"Performance" coil springs

[Alan_Myers]

Hi all,

I'm workin' hard on my TR4 and have a question about the uprated coils sold by various vendors. I bought mine from Moss, as a "matched" set with uprated rear leaf springs.

Anyway, my car originally had the 11" front springs *and* 1-1/2" aluminum spacers. Those are out now and most of the front end is rebuilt.

I fitted up the new springs for the first time, and was very surprised that they seem quite short, especially when the suspension is at "full droop", i.e. sitting on the lower bump stop. In fact, one spring dropped off the upper locating ring already and is mis-located, even with the spring pan bolted tightly back up in place.

I was told the 9" performance springs were to be used without the spacers and that they would lower the car at the same time the front end was stiffened up, both of which are part of the overall plan. However, these springs won't even stay in place when the suspension is at it's maximum extension!

Has anyone installed these on a TR4 (early 3 degree caster style)? If so, did you put the 1-1/2" aluminum spacers back in? (BTW: I also have custom 3/4" spacers that might help, which were intended for some lowering with the original rate springs, an alternative possibility.)

Note, I've heard these same "uprated" springs are used on 2 up through 6, but might have originally been sold for TR6.

It may or may not be related to the spring issue, but I've also got Revington adjustable upper control arm fulcrums installed, in the lower position (for decreased ride height). The rest of the front suspension is relatively stock.

Any suggestions would be appreciated!

Alan

 

[piman]

Hello Alan,
certainly higher rate springs will be shorter to keep the ride height equal or more often lower than standard.
The first thing to determine is are you happy with the ride height with the springs fitted and the car on it's wheels. If it is too low then spacers under the spring are required.
If you are happy with the height either you need to fit additional helper springs (Helper springs are flat section coil springs of equal diameter to your main spring, and are just strong enough to keep the spring in position. They totally collapse when there is load on the spring and will increase the ride height by their compressed height) or adjust the droop bumpstop up so the springs do not unseat.

Alec

 

[Dave Russell]

I agree with Alec.
Taller upper rebound stops or spacers are available for many cars to limit the suspension drop. You can make your own if so inclined.
D

 

[Alan_Myers]

Hi Alec and Dave,

Thanks for your input.

I bit the bullet and installed the 'standard' 1.25" spacers with the heavy duty springs. It definitely looks more secure. The springs themselves are about .50 inch shorter than the OEM springs (free length of each) and both actually have the same load rating, but the heavy duty versions have fewer windings and are made from heavier stock. Once the car is back together and on the road, I'll see if I like the stance and preformance. If not, I'll fiddle with it! It so happens I've got two other sets of custom made spacers, in addition to the stock 1.25". One is 1", the other is .75". And, there happens to be a little trick possible on TRs that can lower the front an additional .66" simply by installing the lower control arms upside down. They have an offset that is normally upward, but are otherwise symetrical, so can be flipped over very easily.

You're right, both the upper and lower bump stops will need to be modified to acommodate any change to the ride height that's achieved by changing the overall spring length. The lower stop is pretty close to the limit, though, because the spring pan is only fractionally shy of contacting part of the frame already, would definitely need modification to allow any further "droop".

I'm a little concerned about inducing bump steer problems, so will make changes a little at a time. I figure the front is the hardest to dial in. The rear suspension is just getting new heavy duty leaf springs initially. Ride height at the rear is easily adjusted later, to match whatever I end up with in the front.

Thanks again!

Alan