DIY - IFS rear springs into solid axle rear - Updated
Posted: Thu Apr 28, 2005 10:05 pm
DIY – Hilux IFS rear springs into solid axle Hilux rear.
Tools:
Quite a few people have done this mod to their lux’s with positive improvement in rear flex. As they say there is more than one way to skin a cat and so it is with IFS rears (IFS stands for Independent Front Suspension). I will go through the process that I did but im sure others will also include their methods.
I would firstly like to recommend that you get your hands on a Gregory’s manual of your lux. Not only will it help you to do this mod, but will help you to do other mods on your lux and also let you get to know your fine choice of truck
. You will be able to remove your stock springs and shocks with this manual so I wont go into it in detail here. Putting your IFS springs back in is a reverse of this but with some obvious differences.
Along with the leaf springs, your going to need a shackle to suit. The stock one is insufficient so you will need to either make some yourself or you can purchase shackles from the various 4x4 shops around. If you want to make your own its very simple (provided you have the right tools) and I will outline it now for those interested otherwise buy your shackles and scroll down to the Putting in the springs! bit.
Shackles
To make a pair of shackles you will need:
You want the 2 pieces of SHS to be as wide as the bushes are installed into the spring. Its around 72mm but I got them cut to 73mm to allow a little clearance, too small and your springs wont fit, too big and they will be too loose. Another thing to note, and the reason im using washers is, you want the non threaded part to be as long as the inside of the shackle and the thread begining inside the plate so that the thread doesnt chew the bush and their is enough thread so that the nylock will be tight against the plate. I couldnt get a bolt that was perfect to my needs so i used washers to get it right.
Now you need to measure out your drill holes. 200mm eye to eye is good so measure in 30mm from each end to the centre of the bar and centre punch these markings. Measure the distance between the 2 marks making sure its 200mm. Start with a 4mm hole then work your way up to 18mm. It’s a good idea to drill the plates in pairs so that the holes line up perfectly and mark them as pairs. You really need to use a pedestal drill for this, you may be able to get away with a hand drill but I wouldn’t recommend it, either get them drilled up by someone else or just get the shackles already made.
Its a good idea to take the corners off as youll see in the pics if you dont they will hit the shackle hanger. Make sure you do whatever you want to do with the plates before you do the next step of welding in the brace.
Measure the centre point long ways on the plates and mark it on the 10mm side. Measure the width of the SHS at each end and mark the centre and then use a square making sure both marks line up as well as being square to be sure your right and mark a line along the SHS brace.
Line up the pieces centre to centre in a H configuration lining up all your markings and G-clamp it all together. Get your bolts and make sure they will fit and line up within the shackle. Tack it in place. Now that its tacked in at least 4 spots take off the G-clamp. Weld the outside of the brace into place. Before you complete the welds on the inside corners you’ll need the threaded rod, bolts and washers. You want to use this to keep the plates from warping and bending towards each other while your welding. Set it up as:
\\\B|W|Plate|W|B\\\\\\\\\\B|W|Plate|\\\\\\\\
Where:
Tighten the 2 bolts on the left plate to hold the rod in place and tighten the other bolt on the right hand side so that when you measure between the plates its 72-73mm (or the width of your bush/spring) and then increase it by 2mm (to 75mm) as they will flex in a little bit after welding. Start welding the corners in. After each weld run cold water over it to cool it down. Make sure its completely cooled down to room temperature before you take out the threaded rod. With any luck they didn’t warp at all and you can go and see if they will fit around the bush neatly. If they do bend inwards you can use the threaded rod and bolts to fix it by expanding to 75mm and heat it up with an oxy or blow torch, then cool it and remove.
That’s it you can check if your bolts will go through nicely again or clean it up and paint it.
If you have a pedestal drill you can make your bolts greasable quite easy. You just need to take care to keep everything dead straight. Drill a 2mm hole as deep as you can into the bolt then using a piece of wire or skewer measure the depth of the hole then mark out on the bolt and drill this into the middle. I got about 25mm inside where the bush would be. I got 6mm grease nipples so drill a 4.5mm hole and tap into the end of the bolt and your done. Keeping things dead straight is the key!
Putting the springs in!
Start by putting in the springs at the hanger end making sure to grease up the anchor pin and bushes with the grease supplied with the bushes. Put the shackle in its hanger and then proceed to line up the shackle and spring and put the bolt in. Grease up everything, especially if you don’t have greasable bolts. If you got the springs out using the Gregory’s manual then this is pretty straight forward. The diff housing should be on stands in place with a jack under the centre. Maneuver the diff housing and sit the springs in the perch making sure the bolt holding the spring pack together slots into the notch on the perch. While I was at it I decided to get a u-bolt flip kit, there is no reason why you couldn’t source your own u-bolts and plate to make your own kit. So instead of using the stock u-bolts and plate, secure the spring in place with the flip kit. Don’t over tighten just get them firm you don’t want to stress or stretch the u-bolts. You’d want to check once a week for a month or so just out of safety make sure the bolts aren’t coming loose. There are torque values in the manual for the bolts but I don’t have a torque wrench. RTFM its good
Shocks
I opted for a Snake racing mounting kit for the shocks. 2 mounts on the front of the diff housing and 1 cut so that it mounts on the tube cross member. I mounted them on the outside of the diff seams about 6 inches back from the hubs, but its up to you what angle you want for your shocks. The top mount has to be central. Use your old shocks to mock up how everything is going to sit to make sure the eyes don’t get twisted on your shock. Weld it all in place.
Use high tensile 8.8 bolts and nylocks on your shocks if your not supplied with bolts to suit (like i was
)
Another option is making a new cross member as high as possible to allow for even longer shocks and therefore more travel.
Traction Bars
Its a good idea too to add a traction bar if you have taken out leaves from the IFS spring pack. The traction bar solves axle wrap problems caused from softer springs and the addition of lift blocks. I have 2 leaves taken out of the spring packs in my setup but i am not running a trac bar just yet, but it will definitely be done soon, and a DIY write up on it as well
you can buy trac bars ready made if you dont want to make your own.
Widening the track
Once you put the IFS springs in the rear the flex youll get will cause your tyres to rub on the chassis (if your running 12.5" tyres). There are a few solutions to this problem. You could offset or cut and flip your rims, add wheel spacers, or you can put a wider diff housing in. I have gone for the IFS rear housing as everything bolts in without any dramas, you could put landcruiser housings or patrol if you wanted but they would involve quite a bit more work than using IFS housings. The diff centres bolt straight in, the spring perches are identically spaced to the solid axle rear housing, the brake line screws in perfectly and in the same position as the solid axle. The lower shock mounts had to be spaced a bit wider out on the IFS though, this was the only difference I encountered. The problem with the hand brake cable being to short when you add IFS springs to the rear can also be fixed by getting the hand brake cable out of an IFS as well. It is longer and also wider. I would only recommend using the IFS hand brake cable if you use the IFS housing as the cable will be too long between the brake drums on the solid axle.
The brake line
After adding in the wider rear housing i would definitely extend the brake line. Even with the travel being limited by the tyre rubbing on the chassis with the solid axle housing, the stock brake line is almost maxing out at full travel. You can buy extended brake lines from 4x4 shops, or you can take your stock one to a brake specialist and they can extend it to whatever size you wish. I had a new brake line made up 200mm longer than stock, and this seems to be just about right.
Heres some useful links relating to the subject:
IFS rears into rear of gen 2 hilux
IFS rear axle into rear of Solid Axle LN106 Hilux
IFS Bushes
IFS Rear Springs
IFS Springs in rear
Single link trac bar
MQ/MK trac bar
Pics of working trac bars
Tools:
- Socket set, shifter etc
Welder
Pedestal drill and bits
Square
Pencil and texta
Grinder with cutting and grinding discs
12mm or so threaded rod with 3 bolts and washers
Quite a few people have done this mod to their lux’s with positive improvement in rear flex. As they say there is more than one way to skin a cat and so it is with IFS rears (IFS stands for Independent Front Suspension). I will go through the process that I did but im sure others will also include their methods.
I would firstly like to recommend that you get your hands on a Gregory’s manual of your lux. Not only will it help you to do this mod, but will help you to do other mods on your lux and also let you get to know your fine choice of truck
. You will be able to remove your stock springs and shocks with this manual so I wont go into it in detail here. Putting your IFS springs back in is a reverse of this but with some obvious differences.Along with the leaf springs, your going to need a shackle to suit. The stock one is insufficient so you will need to either make some yourself or you can purchase shackles from the various 4x4 shops around. If you want to make your own its very simple (provided you have the right tools) and I will outline it now for those interested otherwise buy your shackles and scroll down to the Putting in the springs! bit.
Shackles
To make a pair of shackles you will need:
- 4 x 260mm lengths of 50mm x 10mm flat bar
2 x 50mm x 50mm x 3mm SHS (Square Hollow Section)
4 x 18mm high tensile 8.8 bolts, 2 washers and a nylock for each one.
You want the 2 pieces of SHS to be as wide as the bushes are installed into the spring. Its around 72mm but I got them cut to 73mm to allow a little clearance, too small and your springs wont fit, too big and they will be too loose. Another thing to note, and the reason im using washers is, you want the non threaded part to be as long as the inside of the shackle and the thread begining inside the plate so that the thread doesnt chew the bush and their is enough thread so that the nylock will be tight against the plate. I couldnt get a bolt that was perfect to my needs so i used washers to get it right.
Now you need to measure out your drill holes. 200mm eye to eye is good so measure in 30mm from each end to the centre of the bar and centre punch these markings. Measure the distance between the 2 marks making sure its 200mm. Start with a 4mm hole then work your way up to 18mm. It’s a good idea to drill the plates in pairs so that the holes line up perfectly and mark them as pairs. You really need to use a pedestal drill for this, you may be able to get away with a hand drill but I wouldn’t recommend it, either get them drilled up by someone else or just get the shackles already made.
Its a good idea to take the corners off as youll see in the pics if you dont they will hit the shackle hanger. Make sure you do whatever you want to do with the plates before you do the next step of welding in the brace.
Measure the centre point long ways on the plates and mark it on the 10mm side. Measure the width of the SHS at each end and mark the centre and then use a square making sure both marks line up as well as being square to be sure your right and mark a line along the SHS brace.
Line up the pieces centre to centre in a H configuration lining up all your markings and G-clamp it all together. Get your bolts and make sure they will fit and line up within the shackle. Tack it in place. Now that its tacked in at least 4 spots take off the G-clamp. Weld the outside of the brace into place. Before you complete the welds on the inside corners you’ll need the threaded rod, bolts and washers. You want to use this to keep the plates from warping and bending towards each other while your welding. Set it up as:
\\\B|W|Plate|W|B\\\\\\\\\\B|W|Plate|\\\\\\\\
Where:
- B=Bolt
W=Washer
\\\\\=Threaded rod
Tighten the 2 bolts on the left plate to hold the rod in place and tighten the other bolt on the right hand side so that when you measure between the plates its 72-73mm (or the width of your bush/spring) and then increase it by 2mm (to 75mm) as they will flex in a little bit after welding. Start welding the corners in. After each weld run cold water over it to cool it down. Make sure its completely cooled down to room temperature before you take out the threaded rod. With any luck they didn’t warp at all and you can go and see if they will fit around the bush neatly. If they do bend inwards you can use the threaded rod and bolts to fix it by expanding to 75mm and heat it up with an oxy or blow torch, then cool it and remove.
That’s it you can check if your bolts will go through nicely again or clean it up and paint it.
If you have a pedestal drill you can make your bolts greasable quite easy. You just need to take care to keep everything dead straight. Drill a 2mm hole as deep as you can into the bolt then using a piece of wire or skewer measure the depth of the hole then mark out on the bolt and drill this into the middle. I got about 25mm inside where the bush would be. I got 6mm grease nipples so drill a 4.5mm hole and tap into the end of the bolt and your done. Keeping things dead straight is the key!
Putting the springs in!
Start by putting in the springs at the hanger end making sure to grease up the anchor pin and bushes with the grease supplied with the bushes. Put the shackle in its hanger and then proceed to line up the shackle and spring and put the bolt in. Grease up everything, especially if you don’t have greasable bolts. If you got the springs out using the Gregory’s manual then this is pretty straight forward. The diff housing should be on stands in place with a jack under the centre. Maneuver the diff housing and sit the springs in the perch making sure the bolt holding the spring pack together slots into the notch on the perch. While I was at it I decided to get a u-bolt flip kit, there is no reason why you couldn’t source your own u-bolts and plate to make your own kit. So instead of using the stock u-bolts and plate, secure the spring in place with the flip kit. Don’t over tighten just get them firm you don’t want to stress or stretch the u-bolts. You’d want to check once a week for a month or so just out of safety make sure the bolts aren’t coming loose. There are torque values in the manual for the bolts but I don’t have a torque wrench. RTFM its good
Shocks
I opted for a Snake racing mounting kit for the shocks. 2 mounts on the front of the diff housing and 1 cut so that it mounts on the tube cross member. I mounted them on the outside of the diff seams about 6 inches back from the hubs, but its up to you what angle you want for your shocks. The top mount has to be central. Use your old shocks to mock up how everything is going to sit to make sure the eyes don’t get twisted on your shock. Weld it all in place.
Use high tensile 8.8 bolts and nylocks on your shocks if your not supplied with bolts to suit (like i was
)
Another option is making a new cross member as high as possible to allow for even longer shocks and therefore more travel.
Traction Bars
Its a good idea too to add a traction bar if you have taken out leaves from the IFS spring pack. The traction bar solves axle wrap problems caused from softer springs and the addition of lift blocks. I have 2 leaves taken out of the spring packs in my setup but i am not running a trac bar just yet, but it will definitely be done soon, and a DIY write up on it as well
you can buy trac bars ready made if you dont want to make your own.
Widening the track
Once you put the IFS springs in the rear the flex youll get will cause your tyres to rub on the chassis (if your running 12.5" tyres). There are a few solutions to this problem. You could offset or cut and flip your rims, add wheel spacers, or you can put a wider diff housing in. I have gone for the IFS rear housing as everything bolts in without any dramas, you could put landcruiser housings or patrol if you wanted but they would involve quite a bit more work than using IFS housings. The diff centres bolt straight in, the spring perches are identically spaced to the solid axle rear housing, the brake line screws in perfectly and in the same position as the solid axle. The lower shock mounts had to be spaced a bit wider out on the IFS though, this was the only difference I encountered. The problem with the hand brake cable being to short when you add IFS springs to the rear can also be fixed by getting the hand brake cable out of an IFS as well. It is longer and also wider. I would only recommend using the IFS hand brake cable if you use the IFS housing as the cable will be too long between the brake drums on the solid axle.
The brake line
After adding in the wider rear housing i would definitely extend the brake line. Even with the travel being limited by the tyre rubbing on the chassis with the solid axle housing, the stock brake line is almost maxing out at full travel. You can buy extended brake lines from 4x4 shops, or you can take your stock one to a brake specialist and they can extend it to whatever size you wish. I had a new brake line made up 200mm longer than stock, and this seems to be just about right.
Heres some useful links relating to the subject:
IFS rears into rear of gen 2 hilux
IFS rear axle into rear of Solid Axle LN106 Hilux
IFS Bushes
IFS Rear Springs
IFS Springs in rear
Single link trac bar
MQ/MK trac bar
Pics of working trac bars
Essentually you need to flex the car and measure the shortest distance from eye to eye. that's the compressed length of the shock you require.
