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Shortened 240 trailing arms.

jonah

jonah

Pastafari !
Joined
Jun 9, 2008
Location
Staffordshire, UK
I'm planning a b230fk/m90 swap to replace the b200f/m47 in my '93 240 Torslanda, I understand this means the driveshaft will require modification as it will be too short.

So, I'm thinking this would be a good time to shorten the rear trailing arms a little (and torque rods obviously) to pull the rear axle forward and centre the wheel in the wheelarch, should help with wheel/tyre clearance and will certainly look better.

Has anyone done this? Is it a bad idea?
 
makes sense to me, was thinking about doing somethig similar now that I lowered mine. Wheels get outta whack in the well, laterally and fore/aft. What I was unsure of was any changes in the geometry/handling with the length of the arms changing, but if everything is changed the same, shouldnt matter much.
 
You might consider using adjustable torque rods, I sell them and IPD sells them.

It will be easier and less stressful then trying to get length correct by cutting and welding.
 
First, swapping the drivetrain will not affect the length of the rear driveshaft. The distance from the center support to the pinion flange remains the same. I have an M90 attached to a whiteblock in my 240 and it doesn't affect the rear driveshaft at all.

Second, I believe the M90 is shorter than the M47- or maybe very similar in length. Therefore the front shaft will need to be longer, not shorter. It's a very short transmission.

Third, you can only change trailing arm length within the constraints of what creates an acceptable pinion angle. Centering the wheels after lowering by shortening the torque rods is nice, but adjustable ones will do that as has been said. But you can't just go screw the pinion angle.

I would be very careful about changing the trailing arms, especially making them shorter. Measure the pinion angle and work backwards from there.
 
JW240: Yeah, I already have your project thread bookmarked. :)

blkaplan: I had considered adjustable torque rods, but they become quite expensive when you factor in shipping to the UK, and I wondered if there would be enough adjustment on them if the whole axle is being moved forward say 30mm? (that's just a guesstimate)

Captain: I think I may have been a little vague in my original post. What I meant was, fitting an M90, and pulling the rear axle forward would both need driveshaft mods (although at different ends), so it would appear to make sense to have all the driveshaft work done at the same time.

I know, from JW240s project thread, that the M90 is shorter than the M47, that's why I said "I understand this means the driveshaft will require modification as it will be too short".

I've read about the need to correct pinion angle after lowering, and as my 240 has -40mm springs it could probably benefit from a tweak in this area, but I hadn't considered how shortening the arms would effect this too. Food for thought.

I have some spare trailing arms and torque arms I can experiment with, I guess I should just get on with it.

Thanks for all the replies.
 
^^^ Thanks, I see there is also a link in Noah's thread to visti's 240, and he mentions pulling the axle forward by shortening the trailing arms. I wonder if he has any pictures...
 
Shortening the trailing arms will decrease the suspension travel arc's radius, increasing the roll steer. Roll steer is the steering effect that occurs when the axle is not perpendicular to the chassis centerline due to uneven compression of the rear suspension (i.e. roll). It's generally not good and people lengthen trailing arms to minimize it. I'm no expert, so I am not sure if it would be good, bad, or neglible for your needs/desires/goals, but I wanted to mention it as it is something to be aware of.
 
Would it be fair to assume that my 240 with lower and stiffer suspension will be affected less by roll steer than a 240 with stock suspension?
 
I'm having the rims reversed on some Peugeot 17" steelies, so I can play with the offset to a degree, but it seems sensible to pull the axle forward to give myself extra clearance before I have the wheels finished.

I'm not trying to fit very wide wheels, I'll be going with 205/50s on 7s on the front and 225/45 or 235/45 on 7.5s on the rear, but I do want to correct the ridiculous narrow rear track that makes 240s look so lame.
 
7.5x17 ET7 with 235/40 have been fit to a 242 with the lips trimmed to leave about 5mm of the lip. If you rolled the lip flat after trimming, it shouldn't rub even when lowered. Rear suspension links were all stock and the car was lowered a couple inches at least.

If you're set on pulling the axle forward, go for it. But it's not really necessary. Making the rear track wider is OK if you are adding grip to the front. Otherwise, you're just making the car understeer worse, especially if you put wider tires on the rear as compared to the front.
 
I'm pretty set on doing this, and I'm happy to tune the car's handling around the wider rear tyres and track. I'm intending to use coilovers on the front so I can add negative camber to help add grip.
 
Decided to have a go at this with a mate who can weld, and has lots more tools than me. :-D

Measured the distance between front bush and shock mount as approx 425mm, so decided to shorten them 25mm and make it a nice round 400mm.

Edit: I discovered that when I came to fit the arms onto the car, I had made them a little too short to work with the wheel offset and tyre size I wanted. I could've used a slightly smaller rear tyre. but decided to shorten a second set of trailing arms approx 15-17mm instead of 25mm.

Cut the arms in two:

N95pics239.jpg


Bolted into this Heath Robinson contraption :-P :

N95pics240.jpg


Front fits inside the rear section beautifully:

N95pics241.jpg


Cut the ends of the lip off the front section at the top:

N95pics233.jpg


And the rear section at the bottom:

N95pics232.jpg


Lined up:

N95pics242.jpg


Tacked:

N95pics244.jpg


Welder in action:

N95pics245.jpg


Done:

N95pics246.jpg


One down, one to go:

N95pics238.jpg


Seems a good time to add some extra reinforcing plates to the top and bottom of the arms, and I'm thinking a coilover mount would be nice too...
 
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Hi Jonah.

Is't complete safe to to this operation, just make a decent weld.

I have been driving with my trailingarms shortened for many years now with no problems and doesent feel any damage to the cars handling at all:) but makes a big different to the fitment of wide wheels without pulling out the rear fenders.

Go fore it..:cool:

Visti.
 
Now i can se the pictures. God idea with the cut in the middle of the arm, Great job.:)

And what a fine FH 12 you was driving, they are mutch better to drive than the old F12.

But i have never seen a trailer like the one you are driving with, the roof is aerodynamic in the front, we don't have them in Denmark ore the nordic contrys.

Visti.
 
Yeah thanks Visti, I'm really happy with the result. Probably won't get them on the car until summertime though.

There are quite a lot of the streamlined double-decked trailers in the UK now, more pallets = more money! Must be careful of bridges though...

I've never driven an F12, I'd really like to, or maybe an F16. :)

My favourite truck of all time F88/F89.

f88.jpg
 
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jonah said:
Yeah thanks Visti, I'm really happy with the result. Probably won't get them on the car until summertime though.

There are quite a lot of the streamlined double-decked trailers in the UK now, more pallets = more money! Must be careful of bridges though...

I've never driven an F12, I'd really like to, or maybe an F16. :)

My favourite truck of all time F88/F89.

f88.jpg
Click to expand...

What a great photo:) How high is your streamline trailers?

Take a look here http://www.youtube.com/watch?v=Go8dWSTSNAg

And Look what i have got by my parents house.

http://www.bilgalleri.dk/alb_vis.aspx?albumid=37099

And take a loke at my other albums.

http://www.bilgalleri.dk/alb_vis.aspx?albumid=37302

http://www.rcgalleri.dk/html/alb_vis.asp?AlbumID=1645

Greetings Visti.
 
The streamline trailers are 16ft, about 4.87m high.

Wow, some very nice trucks there Visti, and you have an F89! Love it! :hyper: Are you restoring it? And an F86 too?

This is some outfit :omg::

27931_l.jpg
 
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