Front diff mounting bolts - can they be too long ?

[Kingbrown]

The plot thickens !

I took a few measurements and find that a lower control arm pivot bolts has the same diameter but is about 12mm longer than the bolts for the front mounting of the diff.

Long bolts are also used for attaching the front suspension rear crossmember.

Could someone have mixed up these bolts during assembly ?

The lca pivot bolt has a square end (as do the rear crossmember bolts), whereas the diff front mount bolt has a tapered end.

Can you use a finger to feel up where the problem bolt is touching the lca to see whether it has a square or a tapered end ?

[Jayctee]

LHS bolt has a tapered end. I pulled the wheel off and got a good look and a reasonable pic.

[Jayctee]

From the zoomed in pic from the mirror on the arm, you can see the groove cut in the LCA. Fortunately I have done mostly beach and bitumen driving. A few hundred k's of corrugations would have done more damage. The Fulcrum people, as they do, advised that a control arm may fail with the damage from the bolt cutting into it.

[Jayctee]

Pics not included in previous post.

[Kingbrown]

The end of your bolt looks like a square ended one to me, not tapered.

Also, do you have a gap between the front diff mount bushing and the metalwork where the bolt passes into the nut ?
Or are the components squeezed hard up against each other ?

Through the gap on mine I can see the rubber of the diff mount bushing.

[Jayctee]

The end is definitely tapered. It is not the bolt at the top of the photo, it is the bolt on the LHS. The other "cut" photo of the bolt end taken by Fulcrum with the "mirror on the stick" shows the taper as well. Yes there is a gap, similar to your photo.

[Jayctee]

I have just checked the clearance from the end of the bolt to the LCA on 3 Tritons which have the same front suspension. I can easily get my finger in that space. Nothing like the zero clearance on my Challenger. I have an appointment with the Mitsy dealer tomorrow. We'll see.

[nj swb]

I am the first to admit I am heavily prejudiced in this area, but I expect its a problem created by the company that did your wheel alignment. I would not trust them to do anything more than minor toe corrections.

Did they give you a full print out of your wheel alignment parameters? Did Fulcrum review wheel alignment specs?

Good luck - I foresee great frustration before this is over.

[old Jack]

The 2 bolts on the forward attachment are Part Number MU000492, theses are a flange head bolt with a tapered thread lead in. The rear attachment bolt is a MU000493 this is a longer bolt and has a conventional squared off threaded end.
My suspicion is the wrong bolt has been fitted.

OJ.

[Jayctee]

Hi nj swb, BJs gave me the print out of the before and after figures. Only minor adjustments. But... what they do under the vehicle, you never know.
Fulcrum put the car on the hoist - looked at the length of the bolts - and said "a wheel alignment will not fix that noise - forget it, the bolts are too long, they need replacing - no charge"

old jack - the bolts have a tapered end, but that part is not threaded, the thread starts after the taper reaches the full diameter of the bolt.
Thanks guys, I hope tomorrow will shed new lights !!

[old Jack]

Front bolts MU000492.

https://partsouq.com/en/search/all?q=MU000492

OJ.

[Jayctee]

Thanks old Jack, that looks the same shape as the ones I have. Are you able to get any dimensions on that bolt, ie total length from washer, and thread length ??

[old Jack]

Thanks old Jack, that looks the same shape as the ones I have. Are you able to get any dimensions on that bolt, ie total length from washer, and thread length ??

Without taking the bolt out I believe it is a Flange Head, 12mm diameter, 55mm plain shank, 25mm thread length and 3 mm tapered lead in.


OJ.

[Just Cruzin]

Sometimes the part number reflects the bolt specs.

[Jayctee]

Thanks OJ and Just Cruzin.

Step 1 - Monday 18 March, 10 am. The Mitsubishi dealership have inspected the suspension on the hoist (again), and have agreed that the bolts are incorrect and too long. I left the car with them - on the hoist The LCAs to be stripped down, damage photographed, and sent to MMA for appraisal. I have requested the photos also.

I also drew their attention to the 2 leaking rear shock absorbers. The leak was only evident on the hoist when the wheels were hanging down. The dealer did not notice this at the 5 year "pre -end of warranty" service on 28 February. MMA were to be contacted about that as well. Thanks to Fulcrum.

Step 2 - Wednesday 20 March 12 pm. Went to Mitsubishi dealer today to be advised that the photos of the "diff mounting bolts contacting the LCAs, and the 2 leaking shock absorbers" had been submitted to MMA. I viewed their photos on their monitor - not much better photos than I had already. Dealer awaiting reply from MMA. The LCAs were not dismantled to view damage and no photos have been sent to me.

Step 3 - Monday 25 March 1pm. Mitsy dealer advises the bolts are too long, ie incorrect for purpose. MMA have given approval to replace the 2 control arms and the diff mounting bolts. MMA has also agreed to replace the 2 leaking rear shock absorbers, BUT I will have to pay for the labour to install them. These 2 photos were taken immediately after the 5 year (end of warranty) service - the car had travelled about 200 klm on Brisbane roads since that service. I would have expected that the leaks would have been noticed at the service. The Mitsy dealer mechanic advised me that MMA would not be likely to replace shocks with that amount of leaking. QUESTION : - Is that a small/medium/large/severe shocky leak that should have been replaced at the 5 year service ???

Step 4 - Thursday 28 March 1130 am. Notified by Mitsy dealer that car is repaired. 2 new LCAs, 2 front diff cross member bolts and 2 new rear shocks. I paid labour of $160 for fitting shocks.
HOWEVER - when I took PC for a freeway test run there was a shudder coming back through the steering wheel for 98 kph to 110 kph !!! All OK up to that speed. Phoned Mitsy dealer who advised that the wheels were probably out of balance.
BJ's had done a 4 wheel alignment, rotation and balance on 4 March, 180 klm prior to this. Decided to take it back to Mitsy - as they were the last to touch anything. Paid for 4 x wheel balance - front and rear wheels were out of balance by up to 20 grams. Will go for freeway test run - asap.


Step 5 - Friday 29 March. Freeway test drive - all good, PC drives as good as new ! Wheel balancing fixed the shudder. Thanks everyone for your contributions to this dilemma !