Four parallel link rear suspension questions

tipo158 · Postby **tipo158** » 19 Jul 2010 01:20

For my TR7 stage rally car project, I am changing to the 4 parallel link rear axle set-up.

1. What is the length of the upper links (that replace the diagonal links in the stock set-up)?

2. What is the precise location where those upper links attach to the rear bulkhead? I know how it should all go together, but I don't have good measurements for where the pick-up points are.

3. How long is the Panhard rod on the works cars?

4. How far out do the Panhard rod pick-up points extend from the axle and the chassis?

Thanks,

alan

V8Wedgehead · Postby **V8Wedgehead** » 19 Jul 2010 01:58

I would message Chris Turner since he has TUD682T works rally car. Other wise I think from pictures of the set ups you can make it work. I would also assume that ever body shell made by safety devices/BL Motorsports were not exactly the same so one cars dimensions will be different from the next. I plan on laying my suspension out from pictures and then making the links to fit once things are in place. If you do find out the measurements let me know!

Michael
1980 TR8 FHC #0020 Rally Conversion

PeterTR7V8 · Postby **PeterTR7V8** » 19 Jul 2010 03:59

This may give you a visual reference...

http://rides.webshots.com/photo/2261365 ... 0108qenQwL

but I'd rather do a Watts link using SD1 bits.

http://www.ss-preparations.co.uk/images ... 1%20(Small).jpg

The map: http://tinyurl.com/wedgemap . The blog: http://www.forum.triumphtr7.com/topic.asp?TOPIC_ID=8548

tipo158 · Postby **tipo158** » 19 Jul 2010 04:42

Thanks, guys. I have shown that rear axle shot to a lot of people while looking for parts.

Is it known which car that is?

When I was showing that shot around last week we decided that it was a Jaguar Mk2 axle. A guy had one in his shop and the backing plate-to-backing plate distance was very close to the same as the TR7 4-speed rear axle.

One of the things that I can't tell from that shot is how far back the Panhard extension off of the axle is. The lengths of some of the other things might look different from what they really because of the perspective. I was looking at John Clancy's DVD and there is a shot of the rear suspension that shows the link, so I am a little closer.

BTW, since I am trying to recreate something approximating the works cars, I am going with the Panhard rod, instead of the Watts link.

I finally got around to pulling the rear suspension apart today.

alan

tipo158 · Postby **tipo158** » 19 Jul 2010 05:19

Two additional points:

1. Some portion of the set-up was standardized. According to the C&CC article, BL Motorsport sold Panhard rod kits.

2. I found my copy of the homologation papers for the 4-cylinder TR7 (3071) and found pictures of the parts (the upper link and the modified lower link), but not any measurements yet.

Marsu · Postby **Marsu** » 19 Jul 2010 08:01

It would be excellent if you could post a copy of the homologation papers here.

Marko · Postby **Marko** » 19 Jul 2010 11:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tipo158
For my TR7 stage rally car project, I am changing to the 4 parallel link rear axle set-up.

1. What is the length of the upper links (that replace the diagonal links in the stock set-up)?
<hr height="1" noshade id="quote"></blockquote id="quote">

why? what are the problems with current suspension that cant be solved?

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tipo158
2. What is the precise location where those upper links attach to the rear bulkhead? I know how it should all go together, but I don't have good measurements for where the pick-up points are.
<hr height="1" noshade id="quote"></blockquote id="quote">

You can measure the lengths of the suspension arms on the current setup, measure the chassis points from cars centerline , same with the rear axle. When you draw it on a piece of paper or some CAD software ( if available) you can see what happens when the suspension goes trough its travel.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tipo158
3. How long is the Panhard rod on the works cars?
<hr height="1" noshade id="quote"></blockquote id="quote">

the longer the better and more horizontal the better. Panhard rod is made to limit the transverse movement of the rear suspension. You are using rotational movement of a rod to limit lateral movement of the rear axle. Paradox in itself rotation of Panhard rod causes lateral movement of the rear axle . Because we cant have "pure translation" caused by "pure rotation". The longer the suspension travel ( like in a rally car [;)] ) the worse lateral movement.

I don't see why would you want to do major surgery on the cars rear suspension. All of the suspension compliance problems can be solved with solid bushings. Cheaper than hacking off half the car.

Gravel or tarmac rally?

mak · Postby **mak** » 19 Jul 2010 12:47

I've got some articles on the last of the leyland rally cars to be developed - Will have to dig them out but from memory I think they went back to a relatively normal arrangement (not the 4 parrallel links) but I can't remember if they had a watts linkage or a panhard rod...

tr8 · Postby **tr8** » 19 Jul 2010 14:11

On my race car I have a 4 bar parallel rear suspension with coil overs, a panhard rod and and adjustable rear sway bar. The guy who built it was a BL dealer at the time about 1980. He told me that he has the BL drawings for the rear suspension set up. I have asked him for a copy. All the suspension is heim jointed. The bottom swing arms are solid aluminum and according to him were a BL special tuning part.

tr8 · Postby **tr8** » 19 Jul 2010 14:59

I was also told by the person who ran the Canadian BL Rally program (they had factory built rally cars when they first started)that the rally cars that were built at the end of the rally program were switched into road race cars as there was very little difference in the build details.

V8Wedgehead · Postby **V8Wedgehead** » 19 Jul 2010 15:17

Here are a bunch of pictures of the interior and underside of the upper link and panard bar connections. The rear axle is a Slaisbury 4HA also in the US a Dana 44.

Some of the pictures are from a thread on Here "Dogs Testies" of conversio EAT400.

Michael
1980 TR8 FHC #0020 Rally Conversion

tipo158 · Postby **tipo158** » 19 Jul 2010 15:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Marko
why? what are the problems with current suspension that cant be solved?

I don't see why would you want to do major surgery on the cars rear suspension. All of the suspension compliance problems can be solved with solid bushings. Cheaper than hacking off half the car.
<hr height="1" noshade id="quote"></blockquote id="quote">

Because I am recreating a works car. That is the point of the exercise.

If I was going to build a REALLY competitive rally car, I would probably base it on something else.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">
Gravel or tarmac rally?
<hr height="1" noshade id="quote"></blockquote id="quote">

Gravel. There are almost no tarmac rallies in the region where I live.

alan

tipo158 · Postby **tipo158** » 19 Jul 2010 15:54

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Marsu

It would be excellent if you could post a copy of the homologation papers here.
<hr height="1" noshade id="quote"></blockquote id="quote">

I'll try. I just have the 4-cylinder papers, not the V8 papers. And some of the photos already look pretty bad ("copy of a copy" problems).

alan

tr8 · Postby **tr8** » 19 Jul 2010 15:58

Michael

Is the Smeet's car or the rally car in the pictures above an original set up or an improved version of what the factory built. Looks like a lot of new work,it looks terrific, but not original, just MHO.

V8Wedgehead · Postby **V8Wedgehead** » 19 Jul 2010 16:23

The first two black interior shots are of Bert Smeets original car, OOM514R and the bottom one with all the fabrication marks and final paint is EAT400.

Michael
1980 TR8 FHC #0020 Rally Conversion

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Four parallel link rear suspension questions

Four parallel link rear suspension questions

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