Saggy Rear Suspension Debacle

Technical advice Q&A

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Retroman
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#1 Saggy Rear Suspension Debacle

Post by Retroman » Wed Sep 02, 2020 11:34 am

Hi Again
Appreciate that there has been much debate on ride heights and shock spring lengths etc etc
I find it all baffling
For the less technically minded amongst you could I ask which supplier you would recommend for the correct length springs and suitable shocks
My 2 + 2 is habitually grounds the exhaust over mild bumps and the wheel rim is at the same height as the wheel arch top which looks a little low
On measuring from the IRS plate to the ground there is 5 3/4 inch clearance with a full tank of fuel which I understand is 1 1/2 inch lower than it should be
Any advice would be much appreciated
Thanks
Nigel
1969 E Type Series 2 2+2 Auto with Power Steering UK Registered

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Tom W
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#2 Re: Saggy Rear Suspension Debacle

Post by Tom W » Wed Sep 02, 2020 11:52 am

What springs and dampers do you have on at the moment?

If you look through the parts books and spares bulletins, you’ll see there were several different combinations of springs, dampers and sometimes spacers specified over the years. The spec was all settled on by the time the Series 2 was introduced, though there’s no guarantee that your car has all the correct original spec parts on now.
Tom
1970 S2 FHC

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mgcjag
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#3 Re: Saggy Rear Suspension Debacle

Post by mgcjag » Wed Sep 02, 2020 11:55 am

Hi Nigel...yes you are very low......when i refurbed my 2+2 i used the standard springs and Boge shocks from SNGB...the ride hight on mine is now good....however as far as im aware the Boge are no longer available.....if i was doing the job again i would get the adjustable height Gaz and spring combo from SNG.....they are useing this setup on their demo ots.....you can then set height to suit.....Steve
Steve
1969 S2 2+2 & Building a C type replica

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#4 Re: Saggy Rear Suspension Debacle

Post by Retroman » Wed Sep 02, 2020 9:17 pm

Hi Guys,

From what I can see the car is fitted with Koni Classics as I can seen the label on one of them.
Having checked the old invoices they were purchased in August 2005 from SNG.
Cannot find any invoices for springs.

However they all look like new, no leaks, as the car has only covered 2000 miles during this time.
Has being stood caused the issue?

I have heard that KONIs are not liked in this application although I have always thought of them as a quality shock on par with SPAX?

Am I right in thinking it is doubtful that the springs would have degenerated in strength but lack of use may have adversely affected the KONIs?

Thanks for the help,
Nigel.
1969 E Type Series 2 2+2 Auto with Power Steering UK Registered

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abowie
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#5 Re: Saggy Rear Suspension Debacle

Post by abowie » Wed Sep 02, 2020 10:41 pm

In this application the problem is more likely your springs rather than the shocks.

The springs will determine the ride height by virtue of their resistance to compression. The dampers just damp out oscillations.

The usuals offer C25939 rear spring. They claim these are suitable for all models which is not correct as they are too strong for S1 cars resulting in rear ride height being too high. If you're bored there's hours of threads about this problem.

At £20 each you could just buy 4 and fit them and see if they work for you.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
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mgcjag
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#6 Re: Saggy Rear Suspension Debacle

Post by mgcjag » Thu Sep 03, 2020 8:01 am

Hi Nigel......its not just the springs that derermin ride height but also the length of the perches top and bottom of each shock.....you need to find out exactly what model shock you have and find out if it was a direct replacement for the originals or if it should have spacers fitted to give correct ride height.....Steve
Steve
1969 S2 2+2 & Building a C type replica

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#7 Re: Saggy Rear Suspension Debacle

Post by Tom W » Thu Sep 03, 2020 8:15 am

C25939 is suitable for all 6cyl models, provided they are used with the appropriate dampers, appropriate lower spring seats and without spacers. They were introduced part way through the Series 1 4.2. The data is in the spare parts bulletins.
Tom
1970 S2 FHC

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#8 Re: Saggy Rear Suspension Debacle

Post by mgcjag » Thu Sep 03, 2020 8:47 am

C25939 may well have been ok for all models if they are original parts......reproductions are a different thing..Steve
Steve
1969 S2 2+2 & Building a C type replica

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#9 Re: Saggy Rear Suspension Debacle

Post by abowie » Thu Sep 03, 2020 9:08 am

Tom W wrote:
Thu Sep 03, 2020 8:15 am
C25939 is suitable for all 6cyl models, provided they are used with the appropriate dampers, appropriate lower spring seats and without spacers. They were introduced part way through the Series 1 4.2. The data is in the spare parts bulletins.
What is being sold as C25939, however, is not.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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#10 Re: Saggy Rear Suspension Debacle

Post by Tom W » Thu Sep 03, 2020 9:53 am

Yes, the accuracy of pattern parts are another matter. I re-used my original springs, so haven’t compared what’s available from the various suppliers.
Tom
1970 S2 FHC

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Geoff Allam
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#11 Re: Saggy Rear Suspension Debacle

Post by Geoff Allam » Thu Sep 03, 2020 2:58 pm

Nigel, from your original post I understand that your main complaint is that you bottom out easily and believe that your ride hight at the rear is 1 1/2 inches low at the rear. Assuming that your components are working fine otherwise your easiest and cheapest fix is to install a spacer. The gain in height will be approx double the height of the spacers. I did this on my fhc 20 years ago and have not changed anything since. I manufactured my spacers myself from heavy nylon using a holesaw and a router but expect if you contact sng or one of the other suppliers they will have the correct parts. Changing shocks and springs seems like an unnecessary expense if yours are in good shape. Installing new parts is also no guarantee that you will have the correct ride height.
Geoff Allam
67 series1 ots under restoration
64 series 1 fhc burning lots of oil
53 xk 120 fhc sitting in garage waiting for attention

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Retroman
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#12 Re: Saggy Rear Suspension Debacle

Post by Retroman » Thu Sep 03, 2020 4:53 pm

Hi Guys,

Well the plot thickens.

I have taken the offending suspension off today and found that although the shocks are all KONIs the pairs are mixed.

The two front ones are 'Classics' without spacers and the two rearward ones are stamped KONI 'adjustables' and appear to have been originally orange but sprayed black with spacers!!

It gets worse:

To add to my misery spax adjustables are out of stock with everyone for a month with only MONROE £35 and SPAX non adjustable £45 available; unless I go down the KONI route so......... decisions decisions

I will dismantle them the take some measurements etc but provided everything looks serviceable maybe putting spacers on all of them or even doubling them up would be a simple and cost friendly option for the time being.

Thanks for all the help.

Nigel.
1969 E Type Series 2 2+2 Auto with Power Steering UK Registered

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#13 Re: Saggy Rear Suspension Debacle

Post by abowie » Thu Sep 03, 2020 11:16 pm

Retroman wrote:
Thu Sep 03, 2020 4:53 pm

with only MONROE £35 and SPAX non adjustable £45 available
As I said above, your ride height is most likely unrelated to your shocks; it is the spring strength that is the issue. Replace the springs, or as suggested try fitting spacers.

While having a dubious mix of shocks is not ideal, it's not causing your low ride height. By all means replace the dampers if they're not actually working; you can get them tested at any shock absorber place.

The Monroe shocks have recently replaced the old tried and tested Boge shocks. I haven't used them personally but we must have fitted dozens of pairs of the Boges over the last 10 years and they are perfectly adequate for the task.

You really don't need adjustable shocks on the rear of a E Type. Indeed if you look at the Koni literature they offer "adjustability" to allow you to adjust the shocks back into spec as they wear and become less powerful. To adjust the damping force you need to remove the shock from the car and twist the top.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
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#14 Re: Saggy Rear Suspension Debacle

Post by mgcjag » Fri Sep 04, 2020 7:47 am

There are different types of adjustable shock....one for damping, one for height.....and a combination of both....Steve
Steve
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#15 Re: Saggy Rear Suspension Debacle

Post by abowie » Fri Sep 04, 2020 8:36 am

mgcjag wrote:
Fri Sep 04, 2020 7:47 am
There are different types of adjustable shock....one for damping, one for height.....and a combination of both....Steve
Yes, but with the standard IRS setup all the adjustment does is change the damping. It can't affect ride height.

Now if our OP had fancy aftermarket adjustables like https://xks.com/i-7151180-jaguar-e-type ... -1030.html fitted it would be different.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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#16 Re: Saggy Rear Suspension Debacle

Post by mgcjag » Fri Sep 04, 2020 8:54 am

Hi Andrew...as i mentioned SNGB have a very similar shock/spring which is what i was refering to in my post...ride height adjustable https://www.sngbarratt.com/English/#/UK ... 0shocks%60
Steve
1969 S2 2+2 & Building a C type replica

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Retroman
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#17 Re: Saggy Rear Suspension Debacle

Post by Retroman » Sat Sep 05, 2020 2:41 pm

Hi Guys,

Just as an update.

The springs have been condemned by a local suspension supplier.

I am having them made from scratch to the correct spec.

I will keep you posted once the have been fitted.

Thanks again for the interest.

Nigel
1969 E Type Series 2 2+2 Auto with Power Steering UK Registered

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#18 Re: Saggy Rear Suspension Debacle

Post by PeterCrespin » Sat Sep 05, 2020 6:40 pm

What were the reasons for condemning the springs, apart from making you spend more?
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#19 Re: Saggy Rear Suspension Debacle

Post by Series1 Stu » Sat Sep 05, 2020 9:32 pm

Retroman wrote:
Sat Sep 05, 2020 2:41 pm
I am having them made from scratch to the correct spec.
Does anybody know what the correct spec. is? Please tell me and I'll get us all some made ........
Stuart

If you can't make it work, make it complicated!

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