Hi guys,

I'm hoping someone can help me here.
I have a Tiger B6 running a zx9r engine, with a 7" 3.62 diff.
Ever since I built my car I have had a vibration from the drivetrain. It sounded like it was coming from the diff itself - I didn't know the history of it as I bought the car as a part build, so I picked up another one and fitted it last night. My problem is still there.

Basically if i'm going along at 55 - 60 and lift off the throttle there is a rattle, but if I touch the throttle again it goes away. Also if I reach an up-hill it goes away without touching the throttle - it seems if there is any load at all the rattle goes away. The main problem however is when the car reaches around 90mph (on track) the rattle becomes constant and the car actually vibrates.
The only thing I can think of now since I replaced the diff is the propshaft. I got the prop shortened and balanced when building the car.

As anyone experienced anything similar?

Thanks in advance,
Paul

only need the one post, people dont just live in one area of the forum.

Have you any play at all in the front bearing on the diff?

Have you tried greasing the prop shaft joints or are they sealed for life?

Is there a welded on tab on the prop shaft that indicates it’s really been balanced?

You should be able to jack up a rear wheel and run the car in gear so you can feel what is actually vibrating. Obviously you need to be extremely careful doing this...

quote:

---

Originally posted by cd.thomson
only need the one post, people dont just live in one area of the forum.

---

if you decide to run it jacked up on one wheel at the back... have a video running paul - at least it it goes tits up.. you will get the £250 or whatever it is for the TV show :-))

I get the same high speed vibration. I thought it was at 70 mph but after calibrating my speedo it to is at about 90mph. I get it through the car.

Someone told me it was the reverse box as he had the same on his Westfield.

I live with mine but eager to see what's causing yours.

try tightening up the reverse box prop flange nut - big nut holding it on can come loose - or the prop bolts

make sure the gearbox flange nut too is tight. i have similar probs - turns out it was that

LOL Mark I'll have the camcorder at the ready!

Going to check the harley splicers are lined up correctly, to make sure the prop is fitted exactly the same way as it was balanced. Also while doing that i'll check that the adapter on the engine is 100% tight.

I don't have a reverse box so it's definitely not that! I could possibly live with the vibration too but i'd really rather not as it shouldn't do it and i'm afraid it is something that could go wrong further down the line!

you coudl leave it as is........

do track days, and charge ladies for a few laps... you coudl make a fortune :-))

I'll expect 20% of revenue for giving you the business idea though Paul

Haha love it Mark - I think you are on to something, 20% profits to you it is! I could maybe even build a proper BEC Seven then!

Hi Paul

I know it was some time ago this thred but i have exactly the same problem with my mk. Did you sus what the problem was?

Cheers
Rog

Just my opinion, but I would recommend making sure the diff flange and the gearbox flange are parallel to each other, they don't need to be in line and can be offset, but need to be parallel. I've done a bit of testing and it definitely makes a massive difference.

Hi mate, ya i have just read the same on another post. There not parrallel. I set the engine up to suit the headers so the exhuast would fit right. I have read that the use of a cv joint at the front end would sort the issue? What do you think?
Cheers
Rog

You can still set the diff flange parallel to the engine/gearbox flange, just rotate the axle. I have cv front and uj rear (not ideal) , when not set parallel I thought my diff and gearbox needed re-build, I then rotated the axle to be parallel and silence in top gear 9000rpm. I think I'm going to re do my prop with two uj's just to be on the safe side.

Hi

Rotating the diff isnt an opion on my chassis. I also have a starter motor reverse that needs the diff to be parrallel. If a cv joint wont do then i would need to move the engine and mod the exhuast. Big job

Just a thought, but how about 2 cv joints, one each end.
The s2000 prop had a pair of cv joints as standard, but I had the prop shortened and a uj replaced the rear cv joint as I was led to believe it would be fine and I needed to match my alfa diff flange. It is fine when all in line (parallel) but when I first fired it up and into gear (on axle stands) with the diff pointing down 5 degrees I thought I had a major problem as it sounded like the gearbox and the diff needed a re-build.

Would a two piece prop help (not sure as might make it worse) , I realise they would be very short, but just an idea as re fitting the engine seems like a lot of work.

I have a 2 piece prop on the car now. I was thinking of trying a cv at the front end. I also am thinking about putting a cush drive in the front section as well to absorb some of the clunck when selecting gear. I was looking at the engine this morning. Its about 4 deg out of parrallel with the diff flange. Both flanges are pretty vertical. It would be a fare job to move the engine now. If i have to do that then its christmas sorted for me!

check the middle bearing in the prop
also check the prop adapter on the engine has not come loose
Jacko

Hi jacko

Ya I've checked both, everything seems ok. The rubber on the centre bearing is a little cracked so I will replace. I might go for the transit centre bearing. The prop place I go to recommended that one last time. Cheers Rog