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Bang in rear when going over bump
- Thread starter 67BJ8
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John Loftus
Darth Vader
Offline
Probably loose shocks (mounting bolts loose) or the shock link was installed upside down (causing the shock to bottom out). You can check the shock dampening by removing the link and manually moving the shock arm up and down. Should have strong resistance both ways with no "gaps" in the resistance.
Cheers,
John
Cheers,
John
Offline
The axle could be either topping out or bottoming out. If bottoming out, the clunk would be somewhat subdued do to the large rubber bumper above the axle. If topping out, there will be considerably more bang due to the thin rebound rubber on the frame under the axle.
Since there is limited room for axle travel between the compression bumper & the frame which passes under the axle, it's important to have the correct ride height. The axle should have two to three inches of rebound travel (between the axle lower side & the frame). If the ride height is correct, then as others have said, anything that reduces shock action is suspect. Ineffective shocks, worn or incorrectly installed shock links, loose shock mounts, can all cause problems.
The "new" rear springs may set the ride height too high which will limit the rebound travel to less than two to three inches & the axle is topping out. Usually new springs will settle a bit in the first few hundred miles of driving. If the shocks & links check out, I would just drive the car for a while & see if the springs settle to give more rebound clearance.
D
Since there is limited room for axle travel between the compression bumper & the frame which passes under the axle, it's important to have the correct ride height. The axle should have two to three inches of rebound travel (between the axle lower side & the frame). If the ride height is correct, then as others have said, anything that reduces shock action is suspect. Ineffective shocks, worn or incorrectly installed shock links, loose shock mounts, can all cause problems.
The "new" rear springs may set the ride height too high which will limit the rebound travel to less than two to three inches & the axle is topping out. Usually new springs will settle a bit in the first few hundred miles of driving. If the shocks & links check out, I would just drive the car for a while & see if the springs settle to give more rebound clearance.
D
BlackHealey
Senior Member
Offline
I had this exact problem recently. I thought I was hearing it on the passenger side only. Sure enough, the newly rebuilt rear shock was leaking, allowing the axle to knock into the frame on big bumps. I replaced the shock with another rebuilt non-leaking shock, and the problem is solved.
[ QUOTE ]
It "would" be possible to get the rear spring shackles installed wrong which would make the ride height too high & prevent spring action. The rear shackles, when viewed from the side, should be angled back from top mount down to spring eye. I doubt if this is the problem, but it "has" happened.
D
[/ QUOTE ]
Dave:
I'm having some difficulties picturing this. I have assumed, perhaps incorrectly, that rear leaf springs are interchageable and have no real right to left orientation.
I've tried to install the reproduction leaf springs (Moss cir. 1998) but they caused the differential to mount incorrectly. When the originals were install agian, things return back to normal.
Maybe the reproductions were the suspect ones or perhaps they were installed incorrectly...could you please clarify
Much thanks GONZO
It "would" be possible to get the rear spring shackles installed wrong which would make the ride height too high & prevent spring action. The rear shackles, when viewed from the side, should be angled back from top mount down to spring eye. I doubt if this is the problem, but it "has" happened.
D
[/ QUOTE ]
Dave:
I'm having some difficulties picturing this. I have assumed, perhaps incorrectly, that rear leaf springs are interchageable and have no real right to left orientation.
I've tried to install the reproduction leaf springs (Moss cir. 1998) but they caused the differential to mount incorrectly. When the originals were install agian, things return back to normal.
Maybe the reproductions were the suspect ones or perhaps they were installed incorrectly...could you please clarify
Much thanks GONZO
Offline
Hi Gonzo,
I'm not surprised at your confusion. My above statement was incorrect, was thinking of a different car. If the springs are installed with the eyes up & the free length is around 34.5 inches, eye to eye, they should fit. Free arch (camber) should be around 4.5" from eye centerline to top of spring. This will decrease somewhat after the springs settle for a while. On the BN2 the distance from eye to axle locating bolt head is the same on the front & rear of the spring so there is no front or rear. Other car models may have different dimensions. If this were the case, putting the springs in backward would locate the axle in the wrong place front to rear.
I have corrected the above post.
D
I'm not surprised at your confusion. My above statement was incorrect, was thinking of a different car. If the springs are installed with the eyes up & the free length is around 34.5 inches, eye to eye, they should fit. Free arch (camber) should be around 4.5" from eye centerline to top of spring. This will decrease somewhat after the springs settle for a while. On the BN2 the distance from eye to axle locating bolt head is the same on the front & rear of the spring so there is no front or rear. Other car models may have different dimensions. If this were the case, putting the springs in backward would locate the axle in the wrong place front to rear.
I have corrected the above post.
D
Keoke
Great Pumpkin
Offline
[ QUOTE ]
I have new rear springs on my BJ8. It makes a loud "bang" when I go over a bump like something is bottoming out. Could bad shocks cause this problem?
[/ QUOTE ]
Well my earlier post pointed to the the springs.I have never purchased an aftermarket set of springs for the BJ8 that were correct. In every case I have had to dismantle the springs and build them up using a combination of new and old leaves. Consequently,after all the comments I am of the opinion that the springs you have are over arched and if not corrected will break the frame under the axel. My favorite expresion here is: "They Kick Like a Mule"---Fwiw--Keoke
I have new rear springs on my BJ8. It makes a loud "bang" when I go over a bump like something is bottoming out. Could bad shocks cause this problem?
[/ QUOTE ]
Well my earlier post pointed to the the springs.I have never purchased an aftermarket set of springs for the BJ8 that were correct. In every case I have had to dismantle the springs and build them up using a combination of new and old leaves. Consequently,after all the comments I am of the opinion that the springs you have are over arched and if not corrected will break the frame under the axel. My favorite expresion here is: "They Kick Like a Mule"---Fwiw--Keoke
The springs on my BJ8 are Moss circa 1998. What do I do now
to correct the problem if it is the springs? If I buy new after market ones they will probably do the same thing. Also
are there measurements that I can take to determine if the springs are indeed the wrong shape? /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
to correct the problem if it is the springs? If I buy new after market ones they will probably do the same thing. Also
are there measurements that I can take to determine if the springs are indeed the wrong shape? /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
Keoke
Great Pumpkin
Offline
Hi 67BJ8, Try this,Measure the vertical distance between the top of the wire wheel hub just behind the knock off to the center of the rear fender. You should get a figure of ~ 14".If you find it is 15" or more this may spot light the problem. To correct it; Initially I would replace the two top leaves of the new spring with those from the old one.However it is a trial and error PITA problem to solve>---Keoke
The reproduction leaf spring purchased from MOSS (cir. 1998)and specified for the BJ-7 measures 36 inches from eye-to-eye and with an equal 18 inches from eye to centerline, these leaf springs would not have a specific orientation. In theory these could be installed either way but in practice they didn't fit correctly.
Options include: purchasing new springs from a supplier or have the original springs re-arched. Results for both would be unpredicable. GONZO
Options include: purchasing new springs from a supplier or have the original springs re-arched. Results for both would be unpredicable. GONZO
Offline
Hi Gonzo,
The following is a comment by Roger Moment, taken from another source. It applies specifically to the earlier cars but the part about quality likely applies to your car also. Your 1998 springs could well be in the "problem" category. As I said earlier, springs purchased from Moss for my BN2 & marked 14/10/2003, made in UK, have worked perfectly.
Below is Rogers comment. Note that it is dated 2002:
Roger Moment On Leaf Springs:
-------------------------------------------
Quote:
--https://www.team.net/html_arc/healeys/200205/msg00819.html
* To: healeys@autox.team.net
* Subject: rear leaf springs
* From: --Rmoment@aol.com
* Date: Fri, 24 May 2002 19:45:04 EDT
* CC: --Rmoment@aol.com
For many years now when people have asked me what to do about sagging rear
leaf springs I told them to have theirs re-arched and not to buy new ones.
This is because I had bought and returned a set about 10 years ago when they
sagged after only about 4 months or so and I had not seen any different ones
being offered for sale from any sources. Furthermore, many other owners had
also experienced sagging of new springs. Thus it seemed there were no
suitable new springs available and to say the least we all were quite
discouraged.
I have recently discovered that good new springs may indeed be available. In
talking with Michael Grant at Moss I was told that the springs Moss had been
buying for years from a manufacturer in England were their "economy grade",
but that they also made a better "original equipment grade" spring . These
latter ones were built to the original specifications. This includes better
steel quality and the correct clip hardware (or almost correct). Finally,
these "OE" springs are test loaded before shipping. Moss has been stocking
these OE springs for about 18 months now and list them for the 6-cylinder
Healeys.
What I was looking for was rear leaf springs for the 100. The Moss catalog
states "N/A" for these. However, Moss does indeed have them in stock under
part number 021-581 and priced at $119.95 ea. These are 8-leaf springs,
correct for all 100s starting with the Hypoid rear axle. Their free-standing
arch is about 1/2 - 3/4" greater than the shop manual specifies, which is in
the right direction if you want to be "safe". To 95% of people looking under
a car, they appear as-original. (The bad springs sold years ago had hex head
bolts holding the clips together and just looked wrong.) However, there are
a few slight differences which perfectionists will want to fix, and these are
easy to do:
1) The paint is horrible and needs to be stripped and redone. However it
might be wise to first remove the new rubber bushes from the main leaves.
2) The 4 clips that are not riveted to leaves have holes which would need to
be filled in and filed smooth. These clips would first need to be removed
from the spring -- an easy job to do.
3) The rivets used to attach two clips per spring to the one leaf have
rather oversized heads. These could be ground smaller without affecting
their fastening function.
4) The lubrication interleaves are not zinc but rather a durable-looking
plastic. They may very well do their job just fine, but if your original
zinc interleaves are in good condition you could swap them over.
5) The slot-head countersunk screws on the clip hardware are the correct
size but have 1/4-28 threads, while the original screws on 100s had 1/4-20
threads. The screws on all 6-cylinder car spring clips had the 1/4-28
threads, so these screws are certainly correct on the later cars.
6) The shouldered center screw is a bit long and also has 1/4-28 threads.
I plan to make up "new" springs for my car using a mixture of original clips
and zinc interleaves and steel leaves from the new springs.
I can't say whether these new springs will not sag as the "economy grade"
ones did before. It sounds like they may be a whole lot better, though.
Anyhow, I thought those on the list might be interested in the above, and
particularly that 8-leaf springs for the 100s are available.
Roger
--------------------------------------------------
The parts above about minor hardware differences may not be of concern to you. I personally believe that the newer "plastic" interleaf inserts are superior to the old zinc inserts.
I suspect that Keoke has the only "for sure" answer to the problem. I do know that cold rearching your old springs would temporarily solve the problem but would not last very long. Good springs need to be hot formed, tempered, & drawn to the correct hardness in order to have a long life.
As Keoke has said, even a good, new spring will settle a bit after it is used for a while.
You might wish to work with a spring shop on this project & it may take several trys.
There is also a discussion here: https://www.britishcarforum.com/ubbthread...p;page=49#97633
Sorry it is such a problem,
D
The following is a comment by Roger Moment, taken from another source. It applies specifically to the earlier cars but the part about quality likely applies to your car also. Your 1998 springs could well be in the "problem" category. As I said earlier, springs purchased from Moss for my BN2 & marked 14/10/2003, made in UK, have worked perfectly.
Below is Rogers comment. Note that it is dated 2002:
Roger Moment On Leaf Springs:
-------------------------------------------
Quote:
--https://www.team.net/html_arc/healeys/200205/msg00819.html
* To: healeys@autox.team.net
* Subject: rear leaf springs
* From: --Rmoment@aol.com
* Date: Fri, 24 May 2002 19:45:04 EDT
* CC: --Rmoment@aol.com
For many years now when people have asked me what to do about sagging rear
leaf springs I told them to have theirs re-arched and not to buy new ones.
This is because I had bought and returned a set about 10 years ago when they
sagged after only about 4 months or so and I had not seen any different ones
being offered for sale from any sources. Furthermore, many other owners had
also experienced sagging of new springs. Thus it seemed there were no
suitable new springs available and to say the least we all were quite
discouraged.
I have recently discovered that good new springs may indeed be available. In
talking with Michael Grant at Moss I was told that the springs Moss had been
buying for years from a manufacturer in England were their "economy grade",
but that they also made a better "original equipment grade" spring . These
latter ones were built to the original specifications. This includes better
steel quality and the correct clip hardware (or almost correct). Finally,
these "OE" springs are test loaded before shipping. Moss has been stocking
these OE springs for about 18 months now and list them for the 6-cylinder
Healeys.
What I was looking for was rear leaf springs for the 100. The Moss catalog
states "N/A" for these. However, Moss does indeed have them in stock under
part number 021-581 and priced at $119.95 ea. These are 8-leaf springs,
correct for all 100s starting with the Hypoid rear axle. Their free-standing
arch is about 1/2 - 3/4" greater than the shop manual specifies, which is in
the right direction if you want to be "safe". To 95% of people looking under
a car, they appear as-original. (The bad springs sold years ago had hex head
bolts holding the clips together and just looked wrong.) However, there are
a few slight differences which perfectionists will want to fix, and these are
easy to do:
1) The paint is horrible and needs to be stripped and redone. However it
might be wise to first remove the new rubber bushes from the main leaves.
2) The 4 clips that are not riveted to leaves have holes which would need to
be filled in and filed smooth. These clips would first need to be removed
from the spring -- an easy job to do.
3) The rivets used to attach two clips per spring to the one leaf have
rather oversized heads. These could be ground smaller without affecting
their fastening function.
4) The lubrication interleaves are not zinc but rather a durable-looking
plastic. They may very well do their job just fine, but if your original
zinc interleaves are in good condition you could swap them over.
5) The slot-head countersunk screws on the clip hardware are the correct
size but have 1/4-28 threads, while the original screws on 100s had 1/4-20
threads. The screws on all 6-cylinder car spring clips had the 1/4-28
threads, so these screws are certainly correct on the later cars.
6) The shouldered center screw is a bit long and also has 1/4-28 threads.
I plan to make up "new" springs for my car using a mixture of original clips
and zinc interleaves and steel leaves from the new springs.
I can't say whether these new springs will not sag as the "economy grade"
ones did before. It sounds like they may be a whole lot better, though.
Anyhow, I thought those on the list might be interested in the above, and
particularly that 8-leaf springs for the 100s are available.
Roger
--------------------------------------------------
The parts above about minor hardware differences may not be of concern to you. I personally believe that the newer "plastic" interleaf inserts are superior to the old zinc inserts.
I suspect that Keoke has the only "for sure" answer to the problem. I do know that cold rearching your old springs would temporarily solve the problem but would not last very long. Good springs need to be hot formed, tempered, & drawn to the correct hardness in order to have a long life.
As Keoke has said, even a good, new spring will settle a bit after it is used for a while.
You might wish to work with a spring shop on this project & it may take several trys.
There is also a discussion here: https://www.britishcarforum.com/ubbthread...p;page=49#97633
Sorry it is such a problem,
D