Milesvtcalais
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- Jan 5, 2020
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- Age
- 23
- Location
- Gold coast
- Members Ride
- Vt calais
Hey guys, So I've recently put a welded diff into my vt calais and I will be answering a few questions that I see go around honestly, dont forget this is my opinion so it may be different to yours so go easy on me 
also, I bought the diff instead of welding mine because mine was buggered from 360.000ks of original oil.
1 Is a welded/locked diff better than a lsd? - Well... No I would definitely recommend spending the extra $150 dollars on a lsd over a welded diff (given I bought mine for $80) So I'd definitely recommend buying a lsd off a SS or something of the sort as they are pretty cheap.
2 Is a welded/locked diff a cheap alternative to a lsd? - If you dont have the money for a mini spool or a lsd yes a welded diff is a good option but the thought will always be in the back of your mind that the welds could break, just a precaution. And also buying a 2nd hand lsd is always risky because u dont know the life its had, for all you know you could be buying a lsd that works just like a open diff.
3 Is there more wear and tear involved with a locked/welded diff? - well so far not personally but I can definitely imagine that there will be in the future, just like everything else in a car the more you beat on it the more likely stuffs gonna break. People talk about axles breaking and bushings taking a beating and yes this may be true but I have my doubts about axles breaking, they are pretty beefy but I'm no man to call another person a liar. I can definitely imagine the bushings taking beating as they are under constant force of the tire trying to grip up and the bushing flexing to try dampen this effect.
4 How will a welded/locked diff affect the way my car drives? - this depends on what type of driving you are doing really. Imagine 2 types of people, you have one guy that lives far out and does most of his driving on the highway, he will barely notice that his diff is locked because the affects of the diff go away at any speed over 30 (in the dry.) Then you have the guy that lives in a city, he does most of his driving in the city doing tight turns and quick maneuvers, this will have a major affect on this guy because you will for sure feel the diff at lower speeds theres no getting around it. But given you do live in the city or somewhere with actual corners I'll tell you from my point of view, its noisy and it makes vibrations but if you can get past this it's also alot of fun and it gives your car alot of character. Your tires will scrub and give off a gravel road sound even on tarmac at low speeds like going from a stop into a corner or around a roundabout but that's it.
5 Is it harder to park? This is a hard one to say as it doesn't bother me personally, it does make noise and maybe my turning circle is a little bit worse but it's really not bad, if your smart and plan your lines parking is as simple as it was in a open diff car. I find that reverse parking puts alot less strain on the car as the wheel has less weight on it, I dont know the science behind it but reverse parking feels better then parking normally.
6 - Is it legal? No it most certainly is not but hold on hear me out, think about your car real quick, and now let me point out some things that could be illegal about your car. Possibly you have some sweet 19 inch wheels on your vt, well anything over the maximum size released on your model illegal (might be specific states). Your exhaust, any modification to your stock exhaust system is also illegal is it may affect with your cars smog control, also illegal if its ear wrenching loud. Tinted headlights, tinted taillights, led headlights, anything below 35% tint and the list goes on. So people do say a welded diff is illegal and yes it is but so are alot of things on your possible car. Also if you are insured and they discover your diff is welded or locked you may not be eligible for claim.
7 Would you recommend it? See this depends on very specific conditions, if you live in a busy city I would recommend a lsd but if you live in a place with long fast roads I would support a locked diff, not recommend as like I said, if you can afford a lsd buy a lsd but if you cannot just weld it until you can.
If you have any questions guys just ask because I'm happy to help
***INSTALLATION***
this is for VN Commodores fitted with IRS to VZ commodores. This also goes for any type of diff you may be installing. This is also installation instructions for people with basic hand tools, no power tools. If you do have power tools follow along and use them but if not this guide will still work
This will be in steps so follow along
Step 1 - loosen your wheel nuts
Step 2 - jack your car up from the diff with a hydraulic Jack, if this isn't available use the jack in the boot of your car from your recommended jack locations on each side of the rear of the car. Place your wheel underneath the side of the car from where your jacking it from and lower, repeat for both sides. Or even better axle stands!
Step 3 - you will want to remove anything that's in risk of being broken so your 2 abs sensors on each side of the diff (this was an option on all vehicles before vt) also dont forget to remove your breather hose from the top of the diff.
Step 4 - driveshaft bolts, if you have a vt series 1 your car will be equipped with a 4 bolt design, vt series 2 to VY series 2 was equipped with a 3 bolt rubber flange design and I believe VZ was beefed up even more but I'm not 100% sure. Anyway you will want to get a wrench on your bolt not your nut as the nut is held in by the driveshaft (only vt not sure for other models) make sure your car is in P so it doesn't spin loosen, get up put car in N so you can access the other bolt, replace shifter in P and repeat. If you are using a diff from your specific model and year car you can skip this but for everyone that is let's say putting a vz diff in a vt follow along because this will only be possible in the car if you have basic tools. Once the driveshaft is out of the way you can reach the spline or the bit that joins the driveshaft to the diff. Get some paint or a marker and mark the bolt relative to the diff so you can achieve the same amount of torque without needing a torque wrench. Make sure your parking break is on tight! And if not place a brick or a stick onto the brake pedal. Now pull as hard as you can until it gives way, trust me your gonna need a breaker bar. Only loosen this a few turns otherwise it will leak fluid.
Step 5 - remove all fluid, just remove the lowest bolt on your diff cover and the fluid will come out. Simple!
Step 6 - your axle bolts, this one is important as it's a pain in the ass by yourself. What you will want to do is get underneath the car and locate your axle bolts on the outer end of each axle. THESE WILL BE TIGHT! just take your time and be patient or you will round them out as they are all allan key types of bolt things. I would recommend if you have a basic allan key set get a bar on the end of it for more leverage. Loosen two on each side, release handbreak move hubs until the other bolts are accessible the re apply handbreak. There are 6 bolts each side so repeat this process until all bolts are out.
Step 7 - now that there isn't any connection from your driveshaft or the axles you will have to pivot the rear cradle, this is simple just get a jack underneath each hub, remove the bolts holding your sway bar on (each side) , put a small amount of pressure on the spring with the jack and loosen the Lower bolt holding the shock absorber on. Repeat for the other side. ***WARNING*** the only thing that will hold the rear suspension set up is the brake line so make sure you have something underneath your hub taking tension off the brake line. This is only so you can remove the diff with the axles still attached as most diffs do not come with axles.
Step 8 - at the rear of the diff you will see 4 bolts that are holding the diff to the body of the car, loosen these not all the way just a little until they are easy to loosen, now place a jack underneath your diff housing with preferably some wood between it and hold the diff in place until all bolts are out, now you will be able to pivot your whole diff mount to an angle where all the bolts on the top of the diff are accessible. Now you will want to completely remove the sway bar as it is in the way of the front bolts holding the diff on. It's simple as there are only 2 bolts holding it on then just twist the mounts towards the back of the car and lift. The sway bar should just easily remove at that point. Now loosen all bolts on the top of the diff and remove. Now you should be able to lower you diff and move it out of the way. So you can replace it with a fresh twin spinner
Step 9 - now that the diff is out swap your spline from your diff onto the new one (this is only for people who are putting diffs in from a different model)
Installation is the same as taking it apart just in reverse. Any questions just ask
I hope this helps some people and I can hopefully make some people's lifes easier
Thanks guys
also, I bought the diff instead of welding mine because mine was buggered from 360.000ks of original oil.1 Is a welded/locked diff better than a lsd? - Well... No I would definitely recommend spending the extra $150 dollars on a lsd over a welded diff (given I bought mine for $80) So I'd definitely recommend buying a lsd off a SS or something of the sort as they are pretty cheap.
2 Is a welded/locked diff a cheap alternative to a lsd? - If you dont have the money for a mini spool or a lsd yes a welded diff is a good option but the thought will always be in the back of your mind that the welds could break, just a precaution. And also buying a 2nd hand lsd is always risky because u dont know the life its had, for all you know you could be buying a lsd that works just like a open diff.
3 Is there more wear and tear involved with a locked/welded diff? - well so far not personally but I can definitely imagine that there will be in the future, just like everything else in a car the more you beat on it the more likely stuffs gonna break. People talk about axles breaking and bushings taking a beating and yes this may be true but I have my doubts about axles breaking, they are pretty beefy but I'm no man to call another person a liar. I can definitely imagine the bushings taking beating as they are under constant force of the tire trying to grip up and the bushing flexing to try dampen this effect.
4 How will a welded/locked diff affect the way my car drives? - this depends on what type of driving you are doing really. Imagine 2 types of people, you have one guy that lives far out and does most of his driving on the highway, he will barely notice that his diff is locked because the affects of the diff go away at any speed over 30 (in the dry.) Then you have the guy that lives in a city, he does most of his driving in the city doing tight turns and quick maneuvers, this will have a major affect on this guy because you will for sure feel the diff at lower speeds theres no getting around it. But given you do live in the city or somewhere with actual corners I'll tell you from my point of view, its noisy and it makes vibrations but if you can get past this it's also alot of fun and it gives your car alot of character. Your tires will scrub and give off a gravel road sound even on tarmac at low speeds like going from a stop into a corner or around a roundabout but that's it.
5 Is it harder to park? This is a hard one to say as it doesn't bother me personally, it does make noise and maybe my turning circle is a little bit worse but it's really not bad, if your smart and plan your lines parking is as simple as it was in a open diff car. I find that reverse parking puts alot less strain on the car as the wheel has less weight on it, I dont know the science behind it but reverse parking feels better then parking normally.
6 - Is it legal? No it most certainly is not but hold on hear me out, think about your car real quick, and now let me point out some things that could be illegal about your car. Possibly you have some sweet 19 inch wheels on your vt, well anything over the maximum size released on your model illegal (might be specific states). Your exhaust, any modification to your stock exhaust system is also illegal is it may affect with your cars smog control, also illegal if its ear wrenching loud. Tinted headlights, tinted taillights, led headlights, anything below 35% tint and the list goes on. So people do say a welded diff is illegal and yes it is but so are alot of things on your possible car. Also if you are insured and they discover your diff is welded or locked you may not be eligible for claim.
7 Would you recommend it? See this depends on very specific conditions, if you live in a busy city I would recommend a lsd but if you live in a place with long fast roads I would support a locked diff, not recommend as like I said, if you can afford a lsd buy a lsd but if you cannot just weld it until you can.
If you have any questions guys just ask because I'm happy to help
***INSTALLATION***
this is for VN Commodores fitted with IRS to VZ commodores. This also goes for any type of diff you may be installing. This is also installation instructions for people with basic hand tools, no power tools. If you do have power tools follow along and use them but if not this guide will still work
This will be in steps so follow along
Step 1 - loosen your wheel nuts
Step 2 - jack your car up from the diff with a hydraulic Jack, if this isn't available use the jack in the boot of your car from your recommended jack locations on each side of the rear of the car. Place your wheel underneath the side of the car from where your jacking it from and lower, repeat for both sides. Or even better axle stands!
Step 3 - you will want to remove anything that's in risk of being broken so your 2 abs sensors on each side of the diff (this was an option on all vehicles before vt) also dont forget to remove your breather hose from the top of the diff.
Step 4 - driveshaft bolts, if you have a vt series 1 your car will be equipped with a 4 bolt design, vt series 2 to VY series 2 was equipped with a 3 bolt rubber flange design and I believe VZ was beefed up even more but I'm not 100% sure. Anyway you will want to get a wrench on your bolt not your nut as the nut is held in by the driveshaft (only vt not sure for other models) make sure your car is in P so it doesn't spin loosen, get up put car in N so you can access the other bolt, replace shifter in P and repeat. If you are using a diff from your specific model and year car you can skip this but for everyone that is let's say putting a vz diff in a vt follow along because this will only be possible in the car if you have basic tools. Once the driveshaft is out of the way you can reach the spline or the bit that joins the driveshaft to the diff. Get some paint or a marker and mark the bolt relative to the diff so you can achieve the same amount of torque without needing a torque wrench. Make sure your parking break is on tight! And if not place a brick or a stick onto the brake pedal. Now pull as hard as you can until it gives way, trust me your gonna need a breaker bar. Only loosen this a few turns otherwise it will leak fluid.
Step 5 - remove all fluid, just remove the lowest bolt on your diff cover and the fluid will come out. Simple!
Step 6 - your axle bolts, this one is important as it's a pain in the ass by yourself. What you will want to do is get underneath the car and locate your axle bolts on the outer end of each axle. THESE WILL BE TIGHT! just take your time and be patient or you will round them out as they are all allan key types of bolt things. I would recommend if you have a basic allan key set get a bar on the end of it for more leverage. Loosen two on each side, release handbreak move hubs until the other bolts are accessible the re apply handbreak. There are 6 bolts each side so repeat this process until all bolts are out.
Step 7 - now that there isn't any connection from your driveshaft or the axles you will have to pivot the rear cradle, this is simple just get a jack underneath each hub, remove the bolts holding your sway bar on (each side) , put a small amount of pressure on the spring with the jack and loosen the Lower bolt holding the shock absorber on. Repeat for the other side. ***WARNING*** the only thing that will hold the rear suspension set up is the brake line so make sure you have something underneath your hub taking tension off the brake line. This is only so you can remove the diff with the axles still attached as most diffs do not come with axles.
Step 8 - at the rear of the diff you will see 4 bolts that are holding the diff to the body of the car, loosen these not all the way just a little until they are easy to loosen, now place a jack underneath your diff housing with preferably some wood between it and hold the diff in place until all bolts are out, now you will be able to pivot your whole diff mount to an angle where all the bolts on the top of the diff are accessible. Now you will want to completely remove the sway bar as it is in the way of the front bolts holding the diff on. It's simple as there are only 2 bolts holding it on then just twist the mounts towards the back of the car and lift. The sway bar should just easily remove at that point. Now loosen all bolts on the top of the diff and remove. Now you should be able to lower you diff and move it out of the way. So you can replace it with a fresh twin spinner
Step 9 - now that the diff is out swap your spline from your diff onto the new one (this is only for people who are putting diffs in from a different model)
Installation is the same as taking it apart just in reverse. Any questions just ask
I hope this helps some people and I can hopefully make some people's lifes easier
Thanks guys
