Home 
Home Search search Menu menu Not logged in - Login | Register
> Jensen Healey & Jensen GT Tech > Suspension > Uneven ride height

 Moderated by: Greg Fletcher
New Topic Reply Printer Friendly
Uneven ride height  Rating:  Rating
AuthorPost
 Posted: 05-05-2015 03:24 am
  PM Quote Reply
1st Post
Jim Picot
Member
 

Joined: 07-09-2012
Location: Melbourne, Australia
Posts: 39
Status: 
Offline
I've had 18024 on the road 5 months now (and driven it 23 times, according to the club permit log book, where does time go??). Brand  new suspension, brakes, clutch and numerous other smaller items.

I completely rebuilt the suspension:
Front subframe - sandblasted, a few weld repairs of corrosion and wear, repainted
Front Upper and lower arms - new
Front ball joints - new
Front lower damper brackets - new
Rear upper and lower arms - sandblasted and repainted
Coil springs - new from Martin Robey (standard)
Dampers - new Spax adjustables
Bushes - all new Superpro polyurethane
Hardware - all bolts and nuts replaced with new

I noticed after I torqued up the last bolts that the car leaned on the driver's side (right side in this country!). I thought maybe it just needs to settle a bit, but after over 5 months and 500 miles, it's the same. Measured at the centre of the wheel arch, the front driver's side is 30 mm (1-1/4") lower than the passenger side, and 20 mm (3/4") lower at the rear.

Any suggestions? I can't imagine that new springs could have that much of a difference in spring rate, surely? New dampers shouldn't be binding and I can't see any sign of that (externally, I haven't removed them to check individually). As far as I can tell, the car is straight. What measurements can I take to try to isolate where the problem might be?

Any help appreciated!

Back To Top PM Quote Reply  

 Posted: 05-05-2015 06:27 am
  PM Quote Reply
2nd Post
subwoofer
Member
 

Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 583
Status: 
Offline
The shop manual contains a measurement chart for the body. Do you have access to that?

--
Joachim

Back To Top PM Quote Reply

 Posted: 05-05-2015 10:16 am
  PM Quote Reply
3rd Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Hi Jim

I've been having almost exactly the same issue with my GT, and with almost the same amount of differential lean to the driver's side. Uncanny! Here is what I have done to try to remedy the situation:

1. All new suspension bushes and shocks front and rear
2. New front coil springs
3. Removed 7mm spacer that was fitted between the passenger side coil spring seat and the sub-frame. This was factory fit on GTs (and possibly later JHs?) but no one knows why

After all this there is still a differential lean to the driver's side, albeit now around 15mm.

My last chance is the sub-frame chassis mounting assemblies. These are rectangular rubber blocks enclosing a horizontal metal crush tube and a vertical steel thread. A bolt through the crush tube affixes the assembly to the sub-frame, while the vertical thread passes through the chassis rail and is fastened with a washer and nut in the engine compartment.

Perishing of the rubber block will allow the crush tube and thread (and the chassis) to move relative to the sub-frame, perhaps accounting for the lean. It's worth taking a look at these mountings (you'll need to drop the sub-frame to access them) and replace them if necessary. Robey's don't have them in stock, but they are available at Delta.

I've just bought a couple and am hoping they'll do the trick. If not, then the problem on my GT must be that the chassis was not welded in alignment...

Hope this helps.

Best wishes,
Nigel

Back To Top PM Quote Reply  

 Posted: 05-05-2015 11:39 am
  PM Quote Reply
4th Post
Jim Picot
Member
 

Joined: 07-09-2012
Location: Melbourne, Australia
Posts: 39
Status: 
Offline
Hi Nigel,

Thanks, but I have already replaced those top suspension mounts with new ones (which I think I got from Robeys, although that would be over a year ago). They are rubber ones and I think I read somewhere (too late) that you can now get them in polyurethane also. As I said, everything is new!

Joachim, yes I do, but it doesn't give much info about ride height or where various suspension components should be. It does mention the distance between the rubber stops and the seat at the back, which I will check, but I was hoping for some systematic way of checking the correct height of suspension arms, spring lengths etc. to see exactly which components are causing the problem. Or am I being too optimistic that such a guide exists?

Back To Top PM Quote Reply

 Posted: 05-05-2015 11:49 am
  PM Quote Reply
5th Post
subwoofer
Member
 

Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 583
Status: 
Offline
If the geometry of the suspension mount points are not in the measurement guide (I thought they were), your best bet would be to contact Martin Robey. I think you should speak with Keith Jackson, I believe he is the archives guy.

--
Joachim

Back To Top PM Quote Reply  

 Posted: 05-05-2015 01:35 pm
  PM Quote Reply
6th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Hi Jim

Yeah, when I was trying to find those mounting assemblies, Andy Brooks at Appleyards had the insulators in polyeurethane but not the metal housings, crush tubes and threads, and I wanted to replace these as well. Plus I've avoided using polyeurethane components in the suspension generally as I want to keep my GT's ride as soft as possible.

Section E14 of the workshop manual states that the distance between the front bump stop and its seating should be 22 mm under normal laden conditions. At the end of section E25 is a drawing which will allow you to check the geometry of the sub-frame. You've already picked up the section E28 reference to the 50 mm clearance between the rear bump stop and its seating. Also check diagram K6 at the end of the body section, which provides the correct measurements for the chassis (albeit not the suspension components). I can email you the relevant pages if you don't have them.

If there's anything else on geometry in the JML literature I would have thought it would be in the JH service bulletins, which I don't have. I think Richard Calver should have all of these, so it might be worth dropping him a line.

Keith Jackson is also worth talking to, but if there is nothing else in the JML literature re geometry then you might also want to speak to some JH restoration gurus, like Andy Brooks or David Booth.

Hope this helps.

Best wishes,
Nigel

Back To Top PM Quote Reply

 Posted: 05-06-2015 12:02 am
  PM Quote Reply
7th Post
Jensen Healey
Super Moderator


Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 977
Status: 
Offline
I thought all Healeys leaned to the drivers side! The rear suspension bolts should be tightened with the weight of the car on the wheels. I would try loosening the bolt on the drivers side trailing arm, jacking the drivers side, and re-torque the bolt.

Swapping the springs and trailing arms side to side might help. If all else fails, installing that shim on the drivers side would certainly make a difference.

Back To Top PM Quote Reply  

 Posted: 05-06-2015 12:50 am
  PM Quote Reply
8th Post
Jim Picot
Member
 

Joined: 07-09-2012
Location: Melbourne, Australia
Posts: 39
Status: 
Offline
Well, the manual refers to an allowance of 1/2" variation from left to right, which seems an awful lot to me!

All the important bolts were torqued up with the weight of the car on them, so there shouldn't be a problem there.

I'll endeavour to check the suspension and chassis geometry as best I can, but frankly I think fitting shims to lift the drivers side might be the expedient way to fix it. I will jack up the front right chassis to lift the car to the same height as the left side, to see if that also brings the rear right to the same as the rear left, in which case I only need to shim the front. Otherwise shims both ends.

Where exactly would the shims be placed, is there a preferred position? Nigel above referred to a 7 mm spacer on his GT, is this the best place? What about at the rear? Are these available or would I have to get them made?

Back To Top PM Quote Reply

 Posted: 05-06-2015 05:58 am
  PM Quote Reply
9th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Hi Jim

I would have thought it would be preferable to replicate the factory position of the front spacer/shim i.e. between the front coil spring insulator and the sub-frame. You can see where it was located in this picture of my GT front driver's side suspension. An alternative location for a shim would be between the top of the sub-frame mounting and the bottom of the chassis rail, but this location is marginally less accessible if you need to make adjustments to the shim widths.

Best wishes,
Nigel

Attachment: Nearside front coil spring top end showing packer a.jpg (Downloaded 21 times)

Last edited on 08-01-2015 05:15 pm by NigelK

Back To Top PM Quote Reply  

 Posted: 05-06-2015 06:06 am
  PM Quote Reply
10th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
I am less sure about the positioning of a rear spacer / shim, because I have not personally had the rear suspension of my GT apart (yet). It might be harder to install a shim at the top of the coil spring than at the bottom, because there is a dowelled seat (Jensen part #91411) at the top of the spring which needs to locate into the chassis rail. It might be easier to put a shim between the spring retainer (Jensen part #91415) at the bottom of the coil spring and the flat surface of the top of the trailing arm.

Also here is a picture of the front coil spring spacer from my GT, so you can get an idea of dimensions. I doubt any of the usual spares sellers would have these (as they may only have been fitted to some GTs), but getting one fabricated should not be too difficult.

Hope this helps...

Attachment: Nearside front coil spring packer a.jpg (Downloaded 22 times)

Last edited on 08-01-2015 05:13 pm by NigelK

Back To Top PM Quote Reply

 Posted: 05-19-2015 07:12 am
  PM Quote Reply
11th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Hi Jim

Further investigation of the body lean on my GT has revealed incorrect positioning of the bolt hole in the driver's side chassis rail for the rearmost subframe mounting - it is 1cm higher on that side, which could account for the lean. There is a lot of welding in this area, which I suspect is highly prone to rust. A PO has also installed 6mm shims between the front subframe/chassis mounting blocks and the chassis rail, to try to correct the lean.

If this part of your JH has been welded, it would be worth checking that the bolt hole is in the right place, using the measurements in the chassis alignment diagram.

Best wishes,
Nigel

Back To Top PM Quote Reply  

 Posted: 05-20-2015 01:58 am
  PM Quote Reply
12th Post
Jim Picot
Member
 

Joined: 07-09-2012
Location: Melbourne, Australia
Posts: 39
Status: 
Offline
Hi Nigel, thanks for that. I don't think that is the problem, but will still check, of course.

It will be a couple of weeks (at least!) before I can look at it, but I'll put the car up on four wheel ramps so that it's sitting level on its wheels but I can get good access underneath. Then I'll be taking as many measurements as possible from side to side to compare - this should show up where the difference (and therefore the problem) is.

I'll post the outcome when I have it!

Back To Top PM Quote Reply

 Posted: 05-20-2015 07:03 am
  PM Quote Reply
13th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Hi Jim

Given all the suspension components you have replaced, I suspect the most likely causes of your body lean are:

1. Distorted front subframe
2. Incorrect positioning of the chassis/body relative to the subframe
3. Distortion/incorrect mounting of the front wing(s)

Re 1, it will hopefully be possible to verify the subframe alignment measurements from the workshop manual with the subframe still in the car. Re 2, I suggest you use the chassis rails as data to assess the positioning of the suspension relative to the chassis (as with the chassis alignment diagram in the workshop manual). This is hard in my GT because there's been so much welding on the front of the o/s chassis rail, but it was possible in the end by levelling the two rear suspension mounting points and then the n/s chassis rail. This then revealed (using the alignment diagram, levelling across from the front n/s mounting points) incorrect positioning of the front o/s chassis mounting points. I think the trick is to level both from side to side and fore and aft, but I fear it may be hard to do this with the subframe in the car. 3 doesn't seem very likely, as it could not account for the lean at the rear (unless the rear wing was incorrectly positioned as well).

On my GT the rearmost front o/s mounting in the chassis rail is in the wrong place and misaligned (the hole in one face of the chassis rail is 10mm too high and the hole in the other face is 14mm too high). The foremost front o/s mounting point is 7mm too high. Interestingly, the front wheel arch to ground measurements are the same o/s and n/s with the chassis properly levelled. I think this means that the front of the o/s chassis rail and the inner wing have distorted over time, as a result of being bolted to the more rigid subframe. We are going to reposition (lower) and properly align (chassis rail face to face) the rearmost front o/s mounting and retain the shims that a PO had installed between the mounting block and the chassis rail. Hopefully this will do the trick. If not it's a new chassis rail and I don't get to drive my GT this summer. Watch this space!

Best wishes,
Nigel

Back To Top PM Quote Reply  

 Posted: 05-28-2015 12:47 pm
  PM Quote Reply
14th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
The body lean is sorted, at least to within a 5 mm difference between front wheel arch height measurements, which is good enough for me. LotusBits did an excellent job of rewelding the driver's side chassis rail, so that the rearmost sub-frame chassis mounting was a) at the correct height, and b) properly aligned. Pictures to follow...

Attachment: IMG-20150527-00154a.jpg (Downloaded 21 times)

Last edited on 08-01-2015 05:18 pm by NigelK

Back To Top PM Quote Reply

 Posted: 05-28-2015 12:49 pm
  PM Quote Reply
15th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
Another photo

Attachment: IMG-20150527-00153a.jpg (Downloaded 21 times)

Last edited on 08-01-2015 05:16 pm by NigelK

Back To Top PM Quote Reply  

 Posted: 05-28-2015 12:49 pm
  PM Quote Reply
16th Post
NigelK
Member
 

Joined: 07-16-2014
Location:  
Posts: 165
Status: 
Offline
And another photo

Attachment: IMG-20150527-00152a.jpg (Downloaded 21 times)

Last edited on 08-01-2015 05:19 pm by NigelK

Back To Top PM Quote Reply

Current time is 04:03 am  
> Jensen Healey & Jensen GT Tech > Suspension > Uneven ride height Top




UltraBB 1.172 Copyright © 2007-2011 Data 1 Systems