Cross member rubbing

Good day,

I own an '79 X1/9. The axle is rubbing on the cross member. Even after replacing all 3 engine mounts it is still rubbing. I heard that the dog bone (upper engine with 2 rubber bushing) might be the wrong one, It might have to be extended 1/4inch to tilt the engine forward some.

Q1. How much clearance should there be between the cross and axle?
Q2. How much up and down play should there be on the transmission axle?

Bob
79 X 1/9
74 Spider

I can't provide any figures for you as I don't have anything for reference. There are different upper engine mounts (sometimes called dog bones for fairly obvious reasons) and you do need the right one. It might not be that one at fault.

The lower engine mount (the big one in the cradle) tends to sag and can cause all kinds of problems so take a good look at that one too.

With regard the top mount I would suggest having something made that is adjustable. I had a solid mounting on my race car (using two rod-end bearings and a nice piece of threaded stock). This might be a bit noisy for a road car but it did a very good job indeed. A more likely solution now would be to use generic polybushes to the same effect. It isn't totally necessary - especially if you can obtain the genuine part. It does mean you have adjustment to compensate for some slack elsewhere though.

As a rule of thumb the best way to find the right "angle" is to get the car on a flat floor and look at the angle of the sump - it should be parallel to the ground. If it is tilting then you do have a problem somewhere...

"Seicento 150bhp+"

Do you have the r/r figures yet?

I promise you - as soon as I have them I will send them on to you.

Well it is fixed; I would like to share this fix with anyone who might have the same problem. The problem was a noise coming from the back of the car. Even after replacing the three engine mounts (upper, side and lower).

The inner CV joint was rubbing against the cross member supporting the transmission and engine. I think that the upper engine support (dog bone) length for the fuel injected and the carburetor X 1/9 are slightly different and easily mixed by the suppliers.

Measuring the dog bone was at 132mm (measurement taken from center to center of the bolt holes), and the lower measurement was around 3mm clearance between support mount and inner CV joint (see pic).

After removing the upper engine mount, the engine naturally tilt toward the front to a level state. The level was taken at the carburetor with air filter housing removed (see pic). The car was on my garage hoist which is routinely checked for a straight level, so the car was level.

Extending the dog bone to 140mm (measurement taken from center to center of the bolt holes) gave a clearance of about 6mm (see pic) which was plenty of space [if it rubs with this clearance than that I would say the differential bearings need replacing].

I cut a piece of rod steel (about 10mm). I cut the dog bone in the middle (**cut in the middle so that the heat from the weld won’t burn the rubber) and giving it a bevel edge to get a deep weld. I sandwiched the cut rod between the two pieces of dog bones (see pic). I then welded the dog bone back together, sandblast it and repainted it.

After installing the modified dog bone the gap between cross member and inner CV joint was 7mm. And no more rubbing 

I thought I would share this to the forum members and X 1/9 DIY.



Bob Lawbla
The full document is attached with all the pictures. (note sure how to do directly attach them here, without the URL)

Thank you for this write up. I am new to the forums and a X 19 followed me home last weekend and it has this issue..
My first search and I found it.
Thanks again.