Front Diff and Dump Pipe Clashing

[vh202]

Gents,

I have a QD32 D22 which Ive put a turbo onto. I ended up getting a 2.5'' exhaust in a ZD30 dump pipe which runs quite close to the front differential drive shaft.

When out 4x4ing last weekend I noticed at very low revs in second gear I could hear a clanging that disappeared when revs increased.

Afterwards i got under and had a look to find that the flange and nuts on the front diffs drive shaft have been hittting the dump ipe and have damaged it slightly. Under no load there is maybe 10mm clearance between the 2 parts.

My assumption is that as it only occurred at low revs(cant remember the exact number) the engine was vibrating quite a bit causing the dump pipe to move closer to the drive shaft and interfere. Ive taken it to the exhaust shop and they have indicated that the front diff chassis/mounting bushes may be worn allowing the diff to move closer to the dump pipe.

Does anyone have any thoughts on what might fix this?

The exhaust shop has moved the dump pipe across slightly which im hoping may help but otherwise my options appear limited.

Cheers
Vh

 

[bods]

Any pics? Was the noise noticeable on acceleration or deceleration? Also, high range or low range? Your engine mounts may be worn also allowing the motor to rotate more than usual resulting in the same sort of impact. If you have any pics of how close they actually are that would be good, might be able to see how else it could be modified to clear better

 

[vh202]

Here are some pics.

The first gives and overall view facing forwards towards the front diff. The second is from directly underneath and shows the clearance on either side. The last shows the damage done so far to the dump pipe from the flange and nuts.

 

[bods]

Looks like a lot of movement in something under there... I would have thought that would be enough clearance if the mounts are all good so I guess that's all you can look at for now...

 

[vh202]

If it is the engine mounts that are shagged, how much would be reasonable to get them replaced? i presume this would help some of the vibration I am experiencing at idle too?

The exhaust guy suggested that it may be the bushes on the Diff cross member. He reckoned there was a fair bit of movement in them just by pushing on them and when the motor is torquing up it might allow the diff room too move the driveshaft towards the exhaust?

I tested it out the other day and was occurring on both deceleration and acceleration but only at really low revs, like around 800 rpm. I thin kthat was the range anyway. I didnt test if it occurred in both high and low range but I suspect I wouldn't really experience it in low as you can keep the revs up a bit.

 

[vh202]

Or for that matter how easy is it to replace the mounts yourself?

 

[bods]

Wouldn't be too hard to do engine mounts, jack and a block of wood under the sump or harmonic balancer to take the weight, then just unbolt and remove old and fit new. Front diff I'm not sure about, I don't know if there are any bushes in there that need pressing in or out. Someone else should know for sure hopefully

 

[vh202]

Well I contacted Nissan about the Engine mounts and they want $185 each. Its only a piece of rubber and some steel :S Where is a good place to source replacement mounts?

The bushes for the diff cross member aren't even sold separately and come as part of the diff cross member, they want $1300 for that part! I guess ill give that a miss hehe

 

[gunning1987]

bursons auto

 

[vh202]

Burson are a bit cheaper ~$100 bucks a mount. Is there any surefire way to determine whether all mounts are buggered or whether I only need to replace one? At the moment when idling cold there is quite substantial vibration within the cabin which can cause everything to shake. When the AC is actuated there is a very substantial shake to the car even when warm. I had assumed this was just normal for this particular motor but in hindsight it could very well be rooted mounts. Prior to me putting a turbo pn which appears to have evened out the revs at idle there was sufficient vibration to cause resonant vibration to occur in the 4WD gear stick!.It used to go nuts!

I suspect its just that the rubber itself is old so I would need to replace them all.....

Also when i looked under the car the other day at the very least I noted that the gearbox mount was sitting very low with little clearance between the upper steel piece and the lower.

 

[vh202]

Well the exhaust guy had offered to modify the pipe to solve the problem for free however ive decided that I will replace the mounts to try and solve the source of the problem. Hopefully it will help with the huge amount of vibration I experience under idle conditions too.

If it doesnt solve the problem I always have him as a back up. I was only planning to replace the LH and RH mounts. Is there any point in me replacing the gearbox mount as well?

 

[vh202]

Well the exhaust guy cut the dump ipe and gave it plenty of clearance and the bloody thing still made a noise. So I got under there and had another look and found this bloody thing rattling around. You can see in the second photos where it was in the cross member that supports the front diff. The welded nut is sticking through the holes. Removing it solved my rattling problem. I feel a bit stupid for getting the exhaust guy to fix it up now!

I cant for the life of me figure out what it does and cant see where it might go. It looks like an agricultural piece of kit if ever ive seen one. Does anybody have an idea whether it is something that is supposed to go somewhere?

 

[bods]

i'd say it was probably for a bash plate that was fitted at some stage. i reckon the big plate is just to stop the nut spinning while it's being tightened up. at least it should have enough clearance all the time now, lol

 

[Gekko]

i had the same issue with my qd32. i have extractors tho, not turbo'd. the bolts on the drive shaft was wacking the side of the extractors at low revs coz the engine mounts and gear box mount were all shagged. i got the mounts from repco and my mechanic to rplace them all for (cant remember exact prices) but was about $500. fixed the problem