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Front Super pro poly bump stops

Here’s where to discuss anything specific about your standard(ish) car or something that applies to the model in general.
smoking joe
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Front Super pro poly bump stops

Postby smoking joe » 02 Feb 2018 18:19

Decided to get on with sorting out my front suspend issue, having replaced the PO Rimmers coils
which were coil bound and unpleasant to drive, with second hand standard coils that has less coils, plus cut 20mm off
standard bump stops ( those were new) but I guess being old coils they're rather soft, but would still hit bump stop quite easily
but still an improvement overall.

So now have NOS coils ( clean Unipart labels attached) and with same number of coils as on car at the moment, plus Super Pro bumps stops, I had been thinking that
I might cut these as well, but it looks like the profile does not allow, plus which way around do they go, I cannot recall whether
the standard ones had a top & bottom ?

Reading the Super Pro packaging it mentions crushers tubes and spacers, this must be just a standard note on their packaging, because
I cannot think it would be applicable in this case, the old ones just slid over the damper !

Thought appreciated.

SJ

saabfast
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Re: Front Super pro poly bump stops

Postby saabfast » 02 Feb 2018 19:58

The profile is 4 ridges? Some do cut them down, seen reports of nominally in half. Personally I have standard springs with KYB gas filled dampers and used the poly bump stops as they came and have not had any problems.
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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Hasbeen
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Re: Front Super pro poly bump stops

Postby Hasbeen » 02 Feb 2018 23:24

Cutting down springs is a no/no, something 18 year olds do to old bombs. Cutting them will not only adjust your ride height, but stiffen the spring rate, but do you know how much? A coil spring is just a bent torsion bar, & shortening it obviously stiffens the rate. I could once do the math to know what change would result from cutting the springs, but it gives me a head ache just thinking about it today.

If you want to adjust your ride height, or bring softened springs back up to strength, take the things to a spring maker. They can adjust the free length to adjust your ride height, & retemper the things to give you the original known spring rate at the ride height you prefer.

If you want to reduce body roll, fit stiffer anti roll bars. This is more work, but improves handling & cornering power, without destroying the ride.

If you want to make your handling easily variable, fit adjustable roll bars. Not easy on a 7, but worth the effort for serious competition. In my Formula 1 & 2 days, we could change from a little understeer to a little oversteer in a minute, by moving the adjustable drop link a quarter of an inch in or out on the roll bars.

Hasbeen.

smoking joe
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Re: Front Super pro poly bump stops

Postby smoking joe » 03 Feb 2018 15:22

Hasbeen,

Couldn't agree more, but you misunderstand me, my query was about cutting the bump stops and not coils, the std ones from Rimmer's
are simple profiled lumps of rock hard rubber, with little or no give and solid, with no top or bottom. But the Super Poly bushes are
a different matter, 70mm tall compared to 80mm, so shorter to start with, but has anyone cut these, there is i could guess some inherent
intended give, with the internal conical profile from one end. If that first section is cut off I am guessing some absorption is lost and, to cut
the other end which has a larger internal dia, similar issue. Looks like i am answering my own question as it turns out.

SJ

REPLIC8
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Re: Front Super pro poly bump stops

Postby REPLIC8 » 03 Feb 2018 20:04

I cut the superpro bumpstops down on my TR8. It was fitted with 1 inch lowered dual rate springs and KYB shocks. The standard height springs bottom out on normal length bump stops so I thought it a no brainer to cut them in half. I've also done it on both my TR7's and they no longer crash over bumps as the springs are able to work properly. From memory I lopped off the lower two rings.
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Andy
1981 Triton Green TR7 FHC (low mileage standard Solihull car)
1980 Inca Yellow TR7 FHC (awaiting restoration/upgrading)

Hasbeen
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Re: Front Super pro poly bump stops

Postby Hasbeen » 03 Feb 2018 23:04

Silly old fart!

We discovered here that the bump stops for some of our Holdens fit the strut, but are too long, so we cut them down to about 65% of the standard TR7 item length.

I know of one owner who does quite a few track days with car lowered a fair bit, [sorry don't know how much], has cut them down to 50% of standard height, with no trouble.

Considering that none of the 5 TR7/8s I have owned had any bump stops existing, [they had totally disintegrated on every one], when I bought them, some has to be better than none.

Hasbeen

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Re: Front Super pro poly bump stops

Postby stevie_a » 04 Feb 2018 09:36

I am confused !!

I will be fitting this lot in a month or two, will i need to cut the bump stops ?


Image

This is the springs from Robsport
[ Robsport]

TKC1328 Uprated , pair of new uprated front spring for all model TR7 and TR8 , approx 1/2 inch lower.

These are the springs that everyone says are 200lb rated , they are in fact 155lb (as opposed to 88lb for standard ones)

Image

And these are the bump stops

Superflex Bushes


Image

Shocks are Gaz

Image
If it's not broke don't fix it.

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supercass
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Re: Front Super pro poly bump stops

Postby supercass » 04 Feb 2018 13:40

If you cut them in half can you use one half each side?I've never seen an intact original bump stop but from the description they have minimal or zero compressibility whereas the Superpro does have some. I need to replace mine together with the dampers and one gaiter and have acquired a nos set of front springs. (They have a green stripe) but wonder if the ride height will then be too high at the front. I had contemplated trimming down the Superpro but was unsure if it mattered which side I reduced. Top or bottom? Which is the top? Intuitively I think I could figure that out but does anyone have a photo of one in situ?
supercass

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Re: Front Super pro poly bump stops

Postby saabfast » 04 Feb 2018 17:13

From memory one end has a reduced hole size. There were no instructions so I put that end to the top on the basis that it would grip the damper rod and tend to keep it at the top. The old (original) ones fell out of the ragged gaiters in pieces so were no good as a guide. I would probably cut both down if reducing so that both stayed at the top, but no real reasoning other than I would not have a lot of use for the offcuts.
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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Beans
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Re: Front Super pro poly bump stops

Postby Beans » 04 Feb 2018 18:26

saabfast wrote:From memory one end has a reduced hole size ...

That's correct :wink: If there is a need to cut down these poly bush bump stops ...

Image

... there's something wrong with either your springs (worn or to short) or your dampers (worn or set to soft)!
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

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stevie_a
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Re: Front Super pro poly bump stops

Postby stevie_a » 04 Feb 2018 18:59

Beans wrote: If there is a need to cut down these poly bush bump stops ...

... there's something wrong with either your springs (worn or to short) or your dampers (worn or set to soft)!


So in short Beans i do not want to cut down what i have got ?
If it's not broke don't fix it.

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supercass
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Re: Front Super pro poly bump stops

Postby supercass » 05 Feb 2018 11:14

Am I correct in understanding that you do need to reduce the length of the original rubber bump stops? supercass

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Re: Front Super pro poly bump stops

Postby busheytrader » 05 Feb 2018 17:14

Back in the late 1980's I fitted Triumphtune's front bump stops along with their 200lb sprint springs and spax shocks. The bump stops were very similar to these on Rimmers website. https://rimmerbros.com/Item--i-UKC6729PB Conical in shape, made of a hard poly and about half the length of the crumbling originals.

The springs have sagged over the years and the bump stops are now working harder than ever. (The roads inside my part of the M25 are shocking as well) I'm looking at the same set of mildly lowered 155lb front springs for mine. No doubt I'll be changing the tca ball joint boots at the same time, they never last long

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Re: Front Super pro poly bump stops

Postby Beans » 06 Feb 2018 22:23

stevie_a wrote: ...So in short Beans i do not want to cut down what i have got ?

Looking at the springs that indeed is what I wouldn't do :wink:
They look rather similar to the ones that were fitted to my '76 FHC (and they will be refitted) ...

Image

And they'll probably give a more or less original stance to the car. No need to shorten the bump stops there ...

Image

And if in doubt, my circa 1" lowered DHC also is fitted with the "stock" polybush bump stops. And so far no problems there ...

Image

Both cars are fitted with Koni dampers.

supercass wrote:Am I correct in understanding that you do need to reduce the length of the original rubber bump stops? supercass

Use the Poly bush bump stops. The original ones are to long, actually almost twice as long as the poly bush items!
And the original bump stops are pretty poor quality ...
Image
1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

http://www.tr7beans.blogspot.com/

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Re: Front Super pro poly bump stops

Postby supercass » 07 Feb 2018 14:12

Smoking Joe suggests that there is just a 10 mm difference (80 mm as against 70 mm) between the Poly bush and originals?.
supercass

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