[terryo]

I am attempting my first street rod a 37 Ford slantback. I have the body off frame and everything has been dipped and is ready to work on. I want to use a Jaguar front crossmember and the Jag IRS(big breaks, smooth ride, great handling and I have em allready) from other projects. What I need to know is how to determine when the frame is at the correct ride height so the stance looks correct when the body is remounted and how to determin the location of the crossmember so that the caster is still adjustable once it is welded to the frame. Is anyone aware of a book, video, or magazine article where the correct way to do this is discussed? I looked at all 65 knowledge threads and couldn't find one that discussed crossmember installation except in a general way. Any help would be greatly appreciated. I am at a standstill and would really like to get started. Thanks, Terry

[Pantaz]

While not specific to hot rodding, there are a number of books on race car suspension and chassis design & engineering. They have formulas and charts for what you need.

Search Google with "race car suspension".

[terryo]

I think what I really need to know is the height of the frame at both ends of the car for a given tire/wheel combination, that results in the cars stance looking good to the eye. I think that 1935 thru 40 cars all share this frame. If anyone out their has a car that they think looks good I would love to know this info. I think this would give me a good starting point. Thanks for any info. Terry

[deuce_454]

there is a couple of things to bear in mind when mounting a jag IRS,
#1 be sure that when the car sits on the tires with the suspension in neutral position the driveshafts ate paralell to the ground, there are a couple of reasons for this

-one is that the shafta dont have U-joints so when the axle is angled it will produce a slight vibration, and as it travels up or down it will become more and more pronounced, and give an iritating rumble.

-secondly when the wheel travels upwards as the body rolls the unequal length of the controll arm and the driveshaft will produle more negative camber in the turn, giving more cornering grip.

# 2, and this is the most important is to rubber mount the carrier to allow some swing (ill explain later)

# 3 if you are runnning more than 300 horsepower (the jag unit is a beefed up dana 44 with corse inputsplines and 9/16 ring gear bolts so it will easily take 700 horses) you have to support the carrier so the pinion wont swing upwards as a result or fte tourque twisting the wheels opposit (this is best accomplished by making a brace from the front part of the inner axles through the lower controll arm

#4 The longitudinal controll arms, that transfer the forward force from the wheels to the chassis should be as long as possible, and as paralell to the ground as achievable. to avoid changing the pinion angle. The lower the attack point of the longitudinal controll arm, the more weight transfer at launch, (since the attack point pushes under the center of gravity, the weight tends to transfer back) . try and place it like you would the instant center of a fourlink.

[terryo]

Thanks deuce_454 for the good advice. My irs is from an xjs and is complete with the factory crossmember which fits very nicely around the frame of the 37 including the use of the stock rubber mounts. All I had to do was thread some 1/2 thick steel and tack it to the frame and the whole unit unbolts in a few minutes. Like you mentioned I will have to build mounts for the longitudinal controll arms which I will try to keep long and low. Final welding has been held up because of not knowing the height of the frame from the ground and what tire size looks good on this style car. I am hoping someone with a 35 thru40 sedan that looks nice will
give me an idea of the specs on their car. Being nearly computer illiterate I erased a private message not knowing what it was. My apologies, this is all new stuff to me. Thanks again. Terry

[deuce_454]

no worries, the message was from me, i just offered to send some plans and pics of some crossmembers to mount the jag unit without the stamped jag oem unit. but if you use the oem mount you should be in the clear...