parabolic spring confusion

[friar mike]

I prefer the explaination that they are to prevent the rear driveshaft from striking the frame (where it passes through that hole).

I can't buy the "prevent shock damage". Why are these the only cars (that I've ever seen) that need straps? The shocks are no different from any other strapless application. It's the driveshaft hole that's unique... not the shocks.

you havn't worked on many english vehicles have you. by the way when it warms up around here we will have to meet up at the range and shoot some odd guns.

[alaskajosh]

...by the way when it warms up around here we will have to meet up at the range and shoot some odd guns.

I'd sure like that!

Some of these same shocks have other, strapless, applications. Why are they subject to damage-by-top-out when mounted on a series LR but no worries (straps) when mounted on most any other car?

Maybe it's not for us to wonder why... it's just an "English Thing"?

Kind regards, Josh

[BackInA88]

I prefer the explaination that they are to prevent the rear driveshaft from striking the frame (where it passes through that hole).

I can't buy the "prevent shock damage". Why are these the only cars (that I've ever seen) that need straps? The shocks are no different from any other strapless application. It's the driveshaft hole that's unique... not the shocks.

Driveshaft doesn't pass thru the frame on an 88.


TeriAnn,

No question that the parabolics flex more and allow more axle movement.
The statement I questioned was about having to SHORTEN the straps to prevent over extending the STOCK shocks.
The straps are designed to do this and if he is running stock shocks and now that his lower mounting point is even closer to the axle because of the thinner springs I can't see why he would need to shorten them.
He could actually make them longer because of the mounting point change.
If anything the bump stops might need to be longer to prevent the shocks from bottoming out under full suspension compression.
It doesn't matter what springs are on the truck we're talking about the relationship between the strap and the shocks.
Maybe he just wants a smoother ride and doesn't care that much about flex if he did the straps would be gone, longer shocks installed and the driveshaft altered for a longer slip yoke?

But these are good points he should be aware of.

Steve



.

[daveb]

Josh

All my old Volvo 122s had check straps. They are there simply to prevent the car from damage cause by the axle dropping lower than the design tolerance. Driveshafts can bend or seperate, springs fall out, brake lines tear, and shocks bottom out. It is just one method for doing this.

I can't imagine needing to make them shorter on a LR.

FWIW I haven't ever had any on my 109.

I'd sure like that!

Some of these same shocks have other, strapless, applications. Why are they subject to damage-by-top-out when mounted on a series LR but no worries (straps) when mounted on most any other car?

Maybe it's not for us to wonder why... it's just an "English Thing"?

Kind regards, Josh

[TeriAnn]

TeriAnn,

No question that the parabolics flex more and allow more axle movement.
The statement I questioned was about having to SHORTEN the straps to prevent over extending the STOCK shocks.

Huh?

I didn't recommend shortening axle straps. I don't think I ever recommended that to anyone. I DID mention that axle straps are normally not used with parabolic springs because they interfere with the spring's downward articulation.

I have never seen a factory statement as to why LR uses rear check straps but I have a guess. Rear springs are longer than the fronts & the shocks are longer allowing for increased axle travel. Land Rover also uses a prop shaft slip joint that is short. They use the shortest slip joint in the class of slip joints they use (certain type of slip joint that is available in different lengths).

I suspect the primary use of the straps is to keep the slip joint from hitting its stop and over time causing the rear prop shaft to separate. Just a guess. Of course it could be to keep from damaging the upper shock limit and the mounts over time. or all the above. Parabolic spring manufacturers usually recommend a shock with a longer extended limit.

Check straps are frequently added to rock buggys to limit rear axle drop. Usually its a single strap at the pumpkin part of the axle so the ends stay free to articulate.

[greenmeanie]

Huh?

I didn't recommend shortening axle straps. I don't think I ever recommended that to anyone. I DID mention that axle straps are normally not used with parabolic springs because they interfere with the spring's downward articulation.

TeriAnn,
I think it was me who originally suggested shortening the straps. In hind site I would just leave them the OEM length with the OEM shocks. I’m sorry for my error and any confusion it generates.

Rm does recommend the use of straps with their springs. From their web site FAQ:
“Q. Do I need check straps on my rear axle?
A. Yes. Check straps are important with parabolic springs because the springs are more supple than conventional springs and there is a danger of damaging the shock absorbers by extending them too far. For this reason we always supply you with the correct check straps when you buy shock absorbers from us.”

Steve,
There is a lot more to the lower shock pin mounting than spring pack height. These springs are called parabolics because of their curvatures which is very different from the eleptical shape of the conventional springs. It is this, along with the taper leaves that give them their properties. As such, the only real way of determining the eye to eye length is to measure them on the truck.

Finally to make TedW feel better about his set up, again from the RM FAQ:
“Q. Can I use my old shock absorbers with your Parabolic springs?
A. Yes if they are in good condition. It pays to replace the rubber shock bushings and we have a kit for that purpose. Using your old shock absorbers will restrict the downward movement of the axles and for off road use using our EXPLORER PRO COMP or OLD MAN EMU shocks will give better axle articulation as they have a longer stroke.”

I hope this clears some stuff up.

Cheers
Gregor

[yorker]

Rm does recommend the use of straps with their springs. From their web site FAQ:
“Q. Do I need check straps on my rear axle?
A. Yes. Check straps are important with parabolic springs because the springs are more supple than conventional springs and there is a danger of damaging the shock absorbers by extending them too far. For this reason we always supply you with the correct check straps when you buy shock absorbers from us.”

that is odd- they make no mention of using check straps on the parabolics they made for Toyota FJ-40s...

[2rovers]

I am finding this thread very interesting as I am in the process of think about papabolics for my 88. What I am trying to decide is, I run with the soft top for part of the year and with the hard top for part of the year. So do I go with 2 or 3 leves on the rear?
I do some off road, but nothing really serious. We do take trips with it loaded up pretty good, with both hard top and soft top.
Any Thoughts?

[daveb]

3. No question. get shocks recommended by the spring manufacturer and some good tires

I am finding this thread very interesting as I am in the process of think about papabolics for my 88. What I am trying to decide is, I run with the soft top for part of the year and with the hard top for part of the year. So do I go with 2 or 3 leves on the rear?
I do some off road, but nothing really serious. We do take trips with it loaded up pretty good, with both hard top and soft top.
Any Thoughts?

[daveb]

Rocky MTn makes springs for fj40s???

that is odd- they make no mention of using check straps on the parabolics they made for Toyota FJ-40s...

[Alaska Mike]

Shock mounting and shock length is different on an FJ, making it less of an issue.

[TeriAnn]

I am finding this thread very interesting as I am in the process of think about parabolics for my 88. What I am trying to decide is, I run with the soft top for part of the year and with the hard top for part of the year. So do I go with 2 or 3 leaves on the rear?
I do some off road, but nothing really serious. We do take trips with it loaded up pretty good, with both hard top and soft top.
Any Thoughts?

I'm not an expert on parabolics but I suspect 3 leaf rear would be a good choice. You might be over sprung going topless unloaded, but you don't want to be under sprung with hard top and loaded and driving off road. Its hard to limp home with a rear main spring broke. "OK everyone sit on the front left wing and front bumper then hold on tight!"

If you have a favorite brand and want to help out an American retailer:

Woodhead brand springs (India) = Rovers North
British Steel brand springs (UK) = Maybe Atlantic British - ask first
Rocky Mountain brand springs (Canada) = British Pacific
Hytsee brand springs (Spain?) company name used to be T.I. Console = Great Basin Rovers

[chester rides again]

springs

I just ordered my RM springs today, with OME shocks. Dana was great in answering my questions on the phone. They had a Christmas special and he threw in the straps for free!

My wife wasn't impressed that I ordered springs right before Christmas, but it's going to give me a good project over the Holidays.

[friar mike]

Josh

All my old Volvo 122s had check straps. They are there simply to prevent the car from damage cause by the axle dropping lower than the design tolerance. Driveshafts can bend or seperate, springs fall out, brake lines tear, and shocks bottom out. It is just one method for doing this.

I can't imagine needing to make them shorter on a LR.

FWIW I haven't ever had any on my 109.

My 109 has them. thay were broken and when raised on my hoist the driveline hit the cross member without them. I work on old english cars and most of them have them and when hard cornering it limits body roll in the rear it old school now we use sway bars in the rear. ( hard cornering just dosn't seem to be a problem on my 109 )

[yorker]

Rocky MTn makes springs for fj40s???

Yes and no. It kind of depends on RM's mood. Once in a while he'll put a set up on ebay, my brother got a set that way.

Ray Wood claims there is no market for them in the TLC community, yet the TLC crowd seem to trip over one another to get the TI Console ones when they were available?