[Fot] FW: FW: TR4A front suspension.

Sun Mar 15 09:31:46 MDT 2015

Macel, I had a similar problem when I modified my TR4A suspension. I had fitted the TR6 lower inner 2 stud frame mounts and the back up plates for additional strength over the single stud original TR4A inner mounts. I needed to loosen the lower mounts to the frame to allow the upright to easily attach to the upper ball joint. Once I did that everything went together as it should and I then tightened the the lower mounts to the frame. There was enough movement in the frame holes which allowed the lower A- Arms to move and make the upright out of position. Get all of the parts together before you final tighten the lower inner frame mounts. 

Of course having the trunnion properly sided is important too.

JVV

From: Marcel Van Mulders via Fot 
Sent: Sunday, March 15, 2015 10:33 AM
To: fot at autox.team.net 
Subject: [Fot] FW: FW: TR4A front suspension.

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Van: Marcel Van Mulders [mailto:van.mulders.marcel at telenet.be] 
Verzonden: zondag 15 maart 2015 15:28
Aan: 'davehogye'
Onderwerp: RE: [Fot] FW: TR4A front suspension.

Quoting Dave : "... of course the trunnions are sided...". Unbelievable, but the left lower trunnion is mounted on the right side of the car and vice versa. I have worked on the front suspension during 5 evenings till 01.00 am and still didn't see it, although these trunnions are marked RH and LH. I noticed it this morning when starting to fit adjustable upper inner fulcrum pins. When correctly fitting the lower outer trunnion bolt, only the part of the upright that is screwed in the trunnion is allowing a little movement , the upper ball joint could not be forced between the upper (original)wishbones. This is the case on both sides of the car and the upper ball joint is 1cm more to the front than the lower trunnion when the car is level(= a little negative caster). I'll report on this forum when I've swapped the trunnions and uprights next week.
Of course I don't want to blame anyone. Everyone does make mistakes and this TR4A of Bob Kramer is a very good car with many great features. I'm very pleased with it and I expect to run in the front.
Marcel.

van: davehogye [mailto:dlhogye at comcast.net] 
Verzonden: dinsdag 10 maart 2015 20:07
Aan: Marcel Van Mulders
Onderwerp: Re: [Fot] FW: TR4A front suspension.

RevingtonTR has adjustable upper, inner fulcrum pins, which allow camber adjustment, but also allow the upright to find a happy place without force.  I would think that if everything is within factory specs, the upright should align as long as you have the 3 degree trunnion.  Of course the 3 degree trunnions are sided.

The adjustable fulcrum pin is probably not allowed by your rule book.  I use them on my TR3 to get negative camber without modifying/shortening the upper arms.  These adjustable pins can be flipped depending on the ride height.  They also come with spacers that fit between the ball joint and the A-arms for further caster adjustment.

Dave H.

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From: "Marcel Van Mulders via Fot" <fot at autox.team.net>
To: fot at autox.team.net
Sent: Tuesday, March 10, 2015 11:13:06 AM
Subject: [Fot] FW:  TR4A front suspension.

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Van: Marcel Van Mulders [mailto:van.mulders.marcel at telenet.be] 
Verzonden: dinsdag 10 maart 2015 19:04
Aan: 'Jack Wheeler'
Onderwerp: RE: [Fot] TR4A front suspension.

All the parts are TR-4A-TR6, so the trunnions are 3° (all TR trunnions that have removable trunnion bolts are handed, trunnions with pressed in pins can be 0° or 3°).
"...the lower trunnion should rotate around the bolt..." If I understand what you mean, I don't believe this is correct : the trunnion bolt is clamping the distance pieces (short pieces of steel tube that slide over the bolt and rotate in the outer wishbone bushings) onto the trunnion and hence the bolt, trunnion and distance pieces should rotate together and only the wishbones can rotate in respect to the bolt (and trunnion and distance pieces). I have assembled the suspension in this way, eliminating thus the play of the trunnion on the bolt and this is the reason I had to drill new holes , more to the rear, in order to get the upperr end of the uprights between the outer ends of the upper wishbones. All parts and also the chassis seem to be all right. Maybe I get it wrong anyway with the assembling of the suspension parts
Marcel.

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Van: Jack Wheeler [mailto:jwheeler1947 at yahoo.com] 
Verzonden: zondag 8 maart 2015 23:40
Aan: Van Mulders Marcel
Onderwerp: Re: [Fot] TR4A front suspension.

Do you have the TR-4A uprights and trunions?  The TR-4A trunion is just the brass piece that fits in between the lower wishbone arms and a bolt slides through it, instead of the fulcrum pin (pressed into the trunion), as you would have had on your TR-3.  The lower trunion should rotate on the bolt, and the wishbone arm bushings.  There is a left and right hand, and when properly installed, you should have about 3 degrees of positive castor on both sides.  I raced a TR-4A for 25 years, so I know the suspension intimately!  Good luck.

Jack

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From: Van Mulders Marcel via Fot <fot at autox.team.net>
To: fot at autox.team.net 
Sent: Sunday, March 8, 2015 5:35 PM
Subject: [Fot] TR4A front suspension.

In June 2014 I bought Bob Kramer's TR4A racecar after I crashed my TR3 at the Zandvoort circuit (The Netherlands). It's a great car and it will get better. Of my TR3, I only kept the engine and overdrive dogbox  Overhauling the front suspension, I found that the lower trunnion was moving on the bolt instead of the bushed lower wishbones : the distance pieces in the wishbones where shorter than original, so the trunnion was not clamped by these distance pieces when fastening the bolt. Correcting this, the upright has less play now, only a little in the trunnion, and this upright with balljoint can't be forced anymore between the outer ends of the upper wihbones, the balljoint is 1/2" too far to the rear. Turning the upper wishbones to the rear (by moving the fulcrum pin) isn't a good option, because binding will occur. I've drilled new holes for the brackets for the inner ends of the lower wishbones : the suspension is moving without any binding now but I don't know if I will leave it like that. I wonder if something is wrong with the uprights? (less than 3° caster?) If I measure the caster, I find 2.2° on both sides, but probably that isn't proving anything. The chassis is as new, no damage. Any idea's someone?
Another question : trying to get at zero bump steer, the best I get at by moving the steering rack is a J : the wheels are toeing in when lowered more than 3 cm below ride height (minimal to 5cm, then more and more toe in). Bending the steering arms to the outside, almost touching the brake disks now, has straightened the J a little.  Is it possible to eliminate the bump steer completely, or have we(TR4A-TR6) to accept some bump steer in the least important part of the suspension travel?
Marcel.

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