Rear spring choice

[Matt George]

Hello all,

After a successful 10CR assault, I've now got a few additions on my 'To Do' list. Slinging my 2000 up the mountain passes revealed a few slight rear end issues, and the trailing arm bushes will be the first to be replaced. Having fitted Konis all round, but retained the original rear springs, they now need replacing too.

My question is whether to go for the PFL575lb Witor springs from Mr Witor, or the fast road FR475 options to match the 205/400 versions I have on the front. Basically, will the extra rigidity of the 575 versions offer a better improvement? Another part of the issue is that when the car is quite heavily loaded, there tends to be a fair bit of vibration through the body when accelerating upto speed. My thinking is that the original 278lb springs simply aren't upto the job on a car that has now received a number of performance upgrades, so both the FR475 and PFL575 springs will offer an improvement regardless?

If anyone can shed any light or experience here, it would be very much appreciated  :)

Thanks,
Matt

[andy thompson]

575 give the best load capacity for big trips - but might seem a little skittish in the wet if only one up although running 26psi in the rear unladen rather than 28-32 with a big load really helps.

If the 575 aren't specifically for fast road then 475 might be better although FR spec  might end up too low when 3 up with a bootful!
Running standard rear ride height length springs 575(?) without rubber spacers or additional ones allow fine tuning of ride height - you need some slight negative camber for stability at all times.

Make sure the 1/2 unf subframe to diff bracket bolts are very TIGHT

[Craig Bennett]

I have had the Witor 575lb springs on the back of my pi for a few years now. Car sits well, handles well. Even when laden with RBRR gubbins or towing caravan doesn't sink on back end. Would certainly recommend them!!

[Matt George]

Thanks both. My fear is that 575 will be a bit too firm. I'm thinking that the FR475s will be the right ones to go for. I usually run the Konis at half stiffness, so maybe setting them to full firmness in conjunction with the 475s for loaded up RBRR/10CR work will do the job?

[Russell]

Matt, I've got PFLR575 on both the 2000 estate and Stag. I tried FR475 on the Stag and it was great when lightly laden, but 2 up with the hardtop on and a load of spares on last year's Historic Counties run, I was hitting the tyres on the inner wheel arches, so I changed them.

I know neither is a saloon, and the estate is heavier by comparison, but here's a vid of my estate at the Ecosse Autosolo a couple of years ago. We are 2 up and there's a fair bit of weight in the boot on this.

http://www.youtube.com/watch?v=JlIIuFDB7EI

Russell.

[James]

The springs are super easy to swap — why not get both :)

I have a pair of 475 that you could borrow and try out if you're close.

[Matt George]

Hi James. That's a kind offer. I had thought of getting both to be honest. From what people are saying, 475s may be the ones for general use, before swapping in the 575s for loading up the car for RBRRs and the like.

[James]

I'd agree — the 475s are quite firm enough for me on my Mk1 — though the Mk2 is probably heavier at the rear end so may seem different.

I have new springs on the rear of mine that are now a lot softer when open and the ride is a lot more pleasant.


James

[DJB_Harvey]

The original "fast road rear" spring from Witor was 575 but he now does that at 475 . The 575 is STD ride height .
I use fast road rear on my Mk2 PI with a + 5 mm spacer at the bottom .
When I did the 2012 RBRR run 3 up / laden I thought it odd my car was down at the rear that's when I discovered Chris had reduced the rate for FRRs . So my conclusion is for heavy runs you need 575 rate , 475 for normal running .
I also use the 475 FRRs on my Mk1 but think that is a slightly lighter car .

Hope I havnt confused the issue ! Dave

[Matt George]

No confusion at all Dave. Seems the general consensus is that you need both sets!

On the RBRR, did you notice any difference in how the car drove when it was fully loaded and down at the rear, or was it simply an aesthetic issue?

[piman]

Hello Matt,

"I usually run the Konis at half stiffness, so maybe setting them to full firmness in conjunction with the 475s "

I have a set Of CW rear springs, but it's that long since I bought them I forget the rating, however my Konis are set as they come out of the box, i.e. soft and the damping is good. I have never thought that using a damper to compensate for a lack of spring rate as a good idea, remember the stiffer you set them the quicker they will heat up  and then become less effective. OK on smooth roads but otherwise?

Alec

[Matt George]

Hi Alec,

Thanks for the input. To be honest I was just thinking out loud, while still getting my head around what exactly sets the ride height of the car. I'm hoping that, given the rear springs on my car are quite likely to be the originals it came out of the factory on, then some fresh ones will address my problems.

Matt

[CRAJ]

Matt when I bought the pi it had the original rear springs and with 2 children in the back it would bottom out over bumpy roads.
I put some Witor 395 prefacelift springs in and the difference was amazing. The car is to my mind fine even four up with luggage.......but if I put our largish trailer on the back for camping or filled with show equipment the limitations of these (mildly uprated springs) are there again.
Your original springs will be very tired. The mk2 has a large overhang on the rear and if 40+ yrs old they have given their best. Springs are cheap from Chris and pretty easy to change so get a couple of pairs, but remember that ride quality for daily use will be compromised if you go too hard and don't load the car up very often. Chris also suggested to me that springs need 1000+miles to 'bed in' ;)

Colin.

[DJB_Harvey]

Matt , the only problem I had on the RBRR was that due to excessive negative camber the driveshafts "Whirred" sometimes presumably due to excessive working angles of the U/J's ... Not good !

[Tim Bancroft]

Got to agree with all the above, the idea of two sets is good.

I have 475s on the back of my mk1, ideal.

Watch your camber though.

[shedmonkey]

I have a set of 475lbs for sale (chris witor ones) £25 if anyone intrested,yep that was a blatant advert on my behalf!  :)  send a PM if intrested or email shedtune@gmail.com - Im not a member anymore so cant afford £10 to post in the classifieds!