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Fitting an anti dive kit

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jclay (RIP 2018)
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Postby jclay (RIP 2018) » 27 May 2009 20:49

Two things:

1. Don't cut the bushings as they are designed to hold the bar in place. Cutting them would weaken them and eventually wear away at the cut allowing the bar to give.

2. The two lead bolts are now the lowest thing on the front of your car! I have hit them on the Parking Stops in parking lots, I don't know how many times. I hit them so hard one time that it messed up the geometry of the front end.

Respect your spoiler and the anti-dive bolts.

jclay

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FI Spyder
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Postby FI Spyder » 27 May 2009 23:09

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jclay</i>


2. The two lead bolts are now the lowest thing on the front of your car! I have hit them on the Parking Stops in parking lots, I don't know how many times. I hit them so hard one time that it messed up the geometry of the front end.

<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

The main reason I won't put it on. Plus my car doesn't dive and it turns in just fine. Don't see any reason to put it on, mind you I haven't driven a TR7 with it on yet.


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bmcecosse
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Postby bmcecosse » 28 May 2009 13:44

Copy away Stevie - and I've had no problems bashing the bolts!

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Postby Odd » 28 May 2009 15:31

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by bmcecosse</i>
... and I've had no problems bashing the bolts! <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote"> Neither have I.
/Odd

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busheytrader
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Postby busheytrader » 28 May 2009 16:36

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">The main reason I won't put it on. Plus my car doesn't dive and it turns in just fine. Don't see any reason to put it on, mind you I haven't driven a TR7 with it on yet.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

It all depends on how you drive and if other parts on the car are uprated I suppose.

I have uprated brakes. Under heavy braking without the anti-dive kit the car practically stands on its nose as it dives down. Lowering the antiroll bar lessens the effect giving better control under braking. Standard brakes won't generate as much retardation so there's probably less benefit in fitting the kit.

I have a warmed over V8 fitted. Potentially my speeds approaching braking points and turning points are a lot higher than a standard car. The polybushes, particularly those at the antiroll bar ends are less compliant allowing a much better turn in.

My lowered suspension means I have to drive carefully over all the speed bumps that plague Northwest London. Front spoiler, front subframe and exhaust all come under attack. However, the lowest point of my car is the front mount for the TR8 radiator. One MOT station had to reverse the car onto their ramps to prevent damaging it. The radiator is too expensive to wreck so I'm just careful of anything that might damage it.

Try out a 7 with antidive and polybushes on the ARB, you might like it!

Adam



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FI Spyder
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Postby FI Spyder » 29 May 2009 01:22

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by busheytrader</i>
[br

It all depends on how you drive and if other parts on the car are uprated I suppose.

Try out a 7 with antidive and polybushes on the ARB, you might like it!

<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

I have poly on everything on the front end and 34 lbs. in the tires so handling is precise. It's true I don't use the brakes heavily (helps prevent rear enders) but I didn't notice it diving on an emergency stop that was hard enough to lock the back brakes.


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Hasbeen
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Postby Hasbeen » 29 May 2009 02:47

I have one with, & one without. The 8, with it's much uprated
suspension, including heavy duty anti roll bars, has a kit, & the 7,
with pretty much stock, [polly bushes] without.

Admitted the 8 also has big brakes, but when all the brakes are
cool, I can detect no difference in the stopping, or the diving with
either car, other than that caused by the quality of the tyres.

I drive both cars in the same way, it could find me fined, & without
a licence, but not likely to get me locked up, & this does not find
any problem with the 7s brakes, stock, in good condition, with green
stuff pads.

On the one occasion, when a bloke in a rice burner hot rod annoyed
me enough to get me to show him how to drive down a 2.5Km steep, &
twisty hill, in the 7, my stock, with green stuff pads, brakes were
smoking gently at the bottom, but the thing was still stopping.

I will accept that competition would find the limit of the 7s
brakes, quite quickly, but even comming close to legal driving
prevents me reaching that point on OUR roads. If you have roads
which can legally stretch the braking capacity of a 7, please advise
me where. I'll come over to have some fun.

Looking at the geometry, I can see absolutely no reason why one of
these kits should reduce the diving under brakes.

The only think I can see is that it will put some preload on the
control arm bushes. With urethane bushes, creep would soon release
this, & things will be back to normal. The effect on dive, & turn in,
probably lasts a few weeks, long enough to notice, & also long
enough to get used to, & no longer notice.

Hasbeem

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Postby Workshop Help » 29 May 2009 03:42

I do like this whole idea of a simple, easy to install, and what should be an inexpensive kit. But, some questions have been raised and each of us has particular environments we traverse that raise issues.

Our 1976 TR7 is used as a daily business car that regularly encounters speed bumps, twisty hilly roads, urban, rural, and expressway driving. I have come to appreciate the nose dive when a sharp prod is applied to the brakes because the tailgating moron behind me wakes up abruptly when the back end of our car rears up in front of him for a brief second. The nose dive/rear end rise has become a safety device.

The increasing use of speed bumps is of no concern. This stock suspension with all the poly bushes sails over the bumps with no discomfort with no slowing down. The ride height is fine where it is and a lower height would create unwanted clearance issues.

I would be more inclined to experiment with a strut brace if one will fit using the stock air cleaner box.

Mildred Hargis

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Postby Beans » 29 May 2009 08:35

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jclay</i>

...Don't cut the bushings as they are designed to hold the bar in place. ...<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
The poly bushes I have on my cars came with a cut to enable fitting them [:I]

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Marko
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Postby Marko » 29 May 2009 10:02

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hasbeen</i>

Looking at the geometry, I can see absolutely no reason why one of
these kits should reduce the diving under brakes.


<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

you all know what front suspension looks like , standard mcpherson suspension , we have a strut and a lower arm. the lower arm is composed of 2 parts , anti-roll bar and a control arm. on a stock tr the plane that the lower arm(antiroll bar & controll arm) defines is parallel to the ground. braking force transmited to the body goes along that plane , and since it is parallel to the ground the distance from the center of gravity to the plane in which the braking force acts is large.

in the picture :
Red dot - center of mass
Green rectangles - standard suspension points
orange line - plane that standard suspension forms
Red letter A - length at which the braking force acts to make the car dive. ( the longer that distance, car dives more , shorter the distance car, dives less, no distance , car doesnt dive at all)


Image

why do all cars dive under braking ,or squat under acceleration, because the forces( and their reactions) act below the center of mass.

so that anti dive kit does the following , moving the suspension points we tilt the plane in which the braking forces act. shortening the distance between center of mass and that plane.

on the picture
Blue rectangles - modified suspension geometry
Red line - the plane in which the braking forces act
Red letter- length at which the braking force acts to make the car dive.

so by moving the suspension point we shorten the leverage of the forces that roll the car over the front suspension. on the same force less leverage means less moment .

ive exaggerated the drawing so the real anti dive gains are much lower ( maybe 5-10%)

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Postby Underdog » 29 May 2009 13:02

Good explanation Marko. Suspension geometry is an interesting subject. I recently did some research on the rear. As a result of this I modified the lower rear axle pivot point by lowering it 1 1/4" Took out the rear squat I was experianceing. I also don't notice the extreme pitch forward under braking. My feeling is the same upset geometry in the rear that causes squat on acceleration would cause the rear to hump up on braking. With the pivot lowered, the braking forces transfer to the body with a downward force. Perhaps why mine doesn't feel like its standing on it's nose.

Hasbeen, One track day and a I toasted the Rimmer brakes and Green pads on mine. One rotor cracked in 3 places and chunks missing out of the pads. They also faded to the floor on the last session.

I have attributed the failure to reinstalling the stock dust shields. Upon examination, I came to realize they all but block off the air flow to the inside of the ventillated rotor. This is most likely due to the additional width of the rotor compared to stock.

I have fitted a set of slotted rotors with Red pads and removed the shields. I also took the frt air dam off, relocated the horns and did some minor surgery to the lower wheel well in an effort to get more air flow.

I've had the MGB to this same track with stock brakes and Green pads with no problem. Big difference slowing down from 110 though! Plus with the V8's acceleration, braking becomes needed in spots where the little 4 cyl could just drive through. So horse power does seem to make a difference in the need for better brakes when pushed to the limit.

Now if I can get this pinched nerve in my neck sorted, I can go try again.[}:)]

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