on a full-throttle corner exit, and I think it's due to the rebuilt OEM TrakLok diff.

 

I figure it'd be stupid easy to fab up a panhard bar, the appropriate mounts, and lower arms to mount an 8.8" rear axle from a '99-'04 Mustang.

 

Thoughts? Suggestions? Links to where it may have been done before if it by chance has? Thanks in advance fellas.

[smallblock12]

are you planning on drag racing it? what are you seting it up for? i always wanted to look into puttin a late 80's camaro diff in but ill likely never make enough power to need that customization

[strang3majik]

put a Dana in that biotche

[D_Venable]

Toyota small pickup rearends have been done before, similar width, and they keep the 5x114.3 hub, so you can keep stock rims if you so choose.

 

if you do a 4 link suspension, you might be able to adapt it the stock rear subframe if you so choose.

[Dave-O]

The car would be set up for pretty much everything, but there would be a basic emphasis on cornering and braking ability. The Starion will see track days, weekend canyon carving sessions, and the occasional drift event. My ideal suspension setup uses very little toe and camber in the rear, as I prefer a more loose-handling rear for my driving style.

 

A solid axle is not necessarily a handling hinderance in my eyes. Also as I was considering Cobra/GT front knuckles and hubs, I figure it would be best to keep the same brand in the rear. I'm most familiar with Ford TrakLok diffs and axles, which is why I'd consider it for such use. They can obviously take heavy punishment, have plenty of gear and diff options, and are very common even with new vehicles. Not to mention the bolt pattern is the same as our cars (compared to 5x5" for most common RWD GMs) and the track-width is relatively similar (60.5" from hub to hub, the narrowbody Starions are listed as having a 55" track-width, with a 66" body-width, I haven't found specs on the widebody cars in my brief search). The axle should also free up some room for exhaust piping.

Edited August 2, 2009 by Dave-O

[D_Venable]

widebody rear suspension is the same as the flatty rear. the body is just about 2-2.5" wider, just based on offset comparisons (18mm for all corners on the flattys, and -10 on the rear 8's of a non-SHP widey wheel

 

SO, you might be able to run front 8's on the rear with the 60.5" axle

[strang3majik]

just so you know....I was serious...lol

[Dave-O]

I'll probably test-fit the axle with my pair of SHP 9"s, and if that's too wide I'll step down to 8"s. My original plan is to run a 17x10.5"+20 in the rear with a 17x9"+24 up front, and enough tire to fit square on the wheel.

 

The suspension design I'm thinking of will be a short-enough stroke that a panhard bar should suffice for axle centering, though I'll probably dig up some info on 4-links and see if maybe that would be the better route. I'll most likely use a setup originally intended for an S13 just to simplify things.

[D_Venable]

the SHP 9's will be too wide.

 

the flatty has the same rear track width as a widebody. You say that's 55", and then your axle is 60.5". That's 5.5 " wider, so 2.75" farther out per side.

 

Now imagine running a 2.75" wheel spacer on the back, with the SHP 9's, not gonna work

[Dave-O]

Hmm. Guess I'll have to keep the 9"s for the front.

 

I think I'll need to take some measurements for myself to see this first-hand before I dive in.

[JustPaus_88TSi]

What about the stock rear do you think needs replaced?

[BrazilBoy]

Your going backwards in technology by going solid...imo

 

[Rick357ci]

I am curios too v8 is hard on diff i imagine

I want to put on some sticky tires but dont want to break the car

[BrazilBoy]

I am curios too v8 is hard on diff i imagine

I want to put on some sticky tires but dont want to break the car

 

Our rear ends hold up just fine as long as wheel hop is controlled...

[strang3majik]

Our rear ends hold up just fine as long as wheel hop is controlled...

 

The more universals, the more places to break. Our stock rears are strong, but, 500hp clutch dumps aren't good for it...especially if it sticks...where, a solid, it won't hurt it...the tranny will probably take the grunt.

[Dave-O]

What about the stock rear do you think needs replaced?

Nothing, but when I break it, I'll be hard-pressed to find a replacement. Also, it's not like we can exactly rebuild our LSDs with off-the-shelf parts, and it's a guarantee I'll wear out the LSD or possibly break a U-joint simply due to the driving I do.

 

Your going backwards in technology by going solid...imo

Sticking with a TBI G54B is going backwards in technology as well, but many people are still using it ...

 

The more universals, the more places to break. Our stock rears are strong, but, 500hp clutch dumps aren't good for it...especially if it sticks...where, a solid, it won't hurt it...the tranny will probably take the grunt.

Ding, winrar.

 

I'm only looking for a simple, durable, well-supported replacement for our rear ends.

[tim si]

2nd launch at the drag strip got my axles clicking.that little rear end is amazing but its not gonna hold up.if everything is preloaded like with an auto it would be different but dumping the clutch will kill it eventually.ive been looking at a 4-link setup with 8.8 and dont think it would hurt handling much if any.ive never been one to push my car that far anyway.if you do this,id like all the info you can give.it would eliminate alot of parts that are getting hard to find.

[Dave-O]

2nd launch at the drag strip got my axles clicking.that little rear end is amazing but its not gonna hold up.if everything is preloaded like with an auto it would be different but dumping the clutch will kill it eventually.ive been looking at a 4-link setup with 8.8 and dont think it would hurt handling much if any.ive never been one to push my car that far anyway.if you do this,id like all the info you can give.it would eliminate alot of parts that are getting hard to find.

 

Great to hear I'm not the only one considering the 8.8. I'm not sure if I'd go with a 4-link setup initially, as I've yet to actually get my hands on the actual parts and look at what could fit where, but in my experience with solid-axle cars and panhard bar setups, there wasn't necessarily a handling "decrease". Once I get an axle under the car and look at the mounting possibilities, I'll figure something out and go from there.

[JustPaus_88TSi]

We're talking about what kind of motor/tranny build here?

 

 

And this "the tranny will prolly take the grunt". LOL Seriously? The 5spd tranny will flex itself to pieces long before the rear lets loose.

 

 

I swear, you guys kill me.

[strang3majik]

We're talking about what kind of motor/tranny build here?

 

 

And this "the tranny will prolly take the grunt". LOL Seriously? The 5spd tranny will flex itself to pieces long before the rear lets loose.

 

 

I swear, you guys kill me.

 

I said, if a solid axle were to replace the stock one...the shock wouldn't hurt the rear...but, the tranny would probably take the grunt since its the weak link.

Perfectly logical statement.

And, saying the tranny would flex before the stock rear would let loose depends completley on the condition.

 

Plus...someone was talking about a V8 swap, so, the stock tranny would go bye bye anyhow.

[JustPaus_88TSi]

I said, if a solid axle were to replace the stock one...the shock wouldn't hurt the rear...but, the tranny would probably take the grunt since its the weak link.

Perfectly logical statement.

 

What's more expensive to rebuild, the tranny or a rear? Show me one part of the rearend that has failed, ever. The rear has held more power than anyone on this forum has thrown at it, from drag racing with slicks and trans brake equipped trannys(much worse than your "500hp clutch dump"), to circuit track racecars with dogbox transmissions.

 

The only thing that needs replaced is the axles.

 

 

It was a logical statement, in fact it was completely understated. The "LOL" was for the the tranny "probably" taking the grunt. It'll flex the shafts and pop.

 

 

And, saying the tranny would flex before the stock rear would let loose depends completley on the condition.

 

No it doesn't. The only other "condition" worse than drag launch stress, is losing contact and regaining it during a lap around a track. Like catching too much of a rumble strip, going airborn and not landing squarely while still on the throttle. Unless of course you have a habit of accellerating with one tire in dirt and one on the pavement.

 

The stock tranny is garbage and will eat itself long before the rearend even starts sweating.

 

Plus...someone was talking about a V8 swap, so, the stock tranny would go bye bye anyhow.

 

Which is exactly why I asked "we're talking about what kind of motor/tranny build here?"

 

[JustPaus_88TSi]

Nothing, but when I break it, I'll be hard-pressed to find a replacement. Also, it's not like we can exactly rebuild our LSDs with off-the-shelf parts, and it's a guarantee I'll wear out the LSD or possibly break a U-joint simply due to the driving I do.

 

What motor and tranny are we talking about? And don't get ahead of yourself, it is most certainly "if" you break it. People have been driving these cars "the way you do" for decades, all over the world. What is it exactly about the driving you "do" that will make you the first to grenade a rearend?

 

 

Sticking with a TBI G54B is going backwards in technology as well, but many people are still using it ...

 

That would be a correct statement if SQ's came stock with MPI and then people went TBI. Bit of a difference there, yeah?

 

 

The car would be set up for pretty much everything, but there would be a basic emphasis on cornering and braking ability. The Starion will see track days, weekend canyon carving sessions, and the occasional drift event. My ideal suspension setup uses very little toe and camber in the rear, as I prefer a more loose-handling rear for my driving style.

 

So it's more of a driving preference that fuels the idea of a solid rear, rather than actually posting faster lap times by dialing in the suspension?

 

Do you have experience with building 3 or 4 links, or access to suspension geometry software?

 

 

[strang3majik]

What's more expensive to rebuild, the tranny or a rear? Show me one part of the rearend that has failed, ever. The rear has held more power than anyone on this forum has thrown at it, from drag racing with slicks and trans brake equipped trannys(much worse than your "500hp clutch dump"), to circuit track racecars with dogbox transmissions.

 

The only thing that needs replaced is the axles.

 

 

It was a logical statement, in fact it was completely understated. The "LOL" was for the the tranny "probably" taking the grunt. It'll flex the shafts and pop.

 

 

 

 

No it doesn't. The only other "condition" worse than drag launch stress, is losing contact and regaining it during a lap around a track. Like catching too much of a rumble strip, going airborn and not landing squarely while still on the throttle. Unless of course you have a habit of accellerating with one tire in dirt and one on the pavement.

 

The stock tranny is garbage and will eat itself long before the rearend even starts sweating.

 

 

 

Which is exactly why I asked "we're talking about what kind of motor/tranny build here?"

 

The axles are part of the rear end. I apologize for any play on words, for making you think I meant the center chunk. A solid axle most likely will not break any part of it, unless it was weak to begin with. Therefore my comment on transmitting the shock to further forward components. Maybe our stock diff center chunk is strong...but, that doesn't help when it can't get to the wheels.

 

Lets face it...people have sheered the stock axels with the G54B, with a mild amount of power. I know no figures, but, i know its happened quite a few times.

Say there is a 600hp, 550lb/ft tq V8 in there, with sticky tires and a drop of the clutch....I guarentee the axles would only last a few hard launches, if that.

Put a solid rear in there, it won't break, so, as I said a few times, the shock will transfer through the driveline to the next piece...the tranny.

So, yes, a stock tranny would blow into a bunch of tiny pieces...therefore that needing replaced with a stronger, more bulletproof unit as well...but, if it was a different engine anyway...that wouldn't matter.

 

No where have I said the tranny was strong...I'm just saying, the weak axles act as a cushion for the tranny. Yes rear end work is cheaper...but, theres only so many of those parts...so...he is looking at other options, which we don't really have yet. Others have already made other trannies work...now lets move on to the rear end.

 

Also...just throwing this out there........but, why do you think all the Corvette guys switch out their rear ends if they go drag racing? Exactly, so they don't shear axles, or break any other piece of the IRS.

IRS is a proven system for the handling, and, yes, it probably would post faster lap times.

But, the solid axle is a tried and true method for putting bukoo torque to the ground, over and over again.

 

They both have their strengths and weaknesses...its all in how one prefers to use their car. Honestly, I'd rather have a solid axle...because, I'm afraid to even launch this car in fear of breaking things...whereas my Barracuda with a 360, A833 4 speed, and Dana 60 diff, I can launch all day long, and, probably only have to worry about the clutch.

Do I do this all the time? No, but, nice to know I can.

[Dave-O]

Wow, I didn't think this would spur such a debate.

 

To answer a few questions:

- Yes, I have access to proper tooling andmaterials to tackle such a project.

- Yes, I am familiar enough with the proper geometry.

- Engine/trans combination is yet to be decided, but will be below 450whp and 500ft.lbs. total output.

 

To be honest, I feel that the rear suspension design of our cars sucks.

 

Also, I'm worried about long-term durability. I will not wait for an unobtainable part to fail before replacing it. I also want adjustability, customization, and reliability. The day you can find me a new-in-box LSD rebuild package and OEM relacement axles is the day I'll be comfortable road-coursing an OEM rear with Hoosier slicks and 450whp.

[BrazilBoy]

Dave,

 

IDK man instead of dumping so much into a quest to basically only have the body left seems expensive and somewhat useless.Dave if you want an easy to fix all around track car get a 240 or mustang or something...I am not dogging your passion but keep in mind if want a truely reliable track car that has "off the shelf" parts you have to choose something much more common...

 

Just my opinion Roberto