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Dodgy rear end

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Jeepster

Jeepster

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I am getting more and more worried about the handling issues on my BJ8 Ph2.

As mentioned on a previous post, the car was laid up for 10 years before I recommissioned it a week or so back. The car has a fresh MOT so any obvious issues should have been picked up.

When driving at a steady 40 to 50 MPH, on normal flowing roads (not too twisty) the back end seems to twitch and make me have to correct the steering to keep the car on the road.
There doesnt seem to be any pattern to it, it can happen on a straight piece of road or a corner.
I have checked tyre pressures, bounced the rear end to see if the shocks dampen as they should and looked for leaks on the shocks. All the bushes and rubbers look good. No play in wheels or hubs and spinners tight. It sometimes feels as if a wheel is loose.
Can the leaf springs cause this if faulty?

Any ideas of what to check next?
 
How certain are you that it's the rear end? Perhaps there are front end / steering issues? which can also cause erratic handling.
 
How certain am I that it is the rear end?

I suppose I am not that certain, it could be the front suspension or another area that is the cause?
It just feels like it originates from the rear. I have even had passengers feel it and then I have to correct the steering.
 
I guess that if you have to correct the steering, the amount of movement is pronounced? And you should be able to tell if it is the rear end.

Does it happen in the same direction every time, or over a certain speed, in the dry or the wet, or after/during acceleration, on the straight or on a bend. Have you driven the car in the past - 10 years ago? or is it out of the packing case as it were.

What is it like on the flat, hands off the steering, is there any bias to one direction?

All the spokes are tight? you would/should hear clicking if any were loose.

Are you shure that the anchorage of the back axle to the springs is sound.

Although it has passed the MOT, have you checked that the brake cylinders are free and you don't get the occasional hang up, same goes for the handbrake - all parts nicely lubed up and nothing touching any moving parts.

I have heard it said that the Healey would shift passing over a cigarette paper, I know that mine can on the front end when cornering, but it does not need correction to any major degree.

Bob
 
My bet is the problem lies in the front suspension. A bolt isn't torqued down or a bushing has gone south.
 
The car is new to me so never driven it before or any other Healey for that matter. I am well familiar with old vehicles so I am not comparing it to a modern car.
It can happen at pretty slow speeds, on straights and just before corners, when you are into the corner its not so bad.
I would say it tends to be worse on a slight down hill, as if the weight is shifted slightly.
Brakes are fine, no drag on any wheel and pulls up straight. Also runs pretty straight with hands off the wheel.
I have not checked the spokes and they look like the original wheels but I dont hear any clicking sounds. I will run a screwdriver over them to check tightness.
I need to check all the anchorages when it is up on the ramp next(hopefully in the next few days). I would hope that anything out of order on the running gear would have been picked up at MOT. My tester is very by the book so he wouldnt let any faults pass.
I am a bit concerned about taking the car out with this issue as it can be pretty hairy.
 
I tend to agree that a good MOT station would find problems with bushes, king pins, bearings etc.

( as if the weight is shifted slightly)- The major thing that has mass is the engine, I take it that the engine mounts are OK? rubbers could be debonded and that the rear anchorage of the gear box is fine. Anything wrong there may not be picked up, not sure what the result of that would be, but it would not be good that's for sure.

Bob
 
Verify that the U-bolts on the rear axle are tight.

If the car twitches one way when you get on the gas, then the other (both requiring a steering correction) when you let off the gas, my money's on the U-bolts being less than tight.

I think it would take *many* looses spokes to equal the same condition, so I hope that your vehicle inspection would've picked that up
 
Be sure to check the leaf spring front mountings. I removed one during my frame up restoration and found the curved mounting broken in half. I had similar accel/decel that you describe.
Patrick

Oh yeah, this is not an easy thing to inspect.
 
My outside suggestion would be to check the toe alignment adjustment. A way out toe would give you all sorts of directional problems and would be sensitive to weight transfers.

Also, check your brake drums for balance. I have seen drums that were in excess of 5 ounces out of balance and cause true and balanced wheels to bounce wildly at speeds as low as 40 mph. This bouncing will cause all kinds of directional problems and is the issue of one of the most common Healey ride problems.

Good luck,
Ray (64BJ8P1)
 
RAC68, what exactly do you mean by check the brake drums for balance?

I am not sure if the problem has got slightly better over the past few miles or its just down to me becoming more familiar with the cars handling? Maybe some of the moving parts are loosening up after 10 years of inactivity?
 
:savewave:

What exactly do you mean by check the brake drums for balance?

In some cases the original machining of the drums caused them to be slightly off center , this can be checked in a lathe and corrected.--Fwiw--Keoke
 
First, I would be surprised if your ride is getting better as a result of the car loosening up through activity. Your car should feel consistent and stable and you should feel secure and confident when driving it. Not like a 2011 model but one from the ’60s, but better.

Second, the rear brake drums of a Big Healey are known not to have been balanced during manufacturer. Although this is not as common on an American Car, imbalanced drums are quite common on Little British Cars of the ‘50s and ‘60s and have had many of us misdirected over the years by thinking our tires were the problem or our wheels were not true.

Recently, after purchasing a new set of tires and having them mounted on trued wheels and balanced by a knowledgeable and equipped shop, my first drive had my car’s rear jumping all over the road, especially between 50MPH – 60MPH. Disappointed with my new tires and ready to send my drums to Hendrix Wire Wheel, I borrowed a motor cycle wheel balancer that was equipped with sufficiently sized centering cones. Dismounting my drums and hubs, I bolted the two together and mount them as a unit on the wheel balancer. Using stick-on wheel weights, I was surprised to find my drums as much as 5oz. out of balance when others stated that ¾ oz. would have an effect and be felt.

To verify that a change would have an effect, I borrowed a set of drums from a friend that had enough excess metal (the molded band surrounding the drum) ground off to bring the drums to within ½ oz. of balance. Following installation and bringing the car to speeds of 50MPH to 65MPH on a nearby highway, I found no real indications of shake or bounce. Bringing the car to 95MPH, I found the car to have a very minor indication but was more stable and solid than I had ever remembered (I owned the car since new).

I hope this verbose explanation clears up what I was referring to.
All the best,
Ray (644BJ8P1)
 
My 65 does the same thing. Under a hard shift you can feel like the rear end shift. In my case I think it's the rear radius arm bushings. I new I should have replaced them when they were out, but instead used RTV to build up the rubber that pulled out when I drove out the steel inserts that had galled to the bolts. If the rear end were to twist a little you sure would feel it.
 
You are probably correct that your major problem is from a warn trailing arm bush. Upon acceleration, the warn bushing would allow the rear axel to move out of line and redirect the rear wheels.

After you repair the bushing, I would recommend you also check you drums for balancing.

Ray
 
I thought I would update this post as I have managed to find the problem.

After checking over the suspension and running gear I decided to change the tyres.

They looked fine and with very little wear but when removed one of the rears had a crack on the inner side wall. It was impossible to see when on the car and wheel rim.

Now the new tyres are fitted the handling is much improved and the ride is so much smoother.

I fitted Kumho 165 /80/ 15
 
Thanks for the update. Do you know the age of the tires? Did they have a build day code stamped on them? There has been a lot of posting about old tires coming apart even looking good because of interior deterioration.
 
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